Mariana P. Mazzuchini, Fernando Paixão Lisboa, Jessica I. de Castro, Marco A. Alvarenga, Lorenzo G. T. M. Segabinazzi, Igor F. Canisso

Article Summary

Endometritis is the leading cause of subfertility in horses, and it is a clinical problem where historically antibiotics have not always been used with prudent justification. Because of this, alternative therapies to treat endometritis are necessary for the rational use of antibiotics but there is a relative lack of knowledge regarding their mechanism of action. The aim of this in vitro experimental study was to assess the in vitro antimicrobial activity of non-traditional (hydrogen peroxide, lactated Ringer's, ozonated lactated Ringer's, iodine, dimethylsulfoxide, platelet-rich plasma and platelet-poor plasma) therapies commonly used in clinical practice against microorganisms causing infectious endometritis in mares. 

A microdilution technique was performed to determine the minimum inhibitory concentrations (MIC) of 50%, 90% and 100% of microorganisms and the percentage of inhibition of each therapy against each microorganism (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus and Candida sp.). The MIC 50% and 90% were determined using non-linear regression, while MIC 100% was assessed using the resazurin dye technique. The serial PI was evaluated for each therapy using a spectrophotometer.

All the therapies demonstrated a percentage of inhibition higher than positive controls for all microorganisms (p < 0.05); however, the only therapies that presented MIC 100 values were hydrogen peroxide and platelet-rich plasma and platelet-poor plasma.

Bottom line: Hydrogen peroxide and platelet-rich and -poor plasma might be alternatives to traditional therapies for endometritis to support a reduction in antibiotic use.
 

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Kathleen M. Ivester, Ji-Qin Ni, Laurent L. Couetil, Thomas M. Peters, Marcus Tatum, Lynn Willems, Jae Hong Park

Article Summary

Affordable particulate matter (PM) monitors suitable for use on horses will facilitate the evaluation of PM mitigation methods and improve the management of equine asthma. The aim of this cross-over feed trial was to calibrate a real-time wearable PM monitor (Black Beauty [BB]) and compare the PM exposures of horses fed dry or soaked hay.

Side-by-side sampling with BB monitors and tapered element oscillating microbalances (TEOMs) was performed under varying concentrations of PM from alfalfa hay. Linear regression was used to derive a calibration formula for each unit based on TEOM PM measurements. Precision was evaluated by calculating the coefficient of variation and pairwise correlation coefficients between three BB monitors. PM exposure was measured at the breathing zone of 10 horses for 8 h after they were fed dry or soaked hay. Repeated measures generalised linear models were constructed to determine the effect of hay treatment and measurement duration (initial 20-min vs. 8-h) upon exposure to PM with diameters smaller than or equal to 10 μm (PM10) and 2.5 μm (PM2.5).

BB monitor PM2.5 and PM10 measurements were linearly correlated with TEOM data (coefficient of determination r2 > 0.85 and r2 > 0.90 respectively), but underestimated PM2.5 mass concentrations by a factor of 4 and PM10 concentrations by a factor of 44. Measures from the three BB monitors had a coefficient of variation <15% and pairwise r > 0.98. Feeding soaked hay significantly reduced average PM2.5 exposures (20-min: dry: 160 μg/m3, soaked: 53 μg/m3, p < 0.0001; 8-h: dry: 76 μg/m3, soaked: 31 μg/m3, p = 0.0008) and PM10 exposures (20-min: dry: 2829 μg/m3, soaked: 970 μg/m3, p < 0.0001; 8-h: dry: 1581 μg/m3, soaked: 488 μg/m3, p = 0.008).

Bottom line: With appropriate corrections, the BB monitor can be used to estimate horse PM exposure. While 20-min measurements yielded higher estimates of exposure than 8-h measurements, both intervals demonstrate that soaking hay reduces PM exposures by more than 50%.
 

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Roxane Kirton, Imogen Sandford, Eleanor Raffan, Sarah Hallsworth, Oliver H. P. Burman, Ruth Morgan

Article Summary

Equine obesity is a growing concern. Much of the current management advice centres on dietary restrictions, including the removal or limitation of grazing. Little is known about the impact of these approaches on the welfare of the horse. The aim of this study was to investigate the effect of two commonly used grazing systems advocated for the control of weight—the ‘strip-grazing’ and the ‘track’ systems—on the behaviour and welfare of outdoor-living ponies using four groups of pasture-kept ponies experiencing each system for 4 weeks in a random order.

Time budgets and behavioural indicators of welfare were measured using 24-h electronic surveillance, morphometric parameters including weight, body condition score and cresty neck score were measured weekly and activity levels were tracked. The effect of grazing system on movement and behaviour was tested using a general linear model.

Ponies moved more [median (IQR) % time spent moving, track: 3.23% (2.08%), strip: 2.02% (0.90%); p = 0.001] and travelled a greater distance [median (IQR) metres/24 h, track: 7013.47 m (1761.49 m), strip: 5331.91 m (494.16 m); p < 0.001] and engaged in less overt agonistic behaviour on the track system compared with the strip system [median (IQR) prevalence per hour; track: 0.14 (0.30), strip: 0.21 (0.37) p = 0.02].

Bottom line: Ponies on strip systems moved less and exhibited increased agonistic interactions compared with the track system. Thus, there may be physical as well as psychological health benefits to the track system.

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Erica T. Jacquay, Patricia A. Harris, Amanda A. Adams

Article Summary

It is unknown whether short-term transportation affects endocrine responses similarly in horses with and without insulin dysregulation (ID). The aim of this longitudinal cohort study was to characterise the effect of short-term transportation on stress parameters and insulin responses to an oral sugar test (OST) in horses with and without ID.

Fourteen adult non-pregnant, non-PPID mares of mixed light breeds were categorised as either ID (n = 7) or non-ID (n = 7) based on endocrine testing. Over 2 weeks, horses were transported once, in groups of 3–4 in a horse trailer on a round-trip journey of ~1.5 h. Blood and saliva were collected 24 h and 1 h pre-transportation, directly after unloading and 15 min, 1 h, 3 h plus 24 h post-transportation. An OST was performed 24 h pre-transportation and 3 h post-transportation with a pre- (T0) and post-OST sample collected 60 min later (T60). Heart rates and rectal temperatures were also collected throughout the study. Serum insulin, serum cortisol, and plasma glucose were measured using validated assays. Repeated measures ANOVA were used to determine differences after transportation and between ID and non-ID horses. 

Mean insulin was higher in ID horses versus non-ID horses (mean = 109.9 μU/mL vs. 30.2 μU/mL, p < 0.001; 95% CI for mean difference = [55.6–107.7 μU/mL]). Mean serum insulin increased following OST at T60 in ID horses pre- (154.6 μU/mL, p = 0.04; 95% CI = [86.3–223.0 μU/mL]) and post-transportation (284.6 μU/mL, p = 0.03; 95% CI = [114.3–454.8 μU/mL]). Non-ID horses had a mean OST T60 insulin post-transportation of 56.6 μU/mL (95% CI = [29.1–84.1 μU/mL]); above recognised threshold [45 μU/mL] for ID diagnosis.

Bottom line: Performing an OST 3 h following short-term transportation may result in inaccurate ID status.
 

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Antoine Symoens, Roxane Westerfeld, Berta Mozo Vives, Valentine André, Laurine Moulon, Marine Collomb, Hélène Richard, Tristan Juette, Christian Bédard, Mathilde Leclère

Article Summary

Steaming hay significantly reduces respirable particles and provides a palatable alternative to dry hay for horses with asthma, but there are few prospective studies demonstrating the clinical efficacy of steamed hay. The aim of this controlled crossover study was to compare the efficacy of alfalfa pellets and steamed hay in improving lung function and inflammation of horses with severe asthma (SEA).

Ten horses with SEA were enrolled and nine completed the study. Horses were housed indoors and fed hay. Once in exacerbation, they were fed pellets and steamed hay for 4 weeks, in a crossover design. Weighted clinical scores and lung function were recorded weekly. Bronchoalveolar lavage fluid (BALF) cytology and mucus scores were recorded before and after each diet.

Based on linear mixed model (LMM) analysis, weighted clinical scores significantly improved over time (p < 0.001, no diet effect or time-diet interactions). With pellets, weighted clinical scores decreased from (median (interquartile range)) 13 (5.5) to 2 (1.5), while with steamed hay, they decreased from 10 (9.5) to 6 (8.5). With pellets, lung resistance decreased significantly from a baseline of (mean (SD)) 2.62 (0.77) cmH2O/L/s to 1.17 (0.66), 0.79 (0.54), 0.70 (0.20), 0.62 (0.18) on Weeks 1–4, respectively (LMM with post hoc tests, p < 0.001). With steamed hay, the resistance decreased significantly from a baseline of 2.34 (0.93) cmH2O/L/s to 1.38 (0.49) and 1.51 (0.66) on Weeks 1 and 2, respectively (p < 0.03). Neutrophils BALF decreased significantly with both diets (pellets: 40.2 (24.4) to 20.1 (11.0) %; steamed hay 30.9 (20.2) to 25.7 (17.6) %; LMM, p = 0.006).

Bottom line: Clinical scores, lung function and BALF inflammation of horses with SEA improved with steamed hay and pellets, but the effect on lung function was more pronounced with pellets.

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Juliette F. Preston, Minna P. Mustikka, Simon L. Priestnall, Bettina Dunkel, Maria-Christine Fischer

Article Summary

Immune mediated keratitis (IMMK) is typically described as chronic, non-ulcerative corneal opacity with minimal discomfort in the absence of intraocular inflammation. North America-based publications describe minimal blepharospasm, rare corneal ulceration and no uveitis. In the UK, the epithelial and anterior stromal forms have been inconsistently associated with slight blepharospasm. Corneal ulceration is rarely described in either geographic location, but is reported occasionally in the mid-stromal and endothelial forms in both countries associated with ruptured corneal bullae, which in turn can cause discomfort.  To the authors' knowledge, uveitis has not been described as a clinical feature of IMMK. There is limited literature regarding equine IMMK in Europe. The aim of this retrospective case series was to assess the prevalence of blepharospasm, corneal ulceration and uveitis and their impact on outcome in horses diagnosed with IMMK in Europe (UK and Finland).

Clinical records of 94 horses with IMMK were evaluated. The UK and Finland populations were comparable; therefore, descriptive statistics were performed on combined data on subtypes of IMMK and clinical features. Odds ratios (OR) and confidence intervals (CI) were calculated for impact of blepharospasm, ulceration or presence of uveitis on the outcome of enucleation and treatment duration.

IMMK subtype was classified as 10/94 (10.6%) epithelial, 50/94 (53.2%) anterior stromal, 14/94 (14.9%) mid-stromal, 4/94 (4.25%) endothelial and 16/94 (17.0%) unrecorded. After excluding three horses with incidental corneal ulceration, blepharospasm was documented in 34/91 (37.4%), corneal ulceration in 26/91 (28.6%), and signs of uveitis in 23/91 (25.3%) horses. Increased odds of enucleation were significantly associated with the presence of blepharospasm (OR 5.5, 95% CI 1.6–19.4, p = 0.008) and signs of uveitis (OR 8.9, 95% CI 2.6–30.8, p < 0.001), but not corneal ulceration. The presence of blepharospasm, corneal ulceration or uveitis did not significantly alter the odds of ongoing medication.

Bottom line: The clinical features of IMMK were similar between two European countries but differed to USA descriptions. Blepharospasm, corneal ulceration and signs of uveitis can occur with IMMK; presence of blepharospasm and uveitis increase the odds of enucleation.

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Amie Kapusniak, Laura Nath, Michelle Hebart, Samantha Franklin

Article Summary

Prioritising equine welfare, making evidenced-based policy, and consistent decision-making across sports are crucial to maintaining the social licence for equestrian sport. Regulations on the use of omeprazole during competition differ; all regulators argue that their rules prioritise welfare. This discrepancy is a matter of concern to the public and equestrian stakeholders. The aim of this desk-based ethico-legal study was to apply Campbell's Ethical Framework for the use of Horses in Sport to the question: ‘Should the use of omeprazole be allowed during equestrian competition?’

Campbell's Ethical Framework for the Use of Horses in Sport was applied in a stepwise fashion: definition of the ethical question; analysis of the evidence base; consideration of stakeholders' interests; harm:benefit analysis; application of the three central tenets of the framework, and formulation of conclusions and recommendations.

Stakeholders in equine sports have a variety of (frequently conflicting) interests; all of them share an interest in optimising equine welfare. The incidence of equine gastric ulcer syndrome (EGUS) in competition horses is high. Omeprazole is a cornerstone treatment. There are currently discrepancies in regulation about the use of omeprazole during competitions. Recent evidence suggests that withholding omeprazole treatment for two clear days before competition allows the recurrence of squamous EGUS, whereas withholding treatment on the day of competition only does not have that effect.

Bottom line: Based on recent scientific evidence, if horses are being treated with omeprazole outside of competition, then treatment on the day of competition should be permitted on welfare grounds. Revision of regulations around the use of omeprazole during competition by governing bodies is necessary to safeguard the ethical use of horses in sport.

Why I chose this article

Inconsistencies exist across regulators regarding the use of omeprazole in competition horses. 

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Amie Kapusniak, Laura Nath, Michelle Hebart, Samantha Franklin

Article Summary

Sudden cardiac death is an important cause of exercise-associated fatalities in Thoroughbred racehorses. Equine deaths share similarities with fatalities in human athletes that result from inherited cardiac disease. Whilst genetic causes have been postulated in horses, these have not been confirmed and heritability of sudden cardiac death has not previously been estimated in Thoroughbred racehorses. The aim of this retrospective case–control study was to determine the heritability of sudden cardiac death in a sample population of Thoroughbred racehorses.
Steward and post-mortem reports of Thoroughbred racehorses in Australia between 2007 and 2020 were reviewed to identify horses with sudden cardiac death. Control horses were randomly selected from races in which sudden cardiac death occurred or from races on the date of the case fatality. A five-generation integrated pedigree chart was collected for each horse. Estimates of heritability were obtained using an animal model in the ASReml-R program with variance components estimated assuming sudden cardiac death was normally distributed, and on the logit transformed scale. Inbreeding coefficients were calculated and the risk of producing sudden cardiac death-affected progeny was calculated for stallions that sired ≥5 individuals in the case–control population.
Ninety-three horses with sudden cardiac death and 465 control horses were identified. Heritability on the underlying scale was 0.15 ± 0.09 (logit animal) and 0.24 ± 0.12 (normal animal). Inbreeding coefficients were not significantly different between groups. Of the 16 first generation sires that appeared ≥5 times in the case–control data set, two sires more frequently produced affected progeny (OR 7.95–10.41).

Bottom line: The heritability of sudden cardiac death in this population was relatively low. However, individual stallions appear more likely to produce affected progeny. 

Why I chose this article

The genetics of sudden cardiac death is largely unevaluated in horses.

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Kari Means, Lyndsey Hayden, Joanne Kramer, Megan Jill McCracken, Shannon K. Reed, David A. Wilson, Kevin George Keegan

Article Summary

Compensatory vertical head and pelvis movement asymmetry may occur in trotting horses with a primary cause of lameness in one end of the body due to the weight shifting between limbs, leading to apparent combined forelimb and hindlimb lameness. Little is known about combined forelimb and hindlimb lameness patterns observed with body-mounted inertial sensors and regardless of their underlying mechanisms, compensatory and secondary lameness may complicate the definitive identification of the primary causes of lameness. The aim of this retrospective cohort study was to determine associations between vertical pelvic movement asymmetry and location of primary lameness in ipsilateral combined forelimb and hindlimb lameness cases where hindlimb lameness is solely impact or push-off type.
Cases with a consistent, low-variability ipsilateral impact or ipsilateral push-off hindlimb lameness in a straight-line trot and that had definitive diagnoses were identified from a body-mounted inertial sensor evaluated equine lameness database. Cases were categorised by lameness location to the limb(s), diagnosis, and the ratio of the amplitude of forelimb to hindlimb lameness (Forea/Hinda). Differences in the numbers of ipsilateral impact and ipsilateral push-off cases in these categories were analysed with chi-square tests, effect sizes, and odds ratios.

In total, 49 ipsilateral impact and 36 ipsilateral push-off cases met the criteria for consistency, low variability, and definitive diagnosis. Ipsilateral impact cases were more likely than ipsilateral push-off cases to have forelimb-only lameness causes when Forea/Hinda was >1 (OR = 43, 95% CI = 2.3–798). Ipsilateral push-off cases were more likely than ipsilateral impact cases to have hindlimb-only causes when Forea/Hinda was >1.0 (OR = 20, 95% CI = 2.2–200) and <1.0 (OR = 14, 95% CI = 2.9–66.7). Compared with ipsilateral impact, ipsilateral push-off cases were more frequently diagnosed with tendon, suspensory ligament, or high-motion joint disorders in hindlimbs (OR = 3.6, 95% CI = 1.1–12.3) and less with unknown causes (OR = 13.2, 95% CI = 3.2–75.2). In ipsilateral impact cases, positive forelimb regional anaesthesia often reduced hindlimb lameness, whereas in ipsilateral push-off cases, positive hindlimb regional anaesthesia typically lessened forelimb lameness.

Bottom line: The type of pelvic movement asymmetry observed in ipsilateral impact and ipsilateral push-off cases is linked to the location and underlying cause of the primary lameness. 

Why I chose this article

Little is known about secondary combined forelimb and hindlimb lameness patterns and whether they are more commonly ipsilateral or contralateral.

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Melissa Kamps, Safia Barakzai

Article Summary

Reported complication rates after dental repulsion for equine exodontia are high (up to 80%), but repulsion methods have changed notably in the last 20 years. The aim of this retrospective case series was to describe the outcome for 20 cases after dental repulsion using small diameter repulsion pins.

Clinical records of horses that underwent cheek tooth repulsion were reviewed (2014–2023). Inclusion criteria included: mandibular or maxillary cheek tooth extraction where oral extraction failed and repulsion was used to complete extraction, and where clinical follow-up information was available. Repulsions were carried out under sedation with a regional nerve block or under a short general anaesthetic, using a small diameter repulsion pin (3–5 mm). Intra-operative radiographs facilitated instrument placement. The alveolus was packed with polymethyl methacrylate post-extraction. Horses were re-examined at 4–6 weeks post-operatively.

Twenty cases were included. Patients had a mean age of 10.3 years old (range 5–16 years). The majority (75%) of teeth had pre-existing dental fractures. Maxillary (n = 15) and mandibular cheek teeth (n = 5) were all successfully repulsed, with 16 cases performed with the horse standing and 4 with the horse under general anaesthesia. Intra-operative complications included damage to the mandibular bone (n = 1). Short-term complications (n = 2) included superficial surgical site infection, and dehiscence of one sinus flap. Long-term complications included the recurrence of sinusitis (n = 1) and small intra-alveolar fragments causing persistent bitting problems in another patient.

Bottom line: When oral extraction fails, cheek tooth repulsion using small diameter repulsion pins is an effective extraction technique. The total intra- and post-operative complication rate was 25%.

Why I chose this article

The use of smaller diameter dental punches or Steinmann pins in standing sedated cases has not been objectively reported in the literature.

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Monika Bugno-Poniewierska, Magdalena Jankowska, Terje Raudsepp, Katarzyna Kowalska, Klaudia Pawlina-Tyszko, Tomasz Szmatola

Article Summary

Chromosomal abnormalities occur in the equine population at a rate of approximately 2%. Karyotype disorders, especially sex chromosome aberrations, have been shown to be one of the main causes of reduced fertility or infertility. Large-scale cytogenetic studies have shown that almost 30% of horses with reproductive or developmental problems have chromosomal aberrations. A break-through in the cytogenetic diagnosis of chromosome aberrations, enabling a quick and precise analysis of metaphase plates, was the use of fluorescence in situ hybridisation (FISH) which, unlike banding techniques, allowed the analysis of a larger number of metaphases, even those of poorer quality and with varying degrees of chromosome condensation. This is particularly important in clinical cytogenetic studies of horses, where most chromosome abnormalities occur in mosaic form with a low percentage of abnormal metaphases.

The aim of this cross-sectional study was to focus on sex chromosome disorders using molecular cytogenetics techniques such as FISH and PCR, to estimate the prevalence of sex chromosome karyotypic abnormalities in a sample from the population of young horses in Poland. It was hypothesised that these molecular techniques would allow more precise identification of chromosomal aberrations, especially those with a low percentage of abnormal metaphases, which in turn, would show that the rate of chromosomal abnormalities in horse populations is higher than 2%.

Venous blood samples were collected from 500 young horses representing 5 Polish breeds (Purebred Arabian, Hucul, Polish primitive horse [Konik], Małopolska, Coldblood, Silesian). Chromosomes and DNA were obtained from blood lymphocytes and evaluated by fluorescence in situ hybridisation (FISH) and PCR, using probes and markers for the sex chromosomes and select autosomes.

Nineteen horses, 18 mares and 1 stallion, were diagnosed with different chromosomal abnormalities: 17 cases of mosaic forms of sex chromosome aneuploidies with a very low incidence (0.6%–4.7%), one case of a SRY-negative 64,XY sex reversal mare, and one mare with X-autosome translocation. The percentage of sex chromosomal aberrations was established as 3.8% in the whole population, 6.08% in females and 0.49% in males.

Bottom line: The rate of sex chromosomal abnormalities identified was almost double that reported in previous population studies that used classical chromosome staining techniques.

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Christopher M. Baldwin, Joanne L. Ireland, Safia Z. Barakzai

Article Summary

There is no objective information reporting the effect of unilateral laser ventriculocordectomy on arytenoid abduction or stability. The aim of this prospective cohort study was to evaluate arytenoid stability and abduction in horses with severe recurrent laryngeal neuropathy (RLN) before and after unilateral laser ventriculocordectomy. 

Eight horses with grade C or D exercising laryngeal function that underwent unilateral laser ventriculocordectomy were included. Exercising endoscopy was performed before and ≥6 weeks after treatment. Arytenoid stability at maximal exercise was calculated by measuring the left-to-right quotient angle ratio (LRQ) of the corniculate processes at the points of maximal arytenoid abduction (expiration) and maximal arytenoid collapse (inspiration). For each horse, means of measurements obtained for four breaths pre- and post-operatively were used for statistical analysis.

The difference in LRQ between inspiration and expiration was significantly lower post-operatively (median 0.039; interquartile range [IQR] 0.032–0.047) compared with pre-operatively (median 0.158; IQR 0.083–0.249; p = 0.01) confirming the left arytenoid was more stable following unilateral laser ventriculocordectomy. The degree of improvement was significantly greater for grade D horses compared with grade C horses (p = 0.04). The LRQ measured on maximal abduction was also lower post-operatively (median 0.467; IQR 0.444–0.506) compared with pre-operatively (median 0.578; IQR 0.554–0.655; p = 0.02) indicating the left arytenoid was less abducted following surgery.

Bottom line: Unilateral laser ventriculocordectomy in grade C and D RLN-affected horses results in reduced left arytenoid abduction but increased arytenoid stability.

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Lee Morris, Ria Harteveld, Zamira Gibb

Article Summary

Insemination of mares with frozen–thawed spermatozoa requires intensive management and results in 40%–60% per cycle pregnancy rates. The aim of this uncontrolled field trial was to determine if satisfactory fertility is possible for frozen–thawed semen after processing it through a microfluidic device, followed by storage at 17°C for up to 24 h before fixed-time insemination.

First the motility of frozen–thawed spermatozoa from 5 stallions was evaluated by CASA after centrifugation and storage at 17°C in two different media (Botusemen Gold™ or SpermSafe™) for up to 48 h. Subsequently, the motility of frozen–thawed semen from 4 stallions processed through a microfluidic device, resuspended in the two different media during storage at 17°C for up to 24 h was evaluated. Finally, the fertility of frozen–thawed spermatozoa from 3 stallions after microfluidic sorting and storage at 17°C for up to 24 h, was evaluated after fixed-time insemination of 42 mare cycles in a commercial embryo programme.

The stallion significantly influenced sperm motility, but there was no effect of media on motility parameters. Storage time significantly affected sperm motility after centrifugation but not after microfluidic sorting. Storage time had no effect on the overall embryo recovery rate (52%, n = 42).

Bottom line: Fixed-time insemination of frozen–thawed spermatozoa after microfluidic sorting and storage at 17°C for up to 24 h produced satisfactory embryo recovery rates.
 

Why I chose this article

The paper explores a technique to avoid some of the issues with intensive frozen-thawed insemination of mares.

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Natalia Watrobska, Rachel Gough, Gayle Hallowell, Simon Haugaard, Kate F. McGovern

Article Summary

Post-operative reflux (POR) is rare following large colon volvulus (LCV) but does occur despite the absence of a small intestinal lesion. The prevalence, risk factors and association with survival of POR after LCV are currently unknown. The aim of this retrospective cross-sectional study was to determine the prevalence of POR in horses with an LCV and its association with survival. A further objective was to assess factors which may predict POR. 

Clinical data of client owned horses which underwent colic surgery at a single UK referral hospital between 2008 and 2021 where LCV was the primary finding were retrieved from hospital records. Statistical analyses included chi-squared, t-tests and odds ratios (ORs). Horses with concurrent lesions, and those that did not survive past anaesthetic recovery, were excluded from analysis. POR was defined as ≥2 L of gastric reflux on at least one occasion.

A total of 128 horses were included in the study, 23 of which had POR (18%). Overall survival to hospital discharge was 86%, 95% in the non-POR and 44% in the POR group. Horses with POR were significantly less likely to survive to discharge than those without (OR = 26, 95% confidence interval [CI] [7.68–88.0], p < 0.001), and less likely to be alive 3 years after surgery (OR = 13.4, 95% CI [2.78–64.8], p < 0.001).

Bottom line: POR in LCV cases is a negative prognostic indicator for short and long term survival.
 

Why I chose this article

The presence of post-operative reflux following large colon volvulus has not been investigated and this study showed a poorer outcome with those that did develop reflex when compared to those that did not. 

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Josephine E. Faulkner, Zoë Joostens, Bart J. G. Broeckx, Stijn Hauspie, Tom Mariën, Katrien Vanderperren

Article Summary

Sagittal groove (SG) injuries of the proximal phalanx (P1) are an increasingly recognised cause of lameness in equine athletes and early diagnosis can aid in optimising rehabilitation programmes and prevention of further injury. Several publications have described the variable abnormal imaging features of the SG on radiography, magnetic resonance imaging (MRI), computed tomography (CT) and scintigraphy; however, to date there are no studies evaluating the distribution of lesion type and severity of MRI findings in a large group of horses. Thus, the aim of this retrospective, cross-sectional study was to describe the range of abnormalities that is present in the sagittal groove in a large group of horses diagnosed with sagittal groove disease (SGD) on low-field MRI.

Medical records were searched to identify MRI images of horses diagnosed with SGD and these were blindly evaluated using a semi-quantitative grading scheme and novel SGD MRI classification system reflecting potential pathways of pathological progression and severity of stress injury.

A total of 132 limbs from 111 horses were included in the study: predominantly Warmbloods competing in showjumping (n = 83) and dressage (n = 18). SGD MRI classifications were: 0 (normal, n = 0), 1 (small subchondral defect, n = 2), 2 (osseous densification, n = 28), 3 (subchondral microfissure with osseous densification, n = 7), 4 (bone oedema-like signal within the subchondral ± trabecular bone and ± subchondral microfissure or demineralisation, n = 72), 5 (incomplete macrofissure/fracture, n = 23) and 6 (complete fracture, n = 0). Classification 4c (bone oedema-like signal with demineralisation) and 5 had higher proportions in the plantar third of hindlimbs (3% and 10%, respectively) compared with forelimbs (0% and 0%, respectively). SGD classification and extent of bone oedema-like signal were not significantly different between lame (n = 116) and non-lame limbs (n = 16) (both p > 0.05). Periosteal new bone and oedema-like signal were identified (either confidently or suspected) at the dorsoproximal aspect of P1 in 25% and 39% of limbs, respectively.

Bottom line: The SGD MRI classification system was successfully applied to all limbs. The most prevalent classification was 4 (bone oedema-like signal within the subchondral ± trabecular bone) and more specifically 4a (bone oedema-like signal within the subchondral ± trabecular bone). There was no significant difference in the SGD MRI classifications, sub-classifications, or extent of bone oedema-like signal between lame and non-lame limbs.
 

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Cynthia Xue, Lorenzo Segabinazzi, Alexis Hall, Tarisai Brighton Dzikiti, Hilari French, Robert Gilbert

Article Summary

Clinically, flunixin meglumine and phenylbutazone are preferentially selected for the treatment of visceral and musculoskeletal pain, respectively, in horses. In donkeys, there is no information to support or refute this conventional conjecture. The aim of this retrospective cohort study was to compare postoperative outcomes in a group of jennies treated with intravenous flunixin meglumine or oral phenylbutazone following unilateral ovariectomies by standing left flank laparotomy.

Data from medical records of 14 ovariectomised jennies (case details, weight, non-steroidal anti-inflammatory drug [NSAID] protocol, surgery duration, operative sequence, anaesthesia protocol, physical examination findings and outcomes) were collected. From collated data, postoperative adverse events were defined as fever, tachycardia, tachypnoea, inappetence, altered mentation, abnormal oral mucous membranes, bruxism, colic, incisional complications (i.e., drainage, oedema, peri-incisional emphysema and pain) and non-survival, then further divided into occurrence during the early (≤24 h) or late (>24 h) postoperative period for data analysis using R software. Individual adverse events were compared between groups (phenylbutazone vs. flunixin meglumine) and moments (early vs. late). 

Phenylbutazone treatment (2.2mgkg IV pre-op, then 2.2mgkg PO BID for 3 days post-op) (8/14) was associated with significantly (odds ratio, 95% confidence interval) more total (2.93, 1.97–4.36), early (3.01, 1.87–4.84) and late (2.69, 1.28–5.63) adverse events than flunixin meglumine treatment (1.1mgkg IV pre-op and 1.1mgkg IV BID for 3 days post-op) (6/14). Tachycardia (37.83, 2.21–646.66), tachypnoea (0.29, 0.13–0.66), altered mentation (2.78, 1.01–7.67), altered mucous membranes (18.38, 1.04–325.23), incisional oedema (44.33, 2.60–754.5) and incisional pain (47.78, 2.81–811.61) were significantly different between groups. Early adverse events significantly different between groups included tachycardia (50.2, 2.9–877.0), altered mentation (3.33, 1.08–10.29) and incisional pain (21.0, 1.2–374.5), with late adverse events being tachypnoea (0.07, 0.01–0.62), incisional oedema (32.92, 1.85–584.28) and incisional pain (28.92, 1.62–515.68). Colic (2/8) and non-survival (1/8) were rare events that only occurred in the phenylbutazone cohort and could not be further evaluated for differences.

Bottom line: When surgery length, operative sequence and anaesthetic protocol were controlled for, PBZ-treated donkeys were more likely to show abnormal physiologic parameters, changes in behaviour and incisional discomfort compared with FM-treated jennies. Therefore, IV FM may be the more appropriate NSAID for abdominal surgery in donkeys.
 

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Leonie C. Arnold, Tom A. E. Stout, Anthony N. J. Claes

Article Summary

Management of twin pregnancy after conceptus vesicle fixation in the horse is challenging because the reduction techniques described are either invasive, difficult to perform or associated with disappointing success rates. The aim of this retrospective clinical study was to evaluate the success of transrectal ultrasound-guided fetal thorax compression for reducing post-fixation twin pregnancy in mares.

Sixteen mares were presented for twin reduction between 51 and 79 days of gestation. History obtained from the owner and/or referring veterinarian detailed information regarding the mare (age, breed), pregnancy (day of gestation, dizygotic versus monozygotic twins, unilateral versus bilateral fixation), treatment and outcome (one live fetus at discharge; live singleton at foaling) after twin reduction. Transrectal fetal thorax compression was performed under ultrasound guidance by two experienced operators.

Overall, 9 of 16 twin pregnancies were successfully reduced and the likelihood of success was significantly higher in dizygotic than monozygotic twins. The procedure was successful in 9 of 10 dizygotic twins but unsuccessful in all six cases of monozygotic twins. Among the dizygotic twins, two mares lost the pregnancy after discharge from the clinic, seven mares delivered a healthy foal of normal size.

Bottom line: Transrectal ultrasound-guided fetal thorax compression is a successful technique for reducing dizygotic twin pregnancies at approximately 2 months of gestation but did not lead to any live births in cases of monozygotic twins.

Why I chose this article

This paper discusses a promising alternative for reducing post-fixation, unilateral, dizygotic twin pregnancies in the horse that is less expensive than other techniques described for this stage of gestation, and does not require special equipment.

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Humberto B. Magalhaes, Ilaria Colombo, Kianna M. Spencer, Giorgia Podico, Igor F. Canisso

Article Summary

Accurate prediction of parturition is paramount to ensuring monitoring of delivery and preventing complications. Assessing the pH and electrolytes of the mammary gland secretions helps detect impending parturition. As conductivity is related to electrolyte concentrations and pH, it could be a useful alternative for predicting impending parturition; however, this hypothesis warrants a critical assessment. The aim of this field study was to assess the ability of conductivity, pH, and Brix in the mammary gland secretions to predict parturition and to investigate their associations.

The mammary gland secretions of periparturient mares (n = 241) were assessed daily for conductivity, pH, and Brix index from 320 days until parturition using stable-side handheld devices (Compact Conductivity Meter EC22, Horiba Scientific, Laqua-twin; Compact pH Meter PH22, Horiba Scientific, Laqua-twin; and a Brix refractometer, respectively). Receiving operating curve cut-off values for conductivity (≤4.8 mS/cm), pH (≤6.4), and Brix index (>23.6%) were used to calculate sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for predicting parturition in ≤24 h.

Impending parturition was associated with a significant reduction in conductivity and pH (p < 0.05), and conductivity was strongly correlated with pH (r = 0.88) and Brix (r = −0.80) (p < 0.05). Sensitivity, specificity, PPV, and NPV for parturition in ≤24 h for conductivity (82%, 91%, 77%, and 92%, respectively), pH (79%, 84%, 81%, and 71%, respectively), and Brix (72%, 79%, 66%, and 83%, respectively) were determined separated and pairwise. Of interest, the sensitivity, specificity, PPV, and NPV, of combining conductivity and pH, were 80%, 95%, 90%, and 88%, respectively. Conductivity (≤4.8 mS/cm) presented the greatest odds ratio for predicting parturition in ≤24 h and coupling it with pH (≤6.4 pH units) doubled its odds ratio (i.e., 25.4–62.3).

Bottom line: The conductivity of mammary gland secretions and a combination of conductivity and pH are useful for predicting parturition in mares.

Why I chose this article

This paper discusses a non-invasive technique using a stable-side handheld device to determine the value of monitoring milk electrolytes for impending parturition. 

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Jessica M. Lawson, Charlotte A. Shilton, Victoria Lindsay-McGee, Androniki Psifidi, D. Claire Wathes, Terje Raudsepp, Amanda M. de Mestre

Article Summary

Excessive inbreeding increases the probability of uncovering homozygous recessive genotypes and has been associated with an increased risk of retained placenta and lower semen quality in horses. No genomic analysis has investigated the association between inbreeding and pregnancy loss. Thus the aim of this observational case-control study was to compare genetic inbreeding coefficients (F) of naturally occurring Thoroughbred Early Pregnancy Loss, Mid and Late term Pregnancy Loss and Controls. 

Allantochorion and fetal DNA from Early Pregnancy Loss (n = 37, gestation age 14–65 days), Mid and Late term Pregnancy Loss (n = 94, gestational age 70 days–24 h post parturition) and Controls (n = 58) were genotyped on the Axiom Equine 670K SNP Genotyping Array. Inbreeding coefficients using Runs of Homozygosity (FROH) were calculated using PLINK software. ROHs were split into size categories to investigate the recency of inbreeding.

Mid and Late term Pregnancy Losses had significantly higher median number of ROH (188 interquartile range [IQR], 180.8–197.3), length of ROH (3.10, IQR 2.93–3.33), and total number of ROH (590.8, IQR 537.3–632.3), and FROH (0.26, IQR 0.24–0.28) when compared with the Controls and the Early Pregnancy Losses (p < 0.05). There was no significant difference in any of the inbreeding indices between the Early Pregnancy Loss and Controls. The Mid and Late term Pregnancy Losses had a significantly higher proportion of long (>10 Mb) ROH (2.5%, IQR 1.6–3.6) than the Controls (1.7%, IQR 0.6–2.5), p = 0.001. No unique ROHs were found in the Early or Mid and Late term Pregnancy Losses populations.

Bottom line: Inbreeding is a contributor to Mid and Late term Pregnancy Losses, but not Early Pregnancy Loss in the UK Thoroughbred population. Mating choices remain critical, because inbreeding may predispose to Mid and Late term Pregnancy Losses by increasing the risk of homozygosity for specific lethal allele(s).
 

Why I chose this article

The number of stallions registered for covering has almost halved in the last 10 years. This paper evaluates some of the effects of this decline in relation to pregnancy loss. 

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Marie Michotte, Els Raes, Maarten Oosterlinck

Article Summary

The diagnostic value of plain radiography for diagnosing synovial penetration in limb wounds near synovial structures has not been determined. The aim of this retrospective case study was to assess diagnostic accuracy of plain radiography to identify synovial penetration in horses with traumatic limb wounds.

Case records of horses presented to the Faculty of Veterinary Medicine of Ghent University (2011–2021) with limb wounds near synovial structures were categorised in groups with and without synovial penetration using results of synovial fluid analysis and surgical findings. Plain radiographic images were evaluated retrospectively. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for the total study sample and for the cases with and without use of a metallic probe in the wound during radiographic evaluation.

Based on the 141 horses with synovial penetration and 75 cases without synovial involvement, plain radiography presented a sensitivity of 61% (95% CI: 52%–69%), a specificity of 81% (95% CI: 70%–89%), a PPV of 86% (95% CI: 79%–90%) and a NPV of 53% (95% CI: 46%–58%). With the use of a metallic probe, a sensitivity of 54% (95% Cl: 39%–69%), a specificity of 88% (95% Cl: 64%–99%), a PPV of 93% (95% Cl: 78%–98%) and a NPV of 41% (95% Cl: 32%–49%) were obtained.
 

Bottom line: If plain radiographs suggest synovial penetration in horses with a wound near a synovial cavity, then synovial penetration is likely, but the absence of plain radiographic findings does not rule out synovial penetration. The results were similar in the subsets of cases with and without the use of a metallic probe during radiographic evaluation.

Why I chose this article

Plain radiography is frequently performed when investigating cases of suspected synovial penetration and this study evaluates the sensitivity and specificity of this as a diagnostic test. 

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Rebecca Mouncey, Juan C. Arango-Sabogal, Amanda de Mestre, Kristien L. Verheyen

Article Summary

Early-life locomotor activity during turn out may alter susceptibility to musculoskeletal disease and injury via modulation of behaviours and tissue development during growth. The aim of this prospective cohort study was to investigate associations between turn out practices and rates of musculoskeletal disease and injury in young Thoroughbreds on stud farms in the United Kingdom.

Daily records were kept on location and duration of turn out for 134 Thoroughbred foals on six stud farms, from birth until leaving the farm or study exit. Data on veterinary-attended episodes of musculoskeletal disease or injury were collated concurrently. Average daily turn out times (hours), areas (acres) and group size (n foals) were calculated for rolling 7- and 30-day periods of age. Multivariable Cox regression, including farm as a random effect, was used to investigate associations between turn out practices and musculoskeletal disease and injury.

The overall incidence of musculoskeletal disease or injury was 5.3 cases/100 foal-months at risk (95% confidence interval [CI]: 4.2–6.6). Compared with 24/7 turn out, average daily turn out times of between 9 and 23 hours over a 7-day period were associated with a 4.6-fold increase in musculoskeletal injury rate (95% CI: 1.7–12.3; P < 0.001), adjusting for farm and paddock area. Each 1-acre increase in the average daily turn out area during the 4th month of life, reduced the rate of musculoskeletal disease and injury between 6 and 18 months of age by 24% (hazard ratio 0.76, 95% CI: 0.58–0.99; P < 0.001), adjusting for farm and turn out time.

Bottom line: Results suggest that disruptions or alterations to turn out time routines increase injury risk and should be avoided where possible. Turn out in larger paddocks, particularly before weaning, may confer protection against subsequent musculoskeletal disease and injury.

Why I chose this article

Stud farms' turn out practices influence rates of musculoskeletal injury and disease in young Thoroughbreds (TBs) and this study provides evidence to inform management strategies aimed at improving musculoskeletal health in young TBs.

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Diego E. Gomez, Bettina Dunkel, David L. Renaud, Luis G. Arroyo, Angelika Schoster, Jamie J. Kopper, David Byrne, The MEDS group, Ramiro E. Toribio

Article Summary

Clinicopathological findings and their association with the outcome and development of laminitis in horses with acute diarrhoea has not been investigated in a multicentre study across different geographic regions. The aim of this multicentre retrospective case series was to describe and compare clinicopathologic findings of diarrhoeic horses between different geographic regions, survival rates and factors associated with non-survival and laminitis.

Information from horses with acute diarrhoea presenting to participating institutions between 2016 and 2020 was collected, and clinicopathological data were compared between surviving and non-surviving horses and horses that did and did not develop laminitis. Survival rates and seasonal and geographic differences were also investigated.

A total of 1438 horses from 26 participating institutions from 4 continents were included. Overall, 76% survived to discharge with no differences identified between geographic regions. The presence of SIRS, altered mentation, toxic line on the oral mucosal membranes, and increased PCV, TP, creatinine, and lactate were significantly associated with increased odds of non-survival. The survival proportion of horses with SIRS and creatinine concentrations > 159 μmol/L was 55% (154/279) compared with 81% (358/437) for those with SIRS and creatinine concentrations < 159 μmol/L (p < 0.001). The survival proportion of horses with SIRS that had an L-lactate concentration > 2.8 mmol/L was 59% (175/298) compared with 81% (240/296) in horses with SIRS and L-lactate concentration < 2.8 mmol/L (p < 0.001). The proportion of horses that developed laminitis was lower in Europe (4%, 19/479) compared with North America (8%, 52/619), Australia (8%, 12/138) and Latin America (11%, 16/146) (p < 0.05). More horses developed laminitis in the summer (46%, 39/85) compared with winter (18%, 15/85), spring (18%, 15/85) and fall (19%, 16/85) (p < 0.01). Horses with laminitis had greater odds of non-survival than those without laminitis (OR: 3.73, 95% CI: 2.47–5.65).

Bottom line: The presence of laminitis, SIRS, altered mentation, toxic line on the oral mucosal membranes, increased PCV, TP creatinine and lactate were significantly associated with increased odds of non-survival. 

Why I chose this article

Understanding factors regarding survival with acute diarrhoea can help counsel owners when considering referral or treatment of acute diarrhoea. 

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Diego E. Gomez, Luis G. Arroyo, Angelika Schoster, David L. Renaud, Jamie J. Kopper, Bettina Dunkel, David Byrne, The MEDS group, Ramiro E. Toribio  

Article Summary

An international description of the diagnostic approaches used in different institutions to diagnose acute equine diarrhoea and the pathogens detected is lacking. The aim of this multicentre retrospective case series was to describe the diagnostic approach, aetiological agents, outcome, and development of laminitis for diarrhoeic horses worldwide. 

Information from horses with acute diarrhoea presenting to participating institutions between 2016 and 2020, including diagnostic approaches, pathogens detected and their associations with outcomes, were compared between institutions or geographic regions. 

A total of 1438 horses from 26 participating institutions from 4 continents were included. 630 (44%) were presented to institutions in North America, 483 (33%) in Europe, 149 (10%) in Latin America, 141 (10%) in Australia and 35 (2%) in Japan. Overall, aetiological testing was limited (44% for Salmonella spp., 42% for Neorickettsia risticii [only North America], 40% for Clostridiodes difficile, and 29% for equine coronavirus); however, of those tested, 13% (81/633) of horses tested positive for Salmonella, 13% (35/262) for N. risticii, 9% (37/422) for ECoV, and 5% (27/578) for C. difficile. The overall survival proportion for diarrhoeic horses was 76% (1093/1438, range 40-90%). C. difficile positive cases had greater odds of non-survival than horses negative for C. difficile (OR 2.69, 95% CI 1.23–5.91). In addition, horses that were positive for N. risticii had greater odds of developing laminitis than negative horses (OR 2.76, 95% CI 1.12–6.81; p = 0.029). 

Bottom line: This study highlighted limited and inconsistent diagnostic investigations in cases of acute equine diarrhoea. Detection rates of pathogens are similar to previous reports. Non-survival was associated with C.difficile positive results and development of laminitis associated with N. risticii.  

Why I chose this article

Diagnostic approaches and detected pathogens of horses with acute diarrhoea vary among referral institutions worldwide and there is little information regarding the variation in pathogen testing. This study evaluates the detection of specific pathogens and associated with the outcome and the development of laminitis.  

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Szu-Ting Lin, Nicholas M. Bolas, Vanessa G. Peter, Rachel Pokora, Hayley Patrick, Alastair K. Foote, David R. Sargan, Rachel C. Murray

Article Summary

The aim of this cross-sectional study was to compare diagnoses, imaging details, and measurements of palmar/plantar osteochondral disease (POD) lesions between cone-beam (standing) computed tomography CT, fan-beam CT, and low-field magnetic resonance imaging (MRI) using macroscopic pathology as a gold standard in 35 cadaver limbs from 10 horses.

Forty-eight POD lesions were seen over 70 condyles. Compared with macroscopic examination the sensitivity and specificity of diagnosis were 95.8% (95% CI 88%–99%) and 63.6% (95% CI  43%–81%) for fan-beam CT, 85.4% (95% CI  74%–94%) and 81.8% (95% CI  63%–94%) for cone-beam CT, and 69.0% (95% CI  = 54%–82%) and 71.4% (95% CI 46%–90%) for MRI. Inter-modality agreement on diagnosis was moderate between cone-beam CT and fan-beam CT (κ = 0.56, p < 0.001). POD was identified on CT as hypoattenuating lesions with surrounding hyperattenuation and on MRI as either T1W, T2*W, T2W, and STIR hyperintense lesions or T1W and T2*W heterogeneous hypointense lesions with surrounding hypointensity. Agreement on imaging details between cone-beam CT and fan-beam CT was substantial for subchondral irregularity (κ = 0.61, p < 0.001). Macroscopic POD width strongly correlated with MRI (r = 0.81, p < 0.001) and cone-beam CT (r = 0.79, p < 0.001) and moderately correlated with fan-beam CT (r = 0.69, p < 0.001). Macroscopic POD width was greater than all imaging modality (p < 0.001).

Bottom line: All imaging modalities were able to detect POD lesions, but underestimated lesion size. The CT systems were more sensitive, but the differing patterns of signal intensity may suggest that MRI can detect changes associated with POD pathological status or severity. The image features observed by cone-beam CT and fan-beam CT were similar.

Article Summary

Palmar/plantar osteochondral disease (POD) of the metacarpal/tarsal condyles is a common pathological finding in racehorses and advanced imaging is often required to detect them due to the poor sensitivity of radiographs. However, the diagnostic value of MRI and CT modalities have not previously been compared.

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Sevim Kasap, Serdar Babaeski, Kubra Nur Yildirim, Abdulkadir Orman, Ethem Mutlu Temizel, Engin Kennerman

Article Summary

Prompt diagnosis of passive transfer failure in the neonatal period is important for early treatment. The aim of this study was to compare the diagnostic performance of serum glutaraldehyde coagulation test (GCT) and colostrum BRIX% to detect failure to transfer passive immunity (FTPI) diagnosis with the results of the SNAP foal test; and to evaluate the results of serum GCT and colostrum BRIX% measurements in foals which developed diarrhoea in the 0–1 month period.

Residual serum and colostrum (n=298) from samples collected from newborn foals and their dams for clinical purposes were used. Foals were classified as FTPI positive (IgG < 8 g/L) or negative (IgG ≥ 8 g/L) using the SNAP foal test. The sensitivity and specificity of serum GCT and colostrum BRIX% for diagnosing FTPI in all foals were compared. The relationships between the results of the serum GCT and colostrum BRIX% and the development of diarrhoea in the 0–1 month period in foals with and without FTPI were evaluated.

Serum GCT and colostrum BRIX% were significantly different (p < 0.05) between the foals classified according to the SNAP test as without FTPI and with FTPI. Using a cut-off value for serum GCT of >10 minutes, the sensitivity for the detection of FTPI was 100% (95% CI 92.9%–100%) and specificity 100% (98.3%–100%) while using BRIX% a cut-off value of ≤24%, the sensitivity was 92% (80.9%–97.8%), and specificity was 98% (95.3–99.3). In the sub-group of foals without FTPI using a colostrum BRIX% cut-off value of ≤26 the sensitivity for prediction of diarrhoea in the 0–1 month period was only 72.4% (52.8–87.3, p < 0.001) with specificity 54.3% (47.6–61.1) but the test performance was not robust (ROC AUC 0.61).

Bottom line: Using serum GCT (>10mins), and colostrum BRIX% (≤24%), both economical and practical to use in the field, gave results comparable with the SNAP foal IgG test for the detection of FTPI (<8g/L). The ability to accurately predict diarrhoea in the first month of life with these tests was limited.

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Victoria A. Colgate, Natalie Robinson, Timothy P. Barnett, Andrew P. Bathe, Matthew O. D. Coleridge, Lewis C. R. Smith, Richard J. Payne

Article Summary

Repair of sagittal proximal phalanx (P1) and parasagittal metacarpal/metatarsal III (MC/MTIII) fractures has evolved over recent decades from a procedure carried out solely under general anaesthesia, to one commonly performed under standing sedation. To date, standing fracture repair has not been evaluated for large cohorts.
The aim of this single-centre retrospective cohort study was to determine short-term (survival to discharge) and long-term (return to racing) outcomes of horses undergoing standing repair of MC/MTIII and P1 fractures, and to compare pre-surgical and post-surgical racing performance.

Retrospective clinical record review of 245 cases undergoing standing repair of MC/MTIII or P1 fractures, 1 January 2007–30 June 2021 was performed. Data on signalment, fracture configuration and complications were collected and full race records were retrieved from the Racing Post Database. Chi-squared and Mann–Whitney U tests were used to determine any difference in variables between horses that raced after surgery compared to those that did not. McNemar change and Wilcoxon signed-rank tests were used to compare pre- and post-surgical racing performance.

The proximal phalanx was fractured in 41.2% (101/245) of cases and 58.8% (144/245) had a condylar fracture. Of the repaired fractures; 64.9% (159/245) were bicortical and 35.1% (86/245) unicortical fissure fractures. Ninety-eight percent of horses survived hospital discharge, and 75.1% raced after surgery, a median of 241 days later. Horses that raced post-surgery were significantly less likely to have suffered from complications during hospitalisation than those that did not race again [17.3% vs. 36.5%]. Comparing pre- and post-operative racing performance, there was no significant difference in earnings per start [median £628.00, interquartile range (IQR) 115.90–1934.80 vs. £653.20, 51.00–1886.40, p = 0.7] or proportion of horses winning [51% (95% CI: 41%–61%) vs. 54% (95% CI: 44%–64%), p = 0.8] or being placed first–third [77% (95% CI: 68%–85%) vs. 71% (95% CI: 62%–80%, p = 0.5] in at least one race.

Bottom line: Standing fracture repair is a viable treatment option for MC/MTIII or P1 fractures that returns horses to the racetrack within an acceptable time frame and is capable of restoring pre-surgical athletic ability.

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Tania Sundra, Sarah Gough, Gabriele Rossi, Erin Kelty, David Rendle

Article Summary

Oral omeprazole is the accepted treatment for equine squamous gastric disease (ESGD); however, it is not universally effective. Esomeprazole results in more consistent and pronounced acid suppression in people and is more effective than omeprazole in the treatment of oesophageal and gastric disease. Pharmacodynamic and pilot clinical studies have indicated esomeprazole might also be more effective than omeprazole in horses.

The aim of the randomised, single-blinded controlled trial was to compare the efficacy and safety of oral esomeprazole and omeprazole pastes in the treatment of ESGD and, where present, concurrent equine glandular gastric disease (EGGD).

Horses presenting with grade ≥2 ESGD lesions were randomly allocated to receive 4 mg/kg of either a buffered esomeprazole or omeprazole paste orally once daily for 28 days before gastroscopy being repeated within a further 3 days. Videos and images were anonymised and subsequently graded blind by one researcher. The severity of ESGD (and EGGD) lesions before and after treatment, and thereby treatment responses, were compared using univariable logistic regression.

Horses were mostly in either low-level or no work, with a mix of breeds represented. A higher proportion of horses had ESGD healing in response to esomeprazole treatment (63/74, 85%) than with omeprazole treatment (43/73, 59%) (odds ratio [OR]: 4.00, 95% confidence interval [CI]: 1.81, 8.82, p = 0.001). In a subset of horses that had concurrent EGGD, a greater proportion of the horses treated with esomeprazole had lesions ≤grade 1 (esomeprazole 28/51, 55%; omeprazole 6/24, 25%; OR: 3.65, 95% CI: 1.25, 10.71, p = 0.02) Using grade 0 as the benchmark for EGGD healing, the difference remained significant (OR: 4.44, 95% CI: 1.33, 14.85, p = 0.02).

Bottom line: Oral-buffered esomeprazole was a more effective treatment for ESGD (and concurrent EGGD) than oral-buffered omeprazole in this population of horses.

Why I chose this article

Esomeprazole is widely used in people but there is poor evidence to recommend its use in horses. This paper presents results to support its use in a mixed population of horse in low-level work.

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Brooke L. Boger, Jane M. Manfredi, Abigail R. Loucks, Maya Z. Salamey, Lydia E. Kapeller, Allie G. Fricano, Ani Winkler, Chelsey Yob, Aimee C. Colbath

Article Summary

Corticosteroids are a commonly used, inexpensive intra-articular treatment for osteoarthritis which may increase the risk for laminitis in horses due, in part, to hyperinsulinaemia. Humans with metabolic syndrome experience increases in insulin and glucose concentrations post-injection, but responses in horses are unknown.

The aim of this study was to determine the effect of a single intra-articular (IA) dose of triamcinolone acetate (TA) on blood insulin and glucose concentrations.
Ten horses with normal insulin sensitivity as assessed by an oral sugar test received 18 mg of TA into one middle carpal joint. All horse were fed only grass hay during the study period. Insulin and glucose concentrations were evaluated at baseline and 4, 6, 8, 24, 48, and 72 h following IA corticosteroid injection. 

Mean ± SD blood insulin concentration post IA TA injection was increased at 6 h (15.8 ± 3.1 μIU/mL, p = 0.01), 24 h (23 ± 5.8 μIU/mL, p ≤ 0.001), and 48 h (29 ± 13 μIU/mL, p ≤ 0.01) compared to baseline (10 ± 12.3 μIU/mL), with the peak at 48 h. Median ± 95% CI blood glucose concentration post IA TA injection was increased at 6 h (112.7 ± 20.3 mg/dL, p = 0.006), 8 h (112.9 ± 21.4 mg/dL, p = 0.004), 24 h (122.6 ± 14.6, p ≤ 0.0001), and 48 h (123.5 ± 15.4 mg/dL, p ≤ 0.0001) compared to baseline (89.2 ± 6.6 mg/dL), with the peak at 48 h.

Bottom line: Blood insulin and glucose concentrations modestly increased for 48 h following IA TA in horses with normal insulin sensitivity.

Why I chose this article

 Intra-articular medication is frequently used, and this study adds additional evidence to the risk of laminitis after IA steroids with horses without underlying endocrinopathies.

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Tanja Kloock, Kirstie J. Pickles, Veronica Roberts, Frauke Uhlendorf, Lara Twele, Henriette L. Wilkens, Eva Stehle, Karsten Feige, Tobias Niebuhr

Article Summary

In horses with trigeminal-mediated headshaking, clinical signs are likely to be an expression of neuropathic facial pain. Currently, subjective assessment of disease severity is used as measure of compromise of animal's welfare. The aims of this retrospective observational study were to develop and validate a precise scoring system for trigeminal-mediated headshaking: History, Rest and Exercise Score (HRE-S). The HRE-S consists of three sub scores: history score (H-S), resting score (R-S) and exercise score (E-S).

Seven masked observers with different experience used HRE-S to score 40 video recordings taken during rest and lungeing including five duplicates. Video recordings were taken from nine horses with trigeminal-mediated headshaking and three controls. Inter- and intra-observer reliability and practicability of HRE-S were assessed. For every video recording, severity of clinical signs was graded by every observer using an intuitive global-type-scale and interobserver reliability was calculated.

Reliability for HRE-S was excellent, irrespective of observers’ experience: Spearman's Rho = 0.946, p < 0.001 (intraobserver reliability) and intraclass correlation coefficient = 0.98, p < 0.001 (interobserver reliability). 

Interobserver reliability for intuitive global-type-scale was fair to substantial: Fleiss' Kappa = 0.48 (R-S) −0.63 (E-S). Groups created by intuitive global-type-scale had significantly different R-S and E-S (p < 0.05), demonstrating discriminant validity. 

Convergent validity was proven as horses with grade 3/3 had significantly higher average E-S and total scores compared with an existing score than those with grade 0/3 or 1/3 (p < 0.001).

Bottom Line: HRE-S is a valid and reliable score evaluating disease severity in trigeminal-mediated headshaking, independent of observers' experience.

Why I chose this article

Currently, trigeminal-mediated headshaking disease severity is subjectively assessed. This paper discusses a scoring system for disease severity that includes assessment of the history, rest and exercise. 

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Edward J. Knowles, Patricia A. Harris, Jonathan Elliott, Yu-Mei Chang, Nicola J. Menzies-Gow

Article Summary

Serum insulin concentration at 60 min (InsulinT60) during an oral sugar test (OST) indicates future laminitis risk and insulin dysregulation (ID). Associations between InsulinT60 and physical and owner-reported variables may help clinicians select individuals for ID testing. Associations between InsulinT60 and other metabolic markers may help elucidate ID pathophysiology. The aims of this prospective longitudinal study were to A) Describe associations between binary InsulinT60 status and season, and physically apparent and owner-reported data to inform strategies to target ID screening; and B) Describe more complex associations between continuous InsulinT60 and other metabolic markers, owner-reported data and physical features to indicate relationships relevant to ID pathophysiology.

Non-laminitic ponies were examined and OSTs (0.3 mL/kg Karo syrup) performed every 6 months (autumn and spring) for ≤4 years. Factors associated with InsulinT60 were determined using mixed-effects models with physical, owner-reported, season and serum/plasma markers as fixed effects and pony and premises identifiers as random effects. 

One thousand seven hundred and sixty-three OSTs from 367 ponies were included. High-risk InsulinT60 (>153 μIU/mL) was independently associated with (odds ratio, 95% confidence interval [CI]): age (1.36, 1.16–1.60), body condition score (BCS) (2.38, 1.21–4.69), and bulging supraorbital fat pads (7.25, 2.1–24.98). However, the initial models provided little explanatory power (Nakagawa R2 = 0.1–0.27). InsulinT60 was independently associated with (effect estimate, 95% CI): age (0.02, 0.01–0.04), Welsh/Welsh X breed (0.22, 0.05, 0.39), sex (gelding = −0.2, −0.34 to 0.06), BCS (0.16, 0.08–0.23), plasma adiponectin (−0.02, −0.02 to 0.01) and basal insulin (0.01, 0.01–0.01) in spring, and: age (0.03, 0.02–0.04), BCS (0.17, 0.08–0.26), bulging supraorbital fat pads (0.37, 0.2–0.54), turnout score (0.05, 0.02–0.09), plasma adiponectin (−0.01, −0.02 to 0.01), ACTH (per 10 pg/mL) (0.01, 0.00–0.01), triglycerides (0.28, 0.07–0.49) and InsulinT0 (0.01, 0.01–0.01) in autumn.
 

Bottom line: Season, owner-reported and physical features only explained 10%–27% of the differences in InsulinT60 risk status in this population. Thus, while physical and owner-reported features can be used to suggest ponies with a higher risk of ID, veterinarians should not limit testing for ID to ponies in which these risk factors are present. 

Why I chose this article

Screening for early detection of ID is likely to be useful for the prevention of laminitis and ideally ponies at higher risk of ID would be selected for further testing based on their signalment.

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Frances J. Peat, Christopher E. Kawcak, C. Wayne McIlwraith, David P. Keenan, Jeffrey T. Berk, Daniel S. Mork

Article Summary

Subchondral lucencies in the distal aspect of the medial femoral condyle of young Thoroughbred horses are a source of controversy on presale radiographs. There is limited scientific evidence regarding the risk of progression and impact on future racing performance. The aims of this prospective cohort study were to (1) identify the prevalence of medial femoral condyle subchondral lucencies on sales repository radiographs in yearling and 2-year-old Thoroughbreds; (2) identify any association between grade of medial femoral condyle subchondral lucencies and future racing performance and (3) monitor changes in medial femoral condyle subchondral lucencies grades between yearling and 2-year-old sales.

Radiographs were obtained from a 2016 yearling sale and five 2017 2-year-old sales. Stifle radiographs were evaluated and medial femoral condyle subchondral lucencies graded on a scale of 0–3. Axial medial femoral condyle lucencies were recorded separately. Maximum medial femoral condyle grades per horse were analysed for associations with racing performance outcomes, adjusted for sex, to the end of the horses' 4-year-old racing year.

Radiographs from 2508 yearlings (5016 stifles) and 436 2-year-olds (872 stifles) were included in the study. Medial femoral condyle subchondral lucencies of grades 1–3 were observed in 242 (9.65%) yearlings and 49 (11.2%) 2-year-olds. Bilateral medial femoral condyle subchondral lucencies of grades 1–3 were observed in 54 (2.2%) yearlings and 12 (2.8%) 2-year-olds. Grade 1 medial femoral condyle subchondral lucencies in yearlings either remained unchanged (14/31), progressed to a grade 2 (6/31) or resolved (11/31) by the 2-year-old sale. Grade 2 medial femoral condyle subchondral lucencies in yearlings remained unchanged (6/10), progressed to a grade 3 (2/10) or improved to a grade 1 (2/10). Yearlings with grade 3 medial femoral condyle subchondral lucencies had a 78% probability of starting a race (95% confidence interval [CI] 58.2–89.6%), compared with an 84% probability of racing for grade 0 yearlings (95% CI 82.7–85.8%). Six of the seven yearlings with axial medial femoral condyle lucencies raced.

Bottom line: Grade 1 medial femoral condyle subchondral lucencies were the most common type seen in yearling and 2-year-old sales horses. The majority of yearling grade 1 medial femoral condyle subchondral lucencies resolved or remained static by 2-year-old sales. It was also possible for grade 2 and 3 medial femoral condyle subchondral lucencies to improve one grade between sales. Fewer sales yearlings with a grade 3 medial femoral condyle subchondral lucencies raced, but in those that did race there was no evidence of worse performance compared to unaffected peers. Axial medial femoral condyle lucencies did not affect racing performance.

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Lauren Huggins, Jamie Norris, Alan Conley, Pouya Dini

Article Summary

Abnormal or undesired mare behaviours are often assumed to be associated with ovarian abnormalities. The aim of this retrospective descriptive study was to determine the incidence of abnormal behaviours and their association with concentrations of one or more ovarian hormones associated with a granulosa cell tumour (GCT).

A total of 2914 hormonal profile samples submitted with the words behave, behaviour, or behaving in the submission history were analysed. The association between reported abnormal behaviours and concentrations of testosterone, anti-Müllerian hormone (AMH), inhibins and inhibin-B were assessed.

Overall, 2506/2914 (86%) cases did not have any of the measured hormones reach GCT-like concentrations. The remaining 408 cases had either one (63%), two (25.5%), or three (11.5%) hormones with concentrations consistent with those from confirmed GCT cases. Testosterone had the lowest percent of GCT-like values among the cases (7.7%), compared with AMH (9.4%), inhibins (9.6%) and inhibin B (8.7%). Stallion-like behaviour was significantly associated with increased concentrations of all four hormones. In contrast, aggression, oestrous and other abnormal behaviours were significantly less likely to be associated with increased concentrations of the hormones.

Bottom line: Overall, the abnormal behaviours among mares, except the stallion-like behaviour, were not associated with increased ovarian hormones.

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Mary M. Durando, Joann Slack, Eric Birks, Carolyn Belcher, Catherine Kohn

Why I chose this article

There is increased interest in the reasons for and risk factors for sudden cardiac death in horses. However, less is known about frequency of premature depolarisations in normal horses. 

Article Summary

Injuries and sudden death during the cross-country (XC) phase of eventing have raised interest in the frequency and types of cardiac arrhythmias occurring in these equine athletes. The aim of this prospective, cross-sectional study was to characterise the frequency and types of rhythm disturbances and examine possible risk factors for premature depolarisations (PDs) occurring during the XC phase of United States Eventing Association (USEA) and Fédération Equestre Internationale (FEI)-sanctioned events.

Continuous electrocardiographic (ECG) recordings were obtained from 75 horses prior to, during and immediately following the XC competition. The frequency of PDs was calculated for all horses, as well as by division. PDs were categorised by complexity (singles, couplets, triplets, complex) and variably grouped for statistical analysis. Multiple logistic regression was used to identify risk factors for the presence of specific cardiac arrhythmia groupings during XC.

PDs were identified in 42/75 horses (56% [45, 67]) during XC. Horses competing in the upper divisions of eventing had higher odds for having any PD during XC compared to the lower divisions (OR = 17.5 [4.3, 72.01], p = 0.006). The amount of time the heart rate (HR) was greater than 199 beats per minute (BPM) was associated with more complex arrhythmias (triplets, salvos and tachyarrhythmias) (OR = 1.01 [1.0, 1.02], p = 0.005). An arrhythmia at rest (physiological or PD) was associated with arrhythmia in the early recovery period (OR = 3.5 [1.1, 10.8], p = 0.03).

Bottom line: PDs were seen in a high percentage of horses during the XC competition. Upper divisions and time the HR was greater than 199 BPM were related to PD presence and complexity.

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Kira Madsen, Ann Martens, Maarten Haspeslagh, Michael Meulyzer, Kajsa Gustafsson

Why I chose this article

In equine surgery, medical grade honey has been investigated as a protective measure against surgical site infections. However, the effect on suture material strength has not been investigated. 

Article Summary

Medical grade honey (MGH) has been introduced as a protective measure against surgical site infections in equine surgery, but the effect on suture material has not been investigated. The aim of the in vitro experiment was to evaluate the effect of medical grade honey on the tensile properties of three synthetic absorbable suture materials.

Ten strands of Polydioxanone USP 2 (PD2), Polyglactin 910 USP 2 (PG2) and Polyglecaprone USP 2-0 (PC2-0) were incubated for 1, 7, 14, 21 and 28 days in MGH, phosphate-buffered saline, equine plasma and medical grade honey mixed with equine plasma. Mechanical testing was performed recording maximum load at failure (N), strain at failure and Young's modulus (N/mm2). 

PD2 in medical grade honey had a significantly higher tensile strength compared to PD2 in equine plasma (p < 0.05, mean difference (md) = 16.95 N, CI 95% (9.19–24.70 N)) and phosphate-buffered saline (p < 0.05, md = 14.48 N CI 95% (6.73–22.23 N)) on day 7 and the remaining time points. PG2 incubated in medical grade honey had a significantly higher tensile strength compared to equine plasma (p < 0.05, md = 69.28 N CI 95% (64.16–74.40 N)) and phosphate-buffered saline (p < 0.05, md = 56.90 N CI 95% (51.78–62.02 N)) until day 28. PC2-0 incubated in medical grade honey had a significantly higher tensile strength compared to equine plasma (p < 0.05 md = 12.40 N CI 95% (4.59 N–20.20 N)) and phosphate-buffered saline (p < 0.05 md = 11.23 CI 95% (3.42–19.03 N)) on day 7 and the remaining time points.

Bottom line: Medical grade honey did not negatively affect the tensile strength of the suture material and can safely be applied in contact with suture materials commonly used in equine surgery.

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Pearce Sloan, Brad White. Elizabeth Santschi

Why I chose this article:

OCD is a common finding in Thoroughbred yearlings’ sales radiographs and yet there is no clear consensus on the effect on racing outcomes.

Article Summary:

Osteochondrosis dissecans (OCD) is common in the femoropatellar joint in Thoroughbred yearlings for sale at auction and there is no consensus on the effect on racing outcomes. The aim of this retrospective case–control study was to describe femoropatellar OCD in juvenile Thoroughbreds and compare the racing performance of affected horses to siblings and unaffected horses from the same sale.

Radiographic reports from 27 Thoroughbred auctions of weanling (5–11 months of age) and yearling (12–22 months of age) horses were reviewed to identify femoropatellar OCD. Age and sex of affected and unaffected animals were obtained from the sales catalogue. Racing performance was obtained from an online database. Correlation between lesion characteristics and racing performance were assessed using Pearson and Spearman correlations for continuous and ordinal/categorical variables respectively. Racing performance was compared between affected animals and two unaffected controls for each affected animal (a maternal sibling and an age- and sex-matched animal from the same sale) with Poisson distribution and log link. 

Femoropatellar OCD was identified in 429 horses with North American race records. OCD was present on 519 lateral trochlear ridges and 54 medial trochlear ridges. There were more males in the affected group (70%) than in the sibling unaffected group (47%). Case racing performance was compared to 1042 sibling and 757 sale matched controls. There were significant but small decreases in racing metrics of affected animals and increases in males for years raced, total starts, starts for 2–5 years of age, total placings, and placings at 2–4 years of age. Analysis of specific lesion metrics revealed weak correlations for performance outcomes (positive and negative) resulting in an inability to draw firm conclusions.

Bottom line: Femoropatellar OCD in juvenile Thoroughbreds for sale at auction decreases some racing outcomes.

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Heather Roe, Margo Macpherson, Thomas Denagamage, Scott Hopper, Brett Woodie, Rolf Embertson

Why I chose this article:

There is limited data regarding mortality outcomes in mares and foals, when mares are recumbent at admission for dystocia.

Article Summary:

Mare and foal survival are increased with prompt dystocia management. Data regarding mortality outcomes in mares and foals, when mares are recumbent at admission for dystocia resolution, are scarce. The aim of this retrospective cohort study was to evaluate recumbency at hospital admission as a risk factor for survival of mares and foals following dystocia management. Subsequent mare fertility was also evaluated.

Data were obtained from medical records at Rood and Riddle Equine Hospital of mares with dystocia between 1995 and 2018. Mare signalment, ambulation status, survival data and foaling records were collected. The proportion of mare survival and mare fertility were analysed using chi-squared tests. Foal survival was analysed using Fisher's exact test. Odds ratios were calculated using multivariable logistic regression.

There were 1038 ambulatory mares and 41 recumbent mares included in the analysis. Survival rates after dystocia resolution were 90.5% (977/1079) in mares and 37.3% (402/1079) in foals. Ambulatory mares had higher odds of survival (OR 6.93, 95% CI: 3.25–14.78, p < 0.001) than recumbent mares. Foals delivered from ambulatory mares had higher odds of survival (OR 22.7, 95% CI: 3.11–165.44, p = 0.002) compared with foals delivered from recumbent mares. Fertility was not statistically different for surviving Thoroughbred mares within 3 years following dystocia resolution between ambulatory and recumbent mares.

Bottom line: Mare and foal survival was significantly decreased when mares with dystocia were recumbent at hospital admission, but subsequent mare fertility was not affected by ambulatory status.

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Sanni Hansen, Nina D. Otten, Liv Spang-Hanssen, Christine Bendorff, Stine Jacobsen

Why I chose this article:

NGAL is a promising biomarker in humans for inflammation and as a potential biomarker for asthma. The feature of neutrophils on BAL in equine asthma (EA) make NGAL a potential biomarker for EA, which warrants further research. 

Article Summary:

Studies in people have found neutrophil gelatinase-associated lipocalin (NGAL) concentrations are increased in asthma and can be used to distinguish between asthma subtypes. NGAL has not yet been investigated in equine asthma (EA). The aim of this retrospective cross-sectional study was to investigate the ability of NGAL concentrations in bronchoalveolar lavage (BAL) fluid and serum to distinguish between control horses, horses with mild–moderate EA (MEA) and horses with severe EA (SEA).

Details of endoscopic examination including tracheal mucus score (TMS, scale 0–5) and BAL cytology performed on 227 horses were extracted from records and NGAL concentrations were measured on stored serum and BAL fluid samples. The horses were divided into three groups (control group n = 73, MEA n = 98, SEA n = 56) based on clinical signs and BAL cytology results. Differences between groups and correlations between BAL NGAL, serum NGAL, and BAL cytology were evaluated.

BAL NGAL concentrations were higher in EA than in control horses (median: 25.6 and 13.3 μg/L, respectively, p < 0.001). Concentrations of NGAL in BAL differed between groups, with higher concentrations in MEA than in control horses (median: 18.5 and 13.3 μg/L, respectively, p < 0.001), and higher concentrations in SEA than in MEA horses (median: 54.1 and 18.5 μg/L, respectively, p < 0.001). BAL NGAL concentration differed between horses with TMS ≤2 an >2 (median 15.6 and 21.1 μg/L, respectively, p = 0.004). No differences were found in serum NGAL concentration between any of the groups.

Bottom line: BAL NGAL concentration differed between control and EA and reflected severity of disease. These results justify further research into the potential of NGAL as a biomarker of EA.

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Tania Sundra, Erin Kelty, David Rendle

Why I chose this article:

Treatment at 5-day intervals might be more effective than 7-day intervals as it would avoid the drop in gastric pH between Days 4 and 7. Pending larger clinical trials, these results may suggest that the extended-released injectable omeprazole formulation might have the potential to resolve EGGD lesions more rapidly than other treatments.

Article Summary:

An extended-release injectable omeprazole formulation (ERIO) has become a popular treatment for equine squamous gastric disease (ESGD) and equine glandular gastric disease (EGGD) where it is available; however, published data are limited and optimal treatment regimens have not been determined. The aim of this retrospective clinical study was to compare effects of treatment on ESGD and EGGD when an ERIO formulation is administered at either 5- or 7-day intervals.
Case records and gastroscopy images of horses with ESGD or EGGD treated with ERIO were reviewed. Images were anonymised and graded by one researcher masked to treatment group. Treatment responses were compared between the two treatment schedules using univariable ordered logistic regression.
Forty-three horses were treated with ERIO at 5-day intervals and 39 horses at 7-day intervals. Signalment and presenting signs did not differ between groups. The proportions of horses with EGGD healing (to grade 0 or 1) in association with ERIO used at 5-day intervals (93%) were higher than associated with treatment at 7-day intervals (69%; odds ratio [OR]: 2.41, 95% CI: 1.23–4.74, p = 0.01). For ESGD, there was no significant difference in the proportion of horses healing in association with treatment at 5-day intervals (97%) compared with 7-day intervals (82%; OR: 2.75, 95% CI: 0.91–8.31, p = 0.07). Four of 328 injections were associated with an injection-site reaction (1%).
Bottom line: The use of ERIO at 5-day intervals might be more appropriate than the 7-day interval that is used currently for EGGD.

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Janna Evelina Cornelia Goldkuhl, Yury Zablotski, Volker Sill, Werner Jahn, Ina Lorenz, Jan Brunk, Kerstin Gerlach, Antonia Troillet

Why I Chose This article:

There is conflicting information regarding the need for prophylactic removal in sound horses without clinical signs and the degree of cartilage damage caused by fragments. 

Article Summary:

Osteochondral fragment removal is commonly performed but there are little scientific data supporting this procedure in the absence of clinical signs. More information is needed to facilitate clinical decision-making regarding fragment removal of the metacarpo−/metatarsophalangeal joint. The aim of this retrospective observational study was to assess prevalence of cartilage injury in the equine metacarpo−/metatarsophalangeal joint and its association to fragment size, location, age and lameness. The hypothesis was that (1) Fragments in the dorsal compartment of the MCP/MTP joint result in more clinical signs (lameness) and arthroscopic findings (cartilage injury and synovitis) than fragments in the palmar/plantar compartment; (2) Fragments >5 mm contribute to more visible cartilage lesions and synovitis; (3) MCP/MTP joints of older horses are more likely to present cartilage injury than those of younger horses. 

Clinical records including radiographs of 823 metacarpo−/metatarsophalangeal joints (640 horses) that underwent arthroscopic fragment removal were reviewed. Fragment size, intra-articular fragment location and cartilage injury score were recorded. Presence of synovitis was retrospectively evaluated in 157 joints. 

Cartilage injury was present in 28.8% (95% CI = 25.8–32.0) of joints. Lameness was not associated with fragment location or fragment size. Fragment size was not associated with cartilage injury. Age (OR = 1.35, 95% CI = 1.22–1.48, p < 0.001) and lameness (OR = 5.03, 95% CI = 2.27–11.68, p < 0.001) were associated with cartilage injury as well as fragment location (palmar/plantar, OR = 0.22, 95% CI = 0.13–0.38, p < 0.001), with dorsal fragments being more likely to be associated with cartilage lesions than palmar/plantar fragments. There was a significant association between age and mean cartilage score (b = 0.18, 95% CI = 0.14–0.22, p < 0.001).

Bottom Line: There was no association between radiographic fragment size, presence of synovitis and cartilage injury. The likelihood of a joint presenting with cartilage lesions increases with dorsal fragmentation, lameness and older age. Early fragment removal, especially in joints with dorsal fragmentation, could be beneficial to avoid future cartilage injuries in equine athletes.
 

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Heather A. Cameron-Whytock, Tim D. H. Parkin, Sarah J. Hobbs, Charlotte V. Brigden, Euan D. Bennet

Why I Chose This Article:

Research that aims to identify risk factors for horse falls is needed to highlight potential areas for prevention and set priorities for future research. 

Article Summary:

Equestrian eventing is a dangerous Olympic sport, with 16 rider and 69 horse fatalities at competition in the last 10 years. Despite this, there is limited research that aims to improve safety within the sport. The aim of this retrospective cohort study was to identify risk factors for horse falls, which are the leading cause of rider fatality within the sport.

Competition data between January 2005 and December 2015 were analysed. Descriptive statistics followed by univariable logistic regression to identify risk factors for inclusion in a multivariable logistic regression model were conducted. A total of 749,534 cross-country starts were analysed for association with the risk of horse falls.

Sixteen risk factors were identified including: higher event levels, higher dressage penalties and higher number of days since horses' last start. For example, horse and rider combinations competing at BE100 (OR 1.64, CI 1.37–1.96, p < 0.001), Novice (OR 3.58, CI 3.03–4.24, p < 0.001), Intermediate (OR 8.00, CI 6.54–9.78, p < 0.001), Advanced (OR 12.49, CI 9.42–16.57, p < 0.001) and International (OR 4.63, CI 3.50–6.12, p < 0.001) all had a higher risk of having a horse fall in comparison to combinations competing at BE90 level. Riders that had a horse fall during their previous start (OR 2.39 [1.62-3.53]) were more likely to fall during their current start. Horses competing in their first start (OR 2.06 [1.36-3.12]) were more likely to have a horse fall than horses that had started in the previous 1-14 days. Furthermore, for every additional 10 dressage penalties awarded to a horse and rider combination, there was a higher risk of a horse fall (OR 1.20, CI 1.12–1.28, p < 0.001).

Bottom line: The study results should be utilised by sport governing bodies to inform policy which has the potential to reduce the risk of injury and fatality to sport participants. 

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Virginia Melly, Kyla F. Ortved, Timothy J. Manzi, Dean W. Richardson, Darko Stefanovski, Kathryn B. Wulster

Why i Chose This Paper

It is the first to describe a previously unreported site of tarsal subchondral bone injury in Thoroughbred racehorses.

Article summary

Increasing accessibility and advancements in computed tomographic (CT) imaging improve understanding of the contributors to poor performance in the Thoroughbred racehorse. The aim of this retrospective, cross-sectional analytical study was to characterise an unreported site of tarsal subchondral bone injury (SBI) in Thoroughbred racehorses.

Tarsal CT scans of 108 horses were reviewed for evidence of SBI in the dorsodistolateral calcaneus (DDLC). Signalment, including age, breed, sex, and discipline of horses, was recorded. The association of DDLC SBI with Thoroughbred racehorse compared to other breeds/disciplines was calculated. Nuclear scintigraphic scans of the hindlimbs of Thoroughbreds between 2007 and 2022 were also reviewed for increased radiopharmaceutical uptake (IRU) suggestive of DDLC SBI.
DDLC SBI was identified in tarsal CT scans of 8/108 (7.3%) horses. All lesions were found in racing Thoroughbreds and in 20% (8/40) of racing Thoroughbreds that underwent tarsal CT. DDLC SBI was determined to be the primary cause of lameness in 3/8 animals. Third tarsal bone fracture was considered the primary cause of lameness in a further 3/8 horses. A total of 1663 nuclear scintigraphic scans of 1603 Thoroughbred horses were reviewed. Increased IRU in the DDLC was present in 13 horses (0.9%).

Bottom line: The DDLC is a previously unreported site of SBI in the Thoroughbred racehorse. The lesion can be the primary source of lameness but may also be found in horses with other clinically relevant osseous injuries. 

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Susanne A. Kolding, Johnny N. Sørensen, Joanne Kramer, Megan J. McCracken, Shannon K. Reed, Kevin G. Keegan

Why i Chose This Paper

The prevalence of increased head height asymmetry after palmar digital nerve block finding, or what it means clinically, has not been reported in peer-reviewed literature.

Article Summary

Some horses increase in forelimb lameness, measured as vertical head height asymmetry, or differences in maximums and minimums of head heights (HDmax, HDmin), after a palmar digital nerve (PDN) block. The aim of this retrospective case series was to estimate the prevalence of increasing head height asymmetry after a PDN block and determine if this is associated with cause of forelimb lameness.

Head height asymmetry, normalised to expected vertical head displacement, from inertial-sensor data collections of all horses evaluated for forelimb lameness while trotting in a straight line at two different clinics were screened for cases that had an initial PDN block and then another more proximal block in the same limb during the same lameness evaluation. Medical records of the screened cases (n = 213) were evaluated to determine the cause of lameness. Prevalence of increasing head height asymmetry was calculated. Differences in lameness amplitude between groups of cases that remained unchanged (Group 1), that increased (Group 2), and that decreased (Group 3) in head height asymmetry before and after the initial PDN block were compared (Kruskal-Wallis). Determination of the location of the cause of lameness and final diagnoses of cases were compared between Group 1 and Group 2 (chi-squared tests of independence).
The PDN block increased head height asymmetry at a prevalence of 32.5% (95% 4.5%–41.5%) and 13.8% (95% CI 7.3%–22.9%), in clinic 1 and 2, respectively. Increasing head height asymmetry after an initial PDN block did not predict localization of the cause of forelimb lameness or specific diagnosis, other than indicating that it is unlikely to be in the foot (p = 0.02).

Bottom line: Increasing head height asymmetry after PDN block is common during forelimb lameness evaluations. Other than indicating that the cause of lameness is more proximal in the blocked forelimb, this does not help determine the final diagnosis.
 

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Annamaria Nagy, Sue Dyson

WHY I CHOSE THIS PAPER

The safety of this procedure is based largely on anecdotal evidence and there are no detailed data on complications of sacroiliac joint region injections. 

ARTICLE SUMMARY

The aim of this cross-sectional questionnaire survey was to describe complications following diagnostic, therapeutic, and combined sacroiliac (SI) joint region injections and the details of how these are routinely performed by a large number of clinicians.

Clinicians (members of American and European specialist colleges and veterinarians known to the authors) who had performed ≥1 SI joint region injection were invited to complete an online questionnaire. Data collected included the clinicians’ experience in diagnostic, therapeutic and combined SI joint region injections, details of the injection technique, volume and substance used, and the type of complications seen following SI joint region anaesthesia, medications, and combined injections, respectively. Descriptive data analysis was performed and the association between any complications seen, and the clinicians’ experience, technique, volume, and substance used were assessed using binary logistic regression.

Of the 212 respondents, 110 had performed diagnostic, 187 therapeutic and 49 combined injections. Clinicians experienced significantly more complications after diagnostic (53/110) than after therapeutic (33/187) or combined (6/49) injections (p<0.01). Most clinicians used a cranial contralateral blind approach for diagnostic injections (74/110). The most common complications were hindlimb weakness/ataxia after all types of injections (diagnostic: 44/110, 40%, 95% CI 30.8-49.8; therapeutic: 15/187, 8.0%, 95% CI 4.6-12.9; combined: 2/49, 4.1%, 95% CI 0.5-14.0). Death or horses requiring euthanasia were reported (after therapeutic injections: 5/187; diagnostic injections: 1/110).

Bottom Line: Complications were experienced more commonly following diagnostic injections than after therapeutic or combined SI joint region injections, but the types and distribution of complications were similar. 

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Rachel O. Salz, Christopher R. B. Elliott, Tomas Zuffa, Euan D. Bennet, Benjamin J. Ahern

Why I Chose this paper

Given the advantages and disadvantages of each treatment technique, knowing the efficacy of bone marrow derived (BM-MSCs) compared to adipose derived stem cells (A-MSCs) and controlled exercise is undoubtedly important. This paper is the first to compare racing outcomes of flat racing Thoroughbred horses that received treatment of superficial digital flexor tendon injury with BM-MSCs or A-MSCs compared to a controlled exercise rehabilitation programme alone.

ARTICLE SUMMARY

Overstrain of the superficial digital flexor tendon (SDFT) is a common Thoroughbred racehorse limb injury requiring treatment. Using clinical treatment records with race records, the aim of this retrospective cohort study was to determine whether treatment of SDFT lesions in flat Thoroughbred racehorses with autologous bone marrow-derived mesenchymal stem cells (BM-MSCs) or allogenic adipose-derived mesenchymal stem cells (A-MSCs) is associated with improved likelihood of returning to racing, when compared to racehorses managed with a controlled exercise rehabilitation programme alone.

A total of 213 Thoroughbred racehorses were identified. All were prescribed the same 12-month controlled exercise rehabilitation programme; 66 also received intralesional BM-MSC and 17 received A-MSC treatment. Follow-up was a minimum of 2 years after return to full race training. Multivariable logistic regression models were used to investigate associations between the treatments and the likelihood of returning to racing and completing five or more (C5+) races post-injury.

Compared to controlled exercise rehabilitation programme alone, BM-MSC treatment was associated with increased odds of returning to racing (OR 3.19; 95% CI 1.55–6.81) and C5+ races post-injury (OR 2.64; 95% CI 1.32–5.33). Older age and increasing lesion length were associated with a reduced likelihood of returning to racing. Male sex and increased number of pre-injury starts were associated with increased odds of returning to racing. There was no observed increased likelihood of return to racing or C5+ races associated with treatment with A-MSCs compared to controlled exercise rehabilitation programme alone.

Bottom Line: Intralesional BM-MSC treatment was associated with an increased likelihood of returning to racing and C5+ races post-injury compared to controlled exercise rehabilitation programme alone. Intralesional A-MSC showed no significant benefit.

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Erica Lyn Macon, Patricia Harris, Simon Bailey, Ashley Caldwell Barker, Amanda Adams

Why I chose this article

To help develop appropriate diet recommendations and guidance for ID horses.

Article Summary

Identifying intake levels of nonstructural carbohydrates (NSC) that limits the postprandial insulinaemic response in the insulin dysregulated (ID) horse may help reduce hyperinsulinaemia-associated laminitis (HAL) risk. The aim of this randomised crossover study was to determine if ID horses have thresholds for pure sources of starch and sugar above which there is an augmented insulin response.
Fourteen adult horses (6 ID and 8 non-insulin dysregulated, NID; matched for bodyweight) were fed eight dietary treatments in a randomised order. Dietary treatments were formulated using a base of low-nonstructural carbohydrate pellet (LNSC; 0.04 g of water-soluble carbohydrates [WSC]/kg bwt and 0.01 g of starch/kg bwt), to which pure sugar (dextrose) or starch (50:50 mix of waxy-maize and oat starch powder) sources were titrated to create diets with increasing amounts of either WSC (0.06–0.17 g WSC/kg bwt), or starch (0.03–0.1 g starch/kg bwt). Horses were fed each dietary treatment at a rate of 1 g/kg bwt once over 12 weeks. Serial blood samples were collected pre- and up to 240 minutes postprandially. Serum insulin concentrations were determined using a validated radioimmunoassay and diet analytes were determined via wet chemistry. Statistical analysis was performed with a mixed effect model. Positive incremental area under the curve for insulin (IAUCi) was calculated for all horses and dietary treatments.
There was no significant effect of diet on IAUCi within NID horses, but ID horses had an increased IAUCi for diets between 0.07–0.13 g of total NSC/kg bwt, depending on the starch and sugar composition, compared with the LNSC (p<0.05). IAUCi in ID horses were also significantly different to all NID for diets with NSC > 0.1 g/kg (p<0.04). 
Bottom Line: Based on this study, using supplemental pure starch and sugar sources, ID horses seem to have an apparent threshold for NSC of around 0.1 g/kg bwt/meal, above which significantly increased insulin responses are seen compared to NID horses.

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Veronica Lynn Edwards, Shavahn Loux, Rolf Embertson

Why I chose this article

Evaluating the economic and performance impacts of surgical large colon displacements is important to help advise owners regarding prognosis prior to surgery and when purchasing horses. 

Article Summary

Juvenile Thoroughbreds can be expensive to raise and train to race. Part of the economic return in these juveniles are the weanling, yearling, and 2-year-old in training sales at which major surgeries must be declared. The aim of this retrospective cohort study was to determine if surgically corrected large colon displacements were associated with a reduction of sales price and racing performance.
The medical, sales and racing records of 110 horses less than 2 years old that had a surgical diagnosis of large colon displacement between 1998 and 2016 were examined. Surgical cases were compared to their maternal progeny born prior to 2016 (3 maternal siblings as close in age as possible for each case; total control group n = 299) whose sales and racing data were evaluated.
There was no significant difference in median sale price overall between the two groups. Horses undergoing surgery had a reduced number of starts in the 2-year-old year (1 start; p< 0.001) when compared to control horses (2.32 starts), but there was no significant difference over the 2- to 4-year-old period. There was no significant association with surgery on earnings within the 2- to 4-year-old period of racing when compared to controls.
Bottom Line: Overall, the results of this study suggest that if the juvenile Thoroughbred requires surgery for a large colon displacement, there is minimal association with sales price or race performance compared to their siblings. 

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Emma Partridge, Emma Adam, Courtney Wood, Jordan Parker, Mackenzie Johnson, David Horohov, Allen Page

Why i Chose This Article

The long-lasting effects of intra-articular corticosteroids may improve clinical signs before articular pathology has resolved. This can potentially lead to the masking of musculoskeletal injuries, which may then become exacerbated during exercise and performance. 

Article Summary

Intra-articular (IA) corticosteroids are regularly used in equine athletes for the control of joint inflammation. The aim of this cross-over randomised trial was to utilise an acute synovitis inflammation model to determine the residual effects of IA betamethasone and triamcinolone acetonide on various inflammatory parameters and lameness.
Five mixed-breed 2-year-old horses were randomly allocated to an IA treatment of the radiocarpal joint with 9 mg of either betamethasone or triamcinolone acetonide. Two weeks following treatment, horses were injected with 1μg of lipopolysaccharide (LPS) diluted in 1 mL of saline. Following LPS injection, horses were crossed-over and both sets of injections repeated. Blood samples were collected at multiple time points for mRNA analysis, as well as serum amyloid A (SAA) and cortisol concentration determination. At each time point, lameness was also subjectively scored. Additional injections with saline-only or LPS-only (twice) were conducted as negative and positive controls, respectively. 
Corticosteroid-only treatment results in significant mRNA expression differences, as well as significant and prolonged cortisol suppression. Following LPS injection, there was a residual treatment effect with triamcinolone evidenced by a significant treatment effect on IL-6 and PTGS1 (cyclooxygenase-1), lameness, SAA, and cortisol concentrations, while only IL-6 expression was affected by betamethasone.
Bottom Line: The commonly used intra-articular corticosteroid triamcinolone acetonide has residual anti-inflammatory effects two weeks after administration. Within the context of current racing and competition requirements, this would suggest that 14 days may not be long enough if the concern is that the drug may maintain performance enhancing effects via its anti-inflammatory properties. Additionally, administration of intra-articular corticosteroids is not without risk, as evidenced by significant suppression of serum cortisol and so the benefits of their administration should be weighed against those risks. 

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Sarah E. Allen, Kristien L. P. Verheyen, Dan G. O'Neill, Dave C. Brodbelt

Why I Chose This Paper

This study provides much needed benchmarks to guide ongoing improvement in AMU in UK equine practice. Several equid and practice factors were associated with increased use of systemic and Category B antimicrobials which should encourage more targeted intervention in high usage groups. 

Article SummarY

Judicious antimicrobial use (AMU) is important for preserving therapeutic effectiveness. Large-scale studies of antimicrobial prescribing can provide clinical benchmarks and help identify opportunities for improved stewardship. The aim of this retrospective cohort was to describe systemic AMU in UK equine practice and identify factors associated with systemic and Category B (third and fourth generation cephalosporins, fluoroquinolones and polymixins) AMU.
Anonymised electronic patient records (EPRs) for all equids attended by 39 UK veterinary practices between 1 January and 31 December 2018 were collected via the VetCompass programme. Systemic antimicrobial prescriptions were identified using electronic keyword searches. Indications for AMU were determined through manual review of a randomly selected subset of EPRs. The types and frequency of systemic antimicrobials prescribed, and indications were summarised using descriptive statistics. Mixed-effects logistic regression was used to evaluate practice- and horse-related risk factors.
Systemic antimicrobials were prescribed to 12,538 (19.5%, 95% confidence interval [CI]: 19.2%–19.8%) of 64,322 equids attended in 2018. Category B antimicrobials were prescribed to 1.9% (95% CI: 1.8%–2.0%) of attended equids and in 8.9% (95% CI: 8.5%–9.4%) of antimicrobial courses. Bacteriological culture was performed in 19.1% (95% CI: 17.1%–21.3%) of Category B antimicrobial courses. For courses including Category B antimicrobials, they were used as first-line therapy in 947 cases (71.7%, 95% CI: 69.2%–74.2%). The most commonly prescribed antimicrobial classes were potentiated sulphonamides (50.2% of equids receiving antimicrobials) and tetracyclines (33.5% of equids receiving antimicrobials). Integumentary disorders were the most common reason for systemic AMU (40.5% of courses). Urogenital disorders were the most common reason for Category B AMU (31.1% of courses). Increased odds of systemic and Category B AMU were observed in equids <1 year compared with those aged 5–14 years. Breed was associated with AMU, with odds of systemic and Category B AMU highest in Thoroughbreds and Thoroughbred crosses. 
Bottom line: Empirical use of Category B antimicrobials remains commonplace with intrauterine therapy as the most common reason for use.
 

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Danielle L. Gordon, Jonathan H. Foreman, Sara L. Connolly, Amy N. Schnelle, Timothy M. Fan, Anne M. Barger

Why I Chose This Paper

Serial markers of inflammation can be used to monitor patient responses to antimicrobial therapy, such as IM procaine penicillin G (PPG). Therefore, an increase in these markers in response to therapy with IM PPG should be considered when these test results are interpreted.  

Article summary

Acute phase protein (APP) measurement is used to detect inflammation. Intramuscular (IM) injections could cause tissue injury and induce an acute phase response. The aim of this prospective longitudinal study was to evaluate the effects of IM procaine penicillin G (PPG) injections on APP concentrations in horses.
PPG was administered intramuscularly to six healthy horses, twice daily, for 5 days. Plasma fibrinogen (FIB), serum amyloid A (SAA), haptoglobin (HAP), creatine kinase (CK), and aspartate aminotransferase (AST) were quantified daily for 5 days before the first injection, during the course of administration, and for 4 days after the final dose. 
CK was increased over baseline on days 1-6 and AST was increased above baseline on Days 2-7 and 10. Increased FIB was noted over baseline on Days 6-8 and 10. Clinically significant increases in SAA were noted in half the horses over several days, but, due to the wide individual variability, SAA was only statistically significantly increased above baseline on Day 6. There was no change in HAP. 
Bottom Line: Serial IM PPG injections may result in increased concentrations of some acute phase proteins in horses and this must be considered when these test results are interpreted. 

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Katrijn D. Whisenant, Alan J. Ruggles, Darko Stefanovski, J. Brett Woodie, Scott A. Hopper, Rolf M. Embertson

Why I Chose This Paper

Haematogenous septic arthritis is a major cause of morbidity and mortality in foals and whilst previous studies have found decreased survival with multiple joint involvement, there are few studies evaluating the prognosis of single joint septic arthritis. 

Article Summary

Haematogenous septic arthritis is a major cause of morbidity and mortality in foals. Previous research has demonstrated a variable prognosis for athletic performance in foals diagnosed with septic arthritis. Most studies have analysed a diverse group of subjects with cases having multiple joint involvement and significant comorbidities and have found decreased survival with multiple joint involvement compared to a single affected joint.
The aim of this retrospective cohort study was to determine the racing prognosis for Thoroughbred foals, 6 months of age or less with a single septic joint of presumed haematogenous origin without recognised systemic sepsis or other serious comorbidity compared with a group of maternal sibling controls.
Data were collected from in-patient records from 2009 to 2016. Parameters evaluated included diagnostic tests, therapeutic regimens, final diagnosis, and outcome. Racing records were obtained from a public archive for cases and two maternal siblings. Racing performance data was collected for the number of starts, age at first race, number of wins/places/shows and total winnings per career. Univariable analyses of categorical variables were conducted.
Ninety-five cases were included in this study, of which 93% survived to discharge. The last measured synovial cell count prior to hospital discharge or euthanasia (OR 0.5, p value 0.002, 95% CI: 0.3–0.8) was an indicator of poor prognosis for survival to discharge. In cases nonresponsive to treatment, the last SNCC was measured prior to euthanasia was higher (median 86,800 cells/μL; IQR 30,600–113,200 cells/μL) than the final measured SNCC in cases discharged alive from the hospital (median 7200 cells/μL; IQR 800–91,600 cells/μL). Total winnings per career were the only statistically significant racing performance variable between cases and paired controls (IRR 0.7, p value, 0.05, 95% CI: 0.5–0.99).
Bottom Line: The prognosis for survival was high (93%) and the prognosis to race was similar to healthy maternal siblings, but the total earnings were lower.

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Ann Kristin Barton, Anne Troppenz, Dana Klaus, Inga Lindenberg, Roswitha Merle, Heidrun Gehlen

Why I Chose This paper

Given the controversial use and inconclusive evidence for the efficacy of tongue ties, further evidence is warranted to determine the efficacy in racehorses.

Article Summary

There is contradictory evidence on the potential benefits of tongue ties on upper airway function and their efficacy in inhibiting intermittent dorsal displacement of the soft palate (DDSP) in racehorses. The aim of this prospective, crossover blinded clinical study was to test the hypothesis that tongue ties increase the pharyngeal diameter and decrease the occurrence of dynamic airway obstruction in racehorses.
Data from 22 Thoroughbred and 8 Standardbred racehorses examined using overground endoscopy under full-intensity exercise on training racetracks with and without fixation of the tongue by use of tongue ties were analysed. Equivalent exercise intensity was ensured by measuring heart rate (bpm), speed (GPS) and venous lactate. Pharyngeal diameter was expressed as pharyngeal:epiglottis (PE) ratios and laryngeal abduction accordingly as laryngeal:median ratios. Data were analysed using multivariable repeated-measurements ANOVA.
The PE ratio increased significantly from 1.11 ± 0.19 to 1.28 ± 0.30 in all horses between rest and full-intensity exercise (P < 0.01). This effect decreased significantly by the application of tongue ties (1.15 ± 0.27, P < 0.01). Tongue ties did not influence maximum laryngeal width (P = 0.09) and area (P = 0.2) significantly. DDSP was found in 4/30 examinations with tongue tie and in 1/30 examinations without tongue tie.
Bottom Line: There was no positive effect of tongue ties on pharyngeal or laryngeal diameters; therefore, the results of this study do not support the use of tongue ties to enhance upper airway function.

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Fiona Bloom, Stephen Draper, Euan Bennet, David Marlin, Jane Williams

WHy I Chose This PAPER

Previous studies at FEI level have identified factors that have led to positive changes for horse welfare, but no studies have been performed at a national level in the UK. 

Article Summary

Horse welfare is a priority in the equine sport of endurance riding. Identification and reduction of risk factors associated with elimination and lameness has been the focus of research to date, however this has centred on international competition. National federations recognise there is a need to consider risk factors for elimination at a more local level. This retrospective cohort study aimed to determine current risk factors associated with horse eliminations, specifically lameness eliminations within British endurance.
Data were extracted from the Endurance GB database, for open and advanced horses, competing in rides >64 km in the 2017 and 2018 competitive seasons. Variables were analysed via univariable models which informed subsequent multivariable binary logistic regression modelling. Two models were completed, A: horse eliminated versus not eliminated and B: horse lame versus not lame.
1747 competitive starts were analysed; 542 horses were eliminated. Lameness accounted for 56.1% (n = 304) of eliminations. There was a decreased odds of lameness in graded rides compared with race rides (Adjusted Odds Ratio, OR 0.6; 95% Confidence Interval, CI 0.4-0.8). There were increased odds of elimination (OR 4.7, CI 3.5-6.5) and increased odds of lameness (OR 1.9, CI 1.2-3.06) when competing in FEI competitions of 2* and above, compared to rides run under national rules. Horses and riders who had not competed as a combination previously had increased odds of elimination (OR 2.2, CI 1.5-3.02).
Bottom Line: Competitive history of horses, including the number of previous starts, previous eliminations and the category of ride entered are significant in establishing the likelihood of an elimination and more specifically a lameness elimination in British national endurance.

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Miranda C. M. C. Dosi, Bruce C. McGorum, Roxane D. Kirton, Eugenio Cillán-García, Richard J. Mellanby, John A. Keen, Emma A. Hurst, Ruth A. Morgan

Why i Chose This paper

There are few peer reviewed equine-specific publications on vitamin D in horses and none in relation to endocrine function. 

Article Summary

Vitamin D deficiency is common in humans and is increasingly linked to the pathogenesis of a multitude of diseases including obesity and metabolic syndrome. The biology of vitamin D in horses is poorly described; the relative contribution of the diet and skin synthesis to circulating concentrations is unclear and associations with endocrine disease have not been explored. The aim of this cross-sectional cohort study was to determine the relationship between management, season and endocrine disease and vitamin D status in horses.
Plasma concentrations of 25-hydroxyvitamin D2 (25(OH)D2) and D3 (25(OH)D3) were measured by liquid chromatography-tandem mass spectrometry in 34 healthy unsupplemented grazing ponies and 22 stabled Thoroughbreds receiving supplementary vitamin D3 in feed. A nested group of 18 grazing ponies were sampled on long and short days (>12 and <12h of light/day) to determine the effect of sunlight exposure. Additionally, the relationships between age, sex, adiposity, serum insulin, adrenocorticotropic hormone and vitamin D status were assessed in a mixed group of 107 horses using a linear regression model.
All animals had measurable level of 25(OH)D2 (median 10.7 nmol/L) while 25(OH)D3 was only detected in Thoroughbreds receiving D3 supplementation. Thoroughbreds had lower concentrations of 25(OH)D2 than ponies (7.4 nmol/L versus 12.6 nmol/L p<0.01). In grazing ponies 25(OH)D2 concentrations were significantly higher on long-days compared to short-days (14.4 nmol/L versus 8.7 nmol/L p<0.01), while 25(OH)D3 was undetectable. Measures of increased adiposity, but not basal insulin, were associated with higher 25(OH)D2 concentrations, conversely to humans. Increasing ACTH was associated with lower 25(OH)D2 (p<0.01).
Bottom Line: In horses 25(OH)D2 is the predominant vitamin D metabolite, and there is an apparent lack of endogenous vitamin D3 production. The relationship between vitamin D and endocrine disorders in horses does not reflect that of other species.

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Fleur Whitlock, John Grewar, Richard Newton

Why I chose this Paper

This paper improves our understanding of the 2019 epidemic, which could help prevent outbreaks on a similar scale.

Article Summary

During 2019 an epidemic of equine influenza (EI) occurred in Europe. The aim of this retrospective descriptive study was to describe the epidemiology of the 2019 EI epidemic within GB.
Epidemiological data were obtained from veterinary surgeons referring samples for EI virus testing. Where available, data on confirmed cases and their wider resident population on EI-infected premises were collated and described. On a national level, spatial and temporal representations, consisting of choropleth maps and epidemic curves, described the spread of EI. EI-infected premises-level factors associated with the first of two epidemic phases were investigated using ordinary logistic regression analysis.
There were 412 confirmed cases and 234 EI-infected premises, with the first of two epidemic phases occurring between January and April, followed by a second phase through to August. The median age of confirmed cases was 5 years and sports horses (24%) and Cobs (16%) made up the highest proportions by general horse type and breed. Among confirmed cases 72% were unvaccinated and 18% were vaccinated against EI. New horses arriving within 2 weeks of a confirmed case were reported by 42% of EI-infected premises. Investigation of EI-infected premises biosecurity measures indicated that 23% quarantined new arrivals, 37% had isolation facilities and 57% of resident horses were vaccinated. EI-infected premises were more likely in the first than second epidemic phase to be classified as professional, have a vaccinated confirmed case and EI confirmed in a newly arrived animal.
Bottom Line: EI-infected premises generally had low levels of population vaccine coverage and implemented limited preventive biosecurity measures, particularly linked to horse movements.

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Ludovic Miagkoff, Christiane A. Girard, Guillaume St-Jean, Hélène Richard, Guy Beauchamp, Sheila Laverty

WHY I CHOSE THIS PAPER

Osteoarthritis is frequently diagnosed by equine practitioners. Finding an effective analgesia with minimal side-effects, particularly for prolonged use, is needed for equine patients of all ages. 

ARTICLE SUMMARY

Osteoarthritis (OA) is a major cause of equine lameness. Cannabinoid receptors (CB) are now considered to be promising therapeutic targets in human rheumatology for pain and inflammation, however little is known about the equine endocannabinoid system. The primary aim of this ex vivo experimental study was to assess the presence and expression pattern of CB1 and CB2 receptors in the synovium of healthy joints. A secondary aim was to explore the relationship between the CB expression, degree of synovitis and OA pathology.
Metacarpophalangeal joints (n=25) from a tissue bank were studied. The joints were dissected, and the articular cartilage lesions were scored. Synovial membrane specimens (n=45) were harvested, fixed and the degree of synovitis was graded on histological sections. Co-localised synovial sections were immunostained with antibodies to CB1 and CB2. Five regions of interest (ROIs) were randomly selected from digital images of manually segmented synovial intima and scored blindly for positive cellular immunoreactive staining by two independent observers. Interobserver agreement was calculated with an intraclass correlation coefficient. Relationships between CB1 and CB2 immunoreactive scores and synovitis or joint OA grade were explored.
CB1 was expressed in synovial intimal cells in all specimens studied whereas CB2 expression was identified in 94%. Both receptors were also expressed in the subintimal blood vessel walls. Interobserver agreements were 84.6% (CB1) and 92.9% (CB2) for the immunoreactivity scores. Both CB1 and CB2 expression were significantly upregulated (p=0.04 and p=0.03 respectively) with increasing degree of synovitis. Conversely, CB1 expression significantly decreased (p=0.03) with increasing severity of OA.
Bottom Line: Equine synovial intimal cells constitutively express both CB1 and CB2 receptors that are upregulated with synovitis and may have a role in joint pain. They are potential targets for therapy with cannabinoid molecules or their derivatives.

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Andrea Noguera Cender, Kathrin Mählmann, Anna Ehrle, Roswita Merle, Laura Pieper, Christoph J. Lischer

Why I chose this paper

Digital flexor tendon sheath (DFTS) pathology is an important cause of lameness in horses A pre-tenoscopic diagnosis cannot always be reliably obtained and requires multiple modalities with different diagnostic values. The outcome after surgical treatment is variable and depends on the exact diagnosis.

ARTICLE SUMMARY

The aims of this retrospective case series were to (1) describe the prevalence of lesions associated with lameness caused by non-septic DFTS tenosynovitis in a large population of German sports and pleasure horses; (2) determine the sensitivity and specificity of diagnostic imaging techniques for identifying lesions within the DFTS with tenoscopic-diagnosis being the gold-standard; (3) explore associations between tenoscopically-diagnosed lesions and signalment, purpose, and limb affected; and (4) describe the outcome following DFTS tenoscopy with non-septic DFTS tenosynovitis in this population.
Medical records of horses admitted for tenoscopic surgery of non-septic DFTS tenosynovitis between 2011 and 2020 were reviewed. Follow-up information was obtained via telephone contact. Sensitivity and specificity of ultrasonography and contrast tenography were determined using tenoscopic diagnosis as gold standard and univariable analysis was used to explore associations between signalment, case history, and tenoscopic diagnosis.
Medical records from 131 horses were retrieved, of which 61 were Warmbloods. Eight horses had bilateral disease and 6 horses were presented for tenoscopy on two separate occasions (3 for tenoscopy in the same limb, 3 in a different limb) making a total of 145 limbs. Lesions were most commonly diagnosed in the deep (DDFT, n=55 limbs) and superficial (SDFT, n=55 limbs) digital flexor tendons. Manica flexoria (MF) lesions were detected in 44 limbs and palmar/plantar annular ligament (PAL) constriction in 99 limbs. In 36 limbs, only one structure within the DFTS was injured, whereas in 109 limbs a combination of lesions was noted, the most common being the combination of a SDFT lesion with PAL constriction. All affected limbs were examined with diagnostic ultrasonography; contrast tenography was performed in 86 limbs. For diagnosis of MF and DDFT tears, tenography was more sensitive (89% (CI 65.4-95.2%); 72% (CI 46.4-89.3%) respectively) than specific (64% (CI 52.5-77.6%); 53% (CI 42.2-73.3%) respectively) whereas ultrasonography was more specific (92% (CI 84.5-96.3%); 92% (CI 83.6-96.0%) with lower sensitivity (64% (CI 47.7-77.2%); 54% (CI 39.5-67.9%). For SDFT lesions, ultrasonography was highly specific (94% (CI 86.9-97.9%) with lower sensitivity (66% (CI 51.3-77.4%). Follow-up information following first surgery was obtained for 118 horses (132 limbs): 18/118 (15.3%) horses remained chronically lame, 40 (33.8%) performed at a reduced level and 60 (50.8%) performed at the same or higher level following rehabilitation after tenoscopy. Horses with DDFT lesions had the poorest outcomes with only 36.6% returning to the same or higher level of exercise.
Bottom Line: Diagnostic imaging techniques were complimentary and contrast tenography was sensitive and ultrasonography was specific for the diagnosis of MF and DDFT lesions. 75% of limbs had more than one pathology identified. Following tenoscopic surgery, approximately half the cases were able to return to pre-injury level of exercise.
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Melissa A. Mercer, Harold C. McKenzie, Christopher R. Byron, Robert S. Pleasant, Sophie H. Bogers, Roberto M. Council-Troche, Stephen R. Werre, Travis Burns and Jennifer L. Davis

Why I chose this paper:

There is a need to evaluate adjunctive analgesics for horses with acute and chronic musculoskeletal pain that is not responsive to NSAID administration or where NSAID use is contraindicated. There is no data to support the current paracetamol dose of 20mg/kg and limited studies on its efficacy.

Article Summary

Acetaminophen has been used clinically in horses alone or combined with traditional NSAIDs for treatment of musculoskeletal pain in horses at 20 mg/kg. The aim of this study was to determine the pharmacokinetics and efficacy of acetaminophen at two doses (20 and 30 mg/kg) in horses with mechanically induced lameness compared to phenylbutazone or placebo control.

Nine healthy mares with mechanical lameness induced via a reversible sole pressure horseshoe model were treated with acetaminophen (20 mg/kg per os; A20), acetaminophen (30 mg/kg per os; A30), phenylbutazone (2.2 mg/kg, per os; PB) and oral placebo (C) in a randomised 4-way Latin square model. Plasma concentrations for A20 and A30 were analysed via LC-MS/MS and noncompartmental pharmacokinetic analysis. Heart rate and heart rate variability were measured using a portable telemetry. Lameness was scored by three blinded boarded equine surgeons using the AAEP and 10-point scales.

Mean maximum plasma concentration (C_max) for A20 was 20.01 mg/mL within 0.66 h (T_max) after administration; The mean C_max for A30 was 30.02 mg/mL with a T_max of 0.43 h. Post-treatment heart rate for A30 was significantly lower than A20 at 1 and 7 h; lower than PB at 2, 3, 4.5, and 7 h; lower than C at 2, 3.5, 4.5, 6, 7, and 8 h. 10-point lameness scores were significantly improved for A30 than C at 2 and 4 h post-treatment; PB was significantly improved than C at 8 h post treatment. There were no significant differences in lameness between A20, A30, and PB.

Bottom Line: Acetaminophen at 30 mg/kg produced a more rapid improvement in lameness scores and heart rate compared to other treatments in this model but there were no differences in lameness between A20, A30, and PB groups. Further evaluation of the pharmacokinetics and safety of repeated oral dosing of acetaminophen at 30 mg/kg is needed to determine clinical utility.

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Malou F. Winther, Simon L. Haugaard, Tina H. Pihl and Stine Jacobsen

Why I chose this paper

I selected this paper as horses presenting with peritonitis without an obvious underlying cause can be diagnostically challenging, particularly if deciding if surgery is warranted. Therefore, a biomarker that can help differential non-strangulating intestinal infarctions from other types of peritonitis could be clinically valuable.

Article Summary

Neutrophil gelatinase-associated lipocalin (NGAL) is produced in response to inflammation in horses, but it has not yet been investigated as a biomarker in horses with abdominal disease. The aim of this retrospective clinical study was to investigate NGAL in serum and peritoneal fluid in horses with abdominal disease.

Data from medical records of 270 horses admitted with acute abdominal disease (simple obstructions [n = 43], strangulating obstructions [n = 104], inflammatory abdominal disease [n = 99], non-strangulating intestinal infarction [NSII, n = 24]) and 9 healthy control horses were reviewed, and serum and peritoneal fluid samples were retrieved from a biobank. NGAL was measured in serum and peritoneal fluid by ELISA. Differences in NGAL concentrations between groups were assessed.

Healthy horses had low serum and peritoneal fluid concentrations of NGAL (median = 21.0 and 9.5 mg/L, respectively). Neither serum nor peritoneal fluid NGAL concentrations (median serum, peritoneal fluid) differed between healthy horses and horses with simple (28.1 mg/L, 13.0 μg/L) and strangulating intestinal obstructions (34.7 mg/L, 38.4 μg/L). Horses with NSII (308.0 μg/L, 2163.0 μg/L) and inflammatory abdominal disease (171.1 μg/L, 314.1 μg/L) had higher serum and peritoneal fluid concentrations of NGAL than the other groups (P<0.001). Peritoneal fluid NGAL concentrations in horses with NSII were significantly higher than in horses with inflammatory abdominal disease (P = 0.03).

Bottom Line: NGAL is a marker of inflammation in horses with abdominal disease. The high peritoneal fluid concentration of NGAL in horses with NSII compared to all other groups may render NGAL useful for identifying this condition, which is otherwise difficult to differentiate from other types of peritonitis.

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Objective evaluation for analgesia of the distal interphalangeal joint, the navicular bursa and perineural analgesia in horses with naturally occurring forelimb lameness localised to the foot
Vasiliki Katrinaki, Roberto J. Estrada, Kathrin Mählmann, Panagiotis Kolokythas, Christophorus J. Lischer

The outcome and interpretation of intra-synovial diagnostic analgesia of the distal interphalangeal joint (DIPJ) and the navicular bursa (NB) remain in dispute, and no objective studies have been carried out to establish the percentage of improvement over time from these two analgesia techniques. The aim of this case series was to investigate the qualitative and time-dependent outcome of DIPJ analgesia and NB analgesia in naturally occurring forelimb lameness.
Twenty-three clinical cases with forelimb lameness were evaluated objectively using a body mounted inertial sensor system (BMIS). Lameness was localised to the foot with a palmar digital nerve block and/or an abaxial sesamoidean nerve block on day 1, and analgesia of the DIPJ and NB were performed on days 2 and 3. Improvement following perineural analgesia was measured after 10 minutes and intra-synovial blocks after 2-, 5- and 10-minutes. Horses with at least 70% improvement measured objectively after diagnostic analgesia were included in the study.

There was no significant association between improvement following perineural analgesia and the DIPJ and NB. The mean improvement in the lameness significantly differed between DIPJ and NB at 2 min (p<0.001) and at 5 min (p=0.04), and the difference was no longer observed after 10 minutes. A positive NB analgesia produced a high degree of improvement that remained stable, whereas the DIPJ analgesia improved over time.

Bottom Line: Perineural analgesia is not reliable enough to differentiate pain originating from DIPJ and NB. Early evaluation of the DIPJ and NB can determine the origin of the pain. An improvement following NB analgesia was constant over time, but an improvement following DIPJ analgesia varied by up to 10 minutes.

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Antimicrobial prescribing and antimicrobial resistance surveillance in equine practice

A. Wilson, T. Mair, N. Williams, C. McGowan, G. Pinchbeck

Antimicrobial resistance (AMR) is an increasingly serious threat to human and animal health, therefore responsible use of antimicrobials in equine practice is vital. There is a need to have accurate, up to date data on antimicrobial prescribing in equine practice in the UK. The aim of the online cross-sectional, questionnaire-based survey was to characterise current antimicrobial prescribing practices by equine veterinarians and to describe surveillance, audit processes and identification of AMR.

An online questionnaire targeting veterinarians who treat horses in the UK and Europe was distributed. The questionnaire collected data on participants’ country of origin, practice policies, prescribing practices including use of high priority critical antimicrobials. Four common clinical case-based scenarios were included to further explore prescribing practice. Responses were compared using both descriptive statistics and multivariable logistic regression models.
Questionnaires were completed by 264 veterinarians from Europe (n=33/264) and the UK (n=231/264); 87% respondents worked only with horses and 67% worked at premises with hospitalisation facilities. Approximately half of respondents (54.4%) had a written antimicrobial use or stewardship policy within their practice. Over half of respondents did not perform any environmental surveillance (54.2%), audit of clinical infections (53.1%) or audit of infection control (57.1%). Potentiated sulphonamides were cited as the most used antimicrobial, although 44% reported using enrofloxacin in the last year and 66% used 3rd or 4th generation cephalosporins. Prophylactic antimicrobials before clean surgery were frequently/always prescribed by 48% respondents and 24% respondents frequently/always prescribed antimicrobials post-operatively in clean surgery.

Bottom Line: Compared to a previous similar study conducted in 2009, overall antimicrobial usage appeared to be declining in clinical scenarios and a greater proportion of practices now have stewardship policies. However, the use of high priority critical antimicrobials is still relatively common in equine practice in the UK and Europe.

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Early incisor lesions and Equine Odontoclastic Tooth Resorption and Hypercementosis: Reliability of radiographic findings

Louisa Albers, Astrid Bienert-Zeit, Jonas Albers, Christian Dullin, Carsten Staszyk

In clinical practice, early diagnosis of Equine Odontoclastic Tooth Resorption and Hypercementosis (EOTRH) and other resorptive incisor diseases is difficult to achieve. The radiographic appearance of subtle pathological changes has not been described in detail and might be confused with age-related changes.

The aim of this descriptive and comparative study was to define typical radiographic signs of early incisor lesions and to evaluate the reliability of the radiographic findings, using post-mortem clinical, macroscopic and μCT examination.

The incisor region of 20 cadaveric horse heads, divided into three different age groups, was examined visually and by palpation. Intraoral radiographs were taken. After extraction, each incisor was macroscopically evaluated. Micro-computed tomography (μCT) scans were obtained. These scans were processed with Scry (v6.0, Kuchel & Sautter GbR) to obtain surface meshes which then were transferred to Meshlab (ISTI-CNR, version 2016.12). Attached tissues were virtually removed and surface curvature was computed to visualise and evaluate the quantity of unevenness (roughness) of the teeth's surface.

Scoring systems for each diagnostic modality were developed. Scores were compared to describe and evaluate the radiographic appearance of early incisor lesions. The prevalence and severity of incisor lesions increased with age. Early, subtle lesions develop on the palatal/lingual side of incisors. While radiographically detected lesions were confirmed macroscopically and on the μCT scans, numerous teeth which were radiographically classified as healthy displayed lesions by macroscopic inspection (13.7%) and μCT analysis (58.1%).

Bottom Line: The detection of early and subtle incisor lesions indicating first signs of EOTRH on dorsoventral intraoral radiographs is limited due to the typical localisation of the lesions on the palatal/lingual side of the incisors.

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Predictors of laminitis development in a cohort of non laminitic ponies

Edward J. Knowles, Jonathan Elliott, Patricia A. Harris, Yu-Mei Chang, Nicola J. Menzies-Gow

The relative importance of different risk factors and precise quantification of risk for laminitis development requires further study. The aim of this prospective cohort study was to identify the most useful physical examination, metabolic and management factors to predict laminitis development in client-owned, nonlaminitic ponies.

Physical examination, metabolic and management data were collected from a cohort of nonlaminitic ponies 6-monthly for up to 4 years. Ponies were monitored for the development of laminitis. Metabolic data included basal plasma ACTH ([ACTH]), adiponectin ([adiponectin]), triglycerides and glucose concentrations. Serum insulin concentrations ([insulin]) were measured in the unfasted basal state ([insulin]T0) and 60 minutes ([insulin]T60) after administration of commercial corn syrup (0.3ml/kg). Separate multivariable Cox proportional-hazards models were developed for physical, management/signalment and metabolic data and later combined into two final models. Low-, medium- and high-laminitis risk categories were defined based on basal or T60 [insulin].

Overall, 374 ponies (age 5–32 years) and 891 pony-years were included in the main analysis. Laminitis incidence (95% confidence interval (CI)) was 4.8 (3.5-6.5) cases/100 pony-years. Laminitis development was associated with numerous univariable factors. Significant (P < .05) factors retained in the final multivariable models included [insulin]T0, [insulin]T60, [adiponectin] and divergent hoof growth. [ACTH] was not independently associated with laminitis.

Based on [Insulin]T0, low- (<21.6 μIU/ml), medium- (21.6-45.2 μIU/ml) and high-risk (>45.2 μIU/ml) categories encompassed 70, 20 and 10% of the population and had estimated 4-year laminitis incidences (95%CI) of 6 (2-9)%, 22 (10-33)% and 69 (48-82)% respectively. Based on [Insulin]T60 the low- (<53.4 μIU/ml), medium- (53.4-153 μIU/ml) and high-risk (≥153 μIU/ml) categories comprised 60, 30 and 10% of the population and had estimated 4-year laminitis incidences (95%CI) of 3 (0-6)%, 20 (10-29)% and 73 (52-84)% respectively.

Bottom Line: [Insulin]T0 or [insulin]T60 best quantify the risk of future laminitis development in non laminitic ponies.

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Rib fractures in adult horses as a cause of poor performance; diagnosis, treatment and outcome in 73 horses

Suzy Hall, Roger Smith, Peter H. L. Ramzan, Natalie Robinson, Russell Parker

Rib fractures in adult horses are poorly documented. The aim of this retrospective case series was to describe the presenting signs, diagnosis, treatment, and outcome of horses diagnosed with rib fracture.

The clinical records and diagnostic images of all adult horses diagnosed with a rib fracture at three referral centres over a 15-year period were reviewed. Seventy-three horses met the inclusion criteria. Horses presented due to either resistance to ridden work and poor performance (clinical signs included poor response to rider aids, bucking, bolting, napping, rearing or a reluctance to jump; n = 41), lameness (n = 21) or trauma (n = 7). In four horses, the presenting complaint was not recorded. Clinical assessment and palpation localised the site of injury in 18/47 cases where recorded. In 64 horses (88%; 95% CI 79-94) one rib was affected, in two horses two ribs were affected, in three horses three ribs were affected and in four horses four or more ribs were affected. One horse had fractures on both the left and right sides but in all other horses, the fractures were unilateral: 40 on the left side and 32 on the right side. The 18th rib was most commonly affected (n = 32; 42%; 95% CI 32-54). Nuclear scintigraphic examination identified all fracture sites in which it was performed (59/59). In 10/24 horses, radiographic examination confirmed rib fracture. Ultrasonographic examination confirmed rib fracture in 58/59 horses (98%; 95% CI 92-100). Six horses underwent surgery due to ongoing clinical signs and non-healing fracture; all other horses were managed conservatively. Fifty-five horses were available for long-term follow-up (>1 year), of which 28 (51%; 95% CI 38-64) returned to their previous level of exercise. Twelve horses did not return to their previous level of exercise due to lameness unrelated to the rib fracture and seven horses were subjected to euthanasia, of which three were due to the rib fracture. Eight horses did not return to their previous level of exercise for other reasons.

Bottom line: Although uncommon, rib fractures should be considered in cases of reduced performance or resistance during ridden exercise. Palpation may be unrewarding. Scintigraphy and ultrasonography are useful in identifying the fracture site. Rib fractures in horses carry a fair prognosis and can be managed conservatively in most cases.

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Risk factors for a first episode of primary uveitis in the UK and proportion of cases that experience recurrence following this first episode

F. Malalana, J.L. Ireland, G.L. Pinchbeck, C.M. McGowan

Risk factors for a first episode of primary uveitis in horses have not been determined. In addition, disease progression and the proportion of horses that develop recurrence following the original episode is not known.

The aim of this prospective case-control longitudinal study was to determine risk factors for the development of a first episode of primary uveitis in horses in the UK and to document the proportion of cases that experience recurrence following this first episode.

Horses with a first episode of primary uveitis between July 2014 and August 2018 were recruited to the study. For each case, two controls were selected. A questionnaire was completed for each horse and multivariable logistic regression analysis carried out to identify associations between horse and management-level variables and the risk of uveitis. Each case was then followed longitudinally to determine the rate of recurrence of uveitis.

In total, 23 cases and 46 controls were recruited. Being close to a pig farm (OR 27.8, CI 1.31-592.06) and a recent history of flooding of the pasture (OR 15.43, CI 2.80-84.98) were associated with increased risk of uveitis. Being in the same owner’s possession for a longer amount of time had a protective effect (OR 0.79, CI 0.68-0.93). Horses recovered uneventfully following treatment and showed no evidence of recurrence in 59.1% of the cases (n=13). In five horses (22.7%) the initial episode of uveitis could not be controlled and required surgical therapy. Recurrence was observed in four horses (18.2%).

Bottom Line: The proportion of cases that experience recurrence appears low in the UK.

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Caudal foot placement superior to toe elevation for navicular palmaroproximal-palmarodistal-oblique image quality

Manon W.J. Peeters, Jasmine J. Thursby, Hannah E. Watson, Dagmar Berner

Palmaroproximal-palmarodistal oblique (PaPr-PaDiO) radiographs are regularly obtained for full evaluation of the navicular bone (NB). Despite their routine use, different acquisition techniques are described.

The aim of this in vitro experiment was to determine optimal foot placement and beam angle for obtaining PaPr-PaDiO views.

A convenience sample of twenty-six disarticulated forelimbs were placed in six different positions using a leg press to mimic the weight bearing position. In each position, navicular PaPr-PaDiO images were obtained with eight different beam angles. The resulting 1248 radiographs were graded for their diagnostic quality and the compacta spongiosa demarcation of the NB.

Diagnostic quality and compacta-spongiosa demarcation was graded higher for feet positioned caudally and angles between 40° and 45°. Elevation of the toe significantly decreased the NB palmar border angle (elevated mean: 40.66, SD: 4.46, non-elevated mean: 42.06, SD: 4.70) (p < 0.01), but seemed to have no obvious positive influence on radiographs.

Bottom Line: Caudal foot placement seems to improve image quality of the navicular PaPr-PaDiO view. The standard beam angle of 45° appears to be the favourable angle for acquisition. Elevation of the toe, standard in most commercially available navicular skyline cassette holders, does not influence the obtained image quality.

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Radiographic changes of the proximal third metatarsal bone do not predict presence or severity of proximal suspensory desmopathy in a predominately Quarter Horse population

Frances E. Hinkle, Kurt T. Selberg, David D. Frisbie, Myra F. Barrett

The tarsus and proximal suspensory origin of the metatarsus are commonly imaged regions for lameness. Common radiographic findings in the proximal third metatarsal bone (MtIII) include increased trabecular and endosteal bone density (sclerosis), areas of decreased bone density, and enthesophyte formation. A recent study found that horses with proximal suspensory desmopathy (PSD) had more increased radiopacity in the lateral aspect of the metatarsus and a multifocal distribution pattern was more common in hindlimbs with PSD. Comparison of radiography to magnetic resonance imaging (MRI) can help objectively assess the value and limitations of radiographs in orthopaedic disease processes.

The aim of this retrospective observational study was to compare the radiographic and MRI findings of the proximal third metatarsal bone (MtIII) and proximal suspensory ligament, using MRI as the gold standard.

Single hindlimbs of 35 horses (32 Quarter Horses) with radiographic and high-field (3Tesla (3T)) MRI studies were blindly evaluated by two board-certified veterinary radiologists and a radiology resident. Severity and location of the following parameters were assessed: radiographic MtIII sclerosis and lucent regions, MRI endosteal metatarsal sclerosis and bone marrow lesions, plantar cortical proliferation and resorption, and proximal suspensory desmopathy (PSD).

Radiographic osseous changes of MtIII were identified in 54% of limbs, whereas 40% limbs had osseous changes on MRI. In addition, 43% of limbs had PSD on MRI. No significant association was found between the presence of radiographic changes in MtIII and PSD on MRI. A statistically significant association and positive correlation was found between the severity of radiographic changes and MtIII plantar cortical proliferation and resorption on MRI (P=0.01).

Bottom Line: Radiographic bony changes of proximal MtIII do not reliably predict presence or severity of PSD but are associated with osseous changes at the proximal MtIII. The presence of radiographic changes should warrant additional diagnostics in the region prior to making conclusions about the presence or absence of PSD.

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Pain severity scores for common equine disorders as provided by horse owners and equine veterinarians

Debra C. Sellon, Macarena Sanz, Jamie J. Kopper, Debora Mattei

An important step toward improving communication between veterinarians and horse owners is to understand the factors that influence attitudes and beliefs about pain severity so that communication and consensus-building may be facilitated.

The aim of this cross-sectional study was to compare estimates of pain experienced by horses as provided by veterinarians and horse owners and to determine factors associated with individuals who perceive horses to be experiencing extreme pain or minimal pain.

Internet-based questionnaires were completed by horse owners and veterinarians and included items related to recognition of pain in horses, estimated degree of pain experienced by horses, and demographic information. Variables associated with perception of a high or low degree of pain were investigated using logistic regression analyses.

Final data sets included responses from 553 horse owners and 263 veterinarians. Pain scores varied widely and differences in median scores from horse owners and veterinarians were small. Horse owners providing high pain ratings were more likely to have <10 horses (odds ratio [OR] = 2.0, 95% confidence interval [CI] = 1.1–3.5) and to not have a college degree (OR = 1.5, 95% CI = 1.0–2.2). Those providing low pain ratings were less likely to own <10 horses (OR = 0.6, 95% CI = 0.4–0.9). Veterinarians providing high pain ratings were more likely to be employed in a mixed animal practice (OR = 2.8, 95% CI = 1.3–5.9) and to lack board-certification in a veterinary specialty (OR = 2.1, 95% CI = 1.1–4.2). Veterinarians providing low pain ratings were more likely to be male (OR = 2.4, 95% CI = 1.3–4.2).

Bottom Line: Assessments of the degree of pain that horses are experiencing vary widely among horse owners and equine veterinarians

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Effects of age, disease, and anastomosis on short- and long-term survival after surgical correction of small intestinal strangulating diseases in 89 horses

Meredith J. Rudnick, Thomas N. Denagamage, David E. Freeman

Although survival rates have been reported after small intestinal surgery for strangulating diseases in horses, none have followed survival for periods relevant to the long lifespan of horses and none have described effect of age, disease and surgical treatments over such long survival periods.

The aim of this retrospective clinical study was to examine effects of age, disease, and type of surgery on long-term survival in horses after surgical treatment of small intestinal strangulating diseases over periods relevant to the expected lifespan of a horse.

Post-operative data were gathered from medical records and owner contact for 89 horses with small intestinal strangulation. Survival times from surgery to date of death or date of last follow-up were analysed by Kaplan-Meier statistics. Variables of interest were age, type of strangulating disease, and surgical correction. Cox proportional hazards regression was used to evaluate these variables.

Short-term survival was not affected by any of the variables measured. For long-term survival with Kaplan-Meier statistics, horses ≥16 years old had significantly shorter (P=0.002) median survival times (72 months; 95% CI 32.0–96.0) than younger horses (121.7 months; 95% CI 90.0–162), horses without resection had significantly longer (P = 0.02) survival times (120 months; 95% CI 86–212) than horses that had jejunocecostomy (76.8 months; 95% CI 24–125), and horses with miscellaneous diseases had significantly longer (P=0.02) median survival times (161.9 months (95% CI 72.0–M; note: the upper limit could not be computed by the software package so -M is displayed) than horses with strangulating lipoma (79.8 months; 95% CI 32.0–120.0).

In the multivariable Cox Proportional Hazard model, age (HR = 2.67; 1.49-4.75, P<0.001) and anastomosis (HR = 0.65; 0.46–0.92, P = 0.02) had the most significant effect on median survival time.

Bottom Line: The remaining lifespan of older horses at the time of surgery had the greatest effect on survival. Horses that did not require resection and anastomosis had favourable outcomes, underscoring the potential importance of early intervention to reduce the need for resection.

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Atrial fibrillatory rate as predictor of recurrence of atrial fibrillation in horses treated medically or with electrical cardioversion

Rikke Buhl, Eva M. Hesselkilde, Helena Carstensen, Charlotte Hopster-Iversen, Gunther van Loon, Annelies Decloedt, Glenn Van Steenkiste, Celia M. Marr, Virginia B. Reef, Colin C. Schwarzwald, Katharyn J. Mitchell, Katarina Nostell, Nora Nogradi, Søren Saxmose Nielsen, Jonas Carlson, Pyotr G Platonov

The recurrence rate of atrial fibrillation in horses after cardioversion to sinus rhythm is relatively high. Atrial fibrillatory rate derived from surface electrocardiogram (ECG) is considered a biomarker for electrical remodelling and could potentially be used for prediction of successful atrial fibrillation cardioversion and atrial fibrillation recurrence. The aim of this retrospective multicentre study was to evaluate if atrial fibrillatory rate was associated with successful treatment and if atrial fibrillatory rate could predict atrial fibrillation recurrence in horses.

ECGs from horses with persistent atrial fibrillation admitted for cardioversion with either medical treatment (quinidine) or transvenous electrical cardioversion (TVEC) were included. ECG recordings were analysed by spatiotemporal cancellation of QRST complexes and calculation of atrial fibrillatory rate from the remaining atrial signal. Kaplan-Meier survival curve and Cox regression analyses were performed to assess the relationship between atrial fibrillatory rate and the risk of atrial fibrillation recurrence.

Of the 195 horses included, 74 received quinidine treatment and 121 were treated with TVEC. Ten horses did not cardiovert to sinus rhythm after quinidine treatment and atrial fibrillatory rate was significantly higher in these, compared to the horses that successfully cardioverted to sinus rhythm (median [interquartile range IQR], 383 [367-422] vs. 351 [332-389] fibrillations per minute (fpm), p<0.01). Within the first 180 days following atrial fibrillation cardioversion, in total, 12% of the quinidine and 34% of TVEC horses had atrial fibrillation recurrence. For the horses successfully cardioverted with TVEC, AFR above 380 fpm was significantly associated with atrial fibrillation recurrence (hazard ratio = 2.4, 95% CI 1.2–4.8, p=0.01).

Bottom Line: High atrial fibrillatory rate is associated with failure of quinidine cardioversion and atrial fibrillation recurrence after successful TVEC.

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Visual lameness assessment in comparison to quantitative gait analysis data in horses

Aagje M. Hardeman, Agneta Egenvall, Filipe M. Serra Bragança, Jan-Hein Swagemakers, Marc H. W. Koene, Lars Roepstorff, Rene van Weeren, Anna Byström

Quantitative gait analysis offers objective information to support clinical decision-making during lameness workups including advantages in terms of documentation, communication, education, and avoidance of expectation bias. Very little data exists comparing outcome of subjective scoring with the output of objective gait analysis systems. The aims of this clinical observational study were to investigate between- and within-veterinarian agreement on primary lame limb and lameness grade, and to determine relationships between subjective lameness grade and quantitative data, focusing on differences between 1) veterinarians, 2) live versus video assessment, 3) baseline assessment versus assessment following diagnostic analgesia.

Kinematic data were compared to subjective lameness assessment by clinicians with ≥8 years of orthopaedic experience. Subjective assessments and kinematic data for baseline trot-ups and response to 48 diagnostic analgesia interventions in 23 cases were included. Between and within-veterinarian agreement was investigated using Cohen’s Kappa (κ). Asymmetry parameters for kinematic data (‘forelimb lame pattern’, ‘hindlimb lame pattern’, ‘overall symmetry’, ‘vector sum head’, ‘pelvic sum’) were determined, and used as outcome variables in mixed models; explanatory variables were subjective lameness grade and its interaction with 1) veterinarian, 2) live or video evaluation and 3) baseline or diagnostic analgesia assessment.

Agreement on lame limb between live and video assessment was ‘good’ between and within veterinarians (median κ=0.64 and κ=0.53). There was a positive correlation between subjective scoring and measured asymmetry. The relationship between lameness grade and objective asymmetry differed slightly between 1) veterinarians (for all combined parameters, p-values between p<0.001 and 0.04), 2) between live and video assessments (‘forelimb lame pattern’, ‘overall symmetry’, both p≤0.001), and 3) between baseline and diagnostic analgesia assessment (all combined parameters, between p<0.001 and 0.007).

Bottom Line: Overall, between- and within-veterinarian agreement on lame limb was ‘good’, whereas agreement on lameness grade was ‘acceptable’ to ‘poor’. Quantitative data and subjective assessments correlated well, with minor though significant differences in the number of millimetres, equivalent to one lameness grade between veterinarians, and between assessment conditions. Differences between baseline assessment versus assessment following diagnostic analgesia suggest that addition of objective data can be beneficial to reduce expectation bias.

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The accuracy of ACTH as a biomarker for pituitary pars intermedia dysfunction in horses: A systematic review and meta-analysis

James C. Meyer, László M. Hunyadi, José M. Ordóñez-Mena

Accuracy of baseline adrenocorticotropic hormone (ACTH) for the diagnosis of pituitary pars intermedia dysfunction (PPID) in horses varies between studies. The aim of this systematic review and meta-analysis was to estimate the diagnostic accuracy of ACTH as a biomarker for PPID in adult horses or ponies and appraise potential causes of heterogeneity.

A literature review identified studies reporting diagnostic accuracy data for extraction. Risk of study bias was evaluated using QUADAS-2. To account for variations between studies, such as variable positivity thresholds, two random-effects models (the hierarchical summary receiver operating curve (HSROC) and the bivariate binomial normal model (BBN)) were used to pool accuracy measurements. Meta-regression was performed using study-level variables. The impact of diagnostic test accuracy on the frequency of false-positive and false-negative results at various pre-test probabilities was calculated using the BBN model's accuracy results.

Patient selection and index test evaluation demonstrated significant risk of bias. Mean and 95% confidence intervals for sensitivity and specificity for all studies (n = 11) were (0.72, 95% CI: 0.62–0.82) and (0.88, 95% CI: 0.79–0.93), respectively. When studies with a common positivity threshold of 35 pg/mL ACTH were evaluated (n = 6), sensitivity and specificity were (0.66, 95% CI: 0.54–0.77) and (0.87, 95% CI: 0.74–0.94). In a hypothetical group of 1000 horses with PPID prevalence of 2%, 20%, and 90%, the frequency of resulting false-positive and false-negatives would be (127 and 7), (104 and 68) and (13 and 306), respectively. Factors leading to increased accuracy were case-control design, clinical reference standard and data-driven choice of ACTH threshold.

Bottom line: In horses with clinical signs of PPID, ACTH may be a functional “rule-in” test. Baseline ACTH is not recommended for screening purposes or use in horses without clinical signs of PPID. In order to minimise false negatives in horses with clinical signs of PPID, a negative ACTH test should be followed up with a thyrotropin-releasing hormone (TRH) stimulation test.

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The impact of grade of laryngeal function immediately prior to laryngoplasty and ipsilateral ventriculocordectomy on postoperative performance: 623 Thoroughbred racehorses (1998-2013)

Ali H. Broyles, Rolf M. Embertson, J. Brett Woodie, Vinicius Machado

There is persistent concern among some trainers, owners and veterinarians regarding the effect of preoperative laryngeal function grade on the outcome of laryngoplasty and ventriculocordectomy (LPVC). The aim of this retrospective case-series was to determine the effect of laryngeal function grade prior to LPVC on postoperative performance.

Medical and race records of Thoroughbred racehorses diagnosed with recurrent laryngeal neuropathy (RLN) and treated with LPVC at Rood and Riddle Equine Hospital between 1998 and 2013 were reviewed. Horses were placed into three groups based on preoperative laryngeal function grade (grade III.1, grades III.2/III.3, and grade IV). The effect of preoperative laryngeal function grade on postoperative performance was determined by multivariable logistic regression, Cox proportional hazard model and multivariable linear regression analysis.

In a multivariable logistic regression, grade III.2/III.3 horses had 1.88 times higher odds (95% CI = 1.03-3.43) of racing after LPVC than grade IV (P = .04). A multivariable Cox's proportional hazard analysis controlling for race prior to surgery (P < .01) showed that likelihood of racing postoperatively was not different between grade III.1 and grade IV (P = .6). Kaplan–Meier survival analysis showed that grade IV horses took a longer time to race compared with grade III.1 and grade III.2/III.3. Laryngeal function grade did not influence the mean earnings per start.

The main limitation was the small number of horses in the grade III.1 group (n = 68) compared with the III.2/III.3 (n = 313) and IV (n = 242) groups.

Bottom line: Laryngeal function grade may affect likelihood of racing after LPVC, but not earnings per start. Grade III.2/III.3 horses were more likely to race postoperatively than grade IV horses, and grade IV horses took a longer time to first race after LPVC.

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Retrobulbar lidocaine injection via the supraorbital fossa is safe in adult horses but produces regionally variable periocular anaesthesia

Vanessa Y. Yang, Joshua Seth Eaton, Katherine Harmelink, Scott J. Hetzel, Adriana Sanchez, Jane R. Lund, Lesley J. Smith

Injection techniques for retrobulbar anaesthesia are published in horses, but neither safety nor anaesthetic efficacy and duration have been evaluated objectively in vivo. The aim of this randomised controlled study was to characterise the safety and efficacy of one published technique for retrobulbar anaesthesia.

Unilateral retrobulbar injection with 10 mL lidocaine (2%) was performed in eight sedated adult mares. Contralateral eyes served as untreated controls. Neurophthalmic parameters, intraocular pressure (IOP), and corneal and periocular sensation were measured awake, post-sedation and at periodic time points for 24 hours following injection. Adverse effects were documented.

Injection of 10 mL lidocaine significantly increased IOP for up to 2 hours, maximally at 30 min (mean [95% CI]: 6.0 [2.7, 9.2] mm Hg). Six of the eight treated eyes developed mild to moderate reversible chemosis for 2 to 24 hours. One eye developed severe chemosis and superficial corneal ulceration at 24 and 48 hours following injection, respectively. Corneal sensitivity significantly decreased for 6 hours, maximally at 10 min (−44.4 [−34.6, −54.1] mm). Periocular sensitivity (measured as increase in applied force) significantly decreased dorsally and medially for up to 2 hours (maximal at 2 hours (367.1 [238.5, 495.7] g, and at 30 min: 345.8 [202.6, 488.9] g respectively). Ventral and lateral sensitivity were not effectively decreased beyond 30 min. Optic nerve function was not consistently reduced following injection.

Bottom line: Retrobulbar injection using 10 mL lidocaine is safe in normal eyes of adult horses but causes a transient IOP increase. Reversible chemosis commonly develops 2-4h following injection and may be severe in some horses with risk for corneal ulceration. Corneal anaesthesia is rapid and prolonged, but all periocular regions are not consistently anaesthetised so should be combined with other local anaesthetic injections for eyelid surgeries or enucleations.

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Acute abdominal dehiscence following laparotomy: A multicentre, international retrospective study

Michelle J. Hann, Tim S. Mair, Alison Gardner, Margaret Mudge, Louise L. Southwood, Julie E. Dechant, Michelle H. Barton, Jesus Garcia-Macias, Russell A. Parker, Diana Hassel, Debbie C. Archer

Incisional complications are a common cause of morbidity following laparotomy. Although uncommon, acute abdominal dehiscence (AAD) is a potentially fatal post-operative complication. However, few AAD cases are described in the literature. The aim of this retrospective case series was to describe common features of cases of AAD following ventral midline laparotomy, management and outcomes.

The hospital records of horses that underwent a ventral midline laparotomy at nine hospitals in the UK, Ireland and USA over a 10-year period (2009-2019) were reviewed. Data were collected for pre-, intra- and post-operative factors that were considered relevant.  A total of 63 cases of AAD were identified. AAD occurred due to tearing of sutures through the linea alba or rupture of the body wall adjacent to the suture line in 46 horses (73%). AAD occurred at a median of 5 days (0.5-70 days) post-operatively and broodmares accounted for 25% of the cases (n = 16). Surgical site infection developed prior to AAD in 28 horses (44%); leakage of peritoneal fluid occurred in 5% of horses prior to AAD being identified. Surgical repair was performed in 27 horses (43%), 10 (16%) were treated conservatively and 26 (41%) were euthanised immediately. Repair was most frequently performed using suture (n = 14), wire (n = 5) or a combination (n = 5). Overall survival to hospital discharge was 39% (24/63). Where surgical repair was performed, 15 horses (56%) survived to hospital discharge; 9 horses (90%) managed conservatively survived to hospital discharge.

Bottom line: Surgical site infection following laparotomy and pregnant or early post-partum mares may be important risk factors for AAD and warrant further investigation.

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Horses vaccinated with live attenuated intranasal strangles vaccine seroconvert to SEQ2190 and SeM

Ashley G. Boyle, Catriona Mitchell, Darko Stefanovski and Andrew S. Waller

The dual antigen iELISA uses two Streptococcus equi subsp equi surface protein antigens composed of N‐terminal portions of SEQ2190 (Antigen A) and SeM (Antigen C). It is currently used to identify animals exposed to S. equi which have developed an immune response to the target antigens. This prospective case-control study investigated the usefulness of the ELISA in horses vaccinated with a live attenuated intranasal vaccine against S. equi.

The study consisted of 26 horses vaccinated annually with Pinnacle® IN and 26 non-vaccinated horses. Blood samples were obtained at annual strangles vaccination, 5 weeks post-vaccination and 10 weeks post-vaccination in horses that received a booster. Seropositivity was defined as an OD450 nm value ≥0.5 for one or both antigens.

At the 5-week time point, 76% of vaccinated horses were seropositive compared to 4% of non-vaccinated horses. Vaccinated horses were 14 times more likely to be seropositive or suspect than non-vaccinated horses. The OD450 value was significantly larger for Antigen C (SeM) than Antigen A (SEQ2190) for vaccinated horses.

Bottom line: With a high rate of seroconversion to both antigens due to vaccination, the dual antigen ELISA is not recommended for the diagnosis of previous S. equi exposure in horses that have been vaccinated with Pinnacle® IN.

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Investigating the pathogenesis of high‐serum gamma‐glutamyl transferase activity in Thoroughbred racehorses: A series of case‐control studies

Sabine Mann, Joshua D. Ramsay, Joseph J. Wakshlag, Tracy Stokol, Steven Reed and Thomas J. Divers

High‐serum γ‐glutamyl transferase (GGT) activity has been associated with and thought to be a marker of maladaptation to training and possibly poor performance in racehorses, but the cause is unknown. This study aimed to evaluate the role of oxidative stress, cholestasis, liver injury and infection with equine hepacivirus (EqHV) or equine parvovirus-hepatitis (EqPV-H) infection in racehorses with increased serum GGT activity.

The work consisted of a pilot study with eight horses with elevated serum GGT activity (≥50 U/L) and eight controls with normal GGT activity, followed by a larger study with 27 case-control pairs from three different yards. Serum liver chemistries, selenium measurements, viral PCR, and metabolomics were performed.

With both studies combined, the overall prevalence of EqHV was 9% and the overall prevalence of EqPV-H was 36%. There was no difference in prevalence or copy numbers between cases and controls for either virus. Cases had decreased serum selenium concentrations, higher serum glutamate dehydrogenase (GLDH) and alkaline phosphatase (ALP) activities and higher serum bile acid concentrations compared to controls. Metabolomics findings were not consistent between the two studies, with different metabolites emerging from each analysis. The authors concluded that the mechanism underlying high GGT activity in this population is likely complex and multifactorial, involving hepatic injury and possible cholestasis as well as oxidative stress.

Bottom line: EqHV or EqPV-H infections are unlikely to be the primary cause for the high GGT syndrome seen in Thoroughbred racehorses.

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Equine peripheral caries can cause significant morbidity and can have considerable welfare implications. Recent research suggests that diets with high water soluble carbohydrate (WSC) content are associated with high risk of peripheral caries.

This retrospective study aimed to investigate whether the peripheral caries process can be halted if oaten hay is removed from the diet and replaced with a non-cereal hay which is typically lower in water soluble carbohydrate (WSC). Forty-two horses with peripheral caries were switched from oaten hay to a non-cereal hay or straw (meadow hay, Rhodes hay, lucerne hay or barley straw). Photographs were taken at the time and then again at subsequent visits. The photographs were anonymised, randomised, and scored by six equine veterinary dentists using the Jackson et al. ‘Peripheral Caries Grading System’ grading scale.

At follow-up, 69% of cases were marked as inactive, compared with 47.6% of cases at baseline. Significantly lower grades of peripheral caries were observed in the gingival, middle and occlusive third of the molars at follow-up compared with baseline. Significant improvements were not observed in the premolars.

Bottom line: Recommending that clients change their horse's diet from oaten hay to a lower WSC hay may be useful as part of long-term management of equine peripheral caries. 

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Active equine parvovirus‐hepatitis infection is most frequently detected in Austrian horses of advanced age
Marcha Badenhorst, Phebe de Heus, Angelika Auer, Birthe Tegtmeyer, Alexander Stang, Katharina Dimmel, Alexander Tichy, Jakub Kubacki, Claudia Bachofen, Eike Steinmann and Jessika M. V. Cavalleri

Equine parvovirus‐hepatitis (EqPV‐H) research is in its infancy. Information regarding prevalence, geographical distribution, genetic diversity, pathogenesis and risk factors enhances understanding of this potentially fatal infection.

In this cross-sectional study, the authors analysed sera from 259 healthy horses and 13 healthy donkeys for the presence of EqPV-H antibodies and EqPV-H DNA (PCR). Associations between infection status, sex, age and concurrent equine hepacivirus (EqHV) infection were described. Glutamate dehydrogenase (GLDH), gamma‐glutamyl transferase (GGT), bile acids and albumin concentrations were compared between horses with active infection and PCR‐negative horses. Phylogenetic analysis of the EqPV‐H variants was performed.

In horses, EqPV-H seroprevalence was 30% and DNA prevalence was 8.9%. One horse was co-infected with Equine hepacivirus. No evidence of EqPV-H was detected in donkeys. Horses over 16 years of age were eight times more likely to have active EqPV-H infection compared with 1–8-year-old horses, and were three times as likely to have active EqPV-H infection compared with horses 9–15 years of age. Glutamate dehydrogenase (GLDH), gamma-glutamyl transferase (GGT), bile acids and albumin concentrations were not significantly different between horses with active infection and those without. The EqPV-H variants identified in this Austrian population of horses showed high similarity to sequences worldwide. No evidence of EqPV‐H was detected in donkeys.

Bottom line: EqPV-H antibodies and DNA are frequently detected in Austrian horses, without associated hepatitis. The risk of active EqPV-H infection increases with age.

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This prospective, multicentre, placebo-controlled, randomised, double-blinded study was designed to assess the effectiveness and safety of inhaled ciclesonide for the treatment of severe equine asthma.  

In total, 220 horses with severe equine asthma were included in the study from 24 clinics in Germany, France and Switzerland. Horses were randomised to receive ciclesonide inhalation solution or placebo inhalation. No environmental modifications were implemented. Treatments were administered with a Soft Mist inhaler for horses at doses of eight actuations twice daily for 5 days and 12 actuations once daily for the following 5 days. 

The ciclesonide group had a responder rate of 73% compared with 43% for the placebo group. The mean weighted clinical score reduction after 10 days of treatment was 7.2±4.8 in the ciclesonide treated group, compared with 3.8±4.5 in the placebo group. Horses with more severe clinical signs showed a greater improvement compared to those with mild/moderate clinical signs. Owners perceived an improved quality of life after 5 and 10 days of treatment in 60.2% and 69.3% of ciclesonide treated horses, compared with 32.7% and 43.4% of placebo treated horses. 

Bottom line: Inhaled ciclesonide resulted in a clinical improvement and improved quality of life in horses with severe equine asthma after 10 days of treatment. 

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In this controlled experimental trial, the authors evaluated the effect of amniotic membrane extract on re-epithelialisation of experimentally induced corneal ulcers in 10 healthy horses.  A corneal ulcer measuring 8 mm diameter was created bilaterally in each horse using a diamond burr. One eye was treated with amniotic membrane extract and the opposite was treated with the extract vehicle only (control). All eyes were treated with topical medical therapy (antibiotic, antifungal and mydriatic). Ulcers were stained with fluorescein and photographed in 12-h increments until completely healed. 

All eyes healed within 165.2 ± 76.3 h. Eyes treated with amniotic membrane extract healed in 162.7 ± 68.2 h, whereas eyes treated with the control healed in 167.6 ± 87.4 h. Treatment group was not significantly associated with size of ulcers over time.  Regardless of therapy, healing occurred in two distinct phases: an initial rapid phase with an average duration of 48–54 h and a second, slower phase with a variable duration.

Bottom line: Adding a commercially available amniotic membrane extract topically to antibiotic, antifungal and mydriatic medical therapy for experimentally induced equine superficial corneal ulcers did not significantly increase the rate of re-epithelialisation compared with medical therapy alone.

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Strip‐grazing: Reduces pony dry matter intakes and changes in bodyweight and morphometrics
Annette C. Longland, Clare Barfoot and Patricia A. Harris

This study aimed to compare the effects of three restricted grazing regimens on changes in bodyweight (BW) and morphometric measurements. 

Twelve mature ponies were individually grazed in 10 m wide, rectangular, electric fenced paddocks. The dry matter (DM) herbage yield of each paddock was determined, and paddock length adjusted on Day 1 to provide 1.5% of individual pony BW as herbage DM daily, for 28 days. There were four ponies per treatment. Treatments were: total paddock area (TA) and strip grazing treatments, SG1 and SG2. TA allowed ponies access to the entire paddock. SG1 had a ‘lead’ fence spanning the paddock width being moved a set distance along the paddock length daily. SG2 also had a ‘back fence’ 7‐12 m behind the ‘lead’ fence which was moved the same distance as the lead fence daily. Dry matter intakes, and changes in BW, cresty neck score, body condition score, heart girth, belly girth, and rump width were compared between treatments.

Mean DM intakes in the TA paddock ponies were significantly higher than the two strip grazing groups.  Mean percentage BW changes were higher for total paddock ponies as compared to the strip grazing groups, which did not differ significantly from each other. The TA paddock ponies showed significant increases in body condition score, cresty neck score, rump width and belly girth, while the strip grazing groups did not. The SG1 group showed a significant decrease in heart girth and the SG2 group had a significant decrease in belly girth measurements.

Bottom line: Strip grazing is a useful tool to aid management of body weight and condition of pastured ponies. The presence of a back fence did not appear to confer a significant benefit. 

Immune‐mediated haemolytic anaemia and thrombocytopenia in 25 adult equids: 1997‐2016

Charlotte A. Easton‐Jones, Krista E. Estell, K. Gary Magdesian

This retrospective case-control study aimed to characterise the clinical presentation, clinicopathologic data, underlying conditions, treatment and outcome of immune‐mediated haemolytic anaemia (IMHA) and thrombocytopenia (IMTP) in horses. Horses were classified as primary or secondary IMHA/IMTP cases based on whether they had evidence of underlying infections, neoplasia or drug administration prior to the onset of clinical signs.

Twenty-four horses and one donkey met the inclusion criteria for cases. Two horses were diagnosed with IMHA only. Both horses were positive for anti-RBC antibodies on Coombs test. Eight equids were diagnosed with IMTP only and 15 were diagnosed with IMHA and concurrent thrombocytopenia. Controls were equids presented for nonimmune‐mediated disease immediately prior to and after study animals.

Neoplasia incidence was significantly higher in the study population (28%) versus controls (8%). Overall short-term survival to discharge was 60%. There was no difference in survival between horses with IMHA, IMTP or both. Equids with primary disease were 13 times more likely to survive to discharge than those with secondary disease (8/9 vs 7/16). Treatment with corticosteroids, azathioprine or blood transfusions did not significantly affect outcome, although group numbers were small.

Survivors had a significantly lower blood urea nitrogen (BUN) than those that died or were subjected to euthanasia (survivors, 6.1 ± 2.5 mmol/L vs non- survivors, 9.9 ± 3.1 mmol/L). The odds of short-term mortality were also higher in horses presenting with increased BUN. Elevated BUN may act as a marker of the extent of hypoxic damage and severity of the immune-mediated disease.

Bottom line: Differentiation between primary and secondary aetiologies can be challenging. Primary IMHA/IMTP cases have a reasonable prognosis and warrant treatment. Secondary cases have a poor prognosis and are frequently associated with a neoplastic process. BUN may have utility as a prognostic indicator for IMHA/IMTP cases.

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Factors associated with survival and racing performance of 114 Thoroughbred foals with septic arthritis compared to maternal siblings (2009‐2015)

T.J. O’Brien, S.M. Rosanowski, K.D. Mitchell, J.B. Carrick, T.D. Butt, A.R. Adkins

In this retrospective study future racing performance of 114 Thoroughbred foals (<180 days old) with septic arthritis was compared with their maternal siblings and factors associated with survival were investigated.

Foals had undergone arthroscopic, cannulae or through-and-through needle lavage for the treatment of septic arthritis over a 6-year period.

30  synovial  fluid  samples  were  obtained  for  cytological  analysis  and  bacteriologic  culture.

Bacteriological growth was detected in 80 (61.5%; 95% CI 52.6% to 69.9%) samples.

The stifle (35%) and tarsocrural joints (20%) were most commonly involved. Overall, 130 synovial fluid samples were submitted for culture and cytology. Bacteriological growth was detected in 80 (61.5%) samples. Streptococcus sp. were isolated most frequently (32%), followed by Enterobacteriaceae sp. (28%) and Staphylococcal sp. (15%). Thirty-nine foals (34%) required repeat lavage of the affected synovial structure.

Ninety (78%) foals were discharged alive. Foals <26 days old at the time of admission were 5 times less likely to be discharged alive and foals with concurrent multisystemic disease were 6 times less likely to be discharged alive.

Sixty (67%) foals discharged alive started in >1 race and there was no difference in the proportion of foals that started in a race or racing performance between foals treated for septic arthritis and their maternal siblings.

Ninety (78%) of 115 foals diagnosed with septic arthritis were discharged alive. Foals <26 days old  at  the  time  of  admission  were  5  times  less  likely  (P=0.003)  and  foals  with  concurrent  multisystemic disease were 6 times less likely (P=0.02) to be discharged alive. Sixty (67%) foals discharged alive started in    race,  and  there  was  no  difference  in  the  proportion  of  foals  that  started  in  a  race  or  racing performance between foals treated for septic arthritis and their maternal siblings.

Bottom line: The prognosis for survival in foals with septic arthritis is good. Future racing performance does not appear to be affected. Younger foals and those with concurrent diseases are less likely to survive. Bacterial culture should be attempted on synovial fluid samples to guide treatment.

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Monitoring equine ascarid and cyathostomin parasites: Evaluating health parameters under different treatment regimens

Nielsen, M.K., Gee, E.K., Hansen, A., Waghorn, T., Bell, J. and Leathwick, D.M. 

This longitudinal randomised field trial evaluated egg count levels, bodyweight, and equine health under defined parasite control protocols in foals and mares at four stud farms in New Zealand. 

Foals (n = 93) were divided into two treatment groups; group A were dewormed at 2 and 5 months of age with a fenbendazole/ivermectin/praziquantel product, while group B were dewormed monthly, alternating between the above-mentioned product and an oxfendazole/pyrantel embonate product. 

Mares (n = 99) were divided into three groups; group A were dewormed twice (early summer and winter) with fenbendazole/ivermectin/praziquantel, group B were dewormed with the same product only when egg counts exceeded 300 eggs per gram, and group C were dewormed every 2 months, alternating between the two products. Health data was collected at 2-monthly intervals for a total of 13 months. 

Foals in group A had significantly higher ascarid and strongylid faecal egg counts compared to group B, but no significant differences were observed between mare groups. There were no differences between groups with regards to body weight and body condition score. One foal in group B developed diarrhoea during the monitoring period. No colic signs were reported in any group during the study. 


Bottom line: Reducing anthelmintic treatment intensity can lead to higher ascarid and strongylid egg counts in foals on stud farms; however, no negative health consequences were observed within the timeframe of this study. Longer monitoring periods are needed to assess the effects of increased egg shedding on subsequent foal crops. 

Whole genome sequencing identifies missense mutation in GRM6 as the likely cause of congenital stationary night blindness in a Tennessee Walking Horse

YL Hack, EE Crabtree, F Avila, RB Sutton, RA Grahn, A Oh, B Gilger and RR Bellone

This case report detailed a whole genome sequencing approach to identify a causal variant of congenital stationary night blindness (CSNB) in a Tennessee Walking Horse.  Prior to this, the only known reported genetic cause of CSNB in horses was a 1378 bp insertion in the transient receptor potential cation channel subfamily M member 1 (TRPM1) gene.

A male, 13-year-old Tennessee Walking Horse with clinical signs and examination findings (including dark-adapted electroretinography) consistent with CSNB underwent whole genome sequencing. Results were compared to data from 29 horses of seven other breeds.  A list of 100 candidate genes was compiled based on a literature review of mutations causal for CSNB in other species, and coding variants homozygous in the case and absent in the other horses were further evaluated.  DNA from 90 randomly selected Tennessee Walking Horses and 273 horses of three other breeds was used to estimate the allele frequency of the causal mutation.  

The horse was not found to have any copies of the TRPM1 mutation but had a missense variant in the metabotropic glutamate receptor 6 (GRM6) gene; a G-protein coupled receptor vital for night vision.  They estimated the allele frequency in Tennessee Walking Horses to be 10%.

Bottom line: Congenital stationary night blindness (CSNB) can be associated with a recessive missense variant in GRM6.

Post-operative pain behaviour associated with surgical castration in donkeys (Equus asinus)

Maria Gláucia Carlos de Oliveira, Stelio Pacca Loureiro Luna, Talyta Lins Nunes, Paulo Ricardo Firmino, Amara Gyane Alves de Lima, Josiel Ferreira, Pedro Henrique Esteves Trindade, Raimundo Alves Barrêto Júnior, Valéria Veras de Paula

This prospective study aimed to characterise the behavioural responses of donkeys to acute surgical pain.

Forty healthy adult intact male donkeys ranging from 2 to 14 years old underwent open castration under inhalant general anaesthesia following premedication with xylazine, and induction with guaiacol glyceryl ether and thiopental. Donkeys only received analgesia 4 h following recovery from anaesthesia, consisting of 1.1 mg/kg flunixin meglumine, 10 mg/kg dipyrone and 0.2 mg/kg morphine administered intravenously, repeated every 24 h for 3 days.

The donkeys were filmed for 30 minutes in their individual stalls before castration (M0), 3.5-4 h (M1), 5.5-6 ho (M2) and 23.5-24 h (M3) after recovery from anaesthesia. In an attempt to exclude the influence of flies on donkey behaviour, six apparently pain free donkeys were assessed before and after their stalls were mucked out. The video footage was assessed by the same person, and differences in frequency of various behaviours at the four timepoints analysed.

Twenty-five different behaviours were observed during the 80 hours of video analysis. Lifting of the pelvic limbs was the main behaviour exhibited by donkeys in pain; occurring more frequently during M1 than the other time periods. Eating and water intake increased after analgesia (M2) and time spent in locomotion did not change during the four time periods. Behaviours seen in horses such as flank-watching, kicking the abdomen, pawing the ground, moving the head, were not observed.

Bottom line: Lifting the pelvic limbs was the only specific pain behaviour after castration in donkeys.

An alternative arthroscopic approach to the caudal pouches of the equine lateral femorotibial joint

HD O’Neill and BM Bladon

This cadaver and clinical study described and evaluated a novel arthroscopic approach to the caudal pouches of the lateral femorotibial joint as current approaches are considered challenging and risk iatrogenic nerve and cartilage damage.

The surgical technique was developed initially using 19 cadaver limbs positioned to simulate dorsal recumbency and with the stifle held in 90-degree flexion. A portal was made immediately cranial to the lateral collateral ligament and the arthroscope advanced along the popliteal tunnel of the femorotibial joint in a cranial to caudal direction.

Following the cadaver study, 33 horses underwent inspection of 38 caudal lateral femorotibial joints using the alternative technique as part of routine joint inspection in 33 horses. Entry and examination of both pouches of the caudal lateral femorotibial joint were consistently achieved in both the cadaver and clinical limbs, with no intra‐ or post-operative complications in the latter.

Bottom line: An arthroscopic portal immediately cranial to the lateral collateral ligament permitted consistent entry into the popliteal tunnel and both pouches of the caudal lateral femorotibial joint.

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AE Durham, J Kemp-Symonds

This retrospective study investigated the sensitivity of serological testing for antibodies against Streptococcus equi subspecies equi antigens A and C to detect guttural pouch carriers.

Retrospective data from 287 horses arriving at a welfare charity quarantine unit that underwent microbiological sampling of guttural pouches and serological testing was reviewed. In total, nine (3.1%) horses were found to be guttural pouch carriers on microbiology and 35 (12.2%) horses were seropositive (had at least one ELISA OD value ≥0.5). Of the 35 seropositive horses, one (2.9%) had evidence of S. equi in a guttural pouch lavage. Of the 252 horses with OD values <0.5, eight (3.2%) had evidence of S. equi in guttural pouch samples. Only one (11%) of the nine horses found to be guttural pouch carriers was seropositive at a cut‐off of OD ≥ 0.5, but lowering the cut-off to OD ≥ 0.3 identified two additional guttural pouch carriers.

Bottom line: There was no association between serological status and guttural pouch carriage of S. equi. Therefore seronegativity to antigens A and C should not be relied upon when determining if a horse is a chronic carrier of S. equi.

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Age‐related differences in blood pressure, ultrasound‐derived arterial diameters and arterial wall stiffness parameters in horses

L Vera, G Van Steenkiste, A Decloedt, K Chiers, G van Loon

This study investigated whether arterial wall stiffness increases with age in horses, as it does with humans.

A total of 50 young (3–7 years) and 50 old (>18 years) healthy Warmblood horses underwent cardiovascular ultrasound and non‐invasive blood pressure measurement simultaneously. Arterial diameters, cross‐sectional areas, and arterial wall thickness were measured. Arterial wall stiffness of the aorta and common carotid artery were assessed using pulse wave velocity. Lumen area/diameter change, strain, compliance, and distensibility were also calculated to assess local arterial wall stiffness.

No difference in blood pressure was found between age groups. All systolic and diastolic arterial diameters and the thickness of the common carotid artery were significantly greater in the old horses.  The aorta and caudal common carotid artery local arterial wall stiffness and pulse wave velocities were significantly higher in the old horses compared with the young horses.

Bottom line: This study suggests that arterial stiffness and wall thickness increase with age in horses.

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Effect of infrared and red monochromatic light on equine wound healing

P Michanek, T Toth, E Bergström, H Treffenberg‐Pettersson, A Bergh

This randomised, blinded, controlled study investigated how pulsating visible red light (λ ≈ 637 nm) and near‐infra red (NIR) light (λ ≈ 956 nm), affects swelling and wound healing in healthy horses.

Eight healthy adult Standardbred horses had a full-thickness skin wound created using a custom made, 2 cm diameter circular punch on both sides of their neck under sedation and local anaesthesia. The wounds were left uncovered to heal by secondary intention. One wound per horse was randomly allocated to receive light‐emitting diode (LED) treatment on Days 0–4, 7–11, 14–18 and 21–25, with the wound on the opposite side of the neck acting as an untreated control. Treatment was conducted using a handheld device (BCD 650 Animal, Biolight AB) using a pre‐set programme with a duration of 4 minutes and 40 seconds (red light was emitted for 95 seconds and NIR light for 185 seconds). The wounds were evaluated ultrasonographically for swelling and photographed daily. Wounds were considered to be healed when an epithelial layer covered the entire wound surface.

None of the wounds showed clinical signs of infection over the study period. Wound area and degree of swelling did not differ between the treated and control groups on any day. There was a significant difference in healing time between control and treated wounds, with LED light‐treated wounds taking longer to heal than control wounds.

Bottom line: This study did not find any positive effect of LEDs on experimental wound healing.

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A long‐term study of equine cheek teeth post‐extraction complications: 428 cheek teeth (2004‐2018)

Rebekah Kennedy, Richard J.R. Reardon, Oliver James, Cherith Wilson and Padraic M. Dixon

This retrospective study describes the complications of equine cheek tooth exodontia techniques.

The clinical records of all cheek teeth extractions performed at the University of Edinburgh Veterinary School between February 2004 and September 2018 were examined.  Owners were asked to complete a follow-up questionnaire regarding complications post-extraction.

In all cases, oral extraction was initially attempted prior to Steinman pin repulsion or minimally invasive transbuccal extraction (MTE). A total of 428 cheek teeth extractions were performed over the study period, 58 (13.6%) of which had complications post-extraction. The most frequent complication was the formation of intra-alveolar bony sequestra (32/58). The most severe post-extraction complications were seen in four horses that had swollen mandibles pre-extraction due to apical infections, who went on to develop severe mandibular osteomyelitis post-extraction. Two horses developed sinusitis following maxillary cheek teeth exodontia. Overall, the complication rate was 10.8% for oral extraction, 24.4% for Steinmann pin repulsion, 20% for standard repulsion and 25.6% for MTE. Post-extraction complications caused a longer-term clinical problem in 34/428 (7.9%) of horses and were asymptomatic or quickly self-resolving in the other 24 (5.6%) cases. Risk of developing a post‐extraction alveolar disorder was increased following extraction of the mandibular 06s, 07s or 08s compared to all other cheek teeth combined (P = 0.001); for cheek teeth with apical infections (P = 0.002) compared to those without; and following repulsion or minimally‐invasive transbuccal extraction (MTE) than following oral extraction (P = 0.01 and P = 0.02 respectively).

Bottom line: Oral extraction had the lowest risk of complications. Improved knowledge of the prevalence, types and risk of development of post extraction complications may help reduce these complications.

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The prevalence of uveitis in a population of donkeys in the UK

 Claire Bradley, Rachael Grundon, Philip G. Sansom 

This study investigated the prevalence of uveitis within a population of donkeys in the UK.

Donkeys admitted to two sanctuaries for reasons unrelated to vision underwent ophthalmic examination without sedation. A donkey was determined to have signs of uveitis if it displayed at least three of the following: miosis, corpora nigra atrophy, aqueous flare, keratic precipitates, corneal oedema, anterior lens capsule pigment (‘iris rests’), cataract, iris pigmentary change, synechiae, lens luxation or subluxation, vitreal opacities, retinal detachment or traction bands, or peripapillary scarring.  Donkeys were considered to have active uveitis if observable signs of intraocular inflammation were present.

A total of 207 donkeys were examined, ranging from 2-37 years (median 17 years). Signs consistent with previous or current uveitis were identified in eight eyes from six donkeys. Significant ocular pathology precluded detailed fundic examination in three eyes. Clinical signs included miosis (n = 1), corpora nigra atrophy (n = 6), anterior lens capsule pigment (n = 2), cataract (n = 8), posterior synechiae (n = 3), lens subluxation (n = 1), vitreal changes (n = 2), peripapillary scarring (n = 3), and phthisis bulbi (n = 1). Significant ocular pathology prevented fundic examination in three eyes.  Three donkeys were considered to have active uveitis and three were post-inflammatory or quiescent.  Of those displaying uveitic changes, 3/8 eyes were blinded by the pathology.  The overall prevalence of uveitis in this population of donkeys was 2.9%.

Bottom line: This study revealed a comparable disease prevalence to that reported for horses in the UK.

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Assessment of the immunocrit method to detect failure of passive immunity in newborn foals

E Mortola, G Miceli, L Alarcon, M Azcurra, A Larsen

This study assessed the validity of the immunocrit method to detect failure of passive transfer (FPT) in foals. The technique, which is inexpensive and provides results within minutes, is based on the ability of ammonium sulphate to precipitate the immunoglobulin fraction of serum.

A total of 211 newborn Thoroughbred foals were included in the study over a 2-year period. Blood samples were obtained after foals had suckled from their dam at 10–14 hours old. A 40% ammonium sulphate solution was used to precipitate the immunoglobulins in the serum, and the separation between the precipitate and the liquid supernatant was measured using a haematocrit reader. The assay was performed in triplicate and included a negative control with a serum sample taken before the foal suckled colostrum. Results were compared with those of agarose gel electrophoresis which also measures total immunoglobulins.

The values obtained by the immunocrit method were significantly correlated (R = 0.871; P<0.001) with those measured by agarose gel electrophoresis. A cut‐off value of 8 g/L of serum immunoglobulins by agarose gel electrophoresis and its equivalent of 9.5% for the immunocrit test was indicative of FPT. The sensitivity and specificity of the immunocrit method at this cut‐off point were 94% and 82% respectively.

Bottom line: The immunocrit test is a quantitative, quick, inexpensive, reliable and objective method to detect FPT in foals.

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Inter‐user and intra‐user variation of two tonometers in horses

AC Lewin, C Liu, P Camacho‐Luna, C Alling, RT Carter

This randomised, masked, cross‐over trial aimed to determine whether applanation or rebound tonometry has the lowest inter‐ and intra‐user variation when measuring intraocular pressure (IOP) in horses.

Four examiners used rebound (ICare® TonoVet) and applanation (TonoPen®) tonometers to measure the IOP in triplicate in 10 normal horses before and after sedation with xylazine. The order of examiners, eye examined first and instrument used first were determined randomly and varied between horses. Coefficient of variation (CV) values were calculated from the mean of each examiner for each condition combination to determine inter‐user variation. For intra‐user variation, CV values were calculated from the individual measurements of each examiner for each condition combination. CV values were also assessed in relation to other variables using ANOVA.

The rebound tonometer was found to have significantly (P<0.01) lower inter‐user (15.4% vs 21.7%) and intra‐user (9.1% vs 16.1%) variation in unsedated horses and lower intra‐user (8.4% vs 14.7%,) variation in sedated horses than the applanation tonometer. Both instruments had similar inter‐user variation in sedated horses. For the rebound tonometer, sedation did not affect inter‐user or intra‐user variation, but for the applanation tonometer inter‐user variation was lowest while horses were sedated (16.0% vs 21.7%, P = 0.03). No other variable assessed was found to have an effect on IOP.

Bottom line: Rebound tonometry may be the preferred instrument to minimise intra‐user and inter‐user variation for IOP measurement in unsedated horses.

Associations between the radiographic appearance of vascular channels in proximal sesamoid bones, their microstructural characteristics and past racing performance in Thoroughbreds

Lloyd KA, Ayodele BA, Hitchens PL, Beck C, Mackie EJ, Whitton RC

This cross-sectional study investigated the clinical significance of radiographic changes in proximal sesamoid bone (PSB) vascular channel morphology, or ‘sesamoiditis’.

The paired PSBs were isolated from the forelimbs of Thoroughbreds undergoing post-mortem examination. This included yearlings in pre-training, mature horses in race training and those resting from training or those that had retired from racing in the last 12 months. Each PSB was radiographed and assigned a vascular channel grade using previously published and novel grading systems. The sesamoids were then separated and individual whole bones were imaged with microcomputed tomography (µCT); an imaging modality that allows assessment of bone microstructure in three dimensions. Associations between radiographic, µCT and performance variables were investigated with uni- and multi-variable generalised linear models.

One hundred and eighteen PSBs were collected from 59 horses aged between 16 months and 12 years. Nine horses were resting from training and 50 were in race training at the time of death. All PSBs had at least one vascular channel observed on µCT originating from the abaxial border; 63.6% (75/118) of which were observed radiographically. Proximal sesamoid bones with a higher bone volume fraction and wider channel diameter on µCT were more likely to have vascular channels identified on radiographs. Greater radiographic channel number and diameter were associated with fewer career placings. No association was found between any variable and the horse being subjected to euthanasia due to catastrophic fracture.

Bottom line: This study suggests that more radiographic channels and greater channel diameter are associated with poorer measures of past performance.

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Amikacin induces rapid dose-dependent apoptotic cell death in equine chondrocytes and synovial cells in vitro

Pezzanite L, Chow L, Soontararak S, Phillips J, Goodrich L, Dow S

This in vitro study aimed to evaluate the cytotoxic effects of amikacin on equine chondrocytes, synoviocytes, and bone marrow and adipose-derived mesenchymal stem cells (MSC).

Chondrocytes, synovial cells, and adipose and bone marrow derived MSC were harvested post-mortem from three horses with no evidence of osteoarthritis. The effects of amikacin on cell viability were assessed for different exposure times, concentrations, and with pH buffered or unbuffered in media, as well as in the presence of synovial fluid. Cell metabolism/viability was assessed by colorimetric MTT assay, and cell proliferation was assessed by live cell imaging. Cell viability was assessed using trypan blue and dimeric cyanine nucleic acid stain. Mechanism of cell death was also evaluated.

Amikacin exhibited a dose-dependent killing of chondrocytes, synovial cells, and bone marrow and adipose-derived mesenchymal stem cells. At a concentration of amikacin achieved following typical intra-articular medication (25 mg/mL) rapid cytotoxic effects were seen for all cell types. The primary mechanism of cell death was via apoptosis, and cytotoxicity was not mitigated by the addition of synovial fluid in vitro.

Bottom line: Amikacin at clinically applied doses induces rapid, pronounced cell death of equine joint cells and so amikacin doses currently used intra‐articularly should be reconsidered.

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Evaluation of the effect of laser salpingopharyngostomy on the guttural pouch environment in horses

C.C. Jukic, N.R. Cowling, N.R. Perkins, A.W. van Eps, B.J. Ahern

This study evaluated the effect of laser salpingopharyngostomy on the guttural pouch environment of healthy horses.

Six adult Standardbred horses free from endoscopic evidence of guttural pouch abnormalities were included in the study. A stab incision was made ventral to the sternocephalicus tendon and a customised trocar inserted into the into the floor of the right medial guttural pouch compartment under standing sedation.   Baseline (Day 0) temperature, humidity, oxygen (O2) and carbon dioxide (CO2) levels were recorded. A 2 cm x 2 cm salpingopharyngostomy was created into the dorsocaudal pharynx abaxially off midline into the floor of the right medial guttural pouch compartment. The guttural pouch environment was re-evaluated at 7 and 14 days post-operatively. All horses underwent URT and guttural pouch examination via endoscopy at 3 and 12 months after the completion of sampling. 

The guttural pouch environment was altered by the laser salpingopharyngostomy, with considerable variation between horses and during the sampling period. The level of CO2 post laser salpingopharyngostomy appeared to be linked directly to the horse's respiratory pattern, and the variation in CO2 was significantly different at Days 7 and 14 post laser salpingopharyngostomy compared to baseline levels. Oxygen levels were also more varied during sampling compared to baseline. There was no change in humidity or temperature during the study.

Bottom line: Laser salpingopharyngostomy into the guttural pouch may be useful in clinical cases of guttural pouch disease where alteration of the environment may be beneficial.

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Chondromalacia of the cranial medial femoral condyle; its occurrence and association with clinical outcome in a population of adult horses with stifle lameness

A. K. Croxford, R. A. Parker, J. H. Burford, D. Lloyd, J. C. Boswell, T. K. Hughes, T. J. Phillips

This retrospective cohort study aimed to document the occurrence and significance of chondromalacia of the cranial medial femoral condyle (CMFC) in adult horses with stifle lameness.

Medical records and arthroscopic surgical videos were reviewed from horses with unilateral or bilateral lameness localised to the stifle that subsequently underwent arthroscopy of the cranial medial femorotibial joint at a single equine referral hospital between 2009 and 2014.  The arthroscopy video recording for each was reviewed by three board-certified surgeons for the presence or absence of CMFC. Surgical intervention and post-operative rehabilitation varied based on the pathology and surgeon preferences. Regular exercise was not resumed for at least 6 months post-surgery. Follow-up information was obtained through telephone conversations with owners, with a satisfactory outcome being defined as a horse being in ridden work without requiring ongoing anti-inflammatory medication. 

A total of 104 horses were included in the study; 79 (76%) had CMFC, of which 54 had CMFC in combination with other pathology and 25 had CMFC alone, and 25 (24%) had other pathology. At 12 months, 62 (59.6%) horses had a satisfactory outcome. The only variable that showed any significant effect on outcome was CMFC; with horses with CMFC being 9.9 times more likely to have an unsatisfactory outcome at the 12-month follow-up period compared to those without CMFC. 

Bottom line: CMFC is associated with an increased likelihood of the horse not being in ridden work at long-term follow-up.

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External transcutaneous ultrasound technique in the equine cricoarytenoideus dorsalis muscle: Assessment of muscle size and echogenicity with resting endoscopy

Satoh, M., Higuchi, T., Inoue, S., Miyakoshi, D., Kajihara, A., Gotoh, T., Shimizu, Y.

This study aimed to evaluate the use of transcutaneous ultrasound of the left cricoarytenoideus dorsalis muscle (LCAD) and right cricoarytenoideus dorsalis muscle (RCAD) to diagnose recurrent laryngeal neuropathy (RLN).

A total of 164 Thoroughbreds underwent resting endoscopy without sedation and were graded using the 4-grade Havermeyer system. Horses with resting grades 1 and 2 with no history of abnormal respiratory noise acted as controls, whereas horses with resting grades 3 and 4 with a history of abnormal respiratory noise at exercise were deemed to be clinically ‘affected’ by RLN.

Following endoscopy, the horses were sedated and transcutaneous ultrasonography of the larynx performed. The axial plane thickness, cross-sectional area, and echogenicity of the LCAD and RCAD were measured, and the LCAD:RCAD ratios in thickness and area compared between controls and affected horses.

Thickness and area of the LCAD showed a negative correlation with resting laryngeal grade. In contrast, the thickness of the RCAD showed a positive correlation with resting laryngeal grade. Increasing RCAD thickness was found in horses with resting grades 3.II and 4, while increasing RCAD cross-sectional area was found in horses with grade 3.II. LCAD was more hyperechogenic than RCAD in resting grades 3 and 4. 

Bottom line: Assessment of the CAD using transcutaneous ultrasonography may be a useful technique in determining whether to perform nerve graft or laryngoplasty.

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Annual booster vaccination and the risk of equine influenza to Thoroughbred racehorses

Gildea, S., Lyons, P., Lyons, R., Gahan, J., Garvey, M., Cullinane, A.

This observational study investigated equine influenza (EI) outbreaks at four Thoroughbred racing yards in Ireland over a 4-week period between December 2014 and January 2015.

Repeat sampling (nasopharyngeal swabs and clotted blood samples) of all horses on affected premises was performed on a weekly basis until all horses tested negative for EI by RT-PCR. Antibodies were measured against the Irish Florida sublineage clade 2 which demonstrates 100% HA nucleotide identity to the Florida clade 2 OIE recommended vaccine strain A/eq/Richmond/1/07.

Samples were collected from 118 horses over four affected premises. Forty-five horses (38.1%) developed clinical signs, 28 of which (62.2%) tested positive by RT-PCR. Eighty horses (67.8%) were up to date with their vaccinations, of which 27 (33.8%) developed clinical signs. Eighteen of the 27 horses (66.7%) that developed clinical signs had not received a booster vaccination within the previous 6 months, and 10 (37%) were due their annual booster vaccination at the time of developing clinical signs. The first documented cases on all premises (i.e. the index cases) were vaccinated in accordance with Turf Club rules. Vaccine breakdown (morbidity when vaccinated in accordance with the Turf Club rules) was observed in 27/80 horses (33.8%) with an up to date vaccination record. 

Failure to implement appropriate biosecurity measures following the introduction of new horses and the return of horses from events contributed to disease spread, as did the movement of horses within premises. Mixing of racing and non-racing populations with inadequate vaccination histories also facilitated disease spread. 

Bottom line: Annual booster vaccination should not be relied on as the sole preventative measure against EI.

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Atrial premature depolarisations five days post electrical cardioversion are related to atrial fibrillation recurrence risk in horses

Vernemmen, I., De Clercq, D., Decloedt, A., Vera, L., Van Steenkiste, G., van Loon, G.

This retrospective case series investigated whether a high atrial premature depolarisation (APD) burden after cardioversion is associated with recurrence of atrial fibrillation (AF).

Medical records were searched for horses that successfully underwent transvenous electrical cardioversion (TVEC) for AF between 2008 and 2017.  Horses were included in the study if they met the following inclusion criteria: it was their first episode of AF, there was no AF recurrence in the first 5 days post-cardioversion, 24‐h ECG recording and echocardiographic examination 5 days post-cardioversion were available, no antiarrhythmic treatment was administered during the 24‐h ECG recording and follow‐up information was available for at least 1 year. An APD was defined as a premature P-wave, occurring at least 8% earlier, with a normal or abnormal morphology and, if conducted to the ventricles, followed by a QRS‐complex with a normal morphology. 

A total of 80 horses met the inclusion criteria, 33% of which (n = 26) experienced AF recurrence within 1 year, with a median time to recurrence of 125 days. Horses experiencing recurrence within 1 year showed a significantly higher number (median [range]) of APDs (15 [1–152]) compared with the non‐recurrence group (7 [0–304]).  In the multivariable model, ≥25 APDs/24 h, mitral regurgitation, left atrial active fractional area change and lower body weight were significantly associated with AF recurrence.

Bottom line: The APD burden 5 days post cardioversion could be a useful predictive value for AF recurrence within 1 year in horses.

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A multi‐centre cohort study investigating the outcome of synovial contamination or sepsis of the calcaneal bursae in horses treated by endoscopic lavage and debridement

Isgren, C. M., Salem, S.E., Singer, E.R., Wylie, C. E., Lipreri, G., Graham, R. J. T. Y., Bladon, B., Boswell, J. C., Fiske‐Jackson, A. R., Mair, T. S., Rubio‐Martínez, L. M.

This cohort study reports the outcome of horses with contamination/sepsis of the calcaneal bursae following endoscopic treatment in addition to identifying prognostic factors associated with survival. 

Medical records from seven referral hospitals in the UK were reviewed to identify horses that presented with synovial contamination/sepsis of the calcaneal bursae between 2002 and 2016. A total of 128 horses were included in the study; 123 of which recovered from anaesthesia. Following surgery, clinical signs improved in of 74.8% (n = 92) of cases. A total of 21 horses underwent a second surgery. Both the calcaneal bursa and the subcutaneous bursa were affected in 42.5% (n = 54) of horses, and in 48.0 % (n = 61) only the calcaneal bursa was affected.  All horses with only the subcutaneous bursa involvement survived. There was bone involvement in 23.6% (n = 30) of horses. The most common bacteria isolated were Staphylococcus spp., followed by Streptococcus spp. and Escherichia coli.

Administration of systemic antimicrobials prior to referral was associated with reduced mortality. Bone fracture/osteomyelitis, tendon involvement, duration of general anaesthesia, post‐operative synoviocentesis, and post‐operative wound dehiscence were associated with increased mortality.  At follow‐up, 87.1% horses were alive, 7.1% had been euthanised due to the calcaneal injury and 5.7% had been euthanised for unrelated reasons. From 57 horses with athletic performance follow‐up, 91.2% returned to the same or higher level of exercise.

Bottom line: Endoscopic treatment of calcaneal bursae contamination/sepsis in horses has a good survival rate with the majority of horses returning to their previous athletic use at the same or higher level. 

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Non-surgical and surgical management of metacarpo/metatarsophalangeal joint dorsal chip fracture in the Thoroughbred racehorse

Ramzan, P. H. L., Wylie, C. E.

Arthroscopy is considered the treatment of choice for dorsal osteochondral chip fractures of the metacarpo/metatarsophalangeal (MCP/MTP) joints in the racehorse. This retrospective study compared the surgical (SX) and non-surgical (non-SX) management of MCP/MTP joint dorsal chip fractures in racing Thoroughbreds.

Medical records from 2006 to 2014 were reviewed to identify Thoroughbred racehorses that were diagnosed with a MCP/MTP dorsal osteochondral chip fractures by radiography. In total, 98 horses met the inclusion criteria (70 non-SX, 28 SX), with chip fractures predominantly involving the forelimbs (n = 92, 93.9%) and considered to be clinically active in 86.7% of cases (n = 85). 

Overall, 70 horses were managed non-surgically (71.4%) and 28 underwent surgery (28.6%).   Significantly more SX horses had a reported ongoing problem associated with the affected joint than non-SX horses; however, there was no significant difference between non-SX and SX horses with respect to the number of intra-articular medications of affected joint per month of follow-up. The proportion of horses racing post-diagnosis was not significantly different between the two groups (78.6% non-SX vs 85.7% SX). The median time to first start following diagnosis for non-SX (106 days) was significantly shorter than for SX (203 days).

Bottom line: Non-surgical management may be a valid treatment option for some cases of metacarpo/metatarsophalangeal joint dorsal chip fracture.

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The safety and efficacy of neuromodulation using percutaneous electrical nerve stimulation for the management of trigeminal‐mediated headshaking in 168 horses

Roberts, V. L. H., Bailey, M., Patel, N.K.

This paper reported the results of an international, multi‐centre study investigating the use of EquiPENS™ neuromodulation for idiopathic trigeiminal-mediated headshaking.

Horses were included in analyses if they were diagnosed with trigeminal‐mediated headshaking by exclusion of all other possible causes of the clinical signs and received EquiPENS™ neuromodulation between August 2013 and November 2017. 

Each horse received an initial course of three procedures, with the first two procedures performed 3–7 days apart, and the third procedure 10–14 days after the second. A total of 530 procedures were performed on 168 horses, with 53% (n = 72) of horses going into remission following the initial course. The median duration of remission was 9.5 weeks (range 2 days–156 weeks and ongoing). Horses were significantly more likely to go into remission at the end of the first course if they went into remission after the first procedure and second procedures. Complications were reported in 8.8% (n = 47) of procedures, with worsening of clinical signs being the most frequently reported. In all but one case, complications were mild and transient, without self‐trauma. No predictors for outcome were determined.

Bottom line: Complication rates of EquiPENS™ neuromodulation are low, but there is a wide range of variation in relation to its efficacy.

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Myenteric networks of interstitial cells of Cajal are reduced in horses with inflammatory bowel disease

Fintl, C., Lindberg, R., McLean Press, C.

This retrospective study evaluated the immunohistological changes to the interstitial cells of Cajal (ICC), enteric neurons and glial cells in the small intestine of horses with inflammatory bowel disease (IBD).

Immunohistochemistry was performed on ileal samples collected at post-mortem from eight normal control horses and from 14 horses with clinical signs of IBD. The duration of illness ranged from 3 weeks to 6 months, with two horses having received corticosteroid therapy prior to euthanasia. Tissue sections were labelled with anti-CD117 (c-Kit), anti-TMEM16 (TMEM16), anti-protein gene product (PGP9.5) and anti-glial fibrillary acidic protein (GFAP). Images were then analysed to quantify the presence of ICC, neuronal and enteroglial networks.

ICC networks were significantly reduced in the myenteric plexus region in horses with IBD compared to the controls for both markers.  All IBD cases had villous atrophy and lymphoid hyperplasia of the mucosa and submucosa, but the myenteric ganglia typically appeared normal and free from inflammatory cell infiltrate.

Bottom line: Disruption to ICC networks may contribute to the clinical signs of IBD. 

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Improved diagnostic criteria for digital flexor tendon sheath pathology using contrast tenography

Kent, A.V., Chesworth, M.J., Wells, G., Gerdes, C., Bladon, B.M., Smith, R.K.W., Fiske‐Jackson, A.R.

This multicentre retrospective study aimed to evaluate contrast radiography of the digital flexor tendon sheath (DFTS) in diagnosing intrathecal tendon pathology.   

Medical records from three equine hospitals were reviewed. Horses were included in the study if they were diagnosed with lameness localised to the DFTS and had both contrast radiography and subsequent tenoscopy under general anaesthesia performed to confirm a diagnosis of a manica flexoria (MF) tear, deep digital flexor tendon (DDFT) tear or palmar/plantar annular ligament (PAL) constriction. For contrast radiography, 5-7 mL of sodium meglumine diatrizoate or Iohexol was injected with 10 mL mepivacaine hydrochloride into the DFTS.  Horses were then walked for 4–5 strides before a lateromedial radiograph of the distal limb was taken. Radiographs were reviewed by four operators blinded to case details.  Sensitivity, specificity and inter-observer variability were calculated for each pathology. 

A total of 206 horses met the inclusion criteria. Contrast tenography was a sensitive test for MF tears and specific for DDFT tears, but there was poor agreement between evaluators when diagnosing PAL constriction from contrast radiographs. Ponies and cobs were significantly more likely to be affected with MF tears, whereas Thoroughbreds, Warmbloods and draught breeds were more likely to have DDFT tears. 

Bottom line: Contrast radiography of the DFTS may offer an accurate diagnosis of certain DFTS pathologies. 

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Caudal cervical vertebral morphological variation is not associated with clinical signs in Warmblood horses

Veraa, S., de Graaf, K., Wijnberg, I.D., Back, W., Vernooij, H., Nielen, M., Belt, A.J.M.

This case-control study investigated the clinical relevance of radiographically visible morphologic variations in the caudal cervical vertebrae of Warmbloods.

Cervical radiographic examinations of all Warmblood horses (with and without clinical signs) performed between January 2011 and December 2013 were reviewed by a board certified radiologist. Morphologic variations recorded included absence of a ventral laminar part of the transverse process in combination with a ventral protuberance at another transverse process and the presence or absence of degenerative joint disease of the articular facet joint of C6 and C7. Clinical signs considered relevant included spinal ataxia, restricted flexion of the neck, cervical pain on palpation, abnormal behaviour (e.g. head shaking, bolting), cervical muscle atrophy, presumed thoracic neurological lameness and hypermetric gait. Univariable Pearson’s Chi‐square and multivariable logistic regression was used to compare the cases (horses with clinical signs) and controls (horses with no clinical signs).  

In total, 245 cases and 132 controls were included in the study. Morphologic variation at C6 and C7 was significantly less frequent in horses with clinical signs (23.7%) compared to the control group (38%).  Age, sex, breed and degenerative joint disease were not associated with the presence of clinical signs. 

Bottom line: Radiographic morphologic variations in the caudal cervical spine are more common in horses without relevant clinical signs and so should be interpreted with care.

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Restoration of arterial oxygen tension in horses recovering from general anaesthesia

Bardell, D., Mosing, M., Cripps, P.J.

This prospective study investigated changes in arterial oxygen tension (PaO₂) in horses during recovery from general anaesthesia.

In total, 102 systemically healthy horses undergoing general anaesthesia for elective surgery were included in the study. Arterial blood samples were obtained prior to administration of pre‐anaesthetic medication (baseline), at the end of anaesthesia, when placed in recovery, at 10 minute intervals whilst in lateral recumbency, immediately upon achieving sternal recumbency, at 10 minute intervals until standing and 1 hour after standing (STAND+1).

Pre‐anaesthetic medication consisted of acepromazine, an alpha-2 adrenoreceptor agonist and a µ‐receptor agonist opioid. Induction was achieved with thiopental or ketamine plus a benzodiazepine, and anaesthesia was maintained with isoflurane or sevoflurane. Forty horses received controlled mandatory ventilation (CMV) throughout anaesthesia, 47 breathed spontaneously (SV) and 15 breathed spontaneously before CMV was commenced (S‐CMV). 

Overall, PaO₂ alveolar‐to‐arterial oxygen tension difference (P(A‐a)O₂) and arterial carbon dioxide tension (PaCO₂) remained significantly lower than baseline at the STAND+1 time point. The only group in which these values had returned to baseline values at STAND+1 was S‐CMV.  CMV resulted in higher PaO₂ at the end of anaesthesia and during early recovery than SV. Highest PaO₂ values associated with CMV were also associated with early recovery apnoea. Oxygen supplementation in recovery resulted in higher mean PaO₂ than horses receiving no additional oxygen. High PaO₂ values did not appear to adversely affect outcome.

Bottom line: Controlled mandatory ventilation during general anaesthesia may result in better pulmonary function in horses.

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A 10‐year study of arthroscopic surgery in racing Thoroughbreds and Quarterhorses with osteochondral fragmentation of the carpus

Graham, R. J. T. Y., Rosanowski, S. M., McIlwraith, C. W.

This retrospective study aimed to identify associations between the severity and location of osteochondral fragments in the carpus and to describe the racing performance of horses pre‐ and post‐ arthroscopic removal in Thoroughbreds and Quarter Horses. 

The medical and racing records of racehorses that underwent carpal arthroscopy between 2006 to 2016 due to clinical signs and radiographic findings consistent with carpal chip fragmentation were retrospectively reviewed. Signalment, location of fragmentation and grade of defect after arthroscopic removal and debridement were described and logistic regression used to identify factors associated with an unsuccessful return to racing.

In total, 828 horses (416 Quarter Horses and 412 Thoroughbreds) underwent 880 carpal arthroscopies for removal of fragments. A total of 65% and 27% of lesions were bilateral in Quarter Horses and Thoroughbreds, respectively, with the most commonly affected bone in both breeds being the dorsodistal radial carpal bone.  Overall, 82% of horses raced post‐surgery, with 69.5% racing at the same or a higher level. Factors associated with horses not returning to racing post‐surgery were increasing horse age, being female, and a lesion grade of 4/4, while racing pre‐surgery appeared protective.

There were significant differences between the location and severity of lesions in Quarter Horses compared to Thoroughbreds. The majority of horses returned to racing following surgery, with lesion severity affecting performance.

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A histological and ultrastructural study of equine peripheral caries

Borkent, D., Smith, S., Dixon, P.M.

This study examined cheek teeth affected by periperhal caries (PC) histologically and ultrastructurally in order to try and establish the route of cariogenic bacterial invasion and to describe the resulting pathological changes.

A total of 16 cheek teeth from horses that had died of non‐dental related disease with varying grades of PC were examined alongside four control teeth (no PC). The teeth were macroscopically assessed. Of those with PC, 11 had partial cemental caries (grade 1.1 PC), three had total cemental caries (grade 1.2 PC), three had caries of cementum and the underlying enamel (grade 2 PC) and two had caries of cementum, enamel and dentine (grade 3 PC). Samples for histological and electron microscopy examination were prepared.

Bacteria from plaque entered the peripheral cementum perpendicular to the sides of the teeth alongside Sharpey's fibres or vascular channels or more horizontally alongside exposed intrinsic fibres and cemental growth lines. Intra‐cemental bacterial spread caused varying patterns of cemental caries as identified histologically: horizontal flake‐like lesions (Type A), vertical flake-like lesions (Type B), flask‐like lesions (Type C) and small ellipsoid, lytic lesions (Type D). Regardless of mechanism, cariogenic bacteria commonly tracked along the intrinsic fibres in lines of arrested growth (LAGs), causing further demineralisation of adjacent cementum and disintegration of these fibres. Cemental caries progressed to affect enamel, dentine and pulp.  

Bottom line: Equine peripheral caries cause different patterns of cemental lesions which may be dependent on the route of bacterial invasion. Gross examination can underestimate the true extent of peripheral caries.

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Race performance following epiglottic entrapment surgery in Thoroughbred yearlings

Curtiss, A.L., Aceto, H., Embertson, R.M.

This retrospective study aimed to evaluate the racing performance of horses treated surgically for epiglottic entrapment as yearlings compared to their maternal half‐siblings.

The medical and race records of 66 Thoroughbred (TB) yearlings treated surgically for epiglottic entrapment by axial division with a hook bistoury or diode laser were analysed. For each treated horse, two maternal half‐siblings closest in age were selected as the untreated control cohort. Racing performance was assessed by comparing quarterly starts and earnings, career longevity, rates of racing and earnings. Associations between clinical variables and not racing post‐surgery were evaluated using logistic regression.

In total, 66 treated horses were included in the study, with there being significantly more females than males in the treated group. The proportions of horses that raced were similar in the treated and maternal cohorts, with the treated horses performing to a similar level to their untreated controls. In treated horses, epiglottic entrapment with abnormal right arytenoid movement was associated with never racing.

Bottom line: Thoroughbred racehorses treated in their yearling year for epiglottic entrapment had no differences in performance variables compared to their untreated cohort. 

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Serum amyloid A and plasma fibrinogen concentrations in horses following emergency exploratory celiotomy

De Cozar, M., Sherlock, C., Knowles, E., Mair, T.

This study aimed to compare serum amyloid A ([SAA]) and plasma fibrinogen ([fibrinogen]) concentrations in the immediate post-operative period in horses undergoing exploratory celiotomy for colic unresponsive to medical management.

All horses received preoperative procaine benzylpenicillin (20 mg/kg bwt), gentamicin sulphate (6.6 mg/kg bwt) and flunixin meglumine (1.1 mg/kg bwt). Post-operatively, all horses received balanced polyionic intravenous fluids, with some also receiving a 2% lidocaine continuous rate infusion. Gentamicin sulphate and procaine benzylpenicillin were continued for 24–120 h, and flunixin meglumine (1.1 mg/kg bwt intravenously twice daily) was continued for a further for 3–5 days. [SAA] and [fibrinogen] were measured prior to surgery at admission and daily for 5 days following surgery.

In total, 300 horses were included in the study, 52.0% of which developed post-operative complications and 83.7% survived to discharge. Median [SAA] on days 1, 2, 3, 4 and 5 and median [fibrinogen] on days 3, 4 and 5 were significantly different between horses that did and did not develop post-operative complications, whilst median [SAA] on days 1, 4 and 5 were significantly different between horses that did and did not survive to discharge. Post-operative complications were associated with strangulating lesions and higher [fibrinogen] at admission. Survival to discharge was associated with lower [SAA] at 5 days post-operatively.

Bottom line: Measuring [SAA] daily and [fibrinogen] at admission may help predict the development of post-operative complications.

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Continuous fluid infusion per rectum compared with intravenous and nasogastric fluid administration in horses

Khan, A., Hallowell, G.D., Underwood, C., van Eps, A.W.

This randomised controlled crossover study compared the use of rectally administered fluids to nasogastric and intravenous administration.

Six healthy horses each received each of three different fluid treatment protocols (intravenous Hartmann's, nasogastric polyionic solution and rectally administered tap water) at 5mL/kg/h and also underwent a control protocol (no treatment) while feed and water was withheld for 6 hours.  A minimum 2‐week washout period was observed between each treatment.

Prior to administering rectal fluids the rectum was manually evacuated and a 24 Fr flush enema tube inserted approximately 50 cm into the rectum and secured to the tail. Fluid was delivered continuously by gravity flow.  Packed cell volume (PCV), total solids (TS), albumin, electrolytes, lactate, urine specific gravity, vital parameters, gastrointestinal borborygmi and central venous pressure were measured every 2 hours.

Rectal administration of fluid was well tolerated in all horses. PCV decreased over time with all fluid treatments but not with the control, and TS decreased with intravenous and rectally administered fluid.  There was an increase in gastrointestinal borborygmi with rectally administered fluid. 

Bottom line: Rectal fluid administration may offer an effective, inexpensive alternative or adjunct to intravenous fluid therapy, particularly when administration via nasogastric tube is not possible or contraindicated.

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Intralesional application of medical grade honey improves healing of surgically treated lacerations in horses

Mandel, H. H., Sutton, G. A., Abu, E., Kelmer, G.

This prospective, randomised clinical study aimed to evaluate the effect of intralesional medical grade honey (MGH) on wound infection and dehiscence following closure.

A total of 127 horses were included in the study and randomly allocated into the treatment (MGH; 69 horses) or control (58 horses) group.  Neonatal foals, horses with major systemic illness, penetrating wounds requiring hospitalisation and eyelid lacerations were excluded from the study. 

All wounds were first cleaned thoroughly with diluted chlorhexidine or diluted povidone iodine followed by a balanced sterile electrolyte solution. The MGH group had sterile MGH (L‐Mesitran gel) applied directly onto the subcutaneous tissue prior to skin closure or after partial wound closure. Data relating to wound healing was subsequently collected from the 11 participating practitioners through questionnaires and telephone conversations.

No adverse effects of the MGH were recorded in any of the horses participating in the study. MGH‐treated horses were significantly more likely to heal completely, to have no signs of infection and for the veterinarians to report some degree of satisfaction compared to control cases.

Bottom line: Intralesional application of MGH to lacerations prior to wound closure may help prevent wound infection and therefore dehiscence. 

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Equine ulcerative keratitis with furrow: a review of the outcomes of 72 cases from 1987 to 2015

Berkowski, Jr. W. M., Craft, W. F., Whitley, R. D., Brooks, D.E., Plummer, C. E.

This retrospective case series from the USA aimed to describe the features and outcomes of horses with ulcerative keratitis with an associated peripheral furrow (circumferential thinning of the corneal stroma ≥20% deeper than the central lesion and surrounding cornea).  

A total of 72 horses with furrow-forming ulcerative keratitis seen at the University of Florida between 1987 and 2015 were included in the study. A definitive aetiologic diagnosis was available for 37 eyes; with 27% (n = 10) diagnosed with fungal keratitis, 38% (n = 14) with a mixed fungal and bacterial keratitis and 35% (n = 13) with bacterial keratitis. 

Treatment varied between patients. In total, 36% of eyes (n = 26) were treated with medical therapy alone and the remaining 64% (n = 46) were treated with a combination of medical and surgical therapy. Surgical interventions included keratectomy (superficial keratectomy, anterior lamellar keratectomy, or penetrating keratoplasty) with or without an accompanying graft or conjunctival flap. Grafting materials included frozen equine donor cornea, equine amniotic membrane, and/or processed porcine small intestine. Of those that received medical therapy alone, 20 (77%) healed with a positive visual outcome and 6 eyes were non-visual (23%). Of the 46 eyes which received surgical intervention, 40 (87%) healed with a positive visual outcome and six eyes were non-visual (13%). In total, 83% (n=60) of eyes healed with a positive visual outcome following surgical and/or medical treatment. The remaining 17% (n = 12) were considered treatment failures, with six requiring enucleation and six becoming phthisical.

Bottom line: Cases of ulcerative keratitis with furrow may have a more favourable prognosis than previously thought. The specific aetiologic diagnosis was not a significant predictor of visual outcome.  Surgical treatment was not associated with an increased likelihood of a positive visual outcome.

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Misoprostol is superior to combined omeprazole‐sucralfate for the treatment of equine gastric glandular disease

Varley, G., Bowen, I. M., Habershon-Butcher, J. L., Nicholls, V., Hallowell, G. D.

This prospective UK study compared the efficacy of misoprostol and combined omeprazole‐sucralfate for the treatment of equine gastric glandular disease

Horses were enrolled onto the study if they presented with clinical signs consistent with equine gastric disease and were subsequently found to have grade >1/4 glandular disease identified by gastroscopy. Horses were assigned to one of the two treatment groups (5 μg/kg misoprostol orally twice daily or 4 mg/kg enteric coated omeprazole plus 12 mg/kg sucralfate orally twice daily) based on the hospital at which they were initially examined. Gastroscopy was repeated 28–35 days after the initial examination and images were reviewed by clinicians blinded to the treatment received.  Owners/keepers were not blinded to the treatments and were asked to complete a questionnaire prior to both gastroscopy examinations. Lesion healing was defined as improvement to a grade 0, and horses were considered to have improved if the score decreased by at least one grade. 

A total of 63 horses met the inclusion criteria, with poor performance being the most common presenting sign. All horses had lesions involving the pylorus and/or pyloric antrum, and there was an overall reduction in lesion score in both treatment groups. Of those treated with misoprostol, 72% of lesions healed, compared to 20% of the omeprazole‐sucralfate group. In addition, 98% of horses in the misoprostol group improved, compared to 65% in the omeprazole‐sucralfate group. Overall healing and improvement of lesions were associated with resolution of clinical signs.

Bottom line: Misoprostol was superior to combined omeprazole‐sucralfate treatment both for improvement and healing of gastric glandular lesions.

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Salivary alpha‐amylase activity and concentration in horses with acute abdominal disease: Association with outcome

Contreras‐Aguilar, M. D., Martínez‐Subiela, S., Cerón, J. J., Martín‐Cuervo, M., Tecles, F., Escribano, D.

This prospective cohort study compared salivary alpha‐amylase (sAA) activity and concentration in healthy horses to those with acute abdominal disease.

Horses referred to the Veterinary Teaching Hospital of the University of Extremadura between May and December 2017 for evaluation of colic and subsequently diagnosed with acute gastrointestinal disease were included in the study. A healthy population of horses with normal haematological and biochemical parameters were selected from those admitted for castration or routine health check. Saliva samples were collected from both groups within 30 minutes of arrival at the hospital and prior to examination and treatment.

A total of 25 healthy horses and 33 with acute abdominal disease were included in the study. sAA activity and concentration were significantly different between the two groups. Among the diseased group, sAA activity was higher in non‐survivors compared to survivors. Activity and concentration correlated moderately with heart rate and plasma lactate and weakly with salivary cortisol and systemic inflammatory response syndrome (SIRS) score. The sAA activity was significantly associated with increased risk of nonsurvival.

Bottom line: sAA activity could be a potential biomarker of prognosis in horses with acute abdominal disease.

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Prospective, randomised clinical trial of four different presurgical hand antiseptic techniques in equine surgery

Biermann, N. M., McClure, J. T., Sanchez, J., Saab, M., Doyle, A.J.

Currently, the World Health Organization recommends the use of alcohol‐based hand rubs (ABR) for surgical hand preparation in human surgery. When disinfecting soaps are used, a rubbing technique causes less skin irritation than brush scrubbing. Based on a recent survey, most equine surgeons still use disinfecting soap. This prospective clinical trial compared the efficacy of four surgical hand preparation techniques (three rubs and one scrub) for reduction of aerobic bacterial counts from pre‐ to post‐preparation (immediate efficacy) and at the end of surgery (sustained efficacy). 

The four techniques used were a hand scrub with 4% chlorhexidine gluconate soap (CHx scrub), a hand rub with 4% chlorhexidine gluconate soap (CHx rub), a hand rub with 61% ethanol solution with 1% chlorhexidine gluconate (CHx/ET), and a hand rub with a mixture of 30% 1‐propanol and 45% 2‐propanol solution (IPO). 

Clinicians participating in equine surgical procedures were enrolled during an 18‐month study period and were not blinded to hand preparation technique. Techniques were randomly assigned and a wash out period of approximately 3 days given between them. Samples were collected by the glove juice technique after one‐minute of a neutral soap hand wash (pre‐preparation), following completion of the randomly assigned hand preparation technique (post-preparation), and finally at the end of surgery (post-surgery). Aerobic bacterial log10 colony forming units (CFU) counts were performed.

A total of 228 hands from seven clinicians were sampled in 109 surgical procedures. Immediate mean bacterial log₁₀ CFU reduction was 2.4 for CHx‐scrub, 2.8 for CHx‐rub, 3.1 for CHx/ET rub and 2.1 for IPO rub. CHx/ET rub resulted in significantly lower bacterial counts than CHx‐scrub and IPO rub, while CHx‐rub resulted in significantly lower counts than IPO rub. At the end of surgery bacterial counts were the lowest for CHx‐rub, significantly lower than CHx/ET rub (P<0.001) and IPO rub (P<0.001). There was no difference between CHx‐rub and ‐scrub techniques. 

Bottom line: ABR did not decrease bacterial log₁₀ CFU counts more effectively than CHx products. When using CHx soaps in the equine setting, hand‐rub is as effective as a hand‐scrub technique.

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Diffusion of enrofloxacin to pregnancy fluids and effects on fetal cartilage after intravenous administration to late pregnant mares

Ellerbrock, R. E., Canisso, I. F., Roady, P. J., Rothrock, L. T., Zhong, L., Wilkins, P., Dirikolu, L., Lima, F. S., Honoroto, J.

This study investigated the concentration of enrofloxacin and ciprofloxacin in pregnancy fluids when administered during late‐term pregnancy, in addition to assessing the effect on fetal articular cartilage. 

Sixteen healthy pregnant mares at 260 days gestation were randomly allocated into one of three groups: control (no treatment; n = 3), enrofloxacin 5 mg/kg bwt i.v. (recommended therapeutic dose; n = 7) and enrofloxacin 10 mg/kg bwt i.v. (supratherapeutic dose; n = 6). Enrofloxacin was administered s.i.d. for 11 days. Amniotic and allantoic fluid were sampled on days 1, 5 and 11, and blood samples obtained daily.  

On day 11 abortion was induced by manual cervical dilation and the fetuses euthanased following delivery. Fetal articular cartilage was examined macroscopically and histologically for lesions. Concentrations of enrofloxacin and ciprofloxacin in samples were measured by liquid chromatography-tandem mass spectrometry.

Enrofloxacin and ciprofloxacin reached fetal circulation and accumulated in the pregnancy fluids, reaching the minimum inhibitory concentrations for common pathogens in all fluids. No differences were seen in fetal serum biochemistry values between the control and treatment groups. No lesions were noted on gross inspection of any fetal articular surface and no major abnormal findings were observed on histological evaluation.  

Bottom line: Enrofloxacin and ciprofloxacin are detectable in the fetus and fetal fluids after administration to late‐term mares but did not result in detectable effects on foal cartilage.

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Atypical myopathy‐associated hypoglycin A toxin remains in sycamore seedlings despite mowing, herbicidal spraying or storage in hay and silage

González‐Medina, S., Montesso, F., Chang, Y.‐M., Hyde, C., Piercy, R.J.

This study investigated various pasture management strategies employed to avoid hypoglycin A (HGA) intoxication in horses.

Sycamore seedlings from nine locations were either mowed (n = 6) or sprayed with a herbicide (dimethylamine‐based n = 2; picolinic acid‐based n = 1).  Seedlings were analysed for HGA concentration before intervention and at 48 h, 1 and 2 weeks after. Cut grass in the vicinity of mowed seedlings was also analysed prior to and 1 week after intervention.  Seeds and seedlings maintained for 6 months in processed grass forage (hay and silage) were also analysed. 

There was no significant decline in HGA content in mowed or sprayed seedlings; with mowing inducing a temporary significant rise in HGA in the seedlings. HGA was still present in sycamore material after 6–8 months storage within either hay or silage.

Bottom line: Neither mowing nor herbicidal spraying reduces HGA concentration in sycamore seedlings up to 2 weeks after intervention. Pastures contaminated with sycamore material should not be used to produce processed hay or silage.

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