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.
Bohák Z, Szenci O, Harnos A, Kutasi O, Kovács L.Temperament has not been taken into account in previous studies evaluating the stress response to exercise in horses. The aim of the present study was to investigate the cortisol response in Thoroughbred racehorses to a single exercise bout, and to analyse the results based on the basic personality of the horse examined. Twenty healthy Thoroughbred horses were selected for the study based on a 25-item rating questionnaire survey used for characterising equine temperament. Eight temperamental and twelve calm horses took part in the experiment. The horses trotted as a warm-up activity, and then ...
Lee W, Park KD, Taye M, Lee C, Kim H, Lee HK, Shin D.This study was intended to identify genes positively selected in Thoroughbred horses (THBs) that potentially contribute to their running performances. Methods: The genomes of THB and Jeju horses (JH, Korean native horse) were compared to identify genes positively selected in THB. We performed cross-population extended haplotype homozygosity (XP-EHH) and cross-population composite likelihood ratio test (XP-CLR) statistical methods for our analysis using whole genome resequencing data of 14 THB and 6 JH. Results: We identified 98 (XP-EHH) and 200 (XP-CLR) genes that are under positive selection ...
Miyakoshi D, Sato F, Murase H, Inoue Y, Shikichi M, Iwata K, Okai K, Ito K, Nambo Y.The purpose of this study was to evaluate foaling rates of mares that were rebred after the pregnancy loss in same reproductive season and to examine factors influencing them in Hidaka, Japan. The study included 82 Thoroughbred mares that had experienced pregnancy loss. The foaling rate of the mares that were rebred after pregnancy loss was 57.3%. The foaling rate decreased as the period until detection of pregnancy loss increased. Aging and lower body condition score of mares decreased the foaling rate.
Mizobe F, Wakuno A, Okada J, Otsuka T, Ishikawa Y, Kurimoto S.A total of 20 racehorses with longitudinal fractures underwent internal fixation surgery under sevoflurane anesthesia combined with infusion of medetomidine (3 µg/kg/hr) alone (10 horses, group M) or medetomidine and fentanyl (7 µg/kg/hr) (10 horses, group FM). In group FM, the end-tidal sevoflurane concentration during surgery was maintained significantly lower than in group M (2.8-2.9% for group M vs. 2.2-2.6% for group FM, P<0.01). The mean arterial blood pressure was maintained over 70 mmHg using dobutamine infusion (group M, 0.36-0.54 µg/kg/min; group FM, 0.27-0.65 µg/kg/min), and ...
Clothier J, Hinch G, Brown W, Small A.Clear definitions of 'normal' equine gestation length (GL) are elusive, with GL being subject to a considerable number of internal and external variables that have confounded interpretation and estimation of GL for over 50 years. Consequently, the mean GL of 340 days first established by Rossdale in 1967 for Thoroughbred horses in northern Europe continues to be the benchmark value referenced by veterinarians, breeders and researchers worldwide. Application of a 95% confidence limit to reported GL range values indicates a possible connection between geographic location and GL. Improved kno...
Tozaki T, Kikuchi M, Kakoi H, Hirota KI, Nagata SI.Body weight is an important trait to confirm growth and development in humans and animals. In Thoroughbred racehorses, it is measured in the postnatal, training, and racing periods to evaluate growth and training degrees. The body weight of mature Thoroughbred racehorses generally ranges from 400 to 600 kg, and this broad range is likely influenced by environmental and genetic factors. Therefore, a genome-wide association study (GWAS) using the Equine SNP70 BeadChip was performed to identify the genomic regions associated with body weight in Japanese Thoroughbred racehorses using 851 individua...
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...
Alzola Domingo R, Riggs CM, Gardner DS, Freeman SL.Superficial digital flexor tendon (SDFT) tendinopathy is an important musculoskeletal problem in horses. The study objective was to validate an ultrasonographic scoring system for SDFT injuries. Ultrasonographic images from 14 Thoroughbred racehorses with SDFT lesions (seven core; seven diffuse) and two controls were blindly assessed by five clinicians on two occasions. Ultrasonographic parameters evaluated were: type and extent of the injury, location, echogenicity, cross-sectional area and longitudinal fibre pattern of the maximal injury zone (MIZ). Inter-rater variability and intra-rater re...
Wilson G, Lucas D, Hambly C, Speakman JR, Morton JP, Close GL.To formulate individualized dietary strategies for jockeys, it is vital that energy requirements are quantified. We measured total energy expenditure (TEE) over two separate weeks in spring and summer using doubly labelled water in a group of male flat jockeys (n = 8, 36.9 ± 5.7 years, 164 ± 8 cm, 54.6 ± 2.5 kg). Total energy intake (TEI) was self-recorded, as were all riding and structured exercise activity. Mean daily TEE was 10.83 (±2.3) and 10.66 (±1.76) MJ, (p = .61) respectively. Self-reported TEI were 6.03 (±1.7) and 5.37 (±1.1) MJ (p = .40), respectiv...
Rooney MF, Porter RK, Katz LM, Hill EW.Variation in the myostatin (MSTN) gene has been reported to be associated with race distance, body composition and skeletal muscle fibre composition in the horse. The aim of the present study was to test the hypothesis that MSTN variation influences mitochondrial phenotypes in equine skeletal muscle. Mitochondrial abundance and skeletal muscle fibre types were measured in whole muscle biopsies from the gluteus medius of n = 82 untrained (21 ± 3 months) Thoroughbred horses. Skeletal muscle fibre type proportions were significantly (p < 0.01) different among the three MSTN genotypes and mito...
Shields E, Seiden-Long I, Massie S, Leguillette R.A "high-sensitivity" cardiac troponin-T (hscTnT) assay recently has been validated for use in horses and is a specific biomarker of myocardial damage. Postexercise release kinetics of cTnT utilizing the hscTnT assay have yet to be established in horses. Objective: To determine: (1) cTnT release kinetics in racing Thoroughbreds after a high-intensity 5/8th mile Chuckwagon race; (2) the effects of age on pre- and postrace cTnT concentrations; and (3) sampling guidelines for clinicians evaluating horses presenting after exercise. Methods: Samples were obtained from 38 Thoroughbred geldings aged 5...
McGivney BA, Griffin ME, Gough KF, McGivney CL, Browne JA, Hill EW, Katz LM.Circulating miRNAs (ci-miRNAs) are endogenous, non-coding RNAs emerging as potential diagnostic biomarkers. Equine miRNAs have been previously identified including subsets of tissue-specific miRNAs. In order to investigate ci-miRNAs as diagnostic tools, normal patterns of expression for different scenarios including responses to exercise need to be identified. Human studies have demonstrated that many ci-miRNAs are up-regulated following exercise with changes in expression patterns in skeletal muscle. However, technical challenges such as haemolysis impact on accurate plasma ci-miRNA quantific...
Knych HK, Harrison L, Chouicha N, Kass PH.Intra-articular use of corticosteroids is commonplace in performance horses. Isoflupredone acetate (IPA) is one of four Food and Drug Administration approved corticosteroids for intra-articular use in horses. The lack of published reports describing the efficacy and duration of effects of this drug warrant further study. Objective: To assess the effects of intra-articular administration of IPA on the expression of selected anti- and pro-inflammatory and structural matrix genes following intra-articular administration to exercised Thoroughbred horses and to correlate these effects with drug con...
Hillyer LL, Ridd Z, Fenwick S, Hincks P, Paine SW.While cobalt is an essential micronutrient for vitamin B synthesis in the horse, at supraphysiological concentrations, it has been shown to enhance performance in human subjects and rats, and there is evidence that its administration in high doses to horses poses a welfare threat. Animal sport regulators currently control cobalt abuse via international race day thresholds, but this work was initiated to explore means of potentially adding to application of those thresholds since cobalt may be present in physiological concentrations. Objective: To devise a scientific basis for differentiation b...
Rose BV, Firth M, Morris B, Roach JM, Wathes DC, Verheyen KLP, de Mestre AM.Therapeutic practices in equine reproductive medicine have dramatically evolved over the last 20 years but current usage is not described. The aims of this study were to provide a description of medication use and clinical findings of reproductive examinations alongside measures of reproductive efficiency in thoroughbreds. A prospective cohort study was conducted in the 2013 and 2014 breeding seasons. Mare and stallion details, information on veterinary interventions and findings of reproductive ultrasound scans were collected using questionnaires and entered into a custom-designed Microsoft A...
Martel G, Crowley D, Olive J, Halley J, Laverty S.Extensive osteochondritis dissecans (OCD) lesions of the lateral ridge of the trochlea of the femur (LRTF), the most common OCD-affected site in the stifle, have a poor outcome with surgical debridement and can be career ending. The early detection of osteochondrosis lesions and their conservative management holds the promise to enhance outcome. We hypothesise that ultrasonography is a valuable field screening tool to detect and monitor early subclinical LRTF osteochondrosis. Objective: The goals were to 1) describe the normal ultrasonographic features of the LRTF in foals of different ages an...
Knych HK, Wilson WD, Vale A, Kass PH, Arthur RM, Jones JH.Due to the high prevalence of EIPH in racehorses and its potential impact on the horse's health, furosemide administration is permitted up to 4-h prior to post time in most North American racing jurisdictions. Anecdotal reports suggest that administration of furosemide 24-h prior to strenuous exercise may be equally effective in decreasing the severity of EIPH. Objective: To 1) compare the efficacy of furosemide in reducing the presence and severity of EIPH when administered 4- or 24-h prior to strenuous exercise 2) characterise electrolyte and blood parameters following administration of furo...
Allen WR, Wilsher S.Over the past 50 years, per season pregnancy rate in Thoroughbred mares have risen from 70 to >90% and foaling rates from 55 to >80%. Some of the significant pharmacological treatments and diagnostic methods which have driven this marked improvement in breeding efficiency are reviewed. They include the application of artificial lighting to hasten the onset of ovulatory oestrous cyclicity in early Spring, rapid steroid hormone assays to aid in determining the stage and normality of the mare's cycle, prostaglandin analogues, synthetic progestagens and Gonadotrophin-releasing Hormone (GnRH) anal...
Zakrajsek E.A recently purchased 16-year-old Thoroughbred mare with a history of recurrent colic and low body weight, also had lameness in 3 limbs, pain at the sacro-iliac joint, and increased corneal opacity of the right eye. Response to supportive therapy was poor and euthanasia was elected. A postmortem examination and histopathology confirmed cyathostomiasis within the large colon and cecum and chronic anterior uveitis of the right eye. Une jument Thoroughbred, âgée de 16 ans et récemment achetée, avec une anamnèse de coliques récurrentes et de faible poids corporel souffrait aussi de boiterie ...
Jacob SI, Geor RJ, Weber PSD, Harris PA, McCue ME.Diagnosis of equine pituitary pars intermedia dysfunction (PPID) remains a challenge as multiple factors (stress, exercise, and time of year) influence ACTH and cortisol concentrations. To assess endocrine status in a study designed to evaluate the effects of age and diet on glucose and insulin dynamics, we performed thyrotropin-releasing hormone (TRH) stimulation tests and overnight dexamethasone suppression tests in March, May, August, and October on 16 healthy Thoroughbred and Standardbred mares and geldings. Horses were grouped by age: adult (mean ± SD; 8.8 ± 2.9 yr; n = 8) and aged (20...
Al-Haidar A, Moula N, Leroux A, Farnir F, Deleuze S, Sandersen C, Amory H.The aim of this study was to establish echocardiographic reference values for the equine species using allometric regression equations based on body weight (BW) and thoracic circumference (TC). Methods: A total of 239 horses or ponies were studied, including 65 warmbloods, 33 Standardbreds, 41 Thoroughbreds, 32 Arabian horses, 28 draft horses, and 40 ponies aged from 1 day to 30 years, weighing from 18 to 890 kg, with no evidence of cardiac disease. Methods: For each horse or pony, a two-dimensional and M-mode echocardiography was performed. Within each breed, the relationships between BW or ...
Siwinska N, Zak A, Baron M, Cylna M, Borowicz H.The aim of this study was to determine the normal location, wall thickness and motility of the right dorsal colon in adult ponies and miniature horses. The abdominal ultrasonography examination was performed in a study group consisting of 23 ponies and miniature horses and in a control group comprising ten Thoroughbred horses. The procedure was performed in unsedated standing animals. The location and the thickness of the right dorsal colonic wall was examined on the right side of the abdomen between the 10th and the 14th intercostal space. The contractility was recorded in the 12th intercosta...
Aoki M, Wakuno A, Kushiro A, Mae N, Kakizaki M, Nagata SI, Ohta M.Anesthetic and cardiorespiratory effects of total intravenous anesthesia (TIVA) technique using propofol-guaifenesin-medetomidine (PGM) and alfaxalone-guaifenesin-medetomidine (AGM) were preliminarily evaluated in Thoroughbred horses undergoing castration. Twelve male Thoroughbred horses were assigned randomly into two groups. After premedication with intravenous (IV) administrations of medetomidine (5.0 µg/kg) and butorphanol (0.02 mg/kg), anesthesia was induced with guaifenesin (10 mg/kg IV), followed by either propofol (2.0 mg/kg IV) (group PGM: n=6) or alfaxalone (1.0 mg/kg IV) (group AGM...
Knych HK, Vale A, Wilson WD, Kass PH, Arthur RM, Jones JH.Furosemide is a diuretic agent used commonly in racehorses to attenuate the bleeding associated with exercise-induced pulmonary hemorrhage (EIPH). The current study describes serum and urine concentrations and the pharmacokinetics of furosemide following administration at 4 and 24 hrs prior to maximal exercise. Eight exercised adult Thoroughbred horses received a single IV administration of 250 mg of furosemide at 4 and 24 hrs prior to maximal exercise on a high-speed treadmill. Blood and urine samples were collected at time 0 and at various times for up to 72 hrs and furosemide concentrat...
Miyata H, Itoh R, Sato F, Takebe N, Hada T, Tozaki T.Variants of the Myostatin gene have been shown to have an influence on muscle hypertrophy phenotypes in a wide range of mammalian species. Recently, a Thoroughbred horse with a C-Allele at the g.66493737C/T single-nucleotide polymorphism (SNP) has been reported to be suited to short-distance racing. In this study, we examined the effect of the Myostatin SNP on muscle fiber properties in young Thoroughbred horses during a training period. To investigate the effect of the Myostatin SNP on muscle fiber before training, several mRNA expressions were relatively quantified in biopsy samples from the...
Gim JA, Kim HS.Endogenous retroviruses (ERVs) have been integrated into vertebrate genomes and have momentously affected host organisms. Horses () have been domesticated and selected for elite racing ability over centuries. ERVs played an important role in the evolutionary diversification of the horse genome. In the present study, we identified six equine ERV families (EqERVs-E1, I1, M2, P1, S1, and Y4), their full-length viral open reading frames (ORFs), and elucidated their phylogenetic relationships. The divergence time of EqERV families assuming an evolutionary rate of 0.2%/Myr indicated that EqERV-S3 (7...
Rosanowski SM, Chang YM, Stirk AJ, Verheyen KLP.The incidence of race-day injuries in Great Britain (GB) is higher on all-weather (AW) surfaces than on turf. However, to date no studies have focused on identifying risk factors for injury specific to AW racing. Therefore, the objective of the current study was to determine risk factors for fatality, distal limb fracture (DLF) and episodes of epistaxis in flat racing Thoroughbreds racing on AW surfaces in GB. Data included all flat racing starts on AW surfaces (n=258,193) and race-day veterinary events recorded between 2000 and 2013. Information on additional course-level variables was gather...
Rosanowski SM, MacEoin F, Graham RJTY, Riggs CM.Complications following open standing castration (OSC) in Thoroughbred racehorses are well recognised but variation in their prevalence and severity between populations is not well documented. Objective: To describe the prevalence and severity of complications in the 30 days following OSC. Methods: A retrospective cohort study of veterinary clinical records relating to horses that underwent OSC between July 2007 and July 2012. Methods: Complications were graded on a severity score from N, no complications, to C3, severe complications. Additional data were accessed for each horse including age,...
Miyakoshi D, Senba H, Shikichi M, Maeda M, Shibata R, Misumi K.This study aimed to evaluate whether radiographic abnormalities at yearling sales were associated with the failure to start racing at 2-3 years of age. Radiographic abnormalities in the carpal (n=852), tarsal (n=976), metacarpophalangeal (n=1,055), and metatarsophalangeal joints (n=1,031) from 1,082 horses, recorded at yearling sale, were reviewed. Eighty-two horses (7.6%) failed to start racing. Radiographic abnormalities such as wedged or collapsed tarsal bones, irregular lucency of a sagittal ridge at the distal aspect of the distal third metatarsal bone, and proximal dorsal fragmentation o...
Wylie CE, Newton JR.Racing performance is often used as a measurable outcome variable in research studies investigating clinical diagnoses or interventions. However, the use of many different performance measures largely precludes conduct of meaningful comparative studies and, to date, those being used have not been collated. Objective: To systematically review the veterinary scientific literature for the use of racing performance as a measurable outcome variable in clinical studies of racehorses, collate and identify those most popular, and identify their advantages and disadvantages. Methods: Systematic literat...
Cully P, Nielsen B, Lancaster B, Martin J, McGreevy P.Laterality can be observed as side biases in locomotory behaviour which, in the horse, manifest inter alia as forelimb preferences, most notably in the gallop. The current study investigated possible leading-leg preferences at the population and individual level in Thoroughbred racehorses (n = 2095) making halt-to-gallop transitions. Videos of flat races in the UK (n = 350) were studied to record, for each horse, the lead-leg preference of the initial stride into gallop from the starting stalls. Races from clockwise (C) and anti-clockwise (AC) tracks were chosen alternately at random to ensure...
Herdan CL, Acke E, Dicken M, Archer RM, Forsyth SF, Gee EK, Pauwels FE.Three Thoroughbred horses, a 6-week-old filly (Case 1), a 15-year-old broodmare (Case 2) and a yearling filly (Case 3), sustained synovial sepsis secondary to trauma. Results: Case 1 presented with a heel bulb laceration communicating with the distal interphalangeal joint. Arthroscopic lavage was performed and treatment commenced using systemic and local broad spectrum antimicrobial drugs. A pure growth of multi-drug-resistant (MDR) Enterococcus gallinarum was cultured from samples of synovium and joint fluid. Antimicrobial treatment was changed according to the susceptibility results. Respons...
Hanlon DW, Stevenson M, Evans MJ, Firth EC.The objective of this study was to utilise multivariable statistical methods appropriate for clustered data to identify mare-related explanatory variables that significantly affected the reproductive performance of Thoroughbred mares in the Waikato region of New Zealand. In addition, we aimed to determine the relative contribution of the mare, stallion and stud farm to reproductive performance. Methods: A prospective cohort study was performed involving five stud farms in the Waikato region of New Zealand during three consecutive breeding seasons (2006-2008). A total of 1,482 individual mares ...
Firth EC, Delahunt J, Wichtel JW, Birch HL, Goodship AE.This study was performed to test the hypothesis that a localised bone hypertrophy could occur within the subchondral cancellous architecture of the third and radial carpal bones. Using 2 levels of controlled and defined exercise, it was observed that a high intensity treadmill exercise protocol resulted in functional adaptation of the carpal bones. The increase in trabecular thickening and density was seen to be localised to those regions underlying common sites of cartilage degradation, the interface of the thickened trabeculae with the normal architecture in the third carpal bone was coincid...
Tozaki T, Miyake T, Kakoi H, Gawahara H, Hirota K, Nakano Y, Kurosawa M.This study evaluated the differences between linear and non-linear modelled heritability estimates of racing performance based on lifetime earnings (LE) and lifetime ranking (LR) in Japanese Thoroughbred racehorses. The heritability estimate (h(2) = 0.25) obtained from a non-linear model based on formal Japan Racing Association ranking was much higher than that obtained from a linear model based on the original trait phenotype (h(2) = 0.11). The linear models showed slightly higher heritability estimates under the trait categorizations than under the original phenotypes, while the non-linear c...
Ohmura H, Mukai K, Takahashi Y, Takahashi T.Thoroughbreds have high maximal oxygen consumption and show hypoxemia and hypercapnia during intense exercise, suggesting that the peripheral environment in skeletal muscle may be severe. Changes in metabolites following extreme alterations in the muscle environment in horses after exercise may provide useful evidence. We compared the muscle metabolites before and after supramaximal exercise to fatigue in horses. Six well-trained horses ran until exhaustion in incremental exercise tests. Biopsy samples were obtained from the gluteus medius muscle before and immediately after exercise for capil...
Southwood LL, Schott HC, Henry CJ, Kennedy FA, Hines MT, Geor RJ, Hassel DM.Thirty-five cases of disseminated hemangiosarcoma (21 clinical cases and 14 previously reported cases) were reviewed to describe the disease in horses. Hemangiosarcoma occurred in mature, particularly middle-aged horses, with no apparent sex predilection. Thoroughbreds seemed to be overrepresented (13 cases) but a true breed predilection could not be established. The respiratory and musculoskeletal systems were most commonly affected and presenting complaints included dyspnea (26%), subcutaneous or muscular swelling (24%), epistaxis (17%), and lameness (12%). Heart and respiratory rates were u...
Dahlgren AR, Scott EY, Mansour T, Hales EN, Ross PJ, Kalbfleisch TS, MacLeod JN, Petersen JL, Bellone RR, Finno CJ.Long non-coding RNAs (lncRNAs) are untranslated regulatory transcripts longer than 200 nucleotides that can play a role in transcriptional, post-translational, and epigenetic regulation. Traditionally, RNA-sequencing (RNA-seq) libraries have been created by isolating transcriptomic RNA via poly-A selection. In the past 10 years, methods to perform ribosomal RNA (rRNA) depletion of total RNA have been developed as an alternative, aiming for better coverage of whole transcriptomic RNA, both polyadenylated and non-polyadenylated transcripts. The purpose of this study was to determine which librar...
Bannai H, Takahashi Y, Ohmura H, Ebisuda Y, Mukai K, Kambayashi Y, Nemoto M, Tsujimura K, Ohta M, Raidal S, Padalino B.This study evaluated the effects of 12-hour transportation on immune responses to equine herpesvirus type 1 (EHV-1) and type 4 (EHV-4). Possible replication of EHV-1 and EHV-4 was monitored by real-time PCR of nasal swabs and peripheral blood mononuclear cells (PBMCs), and changes in systemic and mucosal antibodies were investigated. Six healthy Thoroughbreds with transport experience were transported in commercial trucks, repeating the same three-hour route four times. Blood samples for cortisol measurement were taken before departure and every three hours. Nasal swabs, PBMCs, nasal wash and ...
Takahashi Y, Mukai K, Matsui A, Ohmura H, Takahashi T.OBJECTIVE To quantify fatigue-induced electromyographic changes in hind limb muscles in horses. ANIMALS 8 Thoroughbreds. PROCEDURES The left and right hind limb longissimus dorsi, tensor fasciae latae, gluteus medius, and biceps femoris muscles were instrumented for surface electromyography. Hoof strain gauges were attached to confirm stride cycle. Each horse was galloped on a treadmill (grade, 3%) at a constant speed (12.6 to 14.7 m/s) to achieve fatigue after approximately 360 seconds. Before and after this exercise, the horses were trotted at 3.5 m/s. At 30-second intervals during galloping...
Todd ET, Hamilton NA, Velie BD, Thomson PC.Horses produce only one foal from an eleven-month gestation period, making the maintenance of high reproductive rates essential. Genetic bottlenecks and inbreeding can increase the frequency of deleterious variants, resulting in reduced reproductive levels in a population. In this study we examined the influence of inbreeding levels on foaling rate, gestation length and secondary sex ratio in Australian Thoroughbred mares. We also investigated the genetic change in these traits throughout the history of the breed. Phenotypic data were obtained from 27,262 breeding records of Thoroughbred mares...
Crispe EJ, Secombe CJ, Perera DI, Manderson AA, Turlach BA, Lester GD.Exercise-induced pulmonary haemorrhage (EIPH) is considered a progressive disease based on histopathology, but it is unknown if tracheobronchoscopic EIPH severity worsens over time. Objective: The aim of this study was to examine tracheobronchoscopic EIPH changes over time in a population of Thoroughbred racehorses. A secondary aim was to identify factors that affect changes in tracheobronchoscopic EIPH severity between observations. Methods: Prospective, longitudinal, observational cross-sectional study. Methods: Thoroughbred racehorses were examined with tracheobronchoscopy no earlier than 3...
Okabe K, Mukai K, Ohmura H, Takahashi T, Miyata H.We examined the effect of transient hypoxic exposure during high-intensity exercise on satellite cell activation and angiogenesis in Thoroughbred skeletal muscle. Methods: Six Thoroughbreds horses (6.3±0.8 years old) ran on a treadmill in normoxia (N; FIO2=21%) and hypoxia (H; FIO2=16%) at the same speed for the same duration, and oxygen consumption and plasma lactate and hemoglobin concentrations were measured. In addition, muscle biopsy samples were obtained from gluteus medius muscle before exercise and immediately, 4 hours, 24 hours, 3 days and 7 days after exercise, and immunohistochemic...
Fritz KL, McCue ME, Valberg SJ, Rendahl AK, Mickelson JR.Recurrent exertional rhabdomyolysis is a heritable disorder that results in painful skeletal muscle cramping with exercise in up to 10% of all Thoroughbred racehorses. Here, we report a genome-wide association study with 48 282 SNPs analyzed among 48 case and 37 control Thoroughbreds. The most significant SNPs spanned approximately 13 Mb on ECA16, and the P-value of the most significant SNP after correcting for population structure was 8.0 × 10(-6) . This region on ECA16 was further evaluated by genotyping 247 SNPs in both the initial population and a second population of 34 case and 98 contr...
Snow DH, Douglas TA, Thompson H, Parkins JJ, Holmes PH.Toxic effects of phenylbutazone (PBZ) in ponies and horses were studied, using a variety of biochemical, pathophysiologic, and pathologic methods. At dosage levels of 10 to 12 mg/kg of body weight/day for 8 to 10 days, ponies frequently developed clinical signs of toxicosis characterized by hypoproteinemia. Studies using 51CrCl3 demonstrated that PBZ caused a protein-losing gastroenteropathy. The plasma loss was usually associated with gastrointestinal ulceration, but sometimes occurred without obvious lesions in mildly affected animals. Similar studies (8.2 mg/kg/day for 13 days) in Thoroughb...
Jeffcott LB, McCartney RN.A simple non-invasive method is described for calculating the transverse apparent velocity of sound of horse bone. This was achieved, both in vivo and at post mortem examination using the metacarpal bone and its covering soft tissue. On 34 post mortem specimens (ie, 68 limbs) from horses older than one year an average measurement of 2802 +/- 37 (1sd) m/sec was obtained. There were changes noted according to age and at different sites on the shaft of the metacarpus. The highest readings were obtained in the proximal shaft where the cortex was thickest. The velocity values gradually decreased to...
Lee W, Park KD, Taye M, Lee C, Kim H, Lee HK, Shin D.This study was intended to identify genes positively selected in Thoroughbred horses (THBs) that potentially contribute to their running performances. Methods: The genomes of THB and Jeju horses (JH, Korean native horse) were compared to identify genes positively selected in THB. We performed cross-population extended haplotype homozygosity (XP-EHH) and cross-population composite likelihood ratio test (XP-CLR) statistical methods for our analysis using whole genome resequencing data of 14 THB and 6 JH. Results: We identified 98 (XP-EHH) and 200 (XP-CLR) genes that are under positive selection ...
Begg LM, Hoffmann KL, Begg AP.Cardiac troponin I is a potentially useful test to identify cardiac muscle damage in the horse. Measurements of cardiac troponin I from serum or heparinised plasma samples from 23 clinically normal Thoroughbred horses in race training were analysed through a standard Australian commercial laboratory using the ADVIA Centaur Assay. The cardiac troponin I concentrations were < 0.15 microg/L from all samples. The test was then validated using macerated equine myocardium. Cardiac troponin I concentration may be useful in determining whether poor performance in Thoroughbred horses is related to a...
van den Berg JS, Guthrie AJ, Meintjes RA, Nurton JP, Adamson DA, Travers CW, Lund RJ, Mostert HJ.The objectives of this trial were to measure the water and electrolyte intake and loss, of horses during road transportation in relatively hot environmental conditions. Six mature, Thoroughbred horses in full training were used in a balanced crossover design. The horses were conditioned on a treadmill for 6 weeks before the start of the trial in order to simulate the type of horse that is transported most often over long distances in South Africa. The horses were assigned randomly to one of 2 treatment groups. On a particular day 3 horses were transported, while the other horses served as cont...
Gim JA, Ayarpadikannan S, Eo J, Kwon YJ, Choi Y, Lee HK, Park KD, Yang YM, Cho BW, Kim HS.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 ...
Gerhauser I, Geburek F, Wohlsein P.Perosomus elumbis represents a rare congenital anomaly characterized by aplasia of the lumbosacral spinal cord and vertebrae. This anomaly is often associated with arthrogryposis and malformations of the urogenital and intestinal tract. This report describes the first case of perosomus elumbis in an aborted Thoroughbred foal associated with cerebral aplasia with meningocele, cranioschisis, spina bifida, a fused urogenital and intestinal tracts lined by a cutaneous mucosa without uterine glands, atresia ani, and arthrogryposis of the hind legs. Immunohistochemistry detected no abnormalities in ...
Paltrinieri S, Meazza C, Giordano A, Tunesi C.Thromboelastometry is used for identifying or monitoring coagulation abnormalities. It has been validated in several species but not in horses and the characteristics of the equine thromboelastogram have not yet been detailed. Objective: The purpose of this study was to validate a thromboelastometer to be used with equine blood and to define the normal equine thromboelastogram. Methods: A Rotem-gamma thromboelastometer (Pentapharm GmbH, Munich, Germany) was used on 38 citrated blood samples to investigate native coagulation, the intrinsic and extrinsic pathways, the function of fibrinogen (lar...
Lucassen A, Hankel J, Finkler-Schade C, Osbelt L, Strowig T, Visscher C, Schuberth HJ.Feed supplements such as fermentation products (SCFP) alter immune responses in horses. The purpose of this study was to analyze whether a prebiotic activity of the SCFP alters the gut microbiome in horses. Racehorses were fed either SCFP (Olimond BB, OLI, = 6) or placebo pellets (PLA, = 5) for 43 days. Fecal microbiota analysis was performed using 16S rRNA gene sequencing. The numbers and function of circulating immune cell subpopulations were analyzed by flow cytometry. SCFP supplementation resulted in non-consistent differences in fecal microbiota between the PLA and OLI during the feedi...
Mastellar SL, Coleman RJ, Urschel KL.Lysine has been reported as the first limiting amino acid in typical equine diets. Indicator amino acid oxidation (IAAO) has become the standard method for determining amino acid requirements in other species, but prior to this study, it has not been used to determine equine requirements. The aim of this study was to evaluate whole body protein synthesis and plasma and muscle amino acid concentrations in response to graded levels of lysine intake in yearling horses. Six Thoroughbred colts (358 ± 5 kg) were fed each of six treatment lysine intakes ranging from 76 to 136 mg/kg body weig...
Gelberg HB, Zachary JF, Everitt JI, Jensen RC, Smetzer DL.We reviewed case records, necropsy reports, and histologic sections from 25 Thoroughbred racehorses that died suddenly at 3 Chicago racetracks. These were young horses ranging in age from 2 to 5 years. There were more females (n = 16) than males (n = 9), and the incidence of death increased slightly in the spring and summer. Twenty-one of the 25 horses died while racing or training. Only 8 of the 25 horses (32%) had lesions sufficient to account for the death. In 6 of those 8 cases, death was caused by massive thoracic or abdominal hemorrhage. The site or nature of the vascular defect in these...
Lam KK, Parkin TD, Riggs CM, Morgan KL.To identify the risk factors for premature retirement because of tendon injury in a Thoroughbred racehorse population. Methods: 175 Thoroughbred racehorses (cases) at the Hong Kong Jockey Club that were retired from racing because of tendon injury between 1997 and 2004 and for which the last preretirement exercise was at a fast pace were each matched with 3 control horses that were randomly selected from all uninjured horses that had galloped on the same date as that last exercise episode. Methods: Training data for all horses were examined. Conditional logistic regression analyses were perfor...
Barker SA.Beginning in 2004, the horseracing industry experienced an epidemic of drug positives for the amphetamine-like drug aminorex. Investigation of the therapeutic treatment of the horses called positive for this drug suggested that its source was from the administration of the anthelmintic levamisole. This study examines the urine concentrations of aminorex as a function of time following administration of synthetic, racemic aminorex. Confirmation of the presence of aminorex in urine samples from the horses known to be treated with levamisole is also presented as are data concerning the concentrat...
Bentz BG, Granstrom DE, Stamper S.To determine seroprevalence of Sarcocystis neurona-specific antibodies in a population of horses residing in Chester County, Pa. Methods: Prevalence survey. Methods: 117 serum samples from selected members of a population of 580 Thoroughbred horses. Methods: Serum was analyzed for antibodies to Sarcocystic neurona, using a western blot. Information regarding age, sex, and housing of horse was obtained by questionnaire. Data were analyzed, using multivariable logistic regression. Results: Seroprevalence was 45.3% (95% CI, 36.3 to 54.3%). A relationship was not found between seroprevalence and s...
van den Hoven R, Gür E, Schlamanig M, Hofer M, Onmaz AC, Steinborn R.A single nucleotide polymorphism (SNP) in the first intron of the myostatin gene (MSTN) is associated with aptness of elite Thoroughbreds to race over sprint, middle or long distances. This intronic marker (g.66493737 T ≻ C), a short interspersed nuclear element (SINE) of 227 bp (Ins227bp) insertion polymorphism in the MSTN promoter, and the adjacent SNP BIEC2-417495 have not been studied for their association with racing aptness of the average Thoroughbreds raced in countries with lower status of the racing industry. This study investigated these markers regarding their prevalence and assoc...
Meredith K, Bolwell CF, Rogers CW, Gee EK.To obtain data on the use of allied health therapy within competitive equestrian sport in the North Island of New Zealand. Methods: Data were collected during January 2010 by survey at show jumping and dressage championships in the North Island, and from racing yards in the Central Districts of New Zealand. The survey consisted of 30 open, closed and multiple-choice questions, and was conducted face-to-face, by the same interviewer. Information on the demographics of riders or trainers and horses in each discipline (show jumping, dressage, and Thoroughbred racing), the use of allied health the...
