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.
Bueno I, Pearce P, Dunowska M. To estimate the frequency of infection with equine herpesvirus type-1 (EHV-1) among horses from the central North Island of New Zealand, including the frequency of detection of the D genotype. Samples of retropharyngeal lymph nodes (RLN) and submandibular lymph nodes (SLN) were dissected from the heads of 63 horses that were humanely killed for various unrelated reasons between March and November 2015. DNA extracted from these tissues was subjected to enrichment for EHV-1 sequences by hybridisation with biotin-labelled EHV-1 specific probe, followed by recovery of EHV-1 sequences on streptavi...
Denham J, Stevenson K, Denham MM.Telomeres are genetically conserved repetitive terminal DNA that protect against genomic instability and shorten with ageing. Here, we reveal the leukocyte telomere length of Equus caballus by measuring terminal restriction fragments (TRFs) using Southern Blot analysis in a cohort of 43 Thoroughbred horses (age: 24 h-25 years). Heterogeneous TRFs were observed in each animal and large inter-animal variation in mean TRF was observed (range: 10.5-18.7 kbp). Mean TRFs were inversely correlated with age (r = -0.47). The estimated yearly rate of telomere attrition was 134 bp. Horses shoul...
Morrice-West AV, Hitchens PL, Walmsley EA, Stevenson MA, Whitton RC.Musculoskeletal injuries (MSI) in racehorses are commonly due to bone fatigue, a function of the number of cycles (strides) and the magnitude of load applied to the limb. These parameters can be estimated using speed and distance, with greater than 6000 m/month at a gallop (>14 m/s), in combination with canter distances greater than 44,000 m/month, reported to increase fracture risk. Despite their importance, there are limited data on the distances and speeds horses are exposed to during training. Objective: Estimate training volume at different speeds undertaken by Australian Thoroughbr...
Breuhaus BA.Certain breeds of horses may be genetically predisposed to developing insulin dysregulation, which is a risk factor for development of endocrinopathic laminitis in horses. This study was performed to test the hypotheses that Paso Fino horses exhibit evidence of insulin dysregulation compared with Thoroughbred horses and that obesity exaggerates the insulin dysregulation. Intravenous glucose tolerance tests were performed in 14 moderate-weight Thoroughbreds, 12 moderate-weight Paso Finos, and 12 overweight Paso Finos. Moderate Paso Finos had greater baseline serum insulin concentrations, area u...
Moyer CT, Bramlage LR, Werre SR, Ruggles A, Embertson R, Hopper S.To describe the presence of fragments in the dorsal proximal interphalangeal (PIP) joint and to report flat racing performance after surgical treatment. Methods: Retrospective study. Methods: Thirty-nine affected thoroughbred flat racehorses and 169 age- and sex-matched maternal siblings. Methods: Medical records from 2000 to 2015 were reviewed for thoroughbred horses that underwent arthroscopic removal of osteochondral fragments in the dorsal aspect of the PIP joint. The horses' 2-year-old year, 3-year-old year, and career athletic performances were compared with their matched siblings. Resul...
Self Davies ZT, Spence AJ, Wilson AM.The horse has evolved to gallop economically at high speed. Limb force increases with speed but direct measures of limb ground reaction forces (GRFs) at gallop are sparse. This study reports GRFs for multiple limbs, using force plates, across seven Thoroughbred racehorses during ridden galloping. The results show peak vertical GRF values of 13.6 N kg (non-lead hindlimb), 12.3 N kg (lead hindlimb), 14.0 N kg (non-lead forelimb) and 13.6 N kg (lead forelimb) at 11.4 m s and recorded values are consistent with those predicted from duty factor. The distribution of body weight b...
Baldwin CM, Smith MRW, Allen S, Wright IM.Slab fractures of the third carpal bone (C3) are a common injury of Thoroughbred racehorses. Results of arthroscopically guided repair have not been reported since the initial description of the technique in 1986. Additionally, fracture details and racing outcomes in a population of Thoroughbreds racing under UK jurisdiction have not previously been described. Objective: To report the frequency distribution of C3 slab fractures and to determine the impact on racing performance following arthroscopically guided repair in a population of Thoroughbred racehorses. Methods: Retrospective case serie...
Bayly W, Lopez C, Sides R, Bergsma G, Bergsma J, Gold J, Sellon D.Public pressure exists in the United States to eliminate race-day furosemide administration despite its efficacy in decreasing the severity of equine exercise pulmonary hemorrhage (EIPH). No effective alternative prophylaxis strategies have been identified. Objective: To investigate alternative protocols to race-day furosemide that might mitigate EIPH. Methods: Seven fit Thoroughbreds with recent EIPH. Methods: Double-blinded placebo-controlled Latin square crossover using a treadmill followed by a blinded placebo-controlled crossover study at a racetrack. First, horses exercised supramaximall...
Egan S, Brama P, McGrath D.Wearable sensing technologies are increasingly used in human and equine gait research to improve ecological validity of research findings. It is unclear how these tools have penetrated the equine industry or what perspectives industry stakeholders' hold in relation to these relatively new devices. Semi-structured interviews were conducted with Irish equine industry stakeholders to understand their perception of objective tools for biomechanical analysis in the field. The study participants came from professional/elite backgrounds in both the sport horse ( = 6) and thoroughbred ( = 6) sectors. ...
Musiał AD, Ropka-Molik K, Piórkowska K, Jaworska J, Stefaniuk-Szmukier M.In horses, the identification of the genetic background of phenotypic variation, especially with regard to performance characteristics and predisposition to effort, has been extensively studied. As α-actinin-3 function is related to the regulation of muscle contraction and cell metabolism, the ACTN3 gene is considered one of the main genetic factors determining muscle strength. The aim of the present study was to assess the genotype distribution of two SNP variants within the equine ACTN3 gene (g.1104G > A and c.2334C > T) across different utility types and horse breeds. The ana...
Petersen JL, Lewis RM, Embertson R, Valberg SJ, Holcombe SJ.Large colon volvulus (LCV) is a life-threatening form of colic that occurs when the large colon rotates 360° or more on its axis, resulting in colonic distention and ischaemia. Any horse can suffer from LCV, but the risk is greatest for periparturient Thoroughbred broodmares; the objective of this study was to estimate the heritability of LCV in these horses. The criteria for classification as an LCV case were being a Thoroughbred broodmare from one of three farms in central Kentucky and having had surgical correction for LCV. Controls were identified as Thoroughbred broodmares present on the...
Li CX, Chang WS, Mitsakos K, Rodger J, Holmes EC, Hudson BJ.Papillomaviruses (PVs) have been identified in a wide range of animal species and are associated with a variety of disease syndromes including classical papillomatosis, aural plaques, and genital papillomas. In horses, 13 PVs have been described to date, falling into six genera. Using total RNA sequencing (meta-transcriptomics) we identified a novel equine papillomavirus in semen taken from a thoroughbred stallion suffering a genital lesion, which was confirmed by nested RT-PCR. We designate this novel virus (EcPV9). The complete 7656 bp genome of EcPV9 exhibited similar characteristics to th...
Khummuang S, Lee HG, Joo SS, Park JW, Choi JY, Oh JH, Kim KH, Youn HH, Kim M, Cho BW.The study was conducted to investigate variations in the immunophysiological responses to exercise-induced stress in Jeju and Thoroughbred horses. Methods: Blood samples were collected from the jugular veins of adult Jeju (n = 5) and Thoroughbred (n = 5) horses before and after 30 min of exercise. The hematological, biochemical, and immunological profiles of the blood samples were analyzed. Blood smears were stained and observed under a microscope. The concentration of cell-free (cf) DNA in the plasma was determined using real time polymerase chain reaction (PCR). Peripheral blood mononuclear ...
Villarino NF, Lopez CM, Sams RA, Bayly WM.The primary objective of this study was to assess the disposition of furosemide in Thoroughbred horses treated intravenously with 1 mg/kg of furosemide 4 and 24 h before supramaximal treadmill exercise without and with controlled access to water, respectively. Another objective was to determine whether furosemide was detectable in the plasma of horses after exposure to supramaximal treadmill exercise. Thoroughbred horses (n = 4-6) were administered single intravenous doses of 1 mg/kg of furosemide at 4 and 24 h before supramaximal exercise on a high-speed treadmill, with controlled ...
Knych HK, Arthur RM, Kanarr KL, McKemie DS, Kass PH.Methamphetamine is a central and peripheral nervous system stimulant. There is only a single study that describes exposure to and disposition of this compound in horses. The potential for abuse and inadvertent exposure in equine athletes along with the limited data available necessitates further study. The objectives of the current study were to describe drug and metabolite concentrations, develop an analytical method that could be used to regulate its use, and describe selected pharmacodynamic effects. In phase 1, six horses were randomized into three transmucosal dose groups (n = 2/group; ...
Aouane N, Nasri A, Bekara MAA, Metref AK, Kaidi R.The Barb horse occupies a prominent place in the history, culture, and equestrian traditions of the Maghreb (Algeria, Morocco, and Tunisia). Although many studies on the breed standard and morphometry have been published, there are no studies on its fertility and reproductive potential. Thus, this work aimed to study the fertility of Barb, Arabian Purebred, and Thoroughbred horses in Algeria. Methods: A total of 168 stallions and 1202 mares at the Chaouchaoua Stud farm in Tiaret, Algeria, were included in the study. The reproductive performance during 1592 cycles over 10 consecutive mating sea...
Graham RJTY, Rosanowski SM, McILWRAITH CW.Osteochondral fragmentation of the carpus is a common cause of lameness in racehorses. Prognosis following arthroscopic removal of the fragments was reported in 1987, but little is known of recent success rates. Objective: To identify associations between the severity and location of osteochondral fragments in the carpus, and to describe the racing performance of horses pre- and post-surgery in Thoroughbreds and Quarter Horses. To identify factors associated with a horse racing post-surgery. Methods: Retrospective study of clinical records (2006-2016). Methods: Surgical and racing records for ...
Gürelli G, Lyons ET, Kesbiç FI.Species composition and distribution of hindgut ciliates were investigated in the feces of 20 thoroughbred mares in Kentucky, USA. Thirty-three species and six morphotypes belonging to 21 genera were identified. The average density of hindgut ciliates in mares was 13.5 ± 13.7 × 104 cells ml-1, whereas mean number of ciliate species per host was 14.4 ± 5.3. Bundleia nana, B. elongata, B. piriformis, Blepharoconus hemiciliatus, Holophryoides ovalis, H. macrotricha, Blepharoprosthium polytrichum, Prorodonopsis coli, Paraisotrichopsis composita, Blepharocorys microcorys, and Ochoterenaia append...
Fawcett JA, Sato F, Sakamoto T, Iwasaki WM, Tozaki T, Innan H.The domestication process of plants and animals typically involves intense inbreeding and directional selection for various traits. Here, we genotyped 370 Japanese Thoroughbred horses using the recently developed 670k SNP array and performed various genome-wide analysis also using genotype data of other horse breeds. We identified a number of regions showing interesting patterns of polymorphisms. For instance, the region containing the MC1R locus associated with chestnut coat color may have been targeted by selection for a different mutation much earlier on than the recent selection for chestn...
Parkes RSV, Weller R, Pfau T, Witte TH.Objective gait monitoring is increasingly accessible to trainers. A more comprehensive understanding of 'normal' gait adaptations is required. Forty two-year-old thoroughbred racehorses were recruited when entering training and followed for 22 months. Gait analysis was performed by equipping each horse with an inertial measurement unit with inbuilt GPS (GPS-IMU) mounted on the dorsum. Horses were exercised as per their regular training regimen. Data were analysed using a linear mixed model. For two-year-old horses, there was a non-linear pattern of stride duration (SD) over time ( < 0.001) ...
Miller S, Carstens A.Laryngoplasty is commonly used to treat laryngeal hemiplegia in Thoroughbred racehorses. Evaluation of the success of the laryngoplasty is traditionally determined using endoscopy. Laryngeal ultrasonography and normal ultrasonographic appearance have been reported in the standing horse, but post-laryngoplasty and ventriculectomy ultrasonographic evaluation has limited literature coverage. A prospective case series of 10 Thoroughbred racehorses with left laryngeal hemiplegia was examined ultrasonographically and endoscopically prior to 3-10 days, 30-50 days, and 6-12 months after laryngoplasty ...
Uchida-Fujii E, Niwa H, Kinoshita Y, Nukada T.Actinobacillus species are known to be pathogenic to horses. To clarify etiological agents of actinobacillosis in Japanese adult horses, 27 isolates from Japanese Thoroughbred racehorses putatively identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry as Actinobacillus were further identified by PCR of the A. equuli toxin gene, by CAMP test, and by 16S rRNA sequencing analysis. Actinobacillus equuli subsp. haemolyticus was isolated most frequently (16/27) and was related to respiratory infections. Actinobacillus equuli subsp. equuli (4/27) was isolated from...
MacFadyen AC, Waller AS, Paterson GK.Strain 28462T, which had Gram-stain-positive, catalase-negative coccus-shaped cells, was isolated from a routine tracheal sample from a 3 year old thoroughbred horse. 16S rRNA gene sequence analysis revealed it to be most closely related to, but distinct from, Streptococcus henryi (95.7 % identity), Streptococcusplurextorum (95.8 %), Streptococcusporci (96.4 %) and Streptococcus caprae (95.1 %). Similarity values derived from sequences from sodA and rpoB genes were consistent with strain 28462T belonging to a species distinct from these four streptococci. At the whole genome level, str...
Tozaki T, Kikuchi M, Kakoi H, Hirota K, Nagata S, Yamashita D, Ohnuma T, Takasu M, Kobayashi I, Hobo S, Manglai D, Petersen JL.Eight horse breeds-Hokkaido, Kiso, Misaki, Noma, Taishu, Tokara, Miyako and Yonaguni-are native to Japan. Although Japanese native breeds are believed to have originated from ancient Mongolian horses imported from the Korean Peninsula, the phylogenetic relationships among these breeds are not well elucidated. In the present study, we compared genetic diversity among 32 international horse breeds previously evaluated by the Equine Genetic Diversity Consortium, the eight Japanese native breeds and Japanese Thoroughbreds using genome-wide SNP genotype data. The proportion of polymorphic loci and ...
Pusterla N, Bowers J, Barnum S, Hall JA.The objective of this study was to detect Streptococcus equi subspecies equi (S. equi) (Lactobacillales: Streptococcaceae) using quantitative polymerase chain reaction (qPCR) in flies collected from a farm with a documented outbreak of strangles. A total of 1856 face flies [Musca autumnalis (Diptera: Muscidae)] were collected using conventional fly traps. The flies were processed for nucleic acid purification and tested for the presence of S. equi by qPCR. A total of 10/1856 flies (0.54%) tested qPCR-positive for S. equi. The results may implicate the presence of face flies as a risk factor...
Lee SK, Lee I.Twelve Thoroughbred racehorses were diagnosed as epiglottic entrapment at the Korea Racing Authority equine hospital. Four different surgical correction techniques were used to treat epiglottic entrapment: the transnasal hook bistoury, transoral unshielded hook bistoury, transnasal shielded hook bistoury, and transendoscopic laser techniques. Eleven cases were surgically resolved eventually, with one case of recurrence. Five complications related to surgical correction occurred: a severe nasal passage laceration and bleeding (n=1), epiglottic laceration (n=1), epiglottis tip burns (n=2), and m...
Nomura M, Shiose T, Ishikawa Y, Mizobe F, Sakai S, Kusano K.Despite growing recognition of post-race exertional heat illness (EHI) in the horse racing industry, reports on its prevalence are limited. The purpose of this study was to investigate the prevalence of post-race EHI and climate conditions at racecourses in Japan. The overall prevalence of EHI from 1999 to 2018 was 0.04% (387 cases for 975,247 starters) in races operated by the Japan Racing Association (JRA). The yearly prevalence has been increasing, exceeding 0.07% in the last four years of the studied period. The overall prevalence in summer (May-September) was 0.086% (352 cases for 409,908...
Latham CM, Fenger CK, White SH.Responses of equine skeletal muscle characteristics to growth and training have been shown to differ between breeds. These differential responses may arise in part because muscle fiber type and mitochondrial density differ between breeds, even in untrained racing-bred horses. However, it is not known when these breed-specific differences manifest. To test the hypothesis that weanling Standardbreds (SB) and Thoroughbreds (TB) would have higher mitochondrial measures than Quarter Horses (QH), gluteus medius samples were collected from SB (mean ± SD; 6.2 ± 1.0 mo; n = 10), TB (6.1 ± 0.5 mo; n ...
Tokushige H, Araki M, Kusano K, Arima D, Ito H, Yamazaki Y, Urayama S, Kambayashi Y, Tateno O, Ohta M.This study compares clinical characteristics between induction with thiopental/guaifenesin and propofol/ketamine in Thoroughbred racehorses anesthetized with sevoflurane and medetomidine. Clinical records of 214 horses that underwent arthroscopic surgery between 2015 and 2016 were retrospectively retrieved. Horses were premedicated with medetomidine and midazolam to sedate at the adequate level for smooth induction, and then induced with either thiopental (4.0 mg/kg) and guaifenesin (100 mg/kg) in Group TG (n=91) or propofol (1.0 mg/kg) and ketamine (1.0 mg/kg) in Group PK (n=123). Anesthesia ...
Janczarek I, Stachurska A, Kędzierski W, Wiśniewska A, Ryżak M, Kozioł A.Predatory attacks on horses can become a problem in some parts of the world, particularly when considering the recovering gray wolf populations. The issue studied was whether horses transformed by humans and placed in stable-pasture environments had retained their natural abilities to respond to predation risk. The objective of the study was to determine the changes in cardiac activity, cortisol concentrations, and behavior of horses in response to the vocalizations of two predators: the gray wolf (Canis lupus), which the horses of the breed studied had coevolved with but not been exposed to r...
Bentley VA, Sample SJ, Livesey MA, Scollay MC, Radtke CL, Frank JD, Kalscheur VL, Muir P.Failure of functional adaptation to protect the skeleton from damage is common and is often associated with targeted remodeling of bone microdamage. Horses provide a suitable model for studying loading-related skeletal disease because horses are physically active, their exercise is usually regulated, and adaptive failure of various skeletal sites is common. We performed a histologic study of the navicular bone of three groups of horses: (1) young racing Thoroughbreds (n = 10); (2) young unshod ponies (n = 10); and (3) older horses with navicular syndrome (n = 6). Navicular syndrome is a painfu...
Alford P, Geller S, Richrdson B, Slater M, Honnas C, Foreman J, Robinson J, Messer M, Roberts M, Goble D, Hood D, Chaffin M.Risk factors for equine laminitis were examined in a prospective case-control study of the 258 cases seen at six collaborating veterinary teaching hospitals over a 32-month period. Case-control pairs were matched on institution, clinician, and season of diagnosis. The 90% of case-control pairs (78 acute, 155 chronic) that had complete data for age, gender, and breed were used in separate conditional logistic-regression models for acute and chronic laminitis. There was an increase in risk for horses with acute laminitis from 5 to 7 years of age (OR 4.7, 95% CI 1.3-16) and from 13 to 31 years of...
Knubben JM, Furst A, Gygax L, Staﾬher M.Studies on the prevalence and predisposing factors of bite and kick injuries in horses have not been reported in a population-based data sample. Objective: To investigate the prevalence of bite and kick injuries in horses and associated risk factors in a representative sample of horses in Switzerland. Methods: A questionnaire on the incidence of disease and injury, which included the frequency of bite and kick injuries and their association with breed, housing, use and feeding regime, was sent to 2559 horse owners randomly selected throughout Switzerland. Results: The data of 2912 horses with ...
Mader DR, Price EO.The discrimination learning ability of Quarter Horses and Thoroughbreds was compared by means of visual cues in a three-choice test with food as a reward. Quarter Horses learned significantly faster than Thoroughbreds, and learning progressed more rapidly for both breeds in a second discrimination task. Significant negative correlations were observed between age and rate of learning. Quarter Horses tended to be less reactive than Thoroughbreds, but individual emotional reactivity ratings and learning scores were not correlated. No correlation was found between social dominance and learning sco...
Martig S, Hitchens PL, Lee PVS, Whitton RC.Subchondral bone injuries often precede articular cartilage damage in osteoarthritis and are common in thoroughbred racehorses due to the accumulation of fatigue damage from high speed racing and training. Thus, racehorses provide a model to investigate the role of subchondral bone in joint disease. We assessed the association of horse and racing related factors and micro-CT based micromorphology of three separate subchondral bone layers with the initial stiffness and compressive fatigue life of bone plugs. Furthermore, we investigated three different definitions of fatigue failure of subchond...
Farries G, McGettigan PA, Gough KF, McGivney BA, MacHugh DE, Katz LM, Hill EW.Adaptation to early training and racing (i.e. precocity), which is highly variable in racing Thoroughbreds, has implications for the selection and training of horses. We hypothesised that precocity in Thoroughbred racehorses is heritable. Age at first sprint training session (work day), age at first race and age at best race were used as phenotypes to quantify precocity. Using high-density SNP array data, additive SNP heritability (hSNP2) was estimated to be 0.17, 0.14 and 0.17 for the three traits respectively. In genome-wide association studies (GWAS) for age at first race and age at best ra...
Birks EK, Mathieu-Costello O, Fu Z, Tyler WS, West JB.Thoroughbred horses develop extremely high pulmonary vascular pressures during galloping, all horses in training develop exercise-induced pulmonary hemorrhage, and we have shown that this is caused by stress failure of pulmonary capillaries. It is known that the capillary transmural pressure (Ptm) necessary for stress failure is higher in dogs than in rabbits. The present study was designed to determine this value in horses. The lungs from 15 Thoroughbred horses were perfused with autologous blood at Ptm values (midlung) of 25, 50, 75, 100 and 150 mmHg, and then perfusion fixed, and samples (d...
Allen WR, Wilsher S, Tiplady C, Butterfield RM.The growth parameters exhibited by seven Thoroughbred (Tb) foals that had experienced a 'restricted' in utero existence following transfer as embryos to the uteri of smaller Pony (P) mares (Tb-in-P) and, conversely, six P foals that experienced a 'luxurious' in utero existence after transfer to larger Tb mares (P-in-Tb), were compared from birth to 3 years of age with those exhibited by six normal Tb-in-Tb and six P-in-P foals conceived by within-breed artificial insemination. Bodyweight, height at the withers, girth, poll-to-nose length, crown-rump length and three foreleg longbone measuremen...
Lopez Sanchez CM, Kogan C, Gold JR, Sellon DC, Bayly WM.Exercise-induced pulmonary hemorrhage (EIPH) is diagnosed and its severity assessed by post-exercise tracheobronchoscopy, and enumeration of bronchoalveolar lavage fluid red blood cells (BALFRBC). Minimal information is available regarding the relationship of tracheobronchoscopy score to BALFRBC number. Objective: Evaluate the relationship between BALFRBC number and tracheobronchoscopy scores and determine their diagnostic sensitivities. Methods: Nine sedentary horses, 21 fit Thoroughbreds, 129 Barrel Racers. Methods: Normal BALFRBC number and the effect of bronchoalveolar lavage (BAL) on it w...
Parkes RS, Richard Newton J, Dyson SJ.Lameness relating to the foot of the horse is common, but the majority of information concerning risk factors for injury is anecdotal. The objectives of this study were to investigate risk factors for foot-related pain in a referral population of horses, with particular reference to injury/disease of the podotrochlear apparatus (PTA), by comparison with the remainder of the clinic population. It was hypothesised that there would be an increased risk of foot pain associated with breed, work discipline, age, height and bodyweight (BW). A retrospective study of all horses examined at a referral c...
Bleumink-Pluym N, ter Laak EA, van der Zeijst BA.Contagious equine metritis (CEM), a sexually transmitted bacterial disease, was first described in thoroughbred horses. It also occurs in nonthoroughbred horses, in which it produces isolated, apparently unrelated outbreaks. Thirty-two strains of Taylorella equigenitalis, the causative agent of CEM, from all over the world were characterized by field inversion gel electrophoresis of fragments of genomic DNA obtained by digestion with low-cleavage-frequency restriction enzymes. This resulted in a division into five clearly distinct groups. Strains from thoroughbred horses from all continents be...
Hirota K, Kakoi H, Gawahara H, Hasegawa T, Tozaki T.We characterized the SNP 53 JPN System for parentage verification during horse registry. The SNP 53 JPN System was constructed using 53 highly polymorphic single nucleotide polymorphisms (SNPs), which were amplified and genotyped with 2 multiplex assays. The SNP 53 JPN System showed good resolution for 95 unrelated thoroughbreds, and the exclusion probability (PE01) for each SNP ranged from 11.5 to 23.0%, resulting in a total PE01 value of 99.996%. These results indicate that the SNP 53 JPN System is useful for parentage testing of thoroughbreds. Of the 53 SNPs, 8 SNPs could be used to exclude...
Kane AJ, Stover SM, Gardner IA, Case JT, Johnson BJ, Read DH, Ardans AA.To evaluate selected shoe characteristics as risk factors for fatal musculoskeletal injury (FMI) and specifically for suspensory apparatus failure (SAF) and cannon bone condylar fracture (CDY) of Thoroughbred racehorses in California. Methods: Case-control study. Methods: Thoroughbred racehorses (n = 201) that died of were euthanatized at California racetracks between August 1992 and July 1994. Methods: Shoe characteristics were compared between case horses affected by FMI (155), SAF (79), and CDY (41) and control horses that died for reasons unrelated to the appendicular musculoskeletal syste...
Cohen ND, Mundy GD, Peloso JG, Carey VJ, Amend NK.To estimate the relative risk of injury among horses deemed to be at increased risk of injury on the basis of prerace physical inspection findings and to examine the association of injury during races with race-related characteristics. Methods: Cohort study. Methods: 2,187 Thoroughbred horses that started 3,227 races in Kentucky. Methods: All race starts for which a horse was deemed to be at increased risk of injury on the basis of prerace physical inspection findings and a random sample of race starts for which horses were not deemed at increased risk of injury were included in the study. Fin...
Kydd JH, Case R, Winton C, MacRae S, Sharp E, Ricketts SL, Rash N, Newton JR.Identification of risk factors which are associated with severe clinical signs can assist in the management of disease outbreaks and indicate future research areas. Pregnancy loss during late gestation in the mare compromises welfare, reduces fecundity and has financial implications for horse owners. This retrospective study focussed on the identification of risk factors associated with pregnancy loss among 46 Thoroughbred mares on a single British stud farm, with some but not all losses involving equid herpesvirus-1 (EHV-1) infection. In a sub-group of 30 mares, association between pregnancy ...
Menzies-Gow NJ.Eight normal thoroughbred horses were examined by echocardiography before and 10 minutes after they had been sedated by the intravenous administration of 0.03 mg/kg acepromazine. There were significant (P<0.025) increases in the diameters of the pulmonary artery and the aorta, measured at end-systole, and in the thickness of the interventricular septum, measured at end-systole and end-diastole. In addition, there was a significant (P<0.001) decrease in the diameter of the left atrium measured at end-diastole. The remaining cardiac dimensions, all the indices of cardiac function, and the ...
Noble P, Singer ER, Jeffery NS.Sagittal fractures of the first phalanx are a common, potentially catastrophic injury in racehorses. These fractures are often linked to an acute, one time, biomechanical event; however, recent evidence implies that chronic exposure to stress can lead to the accumulation of bony changes that affect the structural integrity of the bone and increase the likelihood of fracture. The aim of the study was to compare variations of two common metrics of bone adaptation - subchondral bone density and thickness across the proximal articular surface of the first phalanx in Thoroughbred horses that (1) ra...
Sp N, Kang DY, Kim DH, Lee HG, Park YM, Kim IH, Lee HK, Cho BW, Jang KJ, Yang YM.Cortisol is a hormone involved in stress during exercise. The application of natural compounds is a new potential approach for controlling cortisol-induced stress. Tumour suppressor protein p53 is activated during cellular stress. Succinate dehydrogenase complex subunit A () and hypoxanthine phosphoribosyl transferase 1 () are considered to be two of the most stable reference genes when measuring stress during exercise in horses. In the present study cells were considered to be in a 'stressed state' if the levels of these stable genes and the highly stress responsive gene p53 were altered. It ...
Brama PA, Holopainen J, van Weeren PR, Firth EC, Helminen HJ, Hyttinen MM.There is ample evidence on topographical heterogeneity of the principal biochemical components of articular cartilage over the surface of the joint and the influence of loading thereon, but no information on depth-related zonal variation in horses. Objective: To study depth-related zonal variation in proteoglycan (PG) and collagen content in equine articular cartilage. Methods: Two techniques (safranin-O densitometry and Fourier transform infrared spectroscopy) were applied to sections of articular cartilage from the proximal phalangeal bone of the metacarpophalangeal joint of 18-month-old Tho...
Baguelin M, Newton JR, Demiris N, Daly J, Mumford JA, Wood JL.We present a metapopulation model of the spread of equine influenza among thoroughbred horses parametrized with data from a 2003 outbreak in Newmarket, UK. The number of horses initially susceptible is derived from a threshold theorem and a published statistical model. Two simulated likelihood-based methods are used to find the within- and between-yard transmissions using both exponential and empirical latent and infectious periods. We demonstrate that the 2003 outbreak was largely locally driven and use the parametrized model to address important questions of control. The chance of a large ep...
Chen CL, Riley AM.Serum thyroxine (T-4) and triiodothyronine (T-3) concentrations were assayed in neonatal foals (1.5 to 4 months) and mature horses (2 to 25 years old) by a modified radioimmunoassay procedure. Blood was collected from 52 clinically healthy foals and horses of various breeds (Thoroughbreds, Quarter Horses, American Saddle Horses, and a single cross-bred horse). Neonatal foals had high serum concentrations of T-4 (mean, 4.02 microgram/dl) and T-3 (192.9 ng/dl) as compared with the values in mature horses (T-4, mean of 1.76 microgram/dl; T-3, mean of 98.69 ng/dl). Stallions had slightly higher T-...
Hori Y, Tozaki T, Nambo Y, Sato F, Ishimaru M, Inoue-Murayama M, Fujita K.Tractability, or how easily animals can be trained and controlled, is an important behavioural trait for the management and training of domestic animals, but its genetic basis remains unclear. Polymorphisms in the serotonin receptor 1A gene (HTR1A) have been associated with individual variability in anxiety-related traits in several species. In this study, we examined the association between HTR1A polymorphisms and tractability in Thoroughbred horses. We assessed the tractability of 167 one-year-old horses reared at a training centre for racehorses using a questionnaire consisting of 17 items....
Allen WR, Wilsher S, Stewart F, Stewart F, Ousey J, Ousey J, Fowden A.Within-breed artificial insemination and between-breed embryo transfer were carried out in small pony (P) and large Thoroughbred (Tb) mares to create 4 types of horse pregnancy in which the fetus experienced spatial and nutritional deprivation (Tb-in-P; n=8), luxury (P-in-Tb; n=7) or normality (Tb-in-Tb; n=7 and P-in-P; n=7) in utero. Measurement of equine chorionic gonadotrophin (eCG), total conjugated oestrogens and progestagen concentrations in serial peripheral serum samples recovered from all the mares throughout gestation showed that the amount of eCG produced during the first half of ge...
Young LE, Wood JL.Cardiac auscultation was carried out on 111 Thoroughbred horses age 2-5 years to test the hypothesis that athletic training might influence the development of atrioventricular (AV) valve regurgitation in young Thoroughbreds. Murmurs of valvular regurgitation were identified and graded on a 1-6 scale. There were 2 sources of auscultation data: 1) 55 2-year-old horses that were examined by auscultation before training commenced and 9 months later when at race fitness; 2) 56 horses age 2-5 years that were examined on one occasion only (25 2-year-olds, 23 3-year-olds, five 4-year-olds and five 5-y...
Parsons KJ, Pfau T, Wilson AM.During locomotion up an incline, power is required to elevate the centre of mass. This is provided when the animal's limbs are in contact with the ground. Measurements of stride timing variables from multiple limbs during high speed, over-ground locomotion would enhance our understanding of locomotor powering during changes in terrain. This study measured foot-on and foot-off times from galloping horses using a previously validated system of limb-mounted accelerometers and a global positioning system data logger. A detailed track survey provided incline information from all areas of the track....
Li R, Liu DH, Cao CN, Wang SQ, Dang RH, Lan XY, Chen H, Zhang T, Liu WJ, Lei CZ.The myostatin gene (MSTN) is a genetic determinant of skeletal muscle growth. Single nucleotide polymorphisms (SNP) in MSTN are of importance due to their strong associations with horse racing performances. In this study, we screened the SNPs in MSTN gene in 514 horses from 15 Chinese horse breeds. Six SNPs (g.26T>C, g.156T>C, g.587A>G, g.598C>T, g.1485C>T, g.2115A>G) in MSTN gene were detected by sequencing and genotyped using PCR-RFLP method. The g.587A>G and g.598C>T residing in the 5'UTR region were novel SNPs identified by this study. The g.2115A>G which have pr...
Knych HK, Vidal MA, Casbeer HC, McKemie DS.The use of triamcinolone acetonide (TA) in performance horses necessitates establishing appropriate withdrawal times prior to performance. Objective: To describe the plasma pharmacokinetics of TA and time-related urine and synovial fluid concentrations following i.m. and intra-articular administration to exercised Thoroughbred horses. Methods: Block design. Methods: Twelve racing fit adult Thoroughbred horses received a single i.m. administration of TA (0.1 mg/kg bwt). After an appropriate washout period, the same horses then received a single intra-articular TA administration (9 mg) into the ...
Marsh AE, Johnson PJ, Ramos-Vara J, Johnson GC.Little information is available about antigenic variation of Sarcocystis neurona isolated from horses with equine protozoal myeloencephalitis, nor is there much information available on the specific antibody pattern to S. neurona antigens of horses from different geographic regions where S. neurona isolates have been obtained. This communication reports on the characterization of a new S. neurona isolate, SN-MU1. The isolate was obtained from a 3-year old Thoroughbred that had asymmetrical neurological signs and localized skeletal muscle atrophy. This S. neurona isolate is similar to other S. ...
McLellan J, Plevin S.Sesamoiditis is believed to be associated with injury to the suspensory branch attachment and is a common radiographic finding in yearling Thoroughbreds. No study has investigated relationships between yearling sesamoiditis and subsequent development of suspensory ligament branch injury (SLBI) in early racehorse training. Objective: To establish the prevalence of SLBI within a population of juvenile training racehorses and retrospectively investigate relationships between clinical signs of SLBI and sesamoiditis to determine if sesamoiditis is a risk factor for clinical suspensory branch injury...
