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.
Suagee JK, Burk AO, Quinn RW, Hartsock TG, Douglass LW.Low-grade inflammation precedes the development of obesity-related metabolic disorders in humans, but whether the same is true in the horse is not known. The objective of this study was to examine the effects of weight gain and diet on the inflammatory state of horses as determined by serum concentrations of tumour necrosis factor-α (TNF), an inflammatory cytokine. Fifteen mature Thoroughbred geldings with an initial body weight (BW) of 519±12 kg and body condition score (BCS) of 4.3±0.1 were fed a diet of hay plus a concentrate that was either high in non-structural carbohydrates (NSC) (i....
Whitton RC, Trope GD, Ghasem-Zadeh A, Anderson GA, Parkin TD, Mackie EJ, Seeman E.Bone modelling and remodelling reduce the risk of fatigue fractures; the former by adapting bone to its loading circumstances, the latter by replacing fatigued bone. Remodelling transiently increases porosity because of the normal delay in onset of the formation phase of the remodelling sequence. Protracted intense loading suppresses remodelling leaving modelling as the only means of maintaining bone strength. We therefore hypothesized that race horses with fatigue fractures of the distal third metacarpal bone (MC3) will have reduced porosity associated with suppressed remodelling while contin...
Kristoffersen M, Parkin TD, Singer ER.Catastrophic biaxial proximal sesamoid bone fractures (PSBF) have not yet been described in detail in the UK racing population. Objective: To determine the incidence and relative risk (RR) of PSBF in different types of racing in the UK; and to describe horse-level characteristics and racing histories of horses sustaining these injuries. Methods: Distal limbs were collected from all racehorses suffering catastrophic fractures during racing at all 59 racecourses in the UK, in a prospective study from February 1999 to December 2004. Post mortem investigation identified the anatomical location and...
Kamm JL, Bramlage LR, Schnabel LV, Ruggles AJ, Embertson RM, Hopper SA.Analysis was performed to examine a method for refining the preoperative prognosis for horses that had surgery to remove apical fractures of the proximal sesamoid bones (PSBs). Objective: To determine if: 1) there was a difference in size or configuration of apical fractures between the different anatomical locations of the PSBs, which have been shown to affect the prognosis; and 2) the size or configuration could predict the prognosis for racehorses with these fractures. Methods: The study included 110 weanlings and yearlings and 56 training racehorses that underwent surgery to remove apical ...
Hawkes CS, Hahn CN, Dixon PM.Dysfunction of the muscles is implicated in the pathogenesis of intermittent dorsal displacement of the soft palate (DDSP) in exercising horses. The histological features of normal equine soft palate muscles have not been previously described. Objective: To describe the histological and morphometric features of normal equine soft palate muscles. Methods: The palatinus, palatopharyngeus, levator veli palatini and tensor veli palatini muscles of 6 Thoroughbred type horses were examined histologically and histochemically to assess their general morphology, fibre-type distribution and mean fibre d...
Yamashita J, Oki H, Hasegawa T, Honda T, Nomura T.To investigate the breeding structure in the Japanese Thoroughbred population, we applied a demographic analysis to the populations of foals produced from 1978 to 2005. The migration rate estimated from the proportion of foals produced by imported breeding horses was around 40% over the investigated period. After early 1990s, the migration rate through stallions imported from USA sharply increased. The average generation interval was within range of 10.5-11.5 years. The longer generation interval of Thoroughbred was considered to be a reflection of the fact that Thoroughbred horses begin breed...
Snook ER, Wakamatsu N.A 17-year-old, Thoroughbred mare was presented for necropsy with a large, invasive oral mass determined via immunohistochemistry to be a soft tissue sarcoma of neural origin. Oral sarcomas are rare in veterinary medicine, and to the authors' knowledge, this is the first oral sarcoma of neural tissue origin reported in a horse.
Sindak N, Kandemir L, Yertürk M, Biricik HS.To determine physiologic levels of tear production in Arabian (AH) and throughbred horses (TH) by using phenol red thread test (PRT). Methods: The study was performed on 16 AH and 14 TH, ranging from 2.5 to 24 years of age, housed in a stable situated in the Sanliurfa of Turkey. Methods: For the measurement of PRT, the strip was placed under the lower eyelid approximately one-third the distance from the temporal to nasal canthus and left for 15 s. The length of the wet area was measured in mm and compared among breed, sex, and age groups and between eyes of both sides. Results: The mean length...
Morel MC, Newcombe JR, Hayward K.The importance of elucidating factors affecting reproductive performance and efficiency is of paramount concern to the equine industry. Oocyte viability is known to be one of the determinants of reproductive success and evidence suggests that it may be linked to follicle size. The aims of this study were, therefore, to ascertain: i) the average diameter and range of pre-ovulatory follicles in Thoroughbred mares; ii) whether this is affected by either mare age, time within the breeding season, or the presence of multiple pre-ovulatory follicles (MO). One thousand, four hundred and ninety two Th...
Nicholson AM, Trumble TN, Merritt KA, Brown MP.To determine the effects of horse age, osteochondral injury, and joint type on a synthesis biomarker and 3 degradative biomarkers of type II collagen in Thoroughbreds. Methods: Healthy rested adult (3- to 12-year-old) Thoroughbreds (n = 19), yearling (1- to 2-year-old) Thoroughbreds (40), and Thoroughbred racehorses (2 to 7 years old) undergoing arthroscopic surgery for removal of osteochondral fragments that resulted from training or racing (41). Methods: Samples of blood and metacarpophalangeal, metatarsophalangeal, or carpal joint synovial fluid (SF) were collected from all horses. Commerci...
Anthenill LA, Gardner IA, Pool RR, Garcia TC, Stover SM.To compare macrostructural and microstructural features of proximal sesamoid bones (PSBs) from horses with and without PSB midbody fracture to gain insight into the pathogenesis of PSB fracture. Methods: PSBs from 16 Thoroughbred racehorses (8 with and 8 without a PSB midbody fracture). Methods: Parasagittal sections of fractured and contralateral intact PSBs from horses with a PSB fracture and an intact PSB from age- and sex-matched control horses without a PSB fracture were evaluated for visual, radiographic, microradiographic, histologic, and his-tomorphometric differences in bone porosity,...
Jalim SL, McIlwraith CW, Goodman NL, Anderson GA.The effectiveness and best method to manage dorsal cortical stress fractures is not clear. This study was performed to evaluate the success of lag screw fixation of such fractures in a population of Thoroughbred racehorses. Objective: Lag screw fixation of dorsal cortical stress fractures is an effective surgical procedure allowing racehorses to return to their preoperative level of performance. Methods: The records of 116 racehorses (103 Thoroughbreds) admitted to Equine Medical Centre, California between 1986 and 2008 were assessed. Information obtained from medical records included subject ...
McGivney BA, McGettigan PA, Browne JA, Evans AC, Fonseca RG, Loftus BJ, Lohan A, MacHugh DE, Murphy BA, Katz LM, Hill EW.Digital gene expression profiling was used to characterize the assembly of genes expressed in equine skeletal muscle and to identify the subset of genes that were differentially expressed following a ten-month period of exercise training. The study cohort comprised seven Thoroughbred racehorses from a single training yard. Skeletal muscle biopsies were collected at rest from the gluteus medius at two time points: T(1) - untrained, (9 +/- 0.5 months old) and T(2) - trained (20 +/- 0.7 months old). Results: The most abundant mRNA transcripts in the muscle transcriptome were those involved in mus...
Hitchens PL, Blizzard CL, Jones G, Day L, Fell J.Riding thoroughbred racehorses is a hazardous occupation. In this study, we investigated risk factors associated with falls by licensed thoroughbred racing jockeys participating in flat races conducted in Australia. Methods: Data on race-day falls were extracted from stewards' reports. Denominator data were provided by Racing Information Services Australia on races conducted in Australia from August 2002 until July 2006. Incidence rate ratios (IRRs) were estimated using Poisson regression. Analyses were stratified by race grade (maiden, class, open/restricted). Results: In multivariable analys...
Cywinska A, Szarska E, Kowalska A, Ostaszewski P, Schollenberger A.Exercise-induced intravascular haemolysis and "sport anemia" are widely reported in human sports medicine. It has been recognized also in horses, however, the clinical importance and the onset of this condition seem different than in human. In this study we investigated the episodes of intravascular haemolysis, indicated by the increase in plasma haemoglobin and the decrease in serum haptoglobin levels, after routine training sessions in race horses. Heart rate and changes in haematological parameters confirmed, that the exertion was relatively high. Intravascular haemolysis did not appear in ...
Nath LC, Anderson GA, McKinnon AO.To evaluate the reproductive efficiency of horse farms in north-east Victoria and identify aspects of management to be targeted for improving reproductive efficiency. Methods: Retrospective study. Methods: Records from seven Thoroughbred (TB) and four Standardbred (STB) studs in north-east Victoria from 1990 to 2001 were reviewed; 8813 cycles in 4455 mares were analysed. TB mares were inseminated by natural mating, whereas STB mares (89%) were artificially inseminated. Results: The overall early pregnancy rate per cycle was 68.8% for TB mares and for STB mares, 68.3%. Multiple pregnancy per cy...
O'Meara B, Bladon B, Parkin TD, Fraser B, Lischer CJ.There is limited information regarding the number of races and the period for evaluation of outcome which is critical for assessment of SDF tendonitis treatments. Objective: To evaluate the re-injury rate and racing performance of Thoroughbred racehorses that sustain SDF tendonitis in relation to matched controls in terms of number of races post treatment and maximum racing performance ratings before and after injury. Methods: Clinical records and racing histories of 401 racehorses with a first occurrence of SDF tendonitis diagnosed by ultrasonography. Controls were of the same age, sex and we...
Cheetham J, Riordan AS, Mohammed HO, McIlwraith CW, Fortier LA.There is no consensus on objective outcome measures that can be used to determine if a medical or surgical treatment affects race performance. Objective: To determine the association between 2 commonly used outcome measures (total starts and total earnings) and age, sex, gait and race surface. Methods: A cross-sectional study was performed using the race performance data for all Thoroughbred horses age 2, 3, 4 and 5 years racing in the United States, and Standardbred horses of the same ages racing in the United States and Canada during the year 2006. Median earnings and starts were determined ...
Nelis SA, Sievers C, Jarrett M, Nissen LM, Kirkpatrick CM, Shaw PN.In this paper, a method for the sensitive and reproducible analysis of lignocaine and its four principal metabolites, monoethylxylidide (MEGX), glycylxylidide (GX), 3-hydroxylignocaine (3-HO-LIG), 4-hydroxylignocaine (4-HO-LIG) in equine urine and plasma samples is presented. The method uses liquid chromatography coupled to tandem mass spectrometry operating in electrospray ionisation positive ion mode (+ESI) via multiple reaction monitoring (MRM). Sample preparation involved solid-phase extraction using a mixed-mode phase. The internal standard adopted was lignocaine-d(10). Lignocaine and its...
Doube M, Firth EC, Boyde A, Bushby AJ.Condylar fracture of the third metacarpal bone (Mc3) is the commonest cause of racetrack fatality in Thoroughbred horses. Linear defects involving hyaline articular cartilage, articular calcified cartilage (ACC) and subchondral bone (SCB) have been associated with the fracture initiation site, which lies in the sagittal grooves of the Mc3 condyle. We discovered areas of thickened and abnormally-mineralised ACC in the sagittal grooves of several normal 18-month-old horses, at the same site that linear defects and condylar fracture occur in older Thoroughbreds and questioned whether this tissue ...
Barrandeguy M, Vissani A, Lezica FP, Salamone J, Heguy A, Becerra L, Olguin Perglione C, Thiry E.The temporary disruption of reproductive activities due to equine coital exanthema (ECE), caused by equid herpesvirus 3 (EHV-3), at thoroughbred breeding facilities and embryo transfer centres, has an appreciable economic impact. The aim of the present study was to estimate the prevalence of excretion of EHV-3 in mares without clinical symptoms under field conditions and the re-excretion patterns of the virus in two seropositive (presumably latently infected) mares maintained in isolation for 11 mo. The EHV-3 virus was detected in perineal-vaginal swabs by real time PCR in 14 (6%) of 220 thoro...
van Loon JP, van Oostrom H, Doornenbal A, Hellebrekers LJ.There is a need for objective evaluation and quantification of the efficacy of analgesic drugs and analgesic techniques in horses. Objective: To determine whether lumbosacral spinal cord somatosensory evoked potentials (SSEP) can be a useful and reliable tool to assess nociception in equines. Methods: SSEPs and electromyograms (EMG) from the epaxial muscles were recorded simultaneously, following electrical stimulation applied to the distal hindlimb in lightly anaesthetised Shetland ponies (n=7). In order to validate the model, the effect of increasing stimulus intensity was documented and the...
Hesse KL, Verheyen KL.Physiotherapists who work in racehorse training yards routinely treat horses' backs and hindquarters and may be able to recognise signs that indicate the presence of (impending) pelvic or hindlimb fracture before it becomes catastrophic. Objective: To establish whether physiotherapy assessment findings in Thoroughbred racehorses referred for routine physiotherapy could be predictive of subsequent (within 30 days) pelvic or hindlimb fracture diagnosis. Methods: Retrospective veterinary and physiotherapy data from a cohort of Newmarket (UK) Thoroughbred racehorses, were used. A case-control stud...
Powell SE.Multidetector-row computed tomographic contrast angiography (MDCTA) is routinely employed to investigate vascular masses in human patients but, to date, the use of this technique to investigate an aneurysmal mass has not been reported in an equine case. The potential of MDCTA to investigate a right-sided parapharyngeal mass in a 6-week-old Thoroughbred foal was therefore investigated. A 4-slice helical computed tomography scanner was used on a superficial, firm, ovoid mass yielding arterial blood on fine needle aspiration. MDCTA enabled identification of the vessels involved thus assisting in ...
Allen KJ, Franklin SH.To date there is no information on the comparison of the more recently documented technique of performing endoscopy during ridden exercise in the field, with the more traditional method of endoscopy during high-speed treadmill exercise. Objective: To compare the results of upper respiratory tract endoscopy in UK Thoroughbred racehorses performed during ridden exercise in the field with those obtained during exercise on the treadmill. Methods: A direct comparison was undertaken in 4 horses whereby both procedures were performed in the same horse within 10 days of each other. An indirect compari...
Veronesi MC, Villani M, Wilsher S, Contri A, Carluccio A.The aim of the study was to compare horse and donkey placentae using stereological techniques. Term placentae were collected at spontaneous foaling from seven Thoroughbred mares, seven pony mares, and six jenny donkeys. Maternal and foal weights were recorded and the mass, volume, and gross area of each allantochorion was also recorded. Ten random biopsies were recovered and processed for light microscopy from which the surface density of the microcotyledons (S(v)) and the total microscopic area of fetomaternal contact were calculated stereologically. Gestation length was longer in the donkeys...
Nath LC, Anderson GA, Savage CJ, McKinnon AO.OBJECTIVE-To assess the use of stored equine colostrum for the treatment of foals perceived to be at risk for failure of transfer of passive immunity (FTPI). DESIGN-Cohort study. ANIMALS-232 Thoroughbred foals and 191 Thoroughbred mares (41 mares gave birth to 1 foal on 2 occasions). PROCEDURES-Postpartum, presuckle colostrum samples were collected from mares; samples with a colostral refractive index (cRI) > or = 23% were frozen (-20 degrees C [-4 degrees F]) and stored for > or = 7 days but < 2 years. Foals of dams that produced colostrum with a cRI value < 20% were treated with > or = 300 m...
Vaughan B, Whitcomb MB, Puchalski SM, Poulin-Braim AE, Nieto JE, Galuppo LD.Thromboses of the cranial tibial vein (Horse 1) and brachial, median, and cranial circumflex humeral arteries (Horse 2) were identified as causes of unilateral lameness in two Thoroughbred racehorses. Nuclear scintigraphy was performed for suspicion of long bone stress fractures but instead allowed identification of unusual areas of increased radiopharmaceutical uptake within soft tissues of the affected limbs. Ultrasonography of these regions allowed identification of occlusive thrombi within a 25 cm length of the cranial tibial vein (Horse 1) and variable lengths of affected arteries in Hors...
Johnson EB, Mackay RJ, Hernandez JA.OBJECTIVE-To estimate prevalence of and identify factors associated with anhidrosis in horses in Florida. Design-Cross-sectional study and case-control study. ANIMALS-4,620 horses on 500 farms. PROCEDURES-A questionnaire was structured and mailed to farm owners or managers to obtain information related to diagnosis of anhidrosis in horses and exposure factors associated with this condition. The frequency of investigated farm- and animal-level factors was compared between farms and horses affected and not affected with anhidrosis, respectively. RESULTS-The prevalence of anhidrosis was 11% at th...
Grewar JD, Allen JG, Guthrie AJ.An outbreak of annual ryegrass toxicity occurred on a Thoroughbred stud in Ceres in the Western Cape Province of South Africa. This is the 1st report of annual ryegrass toxicity in horses in South Africa, although the condition has been reported in cattle and sheep populations in the past. Annual ryegrass toxicity is characterised by a variety of neurological signs including tremors, convulsions, recumbency and in many cases death. The description of the outbreak includes the history, clinical presentation and treatment protocol administered during the outbreak. Various epidemiological variabl...
Davies HM, Watson KM.The aims of this study were to test whether longer third metacarpal (MC3) bones had thicker dorsal cortices in a group of racehorses that were exercising at similar maximum speeds, and to establish if horses with larger differences in length between their right and left MC3 bones showed larger differences in the dorsal cortical thickness between the two limbs. Methods: An observational study. Methods: Forty Thoroughbred racehorses aged between 2 and 6 years and in training at racing speed at two racing stables were used. Two sets of radiographs of each left and right metacarpus of each horse w...
Medina-Torres CE, Hewson J, Stämpfli S, Stalker MJ.A 9-day-old Thoroughbred filly was presented for diarrhea and lethargy. Diagnostic test results were compatible with severe renal dysfunction. Diffuse cystic lesions of both kidneys were identified on ultrasonographic examination. Postmortem examination confirmed the presence of multiple renal cysts. Congenital nephropathy compatible with bilateral diffuse cystic renal dysplasia was diagnosed. Une pouliche Thoroughbred âgée de 9 jours a été présentée pour de la diarrhée et de la léthargie. Les résultats des tests diagnostiques étaient compatibles avec une dysfonction rénale grave. ...
Lund RJ, Guthrie AJ.This study determined the maximal O2 uptake (VO2max) of Thoroughbred horses acclimatised to mild hypobaric conditions using a standard exercise test on a treadmill inclined at a 7% slope. The O2 uptake (VO2) versus speed relationship was linear below the exercise intensity required to attain VO2max. The VO2max of individual horses ranged from 143.5 to 172.6 ml/kg/min. The proportion of total variance for the VO2 versus speed relationship was greater than 0.992, and the coefficients of variation in repeated tests in individual horses ranged between 0.07 and 1.54%. The VO2 versus speed relations...
Pascoe PJ.A 16 year old Thoroughbred mare was presented to the Ontario Veterinary College because of an acute episode of colic. An exploratory laparotomy was performed and a neurofibroma was identified and successfully removed from the small colon. The clinical and pathological features of this case are discussed.
Morris DD, Moore JN.The formation of eicosanoids may be a primary route through which platelet activating factor (PAF) exerts its effects during endotoxemia. Since endotoxemia is a common cause of death in horses, a study was conducted to determine whether PAF could stimulate equine macrophage release of thromboxane A2 (TxA2) and prostacyclin (PGI2) and whether a PAF-receptor antagonist would alter macrophage eicosanoid synthesis. Equine peritoneal macrophages were cultured from clinically normal horses and exposed to various concentrations of PAF, the PAF-receptor antagonist SRI 63-441, endotoxin, or a combinati...
Pearson RC, Hallowell AL, Bayly WM, Torbeck RL, Perryman LE.Pre- and postpartum colostral samples collected from 14 Arabian and 22 Thoroughbred mares were examined for color, consistency, and immunoglobulin (Ig)G concentration. Initial samples, obtained 3 to 28 days before mares had foaled, contained greater than 1,000 mg of IgG/dl. Mean concentration of IgG in colostrum of the Arabian mares at the time of parturition (T0) was 9,691 mg/dl and was significantly (P less than 0.05) higher than the average, 4,608 mg/dl, for the Thoroughbreds. Average times lapsed from T0 until the colostral IgG decreased to 1,000 mg/dl (T1,000) was 19.1 hours for the Arabi...
Murray DR, Ladds PW, Johnson RH, Pott BW.Extensive subcutaneous phycomycosis of the lower hindlimb developed over a period of 8 months in a Thoroughbred filly. There was no response to treatments such as trichlorphon, sodium iodide, or etisazole. Extension of the limb lesion over the following 3 months was associated with an enlarged inguinal lymph node, which was removed. Characteristic phycomycotic lesions were observed in the node, and a fungus having the morphologic features of Hyphomyces destruens was isolated from both the limb and nodal lesions.
Gross DK, Morley PS, Hinchcliff KW, Wittum TE.To determine the effect of furosemide on performance of Thoroughbreds racing on dirt surfaces at tracks in the United States and Canada. Methods: Cross-sectional study. Methods: All Thoroughbreds (n = 22,589) that finished a race on dirt surfaces at tracks in the United States and Canada between June 28 and July 13, 1997 in jurisdictions that allowed the use of furosemide. Methods: Race records were analyzed by use of multivariable ANOVA procedures and logistic regression analyses to determine the effect of furosemide on estimated 6-furlong race time, estimated racing speed, race earnings, and...
Harris RC, Harris DB, Dunnett M, Harris PA, Fallowfield J, Naylor JR.Plasma NH3, formed during intense exercise, results principally from the deamination of AMP in muscle. Its formation during exercise may be influenced both by the pool of fibres recruited and by changes in the intracellular environment affecting ADP homeostasis. This study compared incremental and constant speed exercise as possible protocols for the investigation of plasma NH3 accumulation with intense exercise. Six trained Thoroughbred horses, one of which had recently been operated on for recurrent laryngeal neuropathy, undertook a step-wise treadmill test with 1 min incremental steps of 6,...
Hill T, Carmichael D, Maylin G, Krook L.The incidences of fractures and soft tissue injuries during 68397 starts of thoroughbred horses at New York Racing Association tracks were analyzed concerning track condition, dirt and turf tracks, environmental conditions, length of races, location of fractures on the track, and age of horses. It was concluded that the conditions evaluated are of no importance in the occurrence of racing injuries to thoroughbred horses.
Todhunter RJ, Fubini SL, Freeman KP, Lust G.To determine whether keratan sulfate concentrations in plasma or synovial fluid from clinically normal horses were different from concentrations in horses with joint disease and whether concentrations varied with type of joint disease. Methods: Case-control study. Methods: 67 clinically normal horses, 10 clinically normal foals, and 160 horses with joint disease. Methods: ELISA was used to measure keratan sulfate concentrations. Results: Mean plasma keratan sulfate concentration (mean +/- SEM, 580 +/- 124 ng/ml) in foals peaked at 10 weeks of age. Mean plasma keratan sulfate concentration in c...
Weiss DJ, Evanson OA, Fagliari JJ, Valberg S.To determine whether platelets become activated and form platelet-neutrophil aggregates during near-maximal treadmill exercise in horses. Methods: 4 Thoroughbreds. Methods: Horses were subjected to 4 standardized exercise tests on a treadmill, and blood samples were collected before exercise, at treadmill speed of 12 m/s, and 5 minutes after exercise. Flow cytometric techniques were used to identify activated platelets, and flow cytometric and microscopic techniques were used to identify platelet-neutrophil aggregates. Results: Platelet-neutrophil aggregates increased from 2.8 +/- 0.4% at rest...
Pascoe RR.The epidemiology of dermatomycocis due to Trichophyton equinum var autotrophicum was studied in a number of thoroughbred stables in south-east Queensland. The significant factors in the epidemiology were defined. The infection was readily transmitted, particularly by infected saddle-girths, on which the fungus could survive for 12 months. Mild abrasion from the saddle during work favoured the development of lesions and prolonged the recovery period. A pronounced age and seasonal incidence of the disease was demonstrated as young horses under the age of 3 years were most susceptible, and the ma...
Rivero JL, Ruz A, Marti-Korfft S, Lindner A.The influence of relevant exercise parameters such as intensity and duration of exercise on the muscular response to training has not been reported in Thoroughbreds. This knowledge may be of great value in practice. Objective: To define the relative contribution of the intensity and duration of exercise on the myosin heavy chain (MHC) response to training in Thoroughbred racehorses. Methods: Six 2-3-year-old Thoroughbreds, following a randomised 6 x 6 latin square design, performed 6 consecutive conditioning programmes of varying lactate-guided intensities and durations. Each programme lasted ...
Knych HK, Mama KR, Steffey EP, Stanley SD, Kass PH.OBJECTIVE To measure concentrations of trazodone and its major metabolite in plasma and urine after administration to healthy horses and concurrently assess selected physiologic and behavioral effects of the drug. ANIMALS 11 Thoroughbred horses enrolled in a fitness training program. PROCEDURES In a pilot investigation, 4 horses received trazodone IV (n = 2) or orally (2) to select a dose for the full study; 1 horse received a vehicle control treatment IV. For the full study, trazodone was initially administered IV (1.5 mg/kg) to 6 horses and subsequently given orally (4 mg/kg), with a 5-week ...
Valdez SC, Nieto JE, Spier SJ, Owens SD, Beldomenico P, Snyder JR.To determine the effects of an external nasal dilator strip on cytologic characteristics of bronchoalveolar lavage (BAL) fluid in racing Thoroughbreds. Methods: Clinical trial. Methods: 23 Thoroughbred racehorses in active training. Methods: Each horse raced on 2 occasions: once while wearing an external nasal dilator strip and once while not. Bronchoalveolar lavage was performed 12 to 18 hours after each race, and BAL fluid was analyzed for RBC and leukocyte counts and hemosiderin content. Results: Mean +/- SEM count of RBCs in BAL fluid when horses raced without the nasal dilator strip (84.6...
Martin GS, Strand E, Kearney MT.To develop a statistical model to evaluate the influence of specific parameters on racing performance in Thoroughbreds. Methods: Survey. Methods: Racing records of Thoroughbreds performing in Louisiana from 1981 to 1985. Methods: Race results for 20 randomly selected days from 5 racetracks during 5 years were analyzed, using regression analysis. Results: The most influential parameter was distance raced. There were significant differences in racing performance among horses at different tracks. At the tracks examined, fast racing surfaces resulted in significantly faster finish times than good ...
Reesink HL, Divers TJ, Bookbinder LC, van Eps AW, Soderholm LV, Mohammed HO, Cheetham J.To compare effects of 3 methods of topically applied cold treatment (cryotherapy) on digital laminar and venous temperatures in horses. Methods: 9 healthy adult Thoroughbreds. Methods: Thermocouples were placed in palmar digital veins and digital laminae of both forelimbs of horses. Three methods of cryotherapy were applied to the distal aspects of the limbs: wader boot (63-cm-tall vinyl boot filled with ice and water [ice slurry]), ice bag (5-L fluid bag filled with ice slurry), and a gel pack boot (boot containing frozen gel packs). Gel packs and ice slurries were replenished every hour duri...
Kinobe RT.Cobalt is an essential trace element for many vital physiological functions. Cobalt is also known to stabilise hypoxia-inducible transcription factors leading to increased expression of erythropoietin which activates production of red blood cells. This implies that cobalt can be used to enhance aerobic performance in racing horses. If this becomes a pervasive practice, the welfare of racing animals would be at risk because cobalt is associated with cardiovascular, haematological, thyroid gland and reproductive toxicity as observed in laboratory animals and humans. It is expected that similar e...
Sweeney CR, Soma LR, Bucan CA, Ray SG.Thoroughbreds with a confirmed history of exercise-induced pulmonary hemorrhage (EIPH) were treated pre-exercise with atropine sulfate, cromolyn, ipratropium or furosemide. Atropine prevented EIPH in 3 of 3 trials in 1 horse, while having no significant effect on bleeding status in the other 2 horses. Pre-exercise treatment with cromolyn had no significant effects in the 3 horses. Pre-exercise treatment of ipratropium was apparently responsible for preventing EIPH in 17 out of 18 trials in 2 horses. The pharmacologic properties of ipratropium in the horse have not been studied, but based on hu...
Ellis DR.The common spontaneous fractures of the third metacarpus and
metatarsus of young racehorses are split cannons or condylar
fractures. Meagher (1976) described a series of 45 cases involving
the lateral condyle and Richardson (1984) detailed 15 cases involving
the medial metatarsal condyle. Rick et al. (1983) published a clinical
and pathological study of 75 cases of third metacarpal and metatarsal
condylar fracture. In the United Kingdom, Barr et al. (1989) recorded
8 cases with long fractures, 3 lateral and 5 medial condylar. This
paper reports 124 cases of medial or lateral condylar f...
Navas De Solís C, Biscoe EW, Lund CM, Labbe K, Muñoz J, Farnsworth K.A 14-year-old Thoroughbred gelding was presented for chronic colic and weight loss. Transcutaneous and transrectal abdominal ultrasonography revealed distended, thickened small intestine with primary thickening of the muscularis and a focally more thickened loop with an echoic structure crossing the wall from the mucosa to the serosa. Visualization of diffuse thickening of the muscularis (muscular hypertrophy of the small intestine) and a focal lesion (pseudodiverticulum) helped clinicians make informed decisions. This case illustrates the importance of transabdominal and transrectal ultrasono...
Walbornn SR, Love CC, Blanchard TL, Brinsko SP, Varner DD.Breeding records were analyzed from 24 Thoroughbred stallions that were subjected to dual-hemisphere breeding (DH), including novice (first-year; NOV; n = 11) and experienced (EXP; n = 13) stallions. Fertility variables included seasonal pregnancy rate, pregnancy rate per cycle, and first-cycle pregnancy rate. In addition, values for book size, total number of covers, distribution of mare type (maiden, foaling, and barren) within a stallion's book, cycles per mare, and mare age were examined. Some data were also categorized by mare type (maiden-M, foaling-F, and barren-B). Five separate an...
DeLay J, Peregrine AS, Parsons DA.Strongylus vulgaris migration and cranial mesenteric arterial thrombus formation resulted in fatal colic in a 3-month-old Thoroughbred foal. Vascular damage associated with S. vulgaris occurs early in the course of infection and, despite widespread use of broad-spectrum anthelmintics, appropriate management is still essential to minimize exposure of young animals to this parasite.
Akai M, Hobo S, Wada S.To assess the effect of human interferon-alpha (IFNα) on shipping fever of Thoroughbred racehorses subjected to long-distance transportation, an IFNα preparation was orally administered to 48 horses three times (once daily, 3 successive days) before transportation (IFNα group). In the control group (25 horses), maltose was administered in the same way. These treatments induced no abnormal findings in Thoroughbred racehorses before transportation. Immediately after transportation, significant increases in rectal temperature were observed in both treatment groups, whereas the rectal temperatu...
Tanimoto T, Yamasaki S, Ohtsuki Y.A well-demarcated solitary splenic mass (20 x 20 x 15 cm in size) containing hemorrhagic and necrotic foci was observed in a 4-year-old Thoroughbred stallion. Histologically, the mass consisted of lymphoma cells of the diffuse large non-cleaved type, with a high mitotic index and scattered macrophages that formed a starry sky pattern. The lymphoma cells revealed diffuse positivity for acid phosphatase and alpha naphthyl butyrate esterase, and were also positive for intracytoplasmic IgM on occasion, and mostly for proliferating cell nuclear antigen. Ultrastructural examination revealed moderate...
Evans DL, Golland LC.The aim of this study was to investigate correlations between lactate concentrations in equine whole blood and plasma measured with Accusport1 and Yellow Springs Instruments (YSI2) (2300) methods. The effect of packed cell volume (PCV) on the accuracy of Accusport was also investigated. Blood samples were collected from Thoroughbred horses at 5-10 min intervals after a treadmill exercise test. Blood was added to NaEDTA (for PCV measurement) and to 2 tubes containing lithium heparin anticoagulant (for lactate assays). At concentrations greater than 10 mmol/l, Accusport1 greatly underestimated t...
Carstens A, Kirberger RM, Grimbeek RJ, Donnellan CM, Saulez MN.Radiographic measurement of tracheal dimensions in the horse may be useful in evaluating upper and lower respiratory tract conditions due to the gradient of pressure changes between these areas. Lateral radiographs of the trachea of 15 normal sedated Thoroughbred horses were made at inspiration and expiration and magnification-corrected mean airway heights measured were, respectively: larynx: 5.89 and 5.86 cm; trachea at the third cervical vertebra (C3): 4.17 and 4.04cm; at the fifth cervical vertebra (C5): 3.62 and 3.59 cm; at the first thoracic vertebra (T1): 3.4 and 3.23cm; and carina: 3.85...
Ringger NC, Edens L, Bain P, Raskin RE, Larock R.A 5-year-old Thoroughbred mare presented with a 4 week history of weight loss, fever and leukopenia. Rectally, a large active foetus, thickened spleen and an abdominal mass were palpated. Leukopenia, mild anaemia, marked thrombocytopenia and hyperfibrinogenaemia were found. Cytology and cytochemical staining of a bone marrow aspirate supported a diagnosis of acute myelogenous leukaemia. The mare deteriorated despite medical therapy and was humanely euthanased.
Cathcart MP, Love S, Sutton DG, Reardon RJ, Hughes KJ.Analyses of exhaled breath (EB) and exhaled breath condensate (EBC) are non-invasive modalities for assessing the lower airways but these methods have not been applied to Thoroughbred racehorses in training. The aims of this study were to determine whether EB and EBC could be obtained from Thoroughbred racehorses in the field and to investigate the effects of exercise per se and during different ambient temperatures and humidity on exhaled concentrations of nitric oxide (eNO), carbon monoxide (eCO) and EBC pH. EB and EBC samples were obtained from 28 Thoroughbred racehorses pre- and post-exerc...
