Peptoniphilus equinus sp. nov., a novel Gram-stain-positive anaerobic coccus isolated from the faeces of a thoroughbred racehorse.

A novel, anaerobic, Gram-stain-positive coccoid strain, CBA3646T, was isolated from the faeces of a thoroughbred racehorse. Phylogenetic analysis based on 16S rRNA gene sequencing yielded results indicative of CBA3646T representing a member of the genus Peptoniphilus, with the species most closely related to it being Peptoniphilus asaccharolyticus DSM 20463T, with a similarity of 94.79 %. DNA-DNA relatedness and average nucleotide identity values between CBA3646T and P. asaccharolyticus DSM 20463T were 21.4 and 67.6 %, respectively. CBA3646T has a circular chromosomal genome of 1 709 189 bp (45.5 mol% DNA G+C content), containing 1652 genes in total, 1584 predicted protein-coding genes, 3 complete rRNA loci and 47 tRNA genes. The cells were non-motile diplococci, catalase-positive and oxidase-negative. Growth of CBA3646T was observed at 20-40 °C (optimal temperature, 35 °C) and in the presence of 0-4 % (w/v) NaCl (optimum concentration, 1 %). The major fatty acids (>10 %) of CBA3646T were C16 : 0, C18 : 1ω9c and C18 : 1ω9c dimethyl acetal, with its major polar lipids being diphosphatidylglycerol and phosphatidylglycerol. The elucidated phylogenetic, physiological, chemotaxonomic and molecular properties are indicative of strain CBA3646T representing a novel species of the genus Peptoniphilus, or which the name Peptoniphilus equinus sp. nov. is proposed. The type strain is CBA3646T (= KACC 22890T = JCM 35845T).

Comparison of oxidative stress under different propofol administration protocols in Thoroughbred racehorses by bOS and bAP assessment.

It is desirable to reduce surgery-induced oxidative stress (OS) because it can cause immune suppression and delayed wound healing. Propofol is known to have antioxidant potential and to reduce OS in humans, but there have been no studies of this issue in horses. This study was conducted to evaluate OS under three different propofol administration protocols in Thoroughbred racehorses undergoing arthroscopic surgery with sevoflurane anesthesia. Blood oxidative stress (bOS) and blood antioxidant power (bAP) were used as OS biomarkers. Both bOS and bAP significantly decreased after surgery in all groups, but no differences in these reductions were found among them. Different propofol administration protocols with sevoflurane anesthesia did not cause a difference in OS in Thoroughbred racehorses that underwent arthroscopic surgery.

Epidemiology of racing injuries in Thoroughbred racehorses with special reference to bone fractures: Japanese experience from the 1980s to 2000s.

This report describes the descriptive epidemiology of racing fractures that occurred from the 1980s to 2000s on racetracks of the Japan Racing Association (JRA). The incidence of racehorse fractures during flat racing was approximately 1-2%. Fractures occurring during a race are more likely to occur in a forelimb. Fractures mostly occur at the third and fourth corners of oval tracks and on the home stretch. They also occur more frequently at the time of changing the leading limb. Comparison of the incidence of racing fracture between before and after reconstruction of the geometrical configuration of a racetrack revealed that there was an outstanding reduction in the number of serious fractures in the year before and after reconstruction. It was postulated that the improvement in racing time, possibly influenced by reconstructing the geometrical configuration of the racetrack, was connected to the reduction in the number of fractures. Of non-biological race- and course-related factors, type of course (dirt or turf), track surface condition, differences between racecourses, and racing distance significantly influence racing time. By using an instrumented shoe, vertical ground reaction forces (VGRFs) on the forelimb during galloping and the relationships between a rough dirt and woodchip track surface and a smooth dirt and woodchip surface were measured. Relating the incidence of racing fractures with track conditions in general showed that track surface has significant effects on the incidence of fracture, with the incidence of fractures increasing as track conditions on dirt worsen and a tendency for the incidence of fractures to decrease as track conditions on turf worsen. It seems probable that track condition in general may affect the incidence of fracture. The incidence of fracture in horses during both racing and training decreased as the years progressed.

Reference range of blood biomarkers for oxidative stress in Thoroughbred racehorses (2-5 years old).

The oxidant and antioxidant equilibrium is known to play an important role in equine medicine and equine exercise physiology. There are abundant findings in this field; however, not many studies have been conducted for reference ranges of oxidative stress biomarkers in horses. This study was conducted to determine the reference values of reactive oxygen metabolites (d-ROMs) and biological antioxidant potential (BAP) using blood samples from 372 (191 males, 181 females) Thoroughbred racehorse aged 2 to 5 (3.43 ± 1.10 (mean ± SD)) years old. There were obvious gender differences in oxidative biomarkers, and growth/age-related changes were observed especially in females. Gender and age must be considered when interpreting obtained oxidative stress biomarkers for diagnosis of disease or fitness alterations in Thoroughbred racehorses.

Effect of Regular Training on Platelet Function in Untrained Thoroughbreds.

Training has a significant effect on the physiology of blood coagulation in humans and in horses. Several hemostatic changes have been reported after exercise in the horse but data available are inconclusive. The aim of this study was to investigate platelet activation and primary platelet-related hemostasis modifications in young never-trained Thoroughbreds in the first incremental training period in order to improve knowledge on this topic. Twenty-nine clinically healthy, untrained, 2-year-old Thoroughbred racehorses were followed during their incremental 4-month sprint exercise training. Blood collection was performed once a month, five times in total (T-30, T0, T30, T60, and T90). Platelet aggregation was measured by light transmission aggregometry in response to various agonists: adenosine diphosphate (ADP), collagen, and calcium ionophore A23187. Platelet function was evaluated using a platelet function analyzer (PFA-100®) using collagen/ADP and collagen/adrenaline cartridges. Nitrite-nitrate (NOx) plasma concentrations were measured via a colorimetric assay to assess in vivo nitric oxide bioavailability. Platelet activation was also investigated through gene expression analyses (selectin P-SELP, ectonucleotidase CD39-ENTPD1, prostaglandin I2 synthase-PTGIS, endothelial nitric oxide synthase 3-NOS3). Differences among the time points were analyzed and mean ± SEM were calculated. Significant modifications were identified compared with T-30, with an increase in platelet aggregation (collagen:32.6 ± 4.8 vs. 21.6 ± 4.9%; ADP: 35.5 ± 2.0 vs. 24.5 ± 3.1%; A23187: 30 ± 4.7 vs. 23.8 ± 4%) and a shorter closure time of C-ADP cartridges (75.6 ± 4.4 vs. 87.7 ± 3.4 s) that tended to return to the baseline value at T90. NOx concentrations in plasma significantly increased after 30 days of the training program compared with the baseline. The first long-term training period seems to induce platelet hyperactivity after 30 days in never-trained Thoroughbreds. Regular physical training reduces the negative effects of acute efforts on platelet activation.

Anomalous Incidence of Fatal Musculoskeletal Injury in North American 2-Year-Old Thoroughbred Racehorses in the Year 2020.

Racehorse training and racing schedules in many parts of the United States and Canada were interrupted or otherwise reduced during the first three to six months of 2020. This was an indirect consequence of mitigations to prevent the spread of the pandemic virus COVID-19. Data from the Equine Injury Database, a census-level survey of all race starts made in the USA and Canada, were used to analyse the incidence of fatalities in 2009-2022 among three age cohorts of racehorses within each year. There was a statistically significant increase in the incidence of musculoskeletal fatalities among 2-year-old Thoroughbreds in 2020, compared to the period 2009-2019. In 2021 and 2022, the training schedules of 2-year-old horses returned to pre-2020 levels, as did the incidence of fatalities. The delayed start to training for 2-year-old horses was associated with an increase in risk of fatal musculoskeletal injury for those horses during 2020, but the risk for the same horses in 2021-when they were 3 years old-was not significantly different to the risk for 3-year-olds in any other year. The increased risk of fatal musculoskeletal injury in 2020 was only found among horses that were 2 years old in 2020-horses aged 3 years or more in 2020 were not at increased risk.

Validating a Thoroughbred Racehorse Welfare Index through Horse Behaviour and Trainers' Reports of Welfare Issues in Their Horses.

We validated a Thoroughbred racehorse welfare index, developed initially from expert opinion, by relating it to horse behaviour recorded in a range of training stables and surveying trainers to investigate the environment and management systems for Thoroughbred racehorses. Relationships between the index scores and horse behaviour were observed. Then, an Australia-wide survey of racing industry stakeholders was conducted to identify which parameters are important for welfare in a training stable. Trainers performed well on horsemanship and health/disease aspects. Provisions for ventilation, transportation and nutrition were also scored at high levels. However, provisions for weaning, wastage, assisting horses in coping with heat stress, stabling and the education of racehorses were not as well covered, indicating a need for improvement in these welfare issues. We concluded that our Thoroughbred Racehorse welfare index is able to discriminate between trainers offering differing levels of welfare for the major issues in racehorse training stables.

Classification of racehorse limb radiographs using deep convolutional neural networks.

Purpose: To assess the capability of deep convolutional neural networks to classify anatomical location and projection from a series of 48 standard views of racehorse limbs. Materials and methods: Radiographs (N = 9504) of horse limbs from image sets made for veterinary inspections by 10 independent veterinary clinics were used to train, validate and test (116, 40 and 42 radiographs, respectively) six deep learning architectures available as part of the open source machine learning framework PyTorch. The deep learning architectures with the best top-1 accuracy had the batch size further investigated. Results: Top-1 accuracy of six deep learning architectures ranged from 0.737 to 0.841. Top-1 accuracy of the best deep learning architecture (ResNet-34) ranged from 0.809 to 0.878, depending on batch size. ResNet-34 (batch size = 8) achieved the highest top-1 accuracy (0.878) and the majority (91.8%) of misclassification was due to laterality error. Class activation maps indicated that joint morphology, not side markers or other non-anatomical image regions, drove the model decision. Conclusions: Deep convolutional neural networks can classify equine pre-import radiographs into the 48 standard views including moderate discrimination of laterality, independent of side marker presence.

Stress fracture of the palmar, distal cortex of the third metacarpal bone: A diagnostic challenge with a good prognosis.

BACKGROUND: Transverse stress fracture of the palmar cortex of the distal aspect of the third metacarpal bone (TSF PCD McIII) is poorly documented. OBJECTIVES: To describe the typical signalment of this injury, the common clinical and radiological signs and prognosis. STUDY DESIGN: A retrospective hospital-based case series with follow-up of racing records. METHODS: All cases of TSF PCD McIII diagnosed among racehorses in training at the Hong Kong Jockey Club between 2011 and 2019 were identified. Clinical records were reviewed and documented signs were recorded for each case. Findings from a predefined list of radiological features were listed. Descriptive statistics were used to describe the age and training profile of horses, the clinical and radiological findings and time to return to ridden exercise. RESULTS: Twenty-three cases (n = 23) were identified. The majority (57%) had recently started or returned to training from a break and 35% (n = 8) of cases had not yet undertaken timed gallops at the time of injury. Most cases (20/23; 87%) were lame; in nine (39%), lameness was severe. Localised swelling of superficial soft tissues was reported in 15/23 (65%) cases. Pain on palpation of the distal McIII was present in 15/23 (65%) cases and in response to fetlock flexion in 12/23 (52%). Diffuse, localised increase in radiopacity, disruption to the outline of the bone periosteal surface and outward displacement of the button of the splint bone were common radiological features in early cases (70%, 67% and 67% of all cases). Sixty-one per cent of cases (14/23) were initially misdiagnosed. Most horses (n = 18/23) resumed training and racing after a median of 83 and 246 days. MAIN LIMITATIONS: Clinical notes were not consistent between cases. Radiographs were taken at different times. CONCLUSIONS: Horses commencing training are at risk of TSF PCD McIII, which presents with confusing clinical signs and subtle radiological findings. The long-term outlook is favourable.

Identification of Thoroughbred Racehorse Welfare Issues by Industry Stakeholders.

Identifying key welfare issues for thoroughbred racehorses could lead to an improvement in standards. A lack of scientific information on the relative importance of key issues was addressed by soliciting the views of, first, welfare experts in the industry and, second, a broader group of stakeholders, who selected the best welfare options by adaptive conjoint analysis. The experts represented racehorse breeders, veterinarians, trainers, owners, government officials, salespeople, farriers, transporters, and horse re-trainers for post-racing activities. In a focus group meeting, the experts identified fourteen key welfare issues, each with two to four levels that related to common husbandry practices. Then, in an internet survey, 224 stakeholders ranked the issues using adaptive conjoint analysis, in declining importance, as: horsemanship > health and disease > education of the horse > track design and surface > ventilation > stabling > weaning > transport > nutrition > wastage > heat and humidity > whips > environment > gear. Relatively uniform responses to the survey by the different stakeholder groups suggested that there was a common view on what had the biggest impact on welfare. An exception was a greater rating given by women than men to the importance of correct horse nutrition. The rating of importance for welfare of different levels of provision of each issue mostly conformed to the scientific evidence, with the exception of weaning. This understanding of the importance of welfare issues for thoroughbred racehorses could be used to target interventions to the most serious problems.

Immune Response in Young Thoroughbred Racehorses under Training.

Training has a great impact on the physiology of an athlete and, like all stressful stimuli, can trigger an innate immune response and inflammation, which is part of a wider coping strategy of the host to restore homeostasis. The Thoroughbred racehorse is a valid animal model to investigate these changes thanks to its homogeneous training and highly selected genetic background. The aim of this study was to investigate modifications of the innate immune response and inflammation in young untrained Thoroughbred racehorses during the first training season through haematological and molecular investigations. Twenty-nine Thoroughbred racehorses were followed during their incremental 3-month sprint exercise schedule. Blood collection was performed at time 0 (T0; before starting the intense training period), 30 days after T0 (T30), and 90 days after T0 (T90). Haematological parameters (red and white blood cells, haemoglobin, and platelets) were evaluated and haematocrit (HCT), mean corpuscular haemoglobin concentration (MCHC), and red cells width distribution + standard deviation (RDW-SD) were calculated. Moreover, via RT-qPCR, we investigated the expression of, Interleukin 1ß (IL-1ß), Interleukin 4 (IL-4) Interleukin 6 (IL-6), Interleukin 2 (IL-2), Interleukin 3 (IL-3), Interleukin 5 (IL-5) Interleukin 8 (IL-8), Trasformig Growth Factor ß and α (TGF-ß), Tumor necrosis factor α (TNF-α), and Interferon γ (IFN-γ)genes. Main corpuscular volume (MCV) showed a significant (p = 0.008) increase at T90. Main corpuscular haemoglobin (MCH) and haemoglobin concentration (MCHC) values were significantly augmented at both T30 (p < 0.001) and T90 (p < 0.001). Basophils were significant increased at T30 (p = 0.02) and eosinophils were significantly increased at T90 (p = 0.03). Significant differences in gene expression were found for all the genes under study, with the exception of IFN-γ and TNF-α. In particular, IL-2 (T30, p = 0.011; T90, p = 0.015), IL-4 (T30, p = 0.009; T90, p < 0.001), and IL-8 (T30, p < 0.001; T90, p < 0.001) genes were significantly upregulated at both T30 and T90 with respect to T0, TGF-ß was intensely downregulated at T30 (p < 0.001), IL-5 gene expression was significantly decreased at T90 (p = 0.001), while IL-1ß (p = 0.005) and IL-3 (p = 0.001) expression was strongly augmented at the same time. This study highlighted long-term adjustments of O2 transport capability that can be reasonably traced back to exercise adaptation. Moreover, the observed changes of granulocyte numbers and functions and inflammatory cytokine gene expression confirm a major role of the innate immune system in the response to the complex of stressful stimuli experienced during the training period.

Race-day performance of horses with epiglottic entrapment, and following surgical correction using intra-oral curved bistoury hook in anaesthetised horses.

Epiglottic entrapment is a condition in racing horses, associated with abnormal respiratory noises and exercise intolerance. Epiglottic entrapment has been linked to both poor and superior athletic performance, leading to concerns regarding whether surgery is indicated, and whether surgical correction may have a deleterious effect on future race performance. The objective of the current study was to assess the race-day performance of horses racing with epiglottic entrapment and the effect of surgical correction on performance outcomes using an intra-oral technique in anaesthetised horses. A case-control study was conducted at the Singapore Turf Club from 2008 to 2011. Controls were selected 1:1 to cases, based on Malaysian Racing Authority number. The performance of horses racing with epiglottic entrapment was recorded and post-surgery race performance was described. Further, post-surgery race performance was compared between cases and with non-case controls. Twenty horses raced with epiglottic entrapment were retrospectively enrolled. There was a significant difference in racing performance in case horses racing with and without epiglottic entrapment (P < 0.001). Fourteen horses finished in the top three post-surgery, compared to one horse finishing in the top three when running with epiglottic entrapment present. There was no significant difference between the performance of case horses (n = 33) post-surgery and controls (number of wins P = 0.20; and places P = 0.62). The intra-oral release of epiglottic entrapment is a suitable technique to resolve epiglottic entrapment. This study may assist veterinarians advising clients in the decision-making process when epiglottic entrapment is diagnosed in a racehorse.

Characteristic of inflammatory airway disease in Japanese thoroughbred racehorses.

Inflammatory airway disease (IAD) is a common cause of poor performance, interruption of training and premature retirement in racehorses. It is also reported that up to 80% of horses are affected at some point in the first years of training in UK and Australia. However, no studies with regard to the information on occurrence of IAD in Japanese Thoroughbred racehorses have been reported. To investigate the occurrence and the characteristics of IAD, epidemic research including endoscopic examination of the airway tract and trachea wash was conducted for Thoroughbred racehorses presenting coughs or poor performance which airway tract disease was suspected stalled in training facility managed by Japan Racing Association. Fifty-six out of 76 Thoroughbred racehorses (73.7%) presenting coughing or poor performance were diagnosed as IAD. Mean incidence rate of IAD was 0.3% and it has been confirmed that constant number of IAD exists in Japan. Up to 35.7% of IAD horses showed upper airway abnormalities in some extent. There was a trend for IAD horses to use wood shavings for bedding and fed hay from the ground compared with the control group. Therefore, improvement of stabling environment may aid in preventing IAD. This study demonstrated that Japanese Thoroughbred racehorses are affected by IAD likewise other countries as well as demonstrated the characteristics of IAD which may contribute to the clarification of the pathogenesis of IAD.

Tracheal Endoscopic and Cytological Findings and Blood Examination Results in Thoroughbred Racehorses Suspected to have Lower Respiratory Tract Disease.

Cytology of tracheal aspirates, tracheal endoscopic and blood tests were carried out to 86 Thoroughbred racehorses presenting coughs or poor performance which were suspected to have lower respiratory tract disease (LRTD) to assess the conditions of the disorders. Racehorses were classified into coughing (66 horses) and non-coughing (20 horses) groups based on clinical symptoms. Nine Thoroughbred racehorses without respiratory abnormality were used as controls. Assessment of grades of airway mucus, cytology of tracheal aspirates and serum amyloid A (SAA), fibrinogen (Fbg) and pulmonary surfactant protein D (SP-D) measurements were performed. Relationships between age, gender and racing careers were also investigated to understand the characteristics of LRTD in racehorses. Mean age was significantly higher in non-coughing group compared to coughing group. Existence of racing career and number of starts were significantly greater in non-coughing group compared to coughing group. On the other hand, grades of airway mucus were significantly higher in coughing group compared to control group. Percentages of neutrophils in tracheal aspirates were significantly higher in coughing group compared to non-coughing and control groups. SAA, Fbg and SP-D were higher in coughing group compared to non-coughing and control groups indicating that condition of coughing group is in the acute phase. Positive rate of inflammatory airway disease was significantly higher in coughing and non-coughing groups compared to control group. It was concluded that carrying out comprehensive evaluation including investigation on SAA, Fbg and SP-D analysis with airway assessment to Thoroughbred racehorses which were suspected to have LRTD are useful procedure to understand the pathological condition which aid to initiate appropriate treatment, prognosis judgment or to advise trainers to consider altering training regimen.

Exercise-induced pulmonary hemorrhage: where are we now?

As the Thoroughbreds race for the final stretch, 44 hooves flash and thunder creating a cacophony of tortured air and turf. Orchestrated by selective breeding for physiology and biomechanics, expressed as speed, the millennia-old symphony of man and beast reaches its climax. At nearly 73 kilometers per hour (45 mph) over half a ton of flesh and bone dwarfs its limpet-like jockey as, eyes wild and nostrils flaring, their necks stretch for glory. Beneath each resplendent livery-adorned, latherin-splattered coat hides a monstrous heart trilling at 4 beats per second, and each minute, driving over 400 L (105 gallons) of oxygen-rich blood from lungs to muscles. Matching breath to stride frequency, those lungs will inhale 16 L (4 gallons) of air each stride moving >1,000 L/min in and out of each nostril - and yet failing. Engorged with blood and stretched to breaking point, those lungs can no longer redden the arterial blood but leave it dusky and cyanotic. Their exquisitely thin blood-gas barrier, a mere 10.5 µm thick (1/50,000 of an inch), ruptures, and red cells invade the lungs. After the race is won and lost, long after the frenetic crowd has quieted and gone, that blood will clog and inflame the airways. For a few horses, those who bleed extensively, it will overflow their lungs and spray from their nostrils incarnadining the walls of their stall: a horrifically poignant canvas that strikes at horse racing's very core. That exercise-induced pulmonary hemorrhage (EIPH) occurs is a medical and physiological reality. That every reasonable exigency is not taken to reduce/prevent it would be a travesty. This review is not intended to provide an exhaustive coverage of EIPH for which the reader is referred to recent reviews, rather, after a brief reminder of its physiologic and pathologic bases, focus is brought on the latest developments in EIPH discovery as this informs state-of-the-art knowledge, the implementation of that knowledge and recommendations for future research and treatment.

Transcriptional expression changes of glucose metabolism genes after exercise in thoroughbred horses.

Physical exercise induces gene expression changes that trigger glucose metabolism pathways in organisms. In the present study, we monitored the expression levels of LDHA (lactate dehydrogenase) and GYS1 (glycogen synthase 1) in the blood, to confirm the roles of these genes in exercise physiology. LDHA and GYS1 are related to glucose metabolism and fatigue recovery, and these processes could elicit economically important traits in racehorses. We collected blood samples from three retired thoroughbred racehorses, pre-exercise and immediately after 30 min of exercise. We extracted total RNA and small RNA (≤ 200 nucleotide-long) from the blood, and assessed the expression levels of LDHA, GYS1, and microRNAs (miRNAs), by using qRT-PCR. We showed that LDHA and GYS1 were down-regulated, whereas eca-miR-33a and miR-17 were up-regulated, after exercise. We used sequences from the 3' UTR of LDHA and GYS1, containing eca-miR-33a and miR-17 binding sites, to observe the down-regulation activity of each gene expression. We observed that the two miRNAs, namely, eca-miR-33a and miR-17, inhibited LDHA and GYS1 expression via binding to the 3' UTR sequences of each gene. Our results indicate that eca-miR-33a and miR-17 play important roles in the glucose metabolism pathway. In addition, our findings provide a basis for further investigation of the exercise metabolism of racehorses.