Search Results (251)

Background/Objectives: Vonoprazan is a potassium-competitive acid blocker with potential for the treatment of equine gastric ulcer syndrome. Vonoprazan metabolic pathways in horses have not been characterized. This study aimed to identify vonoprazan metabolites following oral administration and to determine the metabolic enzymes responsible for their metabolism using in vitro models. Methods: Six healthy adult Thoroughbred horses received vonoprazan (0.5 and 1 mg/kg PO) in a randomized crossover design. Plasma concentrations of vonoprazan-N-oxide (M-I) and vonoprazan-nitrone (M-III) were quantified using a validated liquid chromatography-tandem mass spectrometry method, and a non-compartmental pharmacokinetic analysis was performed. In vitro metabolism was evaluated using equine liver microsomes (ELMs) and equine recombinant CYP450 (eq-rCYP) enzymes. Enzyme kinetics were characterized using nonlinear regression modeling. Results: Both metabolites were detected in plasma after oral administration. Systemic exposure to M-I was markedly greater than M-III at both doses. At 1 mg/kg, mean ± SD C_max values were 39.2 ± 28.3 ng/mL for M-I and 1.67 ± 1.66 ng/mL for M-III. AUC_0–∞ increased dose-proportionally for both metabolites. In ELMs, M-I formation followed substrate inhibition kinetics, whereas M-III formation followed Michaelis–Menten kinetics. Among recombinant enzymes, CYP2D50 and CYP3A94 were the primary contributors to metabolite formation, exhibiting metabolite-specific kinetic profiles. Conclusions: These findings demonstrate that vonoprazan undergoes hepatic oxidative metabolism in horses, with M-I as the predominant circulating metabolite. Equine recombinants CYP2D50 and CYP3A94 appear to play central roles in equine vonoprazan metabolism, providing foundation for future evaluation of drug–drug interaction potential and clinical use in this species. Full article

Musculoskeletal injury remains a major welfare and performance concern in Thoroughbred racing, and biomarkers for early risk stratification are of scientific interest. This multicentre observational cohort study characterised serum concentrations of two bone turnover markers, osteocalcin/BGLAP (OC) and C-terminal telopeptide of type I collagen (CTX-I), in 1359 fit-to-race Thoroughbred racehorses sampled across New South Wales, Victoria, and Western Australia. Biomarker distributions, population-wide percentile ranges, demographic and training-related associations, and short-term soundness outcomes were evaluated using nonparametric methods. Both markers were positively skewed, with population-wide percentile ranges (2.5–97.5 percentile) of 0.13–9.44 ng/mL for CTX-I and 0.02–7.25 ng/mL for OC; CTX-I varied substantially by jurisdiction, so this pooled range should not be interpreted as a clinical reference interval for individual horses. CTX-I varied significantly by age, jurisdiction, venue, and training surface, with markedly higher concentrations in New South Wales horses and lower concentrations associated with polytrack training, but did not predict lameness outcomes. OC concentrations were significantly higher in horses classified as lame at sampling and showed modest discriminatory ability for subsequent lameness in univariate analysis, with the strongest performance for persistent lameness at both 7 and 28 days; this association attenuated after adjustment for age, sex, state, and training surface. At an unadjusted operational threshold of approximately 1.24 ng/mL, OC achieved high negative predictive value for persistent lameness. These findings suggest OC may have scientific value as a potential rule-out screening marker for short-term soundness, warranting further investigation, while CTX-I appears more informative for characterising population-level skeletal turnover variation. Full article

Equine herpesvirus type 1 (EHV-1) is a major cause of reproductive loss in mares. This cross-sectional field study evaluated serum concentrations of interleukin-2 (IL-2), interleukin-10 (IL-10), interferon-alpha (IFN-α), and interferon-gamma (IFN-γ), together with the IL-10/IL-2 and IFN-γ/IL-10 ratios, in 26 vaccinated pregnant Thoroughbred mares. The analytical cohort comprised healthy, EHV-1 PCR-negative mares (HM, n = 10), EHV-1 PCR-positive mares sampled within 4 h after fetal expulsion at approximately the sixth month of gestation (AM, n = 9), and EHV-1 PCR-positive pregnant mares without clinically relevant signs (WCS, n = 7). EHV-1 DNA was detected using an EHV-1-specific real-time PCR assay, and serum cytokine concentrations were measured using equine-specific ELISA kits. Serum IFN-α, IFN-γ, and IL-2 concentrations were significantly higher in both AM and WCS mares than in HM mares (all Holm-adjusted p < 0.001), whereas no statistically significant differences in these cytokines were observed between the AM and WCS groups. IL-10 concentrations were significantly higher in WCS mares than in both HM and AM mares (both adjusted p < 0.01), and HM and AM mares did not differ significantly. The IL-10/IL-2 ratio was highest in HM mares, intermediate in WCS mares, and lowest in AM mares, with significant differences among all pairwise comparisons (adjusted p ≤ 0.019). Conversely, the IFN-γ/IL-10 ratio was highest in AM mares, intermediate in WCS mares, and lowest in HM mares, again with significant differences among all pairwise comparisons (adjusted p ≤ 0.044). These findings indicate substantial antiviral immune activation in both EHV-1-positive groups, with a comparatively stronger regulatory immune component in WCS mares and a predominantly pro-inflammatory profile in mares sampled after abortion. Full article

We aimed to investigate the effects of an 8-week 448 kHz radiofrequency (RF) on multifidus cross-sectional area (CSA) and thoracolumbar differential range of motion (ROM). Eight Thoroughbred horseball horses received four RF treatments (T9–L6) at 2-week intervals. Multifidus CSA (T10–L5) and differential spinal ROM between the withers (W), T13, T18, L3 and sacrum (S) were measured before treatment, immediately after the first session, 24 h after the first session, and at 8 weeks (15 days after the last session). Linear mixed models with Tukey post hoc comparisons were used. Significant effects of timepoint for CSA were significant with CSA increased at 8 weeks at all sites (T10–L5; all p < 0.001). No significant Time × Side interactions were identified for CSA (all p ≥ 0.334), demonstrating bilaterally consistent responses. Absolute increases versus baseline were greatest at T18 (+2.52 cm²), L5 (+1.90 cm²), and T16 (+1.77 cm²) (all p < 0.001). Axial rotation ROM increased transiently between W–T13 at 24 h (+4.8°, p < 0.001) but returned toward baseline at 8 weeks. Caudal thoracolumbar motion (T18–L3) decreased at 8 weeks (−4.2°, p = 0.004), suggesting improved segmental stability. Flexion–extension increased immediately post-treatment at W–T13 (+2.29°, p = 0.009) before reducing below baseline at 8 weeks (−2.49°, p = 0.005). Lumbosacral ROM showed minimal change. RF therapy was associated with multifidus hypertrophy alongside region-specific modulation of spinal motion, characterised by transient mobility increases followed by reduced caudal thoracolumbar motion, consistent with improved neuro-muscular dynamic stabilisation via multifidus hypertrophy. Full article

This study aimed to determine the action of a single dose of human chorionic gonadotropin (hCG) on follicular dynamics, CL functionality, ovarian (OV.A) and uterine arteries (MUA) blood flow, hormones (estradiol [E2] and luteinizing hormone [LH]), nitric oxide (NO), and vascular endothelial growth factor (VEGF) levels in Thoroughbred mares. Animals were subjected to ultrasonography scanning, when the dominant follicle (F1) reached 35 mm in diameter, mares were injected with hCG (hCG group; n = 7) at hour 0, while others were injected with saline (control; n = 7). The examination was performed a those points at hours −24 h, −12 h, 0 h, 12 h, 24 h, 36 h, 48 h, 72 h, and 96 h. Blood sampling, ultrasound scanning, hormone assaying, and statistical analysis were performed. F1 was ruptured at 12 h after injection compared to 24 h in the control, with an elevation in its diameter (p ≤ 0.05) and a colored area surrounding F1. The amount of color Doppler area around CL and its diameter were increased (p ≤ 0.05) at 24 and 48 h after injection with an increase (p ≤ 0.05) in the ipsilateral uterine horn colored area from 6 to 36 h after injection. OV.A and MUA Doppler velocity parameters were elevated (p ≤ 0.05) at 24 h. Both NO and VEGF levels were elevated at 24 h after injection, with the elevation (p ≤ 0.05) of E2 occurring only before injection and then declining. hCG and LH levels were increased after injection at 12 and 24 h, respectively, with an interaction (p ≤ 0.05) effect. hCG may speed up and hasten the ovulation process by elevating follicular color amount and CL morphometry via elevating ovarian flow and uterine body total coloration via elevating uterine blood flow (declining Doppler indices) in mares. Full article

Capacitive and resistive electric transfer (TECAR) therapy is increasingly used in equine physiotherapy; however, objective evidence regarding its immediate effects on equine back muscles remains limited. This pilot study aimed to evaluate the effects of TECAR therapy on body surface temperature and muscle tone of the longissimus dorsi muscle in Thoroughbred racehorses. A randomized, single-blinded experimental study was conducted in 20 clinically healthy Thoroughbred racehorses aged 2–3 years. Horses were randomly assigned to either a TECAR treatment group (n = 10) or a sham-treatment control group (n = 10). Thermographic imaging and palpation-based muscle tone assessment were performed before treatment, immediately after treatment, and 10 min post-treatment in the thoracolumbar region (Th15–L6). Differences between groups and changes over time were analyzed using repeated-measures ANOVA for temperature data and Friedman’s test with post hoc Wilcoxon signed-rank tests for palpation scores. TECAR therapy was associated with a significant increase in body surface temperature, with mean values rising from 25.3 ± 1.5 °C before treatment to 28.9 ± 1.3 °C immediately after treatment (p < 0.001) and remaining elevated after 10 min (27.6 ± 1.3 °C; p = 0.002). In contrast, only minor temperature changes were observed in the sham group. Palpation assessment demonstrated a significant reduction in muscle tone following TECAR therapy, with median scores decreasing from 3 [2–3] before treatment to 0 [0–1] immediately afterward (p < 0.001). These findings indicate that TECAR therapy induces an immediate thermal response, which persists for at least 10 min, and is associated with reduced longissimus dorsi muscle tone in racing horses. Further studies are warranted to investigate its clinical applications and long-term effects in equine rehabilitation. Full article

Early and accurate detection of foaling is important for reducing perinatal mortality and labor demands in commercial breeding farms. This study evaluated a fully noninvasive foaling prediction system integrating thermal imaging with artificial intelligence-based behavioral analysis in Thoroughbred mares. A total of 115 pregnant mares across 13 farms were monitored during the 2024 foaling season. Locomotor activity and body surface temperature relative to ambient temperature were extracted from thermal images, while posture changes and tail-raising behavior were identified from visible-light images using a trained prediction model. Prediction was performed at 5 min intervals using a pretrained neural network model implemented in Python, which generated logistic probabilities based on locomotor activity, body surface temperature, posture change frequency, and tail-raising behavior. Data obtained during the 5 h preceding foaling were analyzed. Locomotor activity and surface temperature significantly increased 70–90 min before foaling (p < 0.05), whereas posture changes and tail-raising behavior markedly increased 25–45 min before foaling. These temporal patterns suggest a biologically interpretable two-phase pre-foaling process derived from sequential changes in behavioral and thermal indicators. The model based on locomotor activity and surface temperature achieved an 80.0% detection rate with a mean lead time of 186 ± 20 min. Incorporating posture changes and tail-raising parameters improved detection to 94.8% and reduced the detection-to-foaling interval to 89 ± 14 min. The system achieved high predictive performance under commercial conditions without requiring invasive or wearable devices. Full article

This study evaluated the reliability of five treadmill protocols that assess heart rate (HR) and blood lactate (Bla) responses in Thoroughbred horses to determine their effectiveness in serving as potential tools for monitoring fitness and the wellbeing of racehorses. Of the five exercise tests, four consisted of repeated interval gallops at constant speeds (8 m/s and 10 m/s) and grade (6°) and one test of a continuous gallop at constant speeds (8 m/s) and grade (6°). Eight hundred and twenty-three gallops in total were performed by 64 horses. The test–retest reliability and absolute agreement between treadmill tests were assessed using Intraclass correlation coefficient (ICC) with a two-way mixed-effect model. Statistical significance was set at p < 0.05. Overall, the mean of the mean HR for each of the five test gallops was 203 ± 11.3 bpm. The mean HR ICC of the five tests of 0.756 indicates good reliability of the tests, as HRs during each gallop were consistent between tests. Protocol comparison showed that all protocols have good reliability with gallops 1 and 5 scoring highest (0.79: 0.81) and gallop 4 lowest at 0.621. The recovery mean HR ICC for 30 s, 60 s, 90 s and 120 s recovery were 0.421, 0.504, 0.595 and 0.571 respectively. Overall, the data suggests that gallop HR is the more reliable variable with recovery HRR reliability improving to an acceptable level at 60 s and 90 s recovery. Together, the treadmill tests demonstrated acceptable reliability to measure both gallop HR and HHR responses, whereas BLa responses were less consistent. Full article

Background: In Chuckwagon racing, teams of four Thoroughbreds with two lead horses in front and two wheel horses directly behind pull a 600 kg wagon around a racetrack. Our study focuses on stride parameters that have previously retrospectively predicted impending injuries. We hypothesize that in aid of the initiation of the tight figure-of-eight turn at the start of the race, the more agile lead horses gallop with higher stride frequency (SF) and reduced stride length (SL), and that differences are exacerbated in the initial accelerative race segments. Methods: Speed, SF, and SL were quantified with global navigation satellite system (GNSS) loggers over consecutive 100 m segments over 5 furlongs in sixty horses competing in Chuckwagon racing. Mixed models for SF and SL (p < 0.05, Bonferroni correction) investigated the effect of speed (fixed covariate), race segment (100 m to 1000 m), and position (lead or wheel horse) as fixed factors and their two-way interactions. Results: SF and SL were significantly affected by all two-way interactions (all p ≤ 0.025). At the average speed of 55.5 km/h, SF was 2.333 and 2.293 Hz, SL was 6.624 and 6.735 m for lead and wheel horses, respectively. Larger SF and SL differences between lead and wheel horses were found at the start and the end of the race. Conclusions: Particularly at the start and end of a Chuckwagon race, there are distinct differences in stride parameters between lead and wheel horses. Specific speed–SF–SL models for Chuckwagon lead and wheel horses might benefit from incorporating race phase. Full article

Injuries of the metacarpophalangeal joint are a major cause of morbidity and catastrophic fracture in racing horses, yet early osseous pathology is often difficult to detect using conventional imaging. This pilot study aimed to correlate sodium fluoride Positron Emission Tomography (¹⁸F-NaF PET) radiopharmaceutical uptake with gross and histopathologic changes in the distal third metacarpal bone (MC3) and proximal first phalanx (P1). Five horses (three racing Thoroughbreds with fetlock injury and two non-racing controls) underwent ante-mortem ¹⁸F-NaF PET and cone-beam CT imaging (CBCT), followed by post-mortem gross and histologic examination of predefined anatomic sites. Quantitative PET measures, including maximum standardized uptake value (SUV_max), SUV_ratio, and PET grade, were compared with gross pathology and histopathologic scores for cartilage and subchondral bone. While there were significant regional correlations between PET metrics and gross or histologic scores at select sites, our results need to be considered in light of the small number of horses evaluated. Correlations between PET metrics and gross pathology score were identified on the distal metacarpus on the lateral dorsal condyle and on proximal P1 for lateral dorsal and mid-P1. Correlation of PET metrics and hyaline cartilage histopathology scores were found for dorsal medial and lateral P1, parasagittal dorsolateral P1 and the medial parasagittal groove of MC3. Correlation of PET metrics and histologic subchondral bone scores were significant for medial palmar condyle, medial parasagittal groove, and parasagittal palmar lateral of MC3. For P1, PET metrics and histologic subchondral bone scores were significantly correlated for parasagittal mid-lateral and medial dorsal regions. Overall, these findings demonstrate that ¹⁸F-NaF PET identifies localized bone remodeling that corresponds to histologic and gross pathology at specific fetlock regions, supporting its utility for detecting osseous injury, although relationships varied by anatomic location. Further work with larger numbers of horses is needed. Full article

In equine veterinary medicine, there is a lack of correlation between the structural severity of orthopaedic disease and the perceived severity of presenting signs, resulting in a variable influence on performance, pain and disability. Across equine industries, there is selective pressure through breeding for specific traits, such as the “speed” gene (MSTN) in racing thoroughbreds and the “gait keeper” gene (DMTR3) in pacing breeds, potentially resulting in genetic predispositions that lead to an increased risk of musculoskeletal disorders. With advancements in molecular sequencing techniques, researchers have been able to identify various genes (e.g., ECA, RUNX, and ADAME1) as well as biomarkers influencing performance and the development of orthopaedic disease. In combination, these techniques could be applied clinically in the future to improve welfare and disease management through advanced characterization and treatments to delay the onset of orthopaedic disease. Full article

The horse represents one of the most physiologically specialized athletic mammals, capable of sustaining both high-intensity and prolonged exercise. Central to this remarkable performance capacity is the metabolic adaptability of skeletal muscle and its mitochondrial network. This narrative review synthesizes current evidence from equine, human, and rodent studies on exercise-induced mitochondrial remodeling in equine skeletal muscle. A comprehensive literature search was conducted across PubMed, Web of Science, and Scopus using terms related to equine exercise physiology, mitochondrial biology, and skeletal muscle metabolism. Preference was given to peer-reviewed original research and review articles. Mitochondria regulate oxidative phosphorylation, substrate oxidation, redox signaling, and cellular responses to metabolic stress induced by exercise. Training induces extensive mitochondrial adaptations, including mitochondrial biogenesis, remodeling of the respiratory chain, enhanced oxidative phosphorylation efficiency, and increased metabolic flexibility. These adaptations are believed to contribute to improvements in aerobic capacity, delayed fatigue onset, and enhanced recovery following exercise, although direct mechanistic evidence in horses remains limited. In equine skeletal muscle, mitochondrial plasticity is closely linked to muscle fiber composition and the distribution of oxidative and glycolytic fibers. Exercise-induced signaling pathways involving AMP-activated protein kinase (AMPK), Ca²⁺-dependent kinases, and the transcriptional coactivator PGC-1α regulate mitochondrial biogenesis and metabolic remodeling. In addition, mitochondrial dynamics, including fusion, fission, and mitophagy, maintain mitochondrial quality and functional efficiency during repeated training stimuli. Experimental studies in Thoroughbred and Standardbred horses demonstrate that training has been associated with increases in mitochondrial density and respiratory capacity in equine skeletal muscle, contributing directly to improved aerobic performance and metabolic efficiency. However, mitochondrial adaptations must be interpreted within the broader context of musculoskeletal adaptation, as metabolic improvements may occur faster than structural adaptation of tendons and ligaments. This review synthesizes current knowledge on exercise-induced mitochondrial remodeling in equine skeletal muscle, while highlighting the limited mechanistic evidence available in horses and the need for more standardized longitudinal studies. Full article

Understanding how horses experience their lives is essential for improving their welfare, particularly in high-performance industries such as horseracing. Quality of Life (QoL) frameworks highlight the balance between positive and negative experiences over time, yet there is limited evidence on how racing professionals assess horse emotions and QoL, especially positive emotional states. This study reports findings from an international online survey of 230 racing industry participants. It explored confidence in assessing racehorse emotions, the perceived importance of emotional state for performance and welfare, views on racehorse QoL, and changes in understanding over time. Most respondents (92.5%) reported high confidence in judging racehorse emotions, and 94.8% of these considered emotional state important or very important for performance. The majority (87.7%) believed racehorses experience a good life at least sometimes, although this varied depending on management practices, individual horse characteristics, and human factors. Turnout, social contact, health management, staff experience, and regulatory environments were identified as key influences on QoL. Recognition of the importance of emotional state and QoL within the industry is increasing, alongside a shift towards more individualized, welfare-focused approaches. These findings support developing practical, industry-informed emotional state measures within equine QoL tools for assessing horses’ experiences and inform management decisions. Full article

The aim of the research was to assess how the selected factors could influence the performance of the best horses in dressage, jumping and eventing competitions. The research was based on the Studbook Rankings published by the World Breeding Federation for Sport Horses from 2019 to 2024. Our analysis shows a statistically significant effect of each of the observed factors in at least one discipline. The leading factor in all disciplines was studbook affiliation. The Belgian warmblood, German Sport Horse, Hanoverian, Royal Dutch Sport Horse, Oldenburg and Westphalian studbooks are represented among the significantly best studbooks in all three disciplines. Geldings were statistically highly demonstrably the best in jumping. In eventing, both geldings and stallions were highly significantly better than mares. Significantly, the highest performance was achieved by 11-year-old horses in jumping and by 15-year-old horses in eventing. We have demonstrated a statistical effect of the proportion of thoroughbred genes on performance in dressage. Statistically better performance in a selected elite population of dressage horses was achieved by horses with 20% to 50% thoroughbred genes. Our results confirm the necessity of selecting sport horses based on specialized performance tests and the need for different breeding programs for success in individual equestrian sports. Full article

The temporal and spatial distribution of speed varies with race distance and track condition, influencing where mechanical demand peaks within a race. This study aimed to describe variation in race-day speed with race distance and track condition. Race-day data from 18 flat racing seasons on turf and synthetic surfaces (2007/8–2024/25, n = 200,601 starts in 3389 races) were used to examine initial speed (from barriers until the final 600 m), final-600 m speed, race distance (m), turf track condition score (TCS, 1–10), horse rating and carried weight (kg) using a general linear model. The pattern of racing was consistent for races ≥ 1000 m. Final-600 m speed at all distances was 0.41 (95% CI 0.41–0.42) m/s faster than initial speed (p < 0.001). Both speeds decreased with increasing race distance, but this decrease was smaller for final-600 m speed (β = −0.15 [95% CI −0.16–−0.15] m/s per 200 m) than for initial speed (β = −0.17 [95% CI −0.18–−0.17] m/s per 200 m, p < 0.001). Speeds had a negative quadratic relationship with TCS (differing in magnitude and intercept, p < 0.001), with a rapid decline at TCS 9. Higher horse rating increased speed, while greater carried weight reduced speed (both p < 0.001). The higher race final-600 m speeds were less affected by distance, indicating that mechanical demand is higher late in the race and load accumulation is not uniform. Full article