BACKGROUND:Exercise-associated cardiac arrhythmias may contribute to poor performance and sudden cardiac death in horses. Widespread monitoring is limited by device availability and suitability for field use. OBJECTIVES:To (1) compare electrocardiographic (ECG) quality from a smart textile system (Myant Skiin Equine) with a reference device (Televet II) during exercise, and (2) evaluate whether arrhythmia detection with Myant Skiin Equine is comparable to the Televet II. STUDY DESIGN:Prospective blinded clinical study. METHODS:Fifty racehorses (25 Thoroughbreds, 25 Standardbreds) underwent up to three high-speed exercise sessions, with simultaneous ECG recordings from both devices. Recordings were assessed for diagnostic quality and arrythmia detection. RESULTS:Simultaneous ECGs were recorded with both systems across 123 exercise sessions. Median (IQR) peak speed during exercise was 14.7 m/s (13.5-16.2). Twenty-nine (12%) recordings were non-diagnostic due to ≥10% artefact throughout the session (10 Myant; 19 Televet). The Myant Skiin Equine produced more artefact-free recordings (94/123; 76%) than the Televet II (45/123; 37%) (95% CI 28-46%; p < 0.001). Mean maximum heart rate (217.8 ± 10.1 bpm Myant; 217.6 ± 9.9 bpm Televet) showed strong agreement between devices (ICC = 0.995, mean bias = -0.153 bpm). In 79 paired diagnostic recordings assessed for arrhythmia detection, arrhythmias were detected in 85% of recordings, and in 43/50 horses (86%; 95% CI 73-94%). Agreement for arrhythmia classification was 97.5% (k = 0.96), with all discrepancies occurring because of artefact. MAIN LIMITATIONS:Modest sample size and exclusion of some recordings due to artefact and horse withdrawal. Only the best-quality lead per recording was analysed, limiting multi-lead assessment and arrhythmia characterisation. Differences in device software and data handling may have influenced signal interpretation. CONCLUSION:The Myant smart textile system provides ECG recordings of comparable quality and arrhythmia detection to Televet II during high-speed exercise in racehorses. This technology offers a practical and alternative tool for field-based cardiac monitoring and may facilitate broader adoption.

Equine gastric ulcer syndrome (EGUS) is highly prevalent in horses. Despite its presumed painful nature, evaluation of objective biomarkers associated with EGUS presence and severity remains limited. The objective of this study was to investigate the potential of interleukin-1 beta (IL-1β) release by peripheral blood mononuclear cells (PBMCs) following ex vivo stimulation of toll-like receptors 2 and 4 (TLR2 and TLR4) as a potential biomarker for EGUS status, with gastric lesions used as a proxy for presumed EGUS-associated pain. Venous blood was collected from 77 horses, PBMCs were isolated and stimulated with increasing concentrations of TLR2 and TLR4 agonists (Pam3CSK4 and lipopolysaccharide (LPS)) to assess IL-1β production. Fisher's exact test compared IL-1β responder proportion between horses with and without EGUS. Cochrane-Armitage test assessed trends across severity groups, and diagnostic potential was assessed via Receiver Operating Characteristic (ROC) curve analysis. Statistical significance was set at p < 0.05. Stimulation of TLR2 with Pam3CSK4 was unsuccessful (all <LLOQ) in all horses and was removed from final analysis. After exclusions for lameness and systemic inflammation, 25% of horses were LPS responders and EGUS was present in 92.2% of horses. No associations were identified between IL-1β response and EGUS presence (OR (95% CI) = 0.47 (0.049-6.2); p = 0.6). IL-1β AUC lacked diagnostic ability to differentiate between horses with and without EGUS (area under the ROC curve [AUROC] (95% CI) = 0.39 (0.11-0.67)), Equine Squamous Gastric Disease (ESGD) (AUROC = 0.30 (0.10-0.49)) and Equine Glandular Gastric Disease (EGGD) (AUROC = 0.56 (0.43-0.68)). The tested LPS-induced PBMC IL-1β release protocol was not associated with EGUS status in this cohort.

Neutropenic fever (NF) is often the first sign of infection in patients with hematologic malignancies, but its cause is frequently unknown, leading to broad-spectrum antibiotic use without confirmed infections. Although research links gut microbiome disruptions to treatment-related infections, it typically examines NF as the outcome, leaving a gap in understanding how the microbiome and metabolic factors distinguish infectious from non-infectious cases. Stool samples from acute myeloid leukemia patients were analyzed to characterize gut microbiome composition and fecal metabolites at baseline and at fever onset. Machine learning models, network analyses, and functional profiling were used to differentiate infectious NF vs non-infectious NF at baseline and at fever onset. The baseline model (area under the receiver operating characteristic [AUROC] = 0.769) identified higher levels of Akkermansia, Enterobacter, Escherichia-Shigella, and Flavonifractor as predictors of infectious NF, while Collinsella, Lachnospiraceae, Coprococcus, and acetic acid were linked to non-infectious cases. At fever onset, Enterococcus was enriched in infectious NF, whereas Gemella, Butyrate, Lachnospiraceae, Ruminococcaceae, and Eisenbergiella abundances favored non-infectious NF outcomes (AUROC = 0.752). Network analyses also revealed greater functional diversity and microbiome-metabolome connectivity in non-infectious cases at fever onset. This study suggests that gut microbiota and metabolites may serve as biomarkers for distinguishing infectious from non-infectious neutropenic fever, warranting further validation in larger cohorts. IMPORTANCE:Our study tackles the challenge of managing neutropenic fever (NF) in immunocompromised patients whose numbers have increased due to various immunodeficiencies and treatments that suppress immune function. Fever is often the only sign of a serious infection in these patients, yet there are neither clear patterns linking risk factors to infection nor biomarkers reliable for ruling out non-infectious causes. As a result, febrile patients are typically empirically treated for major pathogens, even in the absence of confirmed infections, which propagates antimicrobial resistance and gut dysbiosis. Our research utilizes gut microbiome and targeted metabolomic profiling from two cohorts of patients with acute myeloid leukemia undergoing chemotherapy and employs a machine learning framework to distinguish between infectious and non-infectious NFs at baseline and upon fever onset.

Artificial intelligence (AI) is increasingly used to enhance electrocardiogram (ECG) interpretation in human medicine. In equine athletes, exercise-associated arrhythmias are common and linked to sudden cardiac death at rates higher than in humans. However, ECG interpretation in horses remains time-consuming and subjective, with the clinical relevance of mild rhythm disturbances often unclear. Evaluate the application of AI to ECG interpretation for arrhythmia detection, with emphasis on current and potential use in athletic species, particularly horses. About 17 studies were included: 13 involving humans, 3 in horses, and 1 in dogs. A scoping review of relevant, peer-reviewed studies published between 2000 and 2024 was conducted to identify research applying AI to ECG interpretation for arrhythmia detection. Studies were assessed for species, AI model type, diagnostic accuracy, and relevance to ECGs recorded during exercise. Primary outcomes included arrhythmia detection performance and applicability to veterinary medicine. Deep learning models, including convolutional neural networks, achieved accuracies ranging from 79.4% to 98.6% in studies of humans. Research in horses showed encouraging results using restitution analysis and transfer learning approaches. However, small sample sizes and species-specific ECG morphology remain major limitations to broader application in veterinary medicine. Artificial intelligence holds promise for enhancing the accuracy and efficiency of arrhythmia detection in ECGs of equine athletes. Development of species-specific algorithms may facilitate real-time monitoring of cardiac function during exercise, supporting improved cardiovascular assessment in athletic horses.

Background: The relationship between Thoroughbred yearling laryngeal function (YLF) grade and race performance is unclear. Objectives: To determine the effect of YLF on future race performance. Study design: Retrospective cohort study. Methods: Post-sale endoscopic recordings were reviewed from Australian yearling sales in 2018-2019. Race performance was evaluated for career and as 2-, 3- and >= 4-year-olds. Multivariable generalised linear modelling examined the association between YLF and performance, with risk estimates presented as coefficients (95% CI). Results: The YLF in 5175 examinations was graded I in 29.8% (n = 1542); II.1 in 49.0% (n = 2537), II.2 in 16.5% (n = 855), III.1 in 3.9% (n = 200), III.2 in 0.8% (n = 39) and III.3 in <0.04% (n = 2). Additional endoscopic abnormalities included ventroaxial luxation of the corniculate process (VLAC, n = 77, 1.5%); arytenoid mucosal lesions (n = 392, 7.6%) and intermittent dorsal displacement of the soft palate (iDDSP, n = 1264, 24.4%). Median (IQR) career earnings were: grade I $45 095 ($15 565, $113 220); grade II.1 $45 315 ($15 915, $107 490), grade II.2 $38 610 ($14 326, $95 218), grade III.1 $32 765 ($8565, $86 030) and grade III.2 $35 810 ($3700, $65 770). There was no difference in career earnings for YLF grades II.2 and III.1, compared with referent grade I/II.1, whereas grade III.2 earned less overall (-$46 015 (95% CI: -$89 994, -$2036), p = 0.04). Earnings in >= 4-year-olds were less for grades III.1 (-$35 076 (-$56 129, -$14 024), p = 0.001) and III.2 (-$53 219, (-$76 062, -$30 375) p < 0.001). Main limitations: Lack of follow-up data due to retrospective nature of study. Exclusion of unraced horses and those with no prize money from analysis. Conclusions: Ninety-five percent of the yearling population had grades I, II.1 or II.2 YLF and minimal difference in race performance was identified between them. Horses with grade III.1 YLF performed similarly to grades I/II.1 in their early careers but had reduced race performance at >= 4-year-old.

BACKGROUND:Artificial intelligence (AI) is increasingly used to enhance electrocardiogram (ECG) interpretation in human medicine. In equine athletes, exercise-associated arrhythmias are common and linked to sudden cardiac death at rates higher than in humans. However, ECG interpretation in horses remains time-consuming and subjective, with the clinical relevance of mild rhythm disturbances often unclear. OBJECTIVES:Evaluate the application of AI to ECG interpretation for arrhythmia detection, with emphasis on current and potential use in athletic species, particularly horses. ANIMALS:About 17 studies were included: 13 involving humans, 3 in horses, and 1 in dogs. METHODS:A scoping review of relevant, peer-reviewed studies published between 2000 and 2024 was conducted to identify research applying AI to ECG interpretation for arrhythmia detection. Studies were assessed for species, AI model type, diagnostic accuracy, and relevance to ECGs recorded during exercise. Primary outcomes included arrhythmia detection performance and applicability to veterinary medicine. RESULTS:Deep learning models, including convolutional neural networks, achieved accuracies ranging from 79.4% to 98.6% in studies of humans. Research in horses showed encouraging results using restitution analysis and transfer learning approaches. However, small sample sizes and species-specific ECG morphology remain major limitations to broader application in veterinary medicine. CONCLUSION AND CLINICAL IMPORTANCE:Artificial intelligence holds promise for enhancing the accuracy and efficiency of arrhythmia detection in ECGs of equine athletes. Development of species-specific algorithms may facilitate real-time monitoring of cardiac function during exercise, supporting improved cardiovascular assessment in athletic horses.

Background: Broad-spectrum antibiotics are often used for suspected infections in patients with hematologic malignancies due to the risk of severe infections. Although antibiotic use can lead to antimicrobial resistance and microbiome dysbiosis, the effects of antibiotics on the microbiome and resistome in patients with acute myeloid leukemia (AML) undergoing remission induction chemotherapy (RIC) are not well understood. Methods: Various statistical models were utilized to examine the effects of antibiotic administration on the microbiome and resistome over time, as well as differences in AR-infection (ARI) and colonization (ARC) by important CDC-threats in 119 AML patients. Results: A greater number of unique antibiotic classes administered correlated with a loss of unique antibiotic resistance genes (ARGs) (R = −0.39, p = 0.008). Specifically, although a greater number of oxazolidinone administrations was correlated with a greater loss of diversity (R = −0.58, p < 0.001), each additional day of linezolid reduced the risk of ARC by ~30% (HR: 0.663, p = 0.047) and decreased the odds of acquiring genes predicted to confer macrolide (HR: 0.50, p = 0.026) resistance. Conclusions: The number of antibiotic administrations and the types of antibiotics used can influence the risk of antibiotic resistance gene (ARG) expansion and ARC events in AML patients undergoing RIC. While certain antibiotics may reduce microbial diversity, they are not always linked to an increase in ARGs or ARC events.

IntroductionAcute myeloid leukemia (AML) patients are highly susceptible to infection. Moreover, prophylactic and empirical antibiotic treatment during chemotherapy disrupts the gut microbiome, raising the risk for antibiotic-resistant (AR) opportunistic pathogens. There is limited data on risk factors for AR infections or colonization events in treated cancer patients, and no predictive models exist. This study aims to combine metagenomic and antibiotic administration data to develop a model predicting AR event outcomes.MethodsBaseline stool microbiome, antibiotic administration, resistome, and clinical metadata from 95 patients were utilized to build a Random Forest model to predict AR infection and colonization events by serious AR threats. Additionally, sparse canonical correlation analysis assessed correlations between microbiome and resistome data, while Spearman correlation networks identified direct associations with AR event outcomes and secondary variables.ResultsAR-events were identified in 14 of the 95 included patients, with 8 developing AR infections and 9 identified as AR colonized. A Random Forest model predicted AR event outcomes (AUC = 0.73), identifying bacterial taxa and antibiotic resistance gene (ARG) classes as key variables of importance. Methanobrevibacter smithii, Clostridium leptum, and Bacteroides dorei were identified as key taxa associated with reduced risk of AR events, suggesting the potential roles of commensals in maintaining gut microbial resilience during chemotherapy. ARG classes, particularly those conferring resistance to lincosamides, macrolides, and streptogramins, were negatively associated with AR events.ConclusionThese results underscore the value of integrating microbiome and resistome features to reveal potential protective mechanisms and improve risk prediction for AR outcomes in vulnerable patients.

OBJECTIVE:Evaluate a prototype dynamic laryngoplasty system (DLPS) in horses; a feasibility study.ANIMALS:7 healthy Standardbred adult horses.METHODS:This was an in vivo experimental study. Horses had a standing surgical procedure to induce complete laryngeal hemiplegia, which was subsequently treated using the dynamic laryngoplasty system (DLPS). Activation of the DLPS was achieved using an injection port exiting through the skin (n = 2) or a subcutaneous injection port (n = 5). For each horse, endoscopic examinations of the upper respiratory tract were performed preoperatively, intraoperatively, and 7 days postoperatively. Left-to-right quotient ratios calculated during inactivated and activated states were obtained from still images of the rima glottidis acquired during day 7. In 3 horses, the device was intentionally overinflated to evaluate for device failure, and postmortem examinations were performed on day 7. For the remaining 4 horses, upper respiratory tract endoscopy was repeated at 1 month postoperatively, with no subsequent postmortem exam.RESULTS:No perioperative complications occurred, and the DLPS was effectively delivered in all horses under standing sedation. The left-to-right quotient ratio at day 7 postoperatively could be altered from a resting position of 0.76 (± 0.06) to a maximum of 0.97 (± 0.06; P < .05). The degree of arytenoid abduction could not be significantly altered after 1 month of device implantation, suspected to be due to peri-implant fibrosis. No coughing nor tracheal contamination was observed at all time points or during inflation.CLINICAL RELEVANCE:The ability to alter the degree of abduction at 7 days postoperatively with the DLPS may be beneficial in selective cases.

OBJECTIVE:To describe left recurrent laryngeal neurectomy (LRLn) performed under standing sedation and evaluate the effect of LRLn on upper respiratory tract function using a high-speed treadmill test (HST). We hypothesized that (1) unilateral LRLn could be performed in standing horses, resulting in ipsilateral arytenoid cartilage collapse (ACC); and (2) HST after LRLn would be associated with alterations in upper respiratory function consistent with dynamic ACC.ANIMALS:6 Thoroughbred horses.METHODS:The horses were trained and underwent a baseline HST up to 14 m/s at 5% incline until fatigue. Evaluation included; airflow, pharyngeal and tracheal pressures, and dynamic upper respiratory tract endoscopy. Trans-laryngeal impedance (TLI) and left-to-right quotient angle ratio (LRQ) were calculated after testing. The following day, standing LRLn was performed in the mid-cervical region. A HST was repeated within 4 days after surgery.RESULTS:Standing LRLn was performed without complication resulting in Havemayer grade 4 ACC at rest (complete paralysis) and Rakestraw grade C or D ACC (collapse up to or beyond rima glottis midline) during exercise. Increasing treadmill speed from 11 to 14 m/s increased TLI (P < .001) and reduced LRQ (P < .001). Neurectomy resulted in an increase in TLI (P = .021) and a reduction in LRQ (P < .001).CLINICAL RELEVANCE:Standing LRLn induces laryngeal hemiplegia that can be evaluated using a HST closely after neurectomy. Standing LRLn may be useful for future prospective evaluations of surgical interventions for laryngeal hemiplegia.

OBJECTIVE:To identify thoroughbred industry stakeholders' views on the yearling sales endoscopy in Australia. DESIGN:Semi-structured qualitative group interviews with equine veterinarians, thoroughbred breeders and yearling purchasers. METHODS:Twenty-nine experienced thoroughbred industry stakeholders participated in online focus groups: (1) equine veterinarians involved in yearling endoscopy; (2) thoroughbred breeders; and (3) yearling buyers. The focus groups were audio and video recorded and digital whiteboards were available. Data was transcribed, live-coded and analysed thematically. RESULTS:The main themes identified included the uncertainty surrounding the relationship between yearling laryngeal function and future performance, especially the significance of yearlings with grade 3 out of 5 laryngeal function; interobserver variability in the laryngeal function grade assigned by veterinarians to the same endoscopic exam; and the presence of intra-horse variability in laryngeal function over different time points. DISCUSSION:Stakeholders raised multiple concerns about the current yearling sales endoscopy process in Australia. Recommendations to address these concerns include further investigation into the race performance of yearlings identified with grade 3 laryngeal function; training of veterinarians to reduce inter-observer variability; and the need to determine the most appropriate grading system to use in yearlings. Future research should evaluate the significance of intra-horse variability in a yearling population.

Background: Yearling laryngeal function (YLF) is frequently assessed at the time of sale and the outcomes of these assessments can have significant economic implications. The YLF of horses that subsequently underwent a prosthetic laryngoplasty (PL) is unknown. Objectives: We hypothesised horses with YLF >= grade II.2 would be at increased risk of requiring PL, compared with YLF = grade II.2 had an OR of 4.61 (3.0, 7.1, p < 0.001) compared with = grade III.1 had an OR of 10.7 (5.6, 20.4, p < 0.001) compared with

Sacroiliac dysfunction (SID) is a condition seen in horses associated with poor performance that affects hind limb gait and impulsion. The condition comprises pain and dysfunction but there lacks clarity around the aetiopathogenesis and whether SID encompasses abnormal joint pathology, abnormal joint movement, abnormal regional biomechanical function, joint laxity and pain, or various combinations of these that may vary over time. Clinical assessment remains challenging for equine clinicians due to the deep location of the sacroiliac joint (SIJ) and surrounding structures which limits access for palpation, diagnostic imaging and joint-specific injection. There is no recognised single reference standard diagnostic test for SID. Clinical diagnosis has been based on ruling out other causes of hind limb lameness, along with combinations of ultrasonography, scintigraphy and periarticular anaesthesia of the SIJ. Recent studies have highlighted the lack of specificity of injections targeting the SIJ, with significant dispersal of injectate into surrounding structures including around the lumbosacral joint (LSJ). Advanced imaging modalities such as computed tomography offers promise for assessment of the structure and pathology of the SIJ and surrounding bony structures. However, there is a need to improve the understanding of the significance of anatomic variation of the sacroiliac region structures, with recent studies reporting detailed anatomic variation in groups of horses with and without SID. There are also limitations around functional assessment of the joint which is still largely reliant on a thorough clinical examination. This review aims to present an update on clinical approaches to the diagnosis of horses with SID, and to consider the challenges and limitations.

Abstract Background Atrial fibrillation (AF) is the most common cardiac arrhythmia in athletes. Despite a lower burden of classical cardiovascular risk factors, the prevalence of AF in athletes is comparable to that in the general population of similar age (~13%, mean age 65.5), suggesting that exercise-induced AF may have different underlying mechanisms. The prevalence of AF in thoroughbred (TB) and standardbred (STB) racehorses is also relatively high (~5%), suggesting exercise as an independent risk factor. Due to selective breeding and complete control of pedigrees, racehorses are well-suited for genetic studies. Common and rare genetic variation explain a substantial part of AF variance, but no study has identified genetic variants associated with exercise-induced AF in any species. Objective In this project, we aimed to use the racehorse as a model to identify genetic variants associated with exercise-induced AF, and in a future study, possibly replicate the results in human athletes. Here we present preliminary results from the genome-wide association study (GWAS) of AF in racehorses. Methods We collected blood or hair samples from 181 STB and TB racehorses in which 71 had paroxysmal or persistent AF verified by ECG. We extracted DNA and performed whole-genome genotyping using a commercial equine genotyping platform (670k markers). We phased and imputed un-genotyped markers and increased the sample size of the control group, using publicly available equine data from similar breeds from the European Nucleotide Archive. We conducted a GWAS of 7.85 million markers in 71 cases and 296 controls using PLINK2 with covariates adjusted for population stratification, batch and sex. Results We identified one significant locus downstream of the protocadherin gene PCDH18 associated with AF in racehorses. The same locus has been associated with the ECG-trait P-wave terminal force in humans. Changes in P-wave terminal force is associated with increased atrial size, delayed interatrial conduction, left ventricular fibrosis and left atrial function, and considered a good predictor of AF occurrence. Several non-significant but interesting signals were also identified including the genes SLC6A15 (amino acid transport), MYBPH (myosin binding), MYF6 and MYOG (myoblast differentiation). Conclusion In these preliminary results, we have identified a new genetic locus associated with AF in racehorses. In addition, we have identified several candidate genes for further studies to elucidate the genetic background of exercise-induced AF. We aim to replicate our findings in a population of human athletes. Our results may aid the development of risk prediction tools for exercise-induced AF and new drugs for tailored treatment of AF in general.

BackgroundSudden cardiac death (SCD) 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 SCD has not previously been estimated in Thoroughbred racehorses.ObjectivesTo determine the heritability of SCD in a sample population of Thoroughbred racehorses.Study designRetrospective case-control study.MethodsSteward and post-mortem reports of Thoroughbred racehorses in Australia between 2007 and 2020 were reviewed to identify horses with SCD. Control horses were randomly selected from races in which SCD 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 SCD was normally distributed, and on the logit transformed scale. Inbreeding coefficients were calculated and the risk of producing SCD-affected progeny was calculated for stallions that sired >= 5 individuals in the case-control population.ResultsNinety-three horses with SCD 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).Main limitationsChallenges in definitively confirming SCD may lead to misclassification of some cases. Some control horses may have not been exposed to environmental influences of SCD. Case numbers are low and the studied population may not represent the entire Thoroughbred genetic pool.ConclusionThe heritability of SCD in this population was relatively low. However, individual stallions appear more likely to produce affected progeny. Further studies are required to understand the genetic and environmental influences that contribute to disease expression.

Due to concerns about disagreement between veterinarians when grading resting laryngeal function (LF), a diagnostic decision tree (DDT) has been developed by codifying the Havemeyer grading system and objectively defining certain terms to remove ambiguity. Videoendoscopic examinations of the equine larynx that had previously been assigned a unanimous LF grade by 3 experienced observers were used to develop the DDT and determine the cut-off values. The DDT is a flow chart consisting of a series of dichotomous (yes/no) decisions, to dictate the order of decision making and direct the observer down a pathway towards the most appropriate LF grade. To use the DDT, the observer must know the frame rate of the video and use frame-by-frame video playback when reviewing the videos. The first decision involves determining if full left arytenoid cartilage (LAC) abduction is achieved (≤ grade III.1), or not achieved (> grade III.1). Maintained full LAC abduction (≤ grade II.2) is defined as maintenance of full abduction for ≥ 0.2 seconds. Full LAC abduction that is achieved but not maintained (grade III.1) is defined as maintenance of full abduction for < 0.2 seconds. Arytenoid abductor deficit is categorized into left arytenoid abduction ≥45° from vertical midline (grade III.2) and <45° abduction (grade III.3). The DDT could be used as a first step towards computer assisted laryngeal function grading.

Summary Background Cardiac arrhythmias in exercising horses are the focus of much interest, both in terms of what is considered normal and potential associations with poor performance and sudden cardiac death. One barrier to performing large‐scale studies is the lack of an easily applicable device, to allow recording of large numbers of high‐quality exercising electrocardiograms (ECGs). The Equimetre TM is a new wearable device, which records a single lead ECG, among other parameters. Validation of such wearable devices is essential before further studies are undertaken. Objectives To evaluate the quality of ECG using the Equimetre TM and compare arrhythmia detection during exercise with the reference Televet TM system. Study design Prospective blinded clinical study. Methods Simultaneous ECGs were recorded with both systems in 49 healthy horses during exercise. High‐intensity exercise (>40 km/h) was performed by 29 racehorses, and lower‐intensity exercise for the remainder of the racehorses and show jumpers. Tracings were excluded if >10% artefact was present (duration of artefact relative to duration of exercise). For included ECGs, the duration of artefact was recorded and compared. ECGs were evaluated using Kubios premium software. Arrhythmia detection (yes/no) and arrhythmia classification (sinus arrhythmia, narrow complex of similar morphology to the sinus complexes or wide complex with a different morphology) were compared using Cohen's Kappa coefficient. Results Nine Televet TM ECGs and 3 Equimetre TM ECGs were excluded due to artefact >10%. Televet TM ECGs included significantly more artefact during exercise than Equimetre TM ECGs (5% vs. 0.25% P < .001). Arrhythmia analysis was performed on 38 horses’ paired ECGs. The kappa coefficient was excellent for arrhythmia detection (K = 0.97) and arrhythmia classification (K = 0.93). Main limitations Relatively low numbers of horses with arrhythmias (n = 21) were included. The ECG recordings only provided one lead, making arrhythmia classification challenging in some cases. Conclusions The Equimetre device provides a reliable ECG for arrhythmia detection during exercise. This system may be useful clinically and for future large‐scale investigations into the occurrence and significance of exercising arrhythmias.

Equine gastric ulcer syndrome (EGUS) is a highly prevalent and presumptively painful condition, although the amount of pain horses might experience is currently unknown. The aims of this study were to determine if the Horse Grimace Scale (HGS) could identify pain behaviours in horses with and without EGUS and if severity would be positively associated with the HGS score. Horse grimace scale scores were assessed blindly using facial photographs by seven observers and involved evaluation of 6 facial action units as 0 (not present), 1 (moderately present) and 2 (obviously present). Lameness examination, serum amyloid A (SAA) measurement and gastroscopy evaluation were performed on all horses. Horses (n = 61) were divided into two and three groups based on the presence (yes, no) and severity (none, mild, moderate-severe) of EGUS, respectively. Presence of lameness and elevated SAA (≥50 µg/mL) were used as exclusion criteria. Inter-observer reliability was analyzed by intra-class correlation coefficients (ICC). HGS scores between groups were compared using Welch's and Brown Forsythe tests (p < 0.05). Overall, HGS ICC was "excellent" (0.75). No significant differences (p = 0.566) were observed in HGS scores between horses with and without gastric lesions (mean, 95% CI; 3.36, 2.76-3.95 and 3, 1.79-4.20, respectively). HGS was not influenced by the presence or severity of EGUS in this current study. Further studies investigating the use of different pain scales in horses with EGUS are needed.

Abstract Background Little is known about potential differences in the left recurrent laryngeal nerve (Lrln) and left cricoarytenoideus dorsalis (LCAD) muscle between domestic and feral horse populations. If a difference exists, feral horses may provide a useful control population for research related to recurrent laryngeal neuropathy (RLN) and increase our understanding of potential population pressures influencing the incidence RLN. Objectives The objective of this study was to compare the Lrln and LCAD of domestic and feral horses using histological and immunohistochemical techniques (IHC). Methods Sixteen horses, domestic (n = 8) and feral (n = 8), without clinical or ancillary examinations that were processed at an abattoir had the Lrln and LCAD muscle harvested immediately following death. Carcass weights were recorded. Subjective and morphometric histologic assessment were performed on Lrln sections. The LCAD was assessed for myosin heavy chain (fibre type proportion, diameter and grouping using IHC. Results Fibre‐type grouping consistent with RLN was seen in both groups. Regenerating fibre clusters were more common in domestic compared to feral horses (p = 0.04). No other histologic differences occurred between groups. Muscle fibre typing demonstrated a lower mean percentage of type IIX fibres in the feral group compared to the domestic group (p = 0.03). There was no difference in type I or IIA proportions or mean diameter of any fibre type between the groups. Conclusions The domestic population showed evidence of nerve regeneration suggesting RLN in this group, yet this was not supported by the higher proportion of type IIX muscle fibres compared to the feral population. Further evaluation to clarify the significance and wider occurrence of the differences is indicated.