Thoroughbreds are a breed of horse known for their agility, speed, and spirit, often associated with horse racing and equestrian sports. Originating from crossbreeding native English mares with imported Arabian, Barb, and Turkoman stallions, Thoroughbreds have a well-documented pedigree that traces back to the late 17th and early 18th centuries. This breed is characterized by a refined head, deep chest, and long legs, contributing to their athletic capabilities. Thoroughbreds are primarily bred for their performance in racing but are also utilized in other equestrian disciplines. This page compiles peer-reviewed research studies and scholarly articles that explore the genetics, physiology, and performance characteristics of Thoroughbreds, as well as their management and welfare in various equine activities.
Anstey S, Lizárraga D, Nyari S, Chalmers G, Carrick J, Chicken C, Jenkins C, Perkins N, Timms P, Jelocnik M.Late-term foal loss due to the traditional avian pathogen Chlamydia psittaci recently emerged as a threat to the Australian Thoroughbred industry. A longitudinal study of 14 stud farms was undertaken to better understand C. psittaci infection in pregnant mares and their foals by evaluating C. psittaci prevalence, equine herpesvirus-1 (EHV-1) co-infection, avian reservoirs, and potential risk factors. Mucosal swabs taken from 228 healthy pregnant mares and their foals were tested for C. psittaci and EHV-1 using species-specific qPCR assays. No foal loss was recorded due to either pathogen, and ...
Kim SM, Yun SW, Cho GJ.The study aimed to evaluate the diversity of donkey populations by comparing with the diversity of Thoroughbred and Jeju Halla horses; identified breeding backgrounds can contribute to management and conservation of donkeys in South Korea. Methods: A total of 100 horse (50 Thoroughbreds and 50 Jeju Halla horses) and 79 donkeys samples were genotyped with 15 microsatellite markers (AHT4, AHT5, ASB2, ASB17, ASB23, CA425, HMS1, HMS2, HMS3, HMS6, HMS7, HTG4, HTG10, LEX3, and VHL20), to identify genetic diversity and relationships among horses and donkeys. Results: The observed number of alleles pe...
Arndt S, Kilcoyne I, Heney CM, Wong TS, Magdesian KG.Dental extractions in horses may result in bacteremia, which can lead to systemic complications. Bacterial meningitis following oral cheek tooth extractions in a 17-year-old Thoroughbred gelding is described in this report. The bacterial meningitis was confirmed by histopathology. The gelding was presented for evaluation of intermittent fever, loose feces, and mild colic signs which started 5 days after cheek tooth extraction. This case illustrates a rare complication associated with oral tooth extraction in a horse and highlights the unusual presenting features of meningitis. Key clinical mes...
Arango-Sabogal JC, Mouncey R, de Mestre AM, Verheyen K.Up-to-date figures on early losses of Thoroughbreds from the racing industry can inform strategies to improve retention and incentivise traceability of Thoroughbreds during this early life period. Methods: Data on Thoroughbred mares bred in 2013-2014 and training, racing and sales information of their live offspring were analysed. The proportions and 95% confidence intervals (95% CI) of the entire 2014-2015 United Kingdom and Ireland foal crops that entered training, raced, were imported and/or exported between birth and the end of their third year of life, as well as the racing performance of...
O'Hara V, Cowan A, Riddell D, Massey C, Martin J, Piercy RJ.Horse racing is a popular and financially important industry worldwide and researchers and horse owners are interested in genetic and training influences that maximise athletic performance. An association has been found between the presence of a short interspersed nuclear element (SINE) mutation in the myostatin (MSTN) gene promoter and optimal race distance in Thoroughbred horses. There is previous laboratory evidence that this mutation reduces MSTN expression in a cell culture model and influences skeletal muscle fibre type proportions in horses. Manipulating MSTN expression has been propose...
Couetil L, Ivester K, Barnum S, Pusterla N.Equine asthma is a common cause of poor performance in racehorses but it is unclear if respiratory viruses contribute to its etiology. The objective of the study was to determine if respiratory viruses were associated with clinical signs and bronchoalveolar lavage fluid (BALF) cytology in Thoroughbred racehorses. Equine herpesviruses (EHV-1, 2, 4, 5) and equine rhinitis A and B viruses (ERBV, ERAV) genomes were quantified by qPCR in nasopharyngeal, tracheal, and BALF samples collected after racing. The relationships between virus detection and load and clinical signs, performance, BALF cytolog...
Yiğin A.The extensive use of antibacterial agents used for treatment in human and veterinary clinics to increase yield in livestock and aquaculture in developing countries causes the detection and spread of multidrug-resistant (MDR) strains in different sources. The presence of Escherichia coli strains is very common in racehorses and it's a serious problem on horse farms. Extended-spectrum beta-lactamase (ESBL) production is an important source of MDR development in Gram-negative strains such as E.coli. This study aimed to detect the presence of ESBL genes in E. coli strains isolated from horse farms...
Conturba B, Lo Feudo CM, Stucchi L, Stancari G, Olivieri L, Ferrucci F.The aim of the present work was to describe a case of recurrent capillary haemangioma at the coronary border of the left front limb in a 6-month-old thoroughbred filly successfully treated with diode laser ablation and adjunctive laser photocoagulation therapy. Le but de cette étude était de décrire un cas d’hémangione capillaire récidivant du bord coronaire du membre antérieur gauche chez un cheval de race de 6 mois traité avec succès par une ablation au laser diode et traitement adjuvant de photo-coagulation au laser. El objetivo del presente trabajo fue describir un caso de hemang...
Picetti TS, Soveral LF, Miotto R, Erpen LMS, Kreutz Y, Guizzo JA, Frandoloso R, Kreutz LC.Immune-modulating molecules mainly act on innate immune cells, which are central to early defense against invading pathogens and contribute to developing adaptive immunity. Yeast-extracted β-glucan, a model immune-modulating molecule, is widely used in several animal species; however, its effect on horse immune parameters has not been thoroughly investigated yet. This study aimed to evaluate the effects of orally administered β-glucan on selected innate immune parameters in horses. Methods: Eighteen thoroughbred horses were assigned equally into three groups as follows: One control group (no...
Ryan D, McKemie DS, Kass PH, Puschner B, Knych HK.The increasing availability of cannabidiol (CBD) and anecdotal reports of its anti-inflammatory effects has garnered it much interest in the equine industry. The objectives of the current study were to (1) describe the pharmacokinetics of oral CBD in exercising thoroughbreds, (2) characterize select behavioral and physiologic effects, and (3) evaluate effects on biomarkers of inflammation using an ex vivo model. This study was conducted in a randomized balanced 3-way crossover design with a two-week washout period between doses. Horses received a single oral dose (0.5, 1, and 2 mg/kg) of CBD...
Pira E, Vacca GM, Dettori ML, Piras G, Moro M, Paschino P, Pazzola M.One hundred and eighty Anglo-Arabian horses running 1239 races were sampled for the present study. DNA was extracted from the blood and myostatin gene, MSTN, was genotyped. Moreover, prizes won and places were achieved for the 1239 races to perform association analyses between the different genotypes and sport traits. Two SNPs already reported in previous studies regarding the Thoroughbred breed, rs69472472 and rs397152648, were revealed as polymorphic. The linkage disequilibrium analysis investigating the haplotype structure of MSTN did not evidence any association block. Polymorphism at SNP ...
Lee H, Hwang H, Ro Y, Kim JH, Lee K, Choi E, Bae Y, So B, Lee I.This study was performed to examine and clarify the cause of hindlimb ataxia and neuropathy seen in the South Korean horse population. Fifty horses diagnosed with hindlimb ataxia and neuropathy were referred for this study. Neurological examination was performed on 47 horses while necropsy was performed in all 50 animals. The occurrence of neurological diseases increased rapidly in the summer and 47 out of 50 horses were referred after the end of July. The incidence of neurological diseases started from the southern part of Korea in July and proceeded northward in August and September. Althoug...
Crawford KL, Finnane A, Greer RM, Phillips CJC, Bishop EL, Woldeyohannes SM, Perkins NR, Ahern BJ.Worldwide, musculoskeletal injuries remain a major problem for the Thoroughbred racing industry. There is a strong interest in developing training and management strategies to reduce the impact of musculoskeletal injuries, however, progress has been limited by studies reporting conflicting findings, and a limited understanding of the role of different training methods in preventing injury. There is little data on patterns of rest periods and exercise data and how these vary between trainers. This prospective study of two-year-old racehorses was conducted in Queensland, Australia and involved w...
Wilson BJ, Thompson KR, McGreevy PD.The annual Melbourne Cup Thoroughbred horse race has iconic status among many Australians but sits in the context of increasing criticism of the welfare of Thoroughbred racing horses and the ethics of gambling. Despite heated debates and protests playing out in the public domain, there is scant empirical research to document Australian attitudes to the Melbourne Cup, or horse racing more generally. Specifically, little is known about how support for or against the Melbourne Cup correlate with age, gender, income and level of education. To provide a more nuanced understanding of attitudes towar...
Hague N, Durham AE, Menzies-Gow NJ.Equine pituitary pars intermedia dysfunction (PPID) is treated with daily pergolide therapy. Owner compliance and its effect on PPID control have not been previously investigated. Clinical records were searched to identify the sample of animals with PPID treated with pergolide from 2016 to 2019. The signalment was noted and the dose of pergolide received calculated. Animals were classified as compliant (receiving ≥90% of the veterinarian recommended dose of pergolide) or non-compliant, and as controlled (follow-up basal adrenocorticotrophic hormone concentrations within the reference range) ...
Ireland JL, McGowan CM.Research demonstrating insulin's causal role in endocrinopathic laminitis has greatly advanced understanding of equine laminitis. However, the degree to which this knowledge has been translated into clinical practice has not been assessed. This two-part study aimed to investigate veterinary surgeons' current diagnostic approach to laminitis, whether this had changed over time, and the impact of diagnosing an endocrinopathy on laminitis case management and outcome. Two cross-sectional online surveys of equine veterinary surgeons working within the UK were undertaken. The first study population ...
Minamijima Y, Niwa H, Uchida E, Yamamoto K.In the past decade, mass spectrometry has become an important technology for protein identification. Recent developments in mass spectrometry allow a large number of identifications in samples; therefore, mass-spectrometry-based techniques have been applied to the discovery of biomarkers. Here, we conducted a proteomic study to compare the proteomes in sera between healthy Thoroughbreds and Thoroughbreds with respiratory disease associated with transport (RDT). We found that four proteins, apolipoprotein F, lipopolysaccharide binding protein, lysozyme and protein S100-A8, were upregulated, whi...
Takahashi Y, Takahashi T, Mukai K, Ohmura H.Exercise intensity during races is considerably high. To understand how Thoroughbreds adapt to fatigue conditions, stride parameters for the first and second lap of the race (2400-m, turf) were compared. A high-speed video system was set in a right lateral position about 20 m before the finishing post, with a field view width of about 16 m. The stride frequency, the length between each limb (hind step, diagonal step, fore step, and airborne step), and stride length were measured and analyzed using a generalized linear mixed model. Compared with the first lap, the mean ± standard deviation val...
Scilimati N, Pepe M, Pressanto MC, Angeli G, Beccati F.A 4-month-old Thoroughbred filly was referred for evaluation of severe left forelimb lameness of 24 hours duration. Radiographic projections of the shoulder revealed mild irregularity and sclerosis of the proximal humeral apophysis. Ultrasonographic examination showed a moderate increase in the amount of anechogenic synovial fluid within the intertubercular bursa and scapulohumeral joint, and irregularity of the ossifying bone surface of the intermediate tubercle of the humerus. Computed tomographic (CT) examination revealed a circular hypoattenuating area at the level of the proximal apophysi...
Vitale V, Laurberg M, van Galen G.Aortic valve malformation is a common congenital abnormality reported in human medicine. The malformation is characterised by an increased or decreased number of cusps. Anatomical variations of the aortic valve that have been documented in humans include unicuspid, bicuspid, quadricuspid and quinticuspid valves. Two reports described a quadricuspid aortic valve in horses associated with either a ventricular septal defect (VSD) or tetralogy of Fallot. In this case report we describe the clinical and echocardiographic findings of a horse with a quadricuspid aortic valve as single congenital abno...
Donnelly CG, Bellone RR, Hales EN, Nguyen A, Katzman SA, Dujovne GA, Knickelbein KE, Avila F, Kalbfleisch TS, Giulotto E, Kingsley NB, Tanaka J....Following the successful creation of a biobank from two adult Thoroughbred mares, this study aimed to recapitulate sample collection in two adult Thoroughbred stallions as part of the Functional Annotation of the Animal Genome (FAANG) initiative. Both stallions underwent thorough physical, lameness, neurologic, and ophthalmic (including electroretinography) examinations prior to humane euthanasia. Epididymal sperm was recovered from both stallions immediately postmortem and cryopreserved. Aseptically collected full thickness skin biopsies were used to isolate, culture and cryopreserve dermal f...
Lizarraga I, Panizzi L, Gieseg MA, Riley CB, Chambers JP.To evaluate thermal nociceptive thresholds (TNTs) before and after inducing a standardized radiocarpal bone osteochondral fracture (OCF) in horses. Methods: Prospective, controlled, randomized, masked study. Methods: A group of 10 Thoroughbred fillies aged 2 years. Methods: Skin temperature and TNTs were measured on the skin over the triceps brachii muscle in both the thoracic limbs before (week 0) and weekly (weeks 1-8) after unilateral arthroscopic induction of a radiocarpal OCF (n = 4) or sham surgery (n = 6) followed by a standardized exercise programme. The contralateral, non-operated t...
Weller D, Franklin S, White P, Shea G, Fenner K, Wilson B, Wilkins C, McGreevy P.This article reports on the results of a survey of racehorse trainers (n = 112) outlining the reasons for tongue-tie (TT) and noseband (NB) use by Thoroughbred trainers (TBTs) (n = 72) and Standardbred trainers (SBTs) (n = 40). The study also investigated the reported effectiveness of TTs and possible complications arising from their use. Tongue-tie use was reported by 62.5% (n = 70) of racehorse trainers. The reasons for TT use varied between TBTs and SBTs. For TBTs, the most common reason for TT use was to prevent or reduce airway obstruction (72.3%, n = 34), followed closely by to prevent o...
Mathew B, Philip M, Perwad Z, Karatt TK, Caveney MR, Subhahar MB, Karakka Kal AK.Hypoxia-inducible factor (HIF) stabilizer belongs to a novel class of pharmacologically active substances, which are capable of inducing the endogenous erythropoietic system. The transcriptional activator HIF has been shown to significantly increase blood hemoglobin and is well set for the treatment of anemia resulting from chronic kidney disease. This research work reports a comprehensive study of the most popular HIF stabilizer roxadustat and its metabolites in thoroughbred horse urine after oral administration. The plausible structures of the detected metabolites were postulated using liqui...
Raidal SL, Hughes KJ, Eastwell B, Noble N, Lievaart J.There is little information on foal mortality and the epidemiology of diseases in the neonatal period in Australian equine breeding enterprises. Methods: This was a prospective cohort study of 1219 foals on 15 breeding farms in south-eastern Australia to identify the proportion of foals recognised on farm as abnormal at birth or within the first 48 h postpartum, determine the prevalence and risk factors for neonatal disease and assess the subsequent performance of foals in the study population. Results: Overall, 27 foals died within 6 weeks of birth in the study population (2.2%), 142 foal...
Mukai K, Ohmura H, Takahashi Y, Kitaoka Y, Takahashi T.We investigated whether horses trained in moderate and mild hypoxia demonstrate greater improvement in performance and aerobic capacity compared to horses trained in normoxia and whether the acquired training effects are maintained after 2 weeks of post-hypoxic training in normoxia. Seven untrained Thoroughbred horses completed 4 weeks (3 sessions/week) of three training protocols, consisting of 2-min cantering at 95% maximal oxygen consumption under two hypoxic conditions (H16, F O = 16%; H18, F O = 18%) and in normoxia (N21, F O = 21%), followed by 2 weeks of post-hypoxic traini...
King L, Cullen SJ, O'Connor S, McGoldrick A, Pugh J, Warrington G, Losty C.Racehorse trainers play an important role within the horseracing industry. Despite this, scarce empirical information exists regarding the mental health of this population. Thus, the purpose of the present study was to explore the prevalence of symptoms related to common mental disorders (CMDs) and their associations with specific risk factors for CMD. Participants completed an anonymous online questionnaire. CMDs were assessed including distress, depression, generalized anxiety and adverse alcohol use. The risk factors examined included career dissatisfaction, social support and financial dif...
Birks EK, Shuler KM, Soma LR, Martin BB, Marconato L, Del Piero F, Teleis DC, Schar D, Hessinger AE, Uboh CE.The incidence and severity of exercise-induced pulmonary haemorrhage (EIPH) in the 2 most commonly raced horse breeds, Thoroughbreds (TB) and Standardbreds (STD), were studied, with particular interest in the possible influence of frusemide (F) and/or the breed (or running gait) on EIPH. The appearance of blood within the trachea was semi-quantified using a published 5-point system, with zero assigned when no blood was observed, and numbers 1-4 assigned with increasing amounts of blood. Considering each endoscopic examination as a separate event, approximately 75% of the postrace endoscopic ex...
Takahashi T, Kasashima Y, Ueno Y.To determine whether race history, including the number of races and total race distance, was associated with risk of superficial digital flexor tendon (SDFT) injury in Thoroughbred racehorses in Japan. Methods: Matched case-control study. Methods: 515 Thoroughbred racehorses (case horses) that sustained an SDFT injury during training or racing in Japan during 2002 and 951 horses (control horses) without SDFT injury that were matched with case horses on the basis of age and month of the latest race. Methods: Variables related to race history were compared between case and control horses by mea...
Ohmura H, Hiraga A, Aida H, Kuwahara M, Tsubone H, Jones JH.To determine whether evaluation of heart rate (HR) and HR variability (HRV) during prolonged road transportation in horses provides a sensitive index of autonomic stimulation. Methods: Five 2-year-old Thoroughbreds. Methods: ECGs were recorded as horses were transported for 21 hours in a 9-horse van. Heart rate, high-frequency (HF) power, low-frequency (LF) power, and LF-to-HF ratio from Fourier spectral analyses of ECGs were calculated and compared with values recorded during a 24-hour period of stall rest preceding transportation. Results: HR, HF power, and LF power had diurnal rhythms durin...
Murray MJ, Murray CM, Sweeney HJ, Weld J, Digby NJ, Stoneham SJ.Gastroendoscopic examinations were conducted on 75 Thoroughbred foals aged two to 85 days on seven breeding farms in England and Ireland. The foals showed no signs of gastric disease. There was no significant difference between lesion prevalence in foals in England (16 of 28 foals; 57 per cent) or Ireland (22 of 47 foals; 47 per cent). Neither was there any sex predilection (18 of 36 males; 20 of 39 females). Lesions were most prevalent in foals under 10 days old (8 of 9) and least prevalent in foals older than 70 days (3 of 10). Lesions occurred most frequently in the squamous mucosa immediat...
Ohmura H, Matsui A, Hada T, Jones JH.Training of young Thoroughbred horses must balance development of cardiopulmonary function and aerobic capacity with loading of the musculoskeletal system that can potentially cause structural damage and/or lameness. High-speed equine treadmills are sometimes used to supplement exercise on a track in the training of young Thoroughbreds because the horse can run at high speeds but without the added weight of a rider. We tested the hypothesis that intermittent high-intensity exercise on a treadmill of young Thoroughbred horses entering training can enhance development of aerobic capacity (VO2max...
Hill EW, Stoffel MA, McGivney BA, MacHugh DE, Pemberton JM.Small effective population sizes and active inbreeding can lead to inbreeding depression due to deleterious recessive mutations exposed in the homozygous state. The Thoroughbred racehorse has low levels of population genetic diversity, but the effects of genomic inbreeding in the population are unknown. Here, we quantified inbreeding based on runs of homozygosity (ROH) using 297 K SNP genotypes from 6128 horses born in Europe and Australia, of which 13.2% were unraced. We show that a 10% increase in inbreeding () is associated with a 7% lower probability of ever racing. Moreover, a ROH-based g...
Todd ET, Fromentier A, Sutcliffe R, Running Horse Collin Y, Perdereau A, Aury JM, Èche C, Bouchez O, Donnadieu C, Wincker P, Kalbfleisch T....Historical genomes can provide important insights into recent genomic changes in horses, especially the development of modern breeds. In this study, we characterized 8.7 million genomic variants from a panel of 430 horses from 73 breeds, including newly sequenced genomes from 20 Clydesdales and 10 Shire horses. We used this modern genomic variation to impute the genomes of four historically important horses, consisting of publicly available genomes from 2 Przewalski's horses, 1 Thoroughbred, and a newly sequenced Clydesdale. Using these historical genomes, we identified modern horses with high...
McGivney BA, Hernandez B, Katz LM, MacHugh DE, McGovern SP, Parnell AC, Wiencko HL, Hill EW.Durability traits in Thoroughbred horses are heritable, economically valuable and may affect horse welfare. The aims of this study were to test the hypotheses that (i) durability traits are heritable and (ii) genetic data may be used to predict a horse's potential to have a racecourse start. Heritability for the phenotype 'number of 2- and 3-year-old starts' was estimated to be = 0.11 ± 0.02 (n = 4499). A genome-wide association study identified SNP contributions to the trait. The neurotrimin (NTM), opioid-binding protein/cell adhesion molecule like (OPCML) and prolylcarboxypeptidase ...
Perkins NR, Reid SW, Morris RS.To describe patterns in training, racing, and general health in a population of Thoroughbred racehorses in New Zealand. Methods: A longitudinal study was designed to collect data on horses training under the care of 20 selected trainers from 20 different stables and five regional training venues in the mid to lower regions of the North Island. Data were collected from trainers at approximately monthly intervals between October 1997 and July 2000, and electronic data containing race and trial results for all starts in New Zealand for the same time period were obtained from New Zealand Thoroughb...
McGowan CM, Fordham T, Christley RM.Telephone surveys of 34 racing yards with 1276 horses in training were made to establish the overall incidence of exertional rhabdomyolysis in the previous year. A case-control study was used to investigate the risk factors for the syndrome in 12 yards selected on the basis of the routine confirmation of diagnoses by the evaluation of the serum activities of creatine kinase and aspartate aminotransferase. The overall incidence of the syndrome was 6.7 per cent and 80 per cent of the trainers had at least one affected horse. In 74 per cent of the affected horses it frequently recurred, with an a...
Lyons ET, Tolliver SC, Collins SS.Fecal samples (n=1,584) for a parasite study were collected from Thoroughbred foals (n=349), 28 to 330 days old, on seven farms in central Kentucky during 49 monthly trips from May to October, November, or December 2004. The main purpose was to determine possible drug resistance of ascarids, also of strongyles, to ivermectin (IVM) and other commercially available compounds [fenbendazole, moxidectin (MOX), oxibendazole (OBZ), and pyrantel pamoate]. In addition, interest was on prevalence of foal parasites. Qualitative data were obtained by recording presence or absence of ascarid and strongyle ...
Kim NY, Seong HS, Kim DC, Park NG, Yang BC, Son JK, Shin SM, Woo JH, Shin MC, Yoo JH, Choi JW.The Jeju horse is an indigenous Korean horse breed that is currently registered with the Food and Agriculture Organization of the United Nations. However, there is severe lack of genomic studies on Jeju horse. This study was conducted to investigate genetic characteristics of horses including Jeju horse, Thoroughbred and Jeju crossbred (Jeju × Thoroughbred) populations. We compared the genomes of three horse populations using the Equine SNP70 Beadchip array. Short-range Linkage disequilibrium was the highest in Thoroughbred, whereas r values were lowest in Jeju horse. Expected heterozygos...
Nagata S, Kurosawa M, Mima K, Nambo Y, Fujii Y, Watanabe G, Taya K.The aim of this study was to clarify the effect of anabolic steroids on the testicular endocrine function of mature stallions. Mature thoroughbred stallions were treated with 800 mg nandrolone decanoate every 3 weeks for 3 months. After the first treatment, plasma concentrations of LH, immunoreactive inhibin and testosterone decreased rapidly to the nadir. These hormones were maintained at significantly lower concentrations compared with concentrations in intact stallions. Histology of the testicular tissue indicated the arrest of advanced spermatogenesis in the seminiferous tubules and a seve...
A breed known for its versatility, the American Quarter Horse (QH), is increasingly bred for performance in specific disciplines. The impact of selective breeding on the diversity and structure of the QH breed was evaluated using pedigree analysis and genome-wide SNP data from horses representing 6 performance groups (halter, western pleasure, reining, working cow, cutting, and racing). Genotype data (36 037 single nucleotide polymorphisms [SNPs]) from 36 Thoroughbreds were also evaluated with those from the 132 performing QHs to evaluate the Thoroughbred's influence on QH diversity. Results s...
McIlwraith CW, Yovich JV, Martin GS.The technique and results of arthroscopic surgery for the removal of osteochondral fragments from 1,000 carpal joints in 591 horses are reported. Of the 591 horses, 580 were racehorses (including 349 Quarter Horses and 220 Thoroughbreds). The distal aspect of the radial carpal bone was the most commonly affected site, followed by the proximal aspect of the intermediate carpal bone and distolateral aspect of the radius. More than one carpal joint was simultaneously operated on in 58.9% of the Quarter Horses and in 37.4% of the Thoroughbreds. Marked differences in the amount of damage were noted...
Cardwell JM, Smith KC, Wood JL, Newton JR.Many studies of respiratory disease in racehorses have focused on a combination of increased tracheal mucus and airway neutrophilia. Examination of each component separately should provide further insight into this condition. Objective: To identify infectious risk factors for endoscopically visible tracheal mucus in National Hunt racehorses. Methods: A 2 year prospective longitudinal study. Methods: Monthly quantitative bacteriological examinations of tracheal wash samples and viral serological examinations were conducted. Risk factors for 'small amounts of mucus' (mucus score = 1/3) and 'incr...
Stepnik MW, Radtke CL, Scollay MC, Oshel PE, Albrecht RM, Santschi EM, Markel MD, Muir P.To examine the fracture failure surfaces from Thoroughbred horses that had sustained a catastrophic condylar fracture. Methods: Bone specimens from the failure surface were obtained from 12 Thoroughbred racehorses with catastrophic injury and 2 non-racing horses with accidental long bone fracture. Methods: Bone specimens from the failure surface of each fracture were incubated with gold microspheres to label microcracks before examination at x50 to x60,000 using scanning electron microscopy. Microcracking at the failure surface was assessed using a visual analog scale. Results: Branching array...
Bailey E.336 Standardbred mares and 334 Thoroughbred mares in the vicinity of Lexington, Kentucky, were lymphocyte typed for 11 allelic antigenic specificities of the equine lymphocyte antigen (ELA) system. The Standardbred mares were divided into a population of pacers and a population of trotters. Substantial differences in ELA gene frequencies were found between the 3 groups. When the distribution of antigens within populations were compared to Hardy-Weinberg equilibrium expectations, relatively good agreement was found.
Donnelly CG, Bellone RR, Hales EN, Nguyen A, Katzman SA, Dujovne GA, Knickelbein KE, Avila F, Kalbfleisch TS, Giulotto E, Kingsley NB, Tanaka J....Following the successful creation of a biobank from two adult Thoroughbred mares, this study aimed to recapitulate sample collection in two adult Thoroughbred stallions as part of the Functional Annotation of the Animal Genome (FAANG) initiative. Both stallions underwent thorough physical, lameness, neurologic, and ophthalmic (including electroretinography) examinations prior to humane euthanasia. Epididymal sperm was recovered from both stallions immediately postmortem and cryopreserved. Aseptically collected full thickness skin biopsies were used to isolate, culture and cryopreserve dermal f...
Parkin TD, Clegg PD, French NP, Proudman CJ, Riggs CM, Singer ER, Webbon PM, Morgan KL.The objective of this study was to identify risk factors, during racing, associated with imminent fatal distal limb fracture in Thoroughbreds. One hundred and nine cases of fatal distal limb fracture were identified from all 59 UK racecourses over a 2-year period (February 1999-January 2001). Three uninjured control horses were randomly selected from the same race as the case horse. Videos of races in which fractures occurred were viewed using a defined protocol. Fractures in flat races occurred at any time during the race, whereas 74% (45/61) of cases in national hunt type races occurred in t...
Linford RL, O'Brien TR, Trout DR.Lameness examinations and radiography of the distal phalanx and associated soft-tissue structures of the front feet of 103 Thoroughbred racehorses, 4 to 9 years old, were performed to determine normal radiographic appearance and morphometry. Of 103 horses examined, 41 were used in the study that were without clinical signs of foot problems or lameness, had raced at least twice prior to radiography, and had raced at least twice more in the 6 months after radiography. Lateromedial and dorsoproximal-palmarodistal radiographic views of each front distal phalanx were used to measure 28 bone and sof...
Peters SE, Wakefield AE, Whitwell KE, Hopkin JM.Genetically distinct forms of Pneumocystis carinii infect several mammalian hosts. We report the amplification of P. carinii DNA from samples of two infected thoroughbred foal lungs by using primers designed from the sequence of a P. carinii mitochondrial rRNA gene; these primers also prime the amplification of P. carinii DNA from other hosts. The nucleotide sequence of part of the mitochondrial rRNA gene amplified from P. carinii infecting one of the foals was determined and found to be distinct from that of published rat-, rabbit-, ferret-, and human-derived P. carinii sequences.
Moore JM, Timperio AF, Crawford DA, Burns CM, Cameron-Smith D.Jockeys are required to maintain very low body weight and precise weight control during competition. This study examined the weight loss and weight management strategies of professional horseracing jockeys in the state of Victoria, Australia. An anonymous, self-completed questionnaire was administered (55% response rate, n = 116). Almost half (43%) reported that maintaining riding weight was difficult or very difficult, with 75% routinely skipping meals. In preparation for racing, 60% reported that they typically required additional weight loss, with 81% restricting food intake in the 24 hours...
Diab SS, Poppenga R, Uzal FA.In racehorses, sudden death (SD) associated with exercise poses a serious risk to jockeys and adversely affects racehorse welfare and the public perception of horse racing. In a majority of cases of exercise-associated sudden death (EASD), there are no gross lesions to explain the cause of death, and an examination of the cardiovascular system and a toxicologic screen are warranted. Cases of EASD without gross lesions are often presumed to be sudden cardiac deaths (SCD). We describe an equine SD autopsy protocol, with emphasis on histologic examination of the heart ("cardiac histology protocol...
Jacquet S, Robert C, Valette JP, Denoix JM.The objective of this study was to evaluate the spontaneous evolution of radiological findings (RF) indicative of juvenile osteochondral conditions (JOCC) in a field study. A radiographic survey was performed at the age of 6 and 18months in 321 young horses from three breeds (French Trotter Standardbred, Selle-Français Warmblood and Thoroughbred). Each RF identified at 6months was re-evaluated at 18months, and classified as (1) disappeared, (2) improved, (3) stable, (4) deteriorated or (5) new when it was not identified at 6months. Only 32.3% of all RF identified at the age of 6months were st...
Davie AL, Evans DJ.The associations between velocity during a standardized, submaximal 800-m exercise test and blood lactate concentration after exercise were investigated in Thoroughbred racehorses on sand and grass racetracks. Predicted lactate concentrations for each horse's exercise test velocity were calculated from the line of best fit derived from results at each racetrack. The repeatability of the differences between the measured and predicted blood lactate response to exercise was also investigated. Exercise tests were conducted at speeds ranging from 12.8 to 16.6 m/s. The variability of velocity within...
Millerick-May ML, Karmaus W, Derksen FJ, Berthold B, Robinson NE.Particle mapping within stalls has demonstrated a relationship between particulate concentrations and visible accumulations of tracheal mucus. However, measurement of breathing zone particulate concentrations, which is the most accurate way to measure exposure, has not been performed to determine the relationship between exposures and accumulations of tracheal mucus sufficient to affect performance. Objective: To compare breathing zone particulate exposures between horses with tracheal mucus scores (MS) previously demonstrated to affect performance (MS≥2) and those without (MS = 0) visible t...
Nath L, Stent A, Elliott A, La Gerche A, Franklin S.Cardiac arrhythmias resulting in sudden cardiac death (SCD) are an important cause of racehorse fatalities. The objective of this study was to determine risk factors for SCD in Thoroughbreds by evaluating a sample with a policy of mandatory post-mortem following racing or training fatalities. Risk factors were compared between case horses with SCD (n = 57) and control horses with other fatal injury (OFI, n = 188) by univariable and multivariable logistic regression. Survival in years for horses with SCD was compared to OFI using the Kaplan−Meier method with log rank test. The following varia...
van Weeren PR, Firth EC, Brommer H, Hyttinen MM, Helminen AE, Rogers CW, Degroot J, Brama PA.Training at a very young age may influence the characteristics of the collagen network of articular cartilage extracellular matrix (ECM) in horses. Objective: To investigate whether increasing workload of foals results in significant changes in the biochemical composition of articular cartilage ECM. Methods: Thoroughbred foals (n = 33) were divided into 2 different exercise groups from age 10 days-18 months. One group (PASTEX; n = 15) was reared at pasture; the other (CONDEX; n = 18) underwent a specific additional training programme that increased workload by 30%. At mean age 18 months, 6 ani...
