Horse racing is a competitive equestrian sport involving horses ridden by jockeys over set distances, often on flat tracks or over obstacles. It is characterized by a variety of race types, including thoroughbred, harness, and steeplechase, each with distinct rules and traditions. The sport emphasizes speed, stamina, and strategy, with races typically categorized by distance, surface type, and horse age or breed. Horse racing plays a significant role in the equine industry, influencing breeding, training, and veterinary care practices. This page compiles peer-reviewed research studies and scholarly articles that explore the physiological demands, training methodologies, and health considerations associated with horse racing.
Cervantes C, Madison JB, Ackerman N, Reed WO.Between January 1985 and May 1989, 53 Thoroughbred horses (mean age 3.2 years) were surgically treated for dorsal cortical fractures of the third metacarpal bone (MC III). All horses were treated with cortical drilling through the fracture line (osteostixis). Diagnosis of the fractures was confirmed by xeroradiography. Lifetime racing records were obtained for all horses. Forty-seven horses returned to racing after surgery (89%). The mean time between surgery and the first race was 6.8 months. Horses had a mean of 10.9 starts before surgery and 16.1 starts after surgery. The mean earnings per ...
Buckingham SH, McCarthy RN, Anderson GA, McCartney RN, Jeffcott LB.Transmission ultrasound speed was determined in the third metacarpal bone of 347 Thoroughbred racehorses in training. In addition to direct measurement of apparent ultrasound speed and lateral bone diameter, several derived parameters were estimated (cortical ultrasound speed, corticomedullary ratio and cortical cross-sectional area). Multiple regression equations were developed for each ultrasound measurement using the explanatory variables: sex, age, duration and intensity of training, preparation number and previous shin soreness. The horses (114 females, 82 entire males and 151 geldings ra...
Stick JA, Nickels FA, Williams MA.Desmotomy of the accessory ligament of the deep digital flexor muscle (inferior check desmotomy) permitted Standardbred foals affected with flexural deformities to reach their full athletic potential. Long-term effects of inferior check desmotomy were examined in 23 Standardbreds over a 10-year period. Six of 11 foals that were treated surgically either raced 6 times and obtained a race record or were training sound (if yearlings). All 12 horses with flexural deformity that did not receive an inferior check desmotomy had an unfavorable outcome (no race record). Foals that had surgery performed...
Harkins JD, Kamerling SG.There is considerable debate regarding the ergogenic effects of sodium bicarbonate (NaHCO3) on racing performance in horses. Anecdotal evidence suggests that NaHCO3 improves performance by increasing the buffering capacity of the blood and delaying the onset of hydrogen ion-induced fatigue. In a cross-over study, 16 Thoroughbred racehorses were given an aqueous solution of NaHCO3 (0.4 g/kg in 1 litre H2O) or a control treatment (1 litre H2O) before a 1600-m race. Treatments were administered 3 h before the race, which was the time to peak buffering capacity (2.5-3.0 h) determined in a separate...
Evans GP, Behiri JC, Vaughan LC, Bonfield W.The behaviour of cortical bone under load is strain rate-dependent, i.e. it is dependent on the rate at which the load is applied. This is particularly relevant in the galloping horse since the strain rates experienced by the bone are far in excess of those recorded for any other species. In this study the effect of strain rates between 0.0001 and 1 sec-1 on the mechanical properties of equine cortical bone were assessed. Initially, increasing strain rates resulted in increased mechanical properties. Beyond a critical value, however, further increases in strain rate resulted in lower strain to...
Mahony C, Rantanen NW, DeMichael JA, Kincaid B.Spontaneous echocardiographic contrast is the term used by ultrasonographers to describe particulate material visible in intracardiac blood by ultrasound. The purpose of the present study was to determine the prevalence of spontaneous contrast in a farm population of Thoroughbreds and in the farm's racehorses. The results showed that spontaneous echocardiographic contrast is common in Thoroughbreds, and that the prevalence of contrast is affected by age, male gender, racing and pregnancy. The amount of right-sided cardiac contrast was quantitated by videodensitometry and was increased in horse...
Harkins JD, Kamerling SG, Church G.The effect of competition and the influence of age and sex on performance were examined in a study of 18 Thoroughbred racehorses. The horses performed two solo and two competitive runs at 1,200 and 1,600 m for a total of eight runs. No group ran faster during competition, which may have been a reflection of the quality of horses used for this study and their susceptibility to stress-induced impairment of performance. Males showed no significant difference between competitive and solo run times, whereas females were consistently slower during competition. Males ran significantly faster than fem...
Wood T, Stanley S, Woods WE, Henry P, Watt D, Tobin T.This study was designed to explore the use of hematocrit values as possible indicators of the threshold doses of adrenergic drugs in the performance horse. Acepromazine, detomidine, and fluphenazine were tested for their effects on hematocrit values, with the threshold dose for these effects investigated. Hematocrit values were shown to be quite sensitive to the administration of acepromazine with doses as low as 50 micrograms/horse producing detectable depressions in hematocrit values for up to 2 hours. Increasing the dose increased the magnitude of the effect, but did not appear to prolong i...
Hanie EA, Sullins KE, White NA.The results of 31 intracortical dorsal metacarpal stress fractures in 28 horses following unicortical osteostixis were reviewed. The incidence was predominately in the middle third of the lateral aspect of the left metacarpus, and males were affected more commonly. Approximately half of the surgical procedures were performed with the horse in the standing position. The mean times to return to training and racing were 4.25 and 6.9 months respectively. There was no correlation between time taken to return to racing and position of surgery. Complications experienced included lack of suture remova...
Johnson AT, Soma LR, Ferouz C.Exercise-induced pulmonary hemorrhage (EIPH) affects a large portion of racing thoroughbred horses. Sites of hemorrhage and causal mechanisms remain unestablished. Our mathematical model was constructed to test the hypothesis that EIPH could be caused by a combination of respiratory and circulatory mechanical factors occurring during exercise. Various physiological data for respiration, blood circulation and exercise were incorporated into the model. Results show that inhalation pressure drops across airway resistances become great enough during exercise to cause rupture of capillaries for bot...
Pick M.Intensive strain of racing-horses during training and race is not an end in itself but should be understood from the social task to create exceptionally efficient horses. This roughness in sports obliges the responsible associations to issue rigorous regulations for the protection of horses. In this paper, some physical and psychical disorders of racing-horses are described. Improved keeping conditions as well as performance-adapted training methods will help to avoid defects. The aids being used during training and races are critically investigated on their effects according to the regulation...
Fogarty U, Buckley T.Significant differences were detected by bronchoalveolar lavage (BAL) between horses racing successfully and those showing exercise intolerance. Neutrophil percentage, haemosiderophage percentage and total bacterial numbers were significantly elevated in horses with exercise intolerance. BAL provided a more accurate indication of the incidence and extent of exercise induced pulmonary haemorrhage (EIPH) than visual inspection.
Mohammed HO, Hill T, Lowe J.A case-control study was conducted on Thoroughbred horses to identify factors associated with the risk of breakdown on racetracks. A total of 310 cases (breakdowns) were identified from the Horse Identification Department records kept by the chief examining veterinarian of New York Racing Association. For each case, two control horses were selected randomly from the Daily Racing Form Inc. records. Multiple logistic regression analysis was used to identify and quantify the risk of factors associated with breakdown, while simultaneously controlling for the effect of other putative factors. Facto...
Stanley S, Jeganathan A, Wood T, Henry P, Turner S, Woods WE, Green M, Tai HH, Watt D, Blake J.We have raised antibodies to morphine and etorphine and developed one-step enzyme-linked immunosorbent assays (ELISA) for these drugs as part of a panel of post race tests for drugs in racing horses. These tests are simple, can be completed in 2 h, and can be read by visual inspection. The morphine ELISA has an I50 for morphine of about 1.5 ng/mL, while the etorphine ELISA has an I50 for etorphine of 250 pg/mL. Cross-reactivity studies show that the antimorphine antibody cross-reacts well with levorphanol, hydromorphone, and oxycodone, while the anti-etorphine antibody showed no cross-reactivi...
Humber KA, Beech J, Cudd TA, Palmer JE, Gardner SY, Sommer MM.Azathioprine, a thiopurine antimetabolite used in the treatment of immune-mediated thrombocytopenia in human beings and dogs, was used in 2 cases of immune-mediated thrombocytopenia in horses that failed to respond to corticosteroid therapy alone. Platelet counts were increased to acceptable values in both horses. One horse returned to a successful racing career, and the other was euthanatized after developing renal disease and mild laminitis.
Willham RL, Wilson DE.Research on the racing performance of quarter horses has been used to develop genetic prediction summaries on all horses with at least one start on record at the American Quarter Horse Association. In the 1987 summary, records from a total of 212,065 horses were used to give genetic predictions on stallions, mares, geldings, fillies, and colts. A reduced animal model was used that incorporated the repeated records of individuals. The individual race was the contemporary group after the data were adjusted for distance, sex, and age. Estimates of heritability of .24 and repeatability of .32 sugg...
Kannegieter NJ, Ryan N.The case record, and subsequent racing performance, of 110 horses that had undergone arthroscopic surgery of the carpus, were reviewed. Of these, 87% resumed racing, with 43% able to win at least one race, after surgery. Horses with chip fractures from the distal radius had the best prognosis, while horses with sagittal fractures of the third carpal bone had the poorest. The performance of horses with bilateral lesions was similar to those with unilateral lesions. It was concluded that arthroscopic surgery was a suitable technique for the diagnosis and treatment of carpal lesions in the horse....
Tulleners EP.A submucosal abscess, located on the dorsal surface of the epiglottis, was diagnosed in 2 Thoroughbred racehorses by use of endoscopy. Both horses had exercise intolerance. One horse had intermittent dorsal displacement of the soft palate, coughed while eating and galloping, and made an abnormal respiratory noise. Both abscesses were drained transendoscopically by use of a contact neodymium:yttrium aluminum garnet laser. Eleven days after surgery, the surgical sites appeared to have healed. Clinical signs resolved permanently, and both horses returned to successful racing careers.
Moyer W, Spencer PA, Kallish M.The relative incidence of dorsal metacarpal disease was examined in two groups of Thoroughbred racehorses training on dissimilar surfaces (dirt and wood fibre). The horses and training methods appeared to be similar. The incidence of disease was significantly greater in the group training on dirt. There was no significant difference in the age distribution of incidence between the two groups and there was no association of incidence with sex or age within the training group. The number of fast miles worked by the two groups prior to the onset of dorsal metacarpal disease was lower in the group...
Morris EA, Seeherman HJ.A clinical sports medicine evaluation was applied to 275 racehorses with a history of poor racing performance. The poor performance evaluation included a) general physical examination and basic laboratory screening; b) respiratory examination including auscultation, thoracic radiographs, ventilation-perfusion lung scintigraphy and upper airway endoscopy at rest and during maximal treadmill exercise c) examination of the musculoskeletal system including lameness examination, video gait analysis at high speed, post exercise serum chemistry to identify obvious as well as sub-clinical myopathies, ...
Johnstone IB, Viel L, Crane S, Whiting T.The purpose of this study was to determine whether a defect in hemostasis might be a factor in the etiology of exercise-induced pulmonary hemorrhage (EIPH). Hemostatic parameters were evaluated in 22 EIPH-positive and ten EIPH-negative racing horses while in a rested state. Nineteen EIPH-positive and ten EIPH-negative horses were further evaluated just before and immediately after a 15 min exercise period on a 260 m oval track. When EIPH-positive and EIPH-negative horses were compared at rest, there was no significant difference in any of the coagulation and fibrinolytic parameters studied. Th...
Sweeney CR, Maxson AD, Soma LR.The frequency of upper respiratory tract abnormalities was determined in a selected population of racing Thoroughbreds. The prevalence of pharyngeal lymphoid hyperplasia was 34.2%; left laryngeal hemiplegia was 1.8%; and epiglottic entrapment was 0.74%. Excluding pharyngeal lymphoid hyperplasia and tracheal exudate, 3.7% of the population examined had upper respiratory tract abnormalities.
Tulleners EP.Epiglottic entrapment in 35 Thoroughbred and 44 Standardbred horses was corrected transendoscopically by use of a neodymium:yttrium aluminum garnet laser. Before surgery, the entrapped epiglottis was classified as hypoplastic or normal in each horse on the basis of endoscopic appearance alone. Using a digitizer, thyroepiglottic length was determined from lateral-view laryngeal radiographs. For 78 racehorses, earnings (less than $5,000 or greater than $5,000) were compared before and after surgery. Earnings category and racing performance after surgery were tested for association with endoscopi...
Clanton C, Kobluk C, Robinson RA, Gordon B.During a pilot study at a Thoroughbred racetrack, information was collected to include weather conditions and track surface properties (moisture content, composition, strength, and coefficient of friction between surface and hoof). Measured weather variables did not correlate to any pattern of horse injuries of breakdowns. Surface moisture content was variable, whereas the moisture content of the compacted cushion was constant. Track surfaces around the starting chutes were more compacted than were other areas of the track. Next to the rail, track surface was softer than the surface toward the...
Busch NA, Ranu HS, Silver IA.Evidence indicating that comparison of a particular animal trace with a population average is an insufficient test of the health of a limb is presented. The methodology involves representing each of three recorded force components (vertical, lateral, and transverse) as a Fourier-Legendre series; the coefficients in the series represent the trace. A history for the horse is built by accumulating the coefficients (along with pertinent experimental data such as date, sex, weight, height, and in the case of race horses the date of last race) over a long duration. Then, on each subsequent recording...
Pfaff G.In South Africa 2,41% of horses bleed in a race. If all raced until they were 7 years old probably another 2,12% would bleed. Many others bleed after the race or during exercise or at rest. The incidence of epistaxis is significantly greater in geldings than in females and uncastrated males (P less than 0,001). There is an age distribution of bleeding which is highest at 4 years and lowest at 2 years of age (P less than 0,001).
Sturm RT, Lang GH, Mitchell WR.The sera of 2596 thoroughbred and standardbred racehorses from Ontario were examined by hemagglutination-inhibition for antibodies to reovirus types 1, 2 and 3. The prevalence of antibodies differed between the standardbred and thoroughbred horses and varied with the age groups within the two populations. While reovirus 1 was the principal virus type infecting thoroughbreds, all three types seemed to infect standardbred horses. Differences of these findings with data from similar studies in Europe are mentioned and the epizootiological and pathological significance of these findings are discus...
Uhlhorn H, Eksell P, Sandgren B, Carlsten J.To assess the significance of radiographic signs of sclerosis of the third carpal bone (C3) in young Standardbred trotters in relation to performance, lameness and bone turnover both carpi in 14 Standardbred trotters were radiographically and scintigraphically examined 6 times, from the beginning of speed training until the beginning of racing, between the mean ages of 20 and 42 months. At the end of the study 8 horses had raced in official qualifying races and 14 limbs in 11 horses had been diagnosed with carpal lameness. All horses but 2 developed sclerosis and all but one had increased bone...
Lindsay WA, Horney FD.During a 6-year period, carpal arthrotomies were performed on 89 horses with carpal fractures. Fifty-two percent of the fractures involved the left forelimb; the 3rd carpal bone was most often involved (42%), followed by the radial carpal bone (30%). The effect of surgery on the performance of a subgroup of 48 thoroughbreds was evaluated by comparing the number of starts, level of racing (claiming value), and earnings for the 12 months of racing preceding and following arthrotomy. The data indicated that carpal arthrotomy in the Thoroughbred carries with it a favorable prognosis inasmuch as 80...
Clarke KL, Reardon R, Russell T.To determine if arthroscopic surgery performed on weanlings/yearlings with trochlear ridge OCD of the femur (stifle OCD), or intermediate ridge of the tibia (tarsal OCD) detected on routine presale radiographs affects future racing performance. Methods: Retrospective case control study. Methods: Thoroughbred weanlings and yearlings. Methods: Stifle (N = 37; 22 male, 15 female) and tarsal (N = 35; 22 male, 13 female) OCD cases were identified. Outcome measures relating to racing performance (number of race starts, wins, places, and prize money earned, from races in their 2- and 3-year-old racin...
Gallagher K, Stowe HD.Blood samples were obtained from 45 racing Standardbred horses immediately before and immediately after a training jog at a commercial race track to establish reference values for serum selenium and related values of the peroxide reduction system of racing horses. Hemoglobin, hematocrit, and serum selenium increased significantly (P < 0.001), whereas RBC-reduced glutathione decreased significantly (P < 0.01) immediately after exercise. Glutathione peroxidase and glutathione reductase were not altered by exercise. Serum copper and magnesium were significantly increased (P < 0.01) after exercise...
Ryan D.Outbreaks of equine influenza (EI) cause major disruption to the racing industry, resulting in cessation of racing until affected horses have recovered from the disease. The introduction of EI to a large population of Thoroughbred horses stabled at a Sydney racecourse provided the opportunity to observe clinical signs and monitor the spread of EI in this predominantly naïve population and to assist in determining an endpoint to infection spread to allow resumption of racing events.
Faulkner J, Vanderperren K, Duchateau L, O'Sullivan C.Ascertain the radiographic prevalence and variation in characteristics of juvenile osteochondral conditions (JOC) in the proximal interphalangeal joint (PIPJ) of Australian Thoroughbred racehorse yearlings. Establish whether there are any significant associations with public auction sale results and racing performance. Unassigned: Retrospective evaluation of 1,098 yearling repository radiograph sets. Comparison of sales results and whole career racing performance of the case group with two control groups: maternal siblings ( = 397) and yearlings without PIP JOC ( = 391). Unassigned: 6.3% of ye...
Soma LR, Stefonovski D, Robinson MA, Tsang DS, Haughan J, Boston RC.A retrospective study was conducted to establish the prerace venous acid-base and blood gas values of Standardbred horses at rest using big data analytics. Methods: Venous blood samples (73,382) were collected during seven racing seasons from 3 regional tracks in the Commonwealth of Pennsylvania. Horses were detained 2 hours prior to race time. Methods: A mixed-effects linear regression model was used for estimating the marginal model adjusted mean (marginal mean) for all major outcomes. The interaction between age and gender, track, and the interaction between month, treatment (furosemide), a...
Blakely JA, Blakely AA.Veterinarians commonly predict mature heart scores for yearling and 2-year-old horses to aid clients in assessing a horse's racing potential. Sixty-six thoroughbreds were assessed as a yearlings or 2-year-olds, then re-assessed as a mature horse (over the age of 3). Of these horses, 82% of the yearlings and 87% of the 2-year-olds had a correctly predicted mature heart score within one heart score range (i.e. three points).
Zahra PW, Jayasinghe NS, Selvadurai NS, Willers SJ, Krsta D, Batty DC, Vine JH.Pre-race dosing of horses with alkalinising agents to manipulate performance has been evident in racing worldwide for over 30 years. To regulate the use of alkalinising agents, racing authorities adopted thresholds for total plasma carbon dioxide (TCO ) in racehorses. Traditionally, racing laboratories have measured plasma TCO using ion selective electrode (ISE) technology, with the Association of Official Racing Chemists (AORC) approving the use of only three ISE instruments for measurement. Because of the manufacture and support of these instruments ceasing, racing laboratories have explor...
Tobin T.In general, blood is the only material on which a practical pre-race testing scheme can be based. Blood testing is not as sensitive as urine testing and detects only about 66 per cent of the drugs detectable in urine. Therefore, pre-race blood testing is always performed in conjunction with post race urine testing. Because blood is easily and rapidly drawn, the use of blood samples in all post race testing schemes is recommended. Pre-race testing is also a relatively expensive proposition, but it is the only method which actually prevents the running of an illegally medicated horse.
Hillidge CJ, Whitlock TW.Post race endoscopy was carried out on 255 two-year-old quarter horses and exercise-induced pulmonary haemorrhage (EIPH) was diagnosed in 166 (65 per cent) of them. Visible epistaxis was seen in a higher proportion of geldings than in either mares or stallions. The prevalence of EIPH was similar in mares (73 per cent) and in geldings (74 per cent). A significantly lower prevalence (49 per cent) was noted in stallions (P less than 0.01). It was concluded that a sex variation in the prevalence of EIPH exists in two-year-old quarter horses.
O'Brien TJ, Rosanowski SM, Mitchell KD, Carrick JB, Butt TD, Adkins AR.There is little consensus on factors associated with survival in foals with septic arthritis and limited data on long-term racing performance of Thoroughbred foals treated for septic arthritis. A more thorough understanding of short- and long-term outcome is necessary to help inform owners, and subsequently guide treatment. Objective: To investigate factors associated with survival, and to analyse racing performance of foals with septic arthritis compared with their maternal siblings. Methods: Retrospective cohort and a case-control study. Methods: Veterinary clinical records of Thoroughbred f...
Milne FJ.FOR MANY YEARS, concern has been expressed at the wastage of young Thoroughbreds at the racetrack. This concern even manifested itself in the publication of a book (1) which referred to the prevailing practice of prematurely start-ing the racing career of the Thoroughbred long before it had attained sufficient maturity to engage in stiff, damaging competition. This is not a fault of the Thoroughbred industry alone, because in certain parts of the U.S.A., Quarter Horses less than two years of age are already racing. We could swing to the opposite extreme, of course, to the pleasure horse world ...
Harrison SM, Whitton RC, Stover SM, Symons JE, Cleary PW.Distal limb injuries are common in racing horses and track surface properties have been associated with injury risk. To better understand how track surfaces may contribute to equine limb injury, we developed the first 3D computational model of the equine hoof interacting with a racetrack and simulated interactions with model representations of 1) a dirt surface and 2) an all-weather synthetic track. First, a computational track model using the Smoothed Particle Hydrodynamics (SPH) method with a Drucker-Prager (D-P) elastoplastic material model was developed. It was validated against analytical...
Kabil E, Göktaş EF, Güneş E, Yatanaslan L, Zor TA, Tektaş MH, İnceman B, Tufan M.A recent trend in the use of high-resolution accurate mass screening (HRAMS) for doping control testing in both human and animal sports has emerged owing to significant improvement in high-resolution mass spectrometry in terms of sensitivity, mass accuracy, mass resolution and mass stability. Several HRAMS methods have been reported for the detection of multidrug residues in human or equine urine. These improved analytical technologies have led to changes in the use of prohibited substances, and the administration of more than one substance at low concentrations as a "cocktail" has become one ...
Guthrie AJ, Nichas E, Viljoen FV, Hartmann AM, Killeen VM.A case of sustained supraventricular tachycardia of unknown aetiology in a two-year-old Thoroughbred filly is reported. The cardiac dysrhythm was successfully treated by the oral administration of quinidine sulphate. Conversion of the dysrhythm to sinus rhythm occurred approximately 80 min after the initial dose of 5 g of quinidine sulphate. The horse returned to training approximately 2 months after treatment and has since successfully returned to racing.
Evans DL, Polglaze KE.The presence of abnormal T waves in three or more electrocardiographic leads has been used to diagnose the cause of poor race performance in horses. This study investigated the relationship between previous racing performance in Standardbred horses and T waves, and the effect of training on the T wave. Thirty-two horses were electrocardiographed in two Sydney racing stables. Sixteen horses (50%) had ECGs with three or more leads with abnormal T waves, and these horses had won more races, had a greater ratio of wins per start and a greater number of dollars earned per start than horses with les...
French jockeys suffer more severe injuries when they fall off their horses than their British counterparts. While it has been shown that jockeys suffer high rates of fatal and non-fatal injuries, little is known about differences in injury rates between countries. To investigate this, researchers from Australia, France and the UK used prospectively collected data on the rates of fatal and non-fatal injuries in flat and jump jockeys in France and compared them with data from the UK.
Ramzan PH.Fractures involving the fetlock region are encountered commonly in Thoroughbred racehorses. Condylar fractures of the distal metacarpus/metatarsus and mid-sagittal fractures of the proximal phalanx account for the majority of fetlock injuries during both racing and training and clinical features, management and outcome of these injuries have been well described. Transverse fractures of the distal diaphysis of the third metacarpus, however, are seldom observed and have received little attention in the literature. This paper describes clinical and radiological findings associated with 6 cases en...
Deane NJ, Davies AS.A photographic study of the angles of 71 carpal joints of horses at the end of a race has shown that overextension of the joint is normal at this stage. Further study is needed to determine the factors which may influence hyperextension, and whether they are relevant to carpal injury.
Vickers KL, Ross MW.A 4-year-old sexually intact male Standardbred trotter was evaluated for left forelimb lameness. A presumptive diagnosis of severe cartilage damage was made because the horse had a history of infectious arthritis involving the left metacarpophalangeal joint. Arthroscopic evaluation revealed what was presumed to be a large villonodular lesion. The mass was surgically removed, and the horse was treated with procaine penicillin G, trimethoprim-sulfamethoxazole, phenylbutazone, and polysulfated glycosaminoglycans and eventually returned to racing. Histologic examination of the mass revealed a bed ...
Manohar M, Goetz TE, Hassan AS.Recently, it was reported that acute hypervolemia improves arterial oxygen tension in human athletes known to experience exercise-induced arterial hypoxemia. Since exercise-induced arterial hypoxemia is routinely observed in racehorses and is known to limit performance, we examined whether pre-exercise induction of acute hypervolemia would similarly benefit arterial oxygenation in maximally exercising thoroughbred horses. Two sets of experiments, namely, placebo [intravenous (IV) physiological saline] and acute hypervolemia (IV 7.2% NaCl, causing an 18.2% expansion of plasma volume) studies we...
Speirs VC, Anderson GA, Bourke JM.The efficacy of treating carpal lesions by arthrotomy was evaluated in 210 Thoroughbred racehorses, using survival analysis to compare their racing performances and earnings with those of 840 control horses. The treated horses were significantly inferior with respect to races contested, and wins plus places (P less than 0.001) and races won (P less than 0.01). There was no difference with respect to earnings (P less than 0.1); after adjusting for other factors, arthritis, site of fracture and presence of a displaced chip had no effect on racing performance in horses with a single-site lesion i...
Tozaki T, Miyake T, Kikuchi M, Kakoi H, Hirota KI, Kusano K, Ishikawa Y, Nomura M, Kushiro A, Nagata SI.Thoroughbred racehorses are produced by mating small numbers of Arabian stallions and native British mares, and have been improved by selection of horseracing performance for about 300 years. While these improvements led to good performance as racehorses, they exposed horses to numerous medical disorders, aggravated by extensive exercise. Fractures are frequent medical disorders in Thoroughbred racehorses. In this study, fracture heritability was estimated using 3,927 Japanese Thoroughbred racehorses to elucidate the risk of racehorse fractures. The heritability estimates of all examined frac...
Spurlock GH, Gabel AA.One-hundred and nine apical fractures of the proximal sesamoid bones were diagnosed in Standardbred racehorses at the Ohio State University Veterinary Hospital during a 5-year period ending December 1978. Lateral sesamoids of the hindlimbs accounted for 61 of the 109 fractures, which was a significantly (P less than 0.05) greater proportion than that for fractures in all other sesamoid bones. Two- and three-year-old horses accounted for 73 of the 109 apical sesamoid fractures. The remaining 36 apical sesamoid fractures were in horses 4 to 9 years old. The apical fragment was removed in 80 of t...
Shimozawa K, Ueno Y, Ushiya S, Kusunose R.Medical and racing records of 155 Thoroughbred racehorses that underwent arthroscopic surgery for carpal chip fractures were investigated. Articular damage for 98.4% of the fractures was classified as G1 or G2 using McIlwraith's criteria. The rate of return to racing after surgery was 82.6%. Evaluation of racing performance after surgery was attempted using a placing index (PI) based on race finish position. There was no significant difference in the PI distribution between horses that underwent surgery and other healthy horses.
Kraus BM, Ross MW, Boswell RP.Two 2-year-old pacers, a 3-year-old pacer and a 2-year-old-trotter with acute forelimb lameness were admitted for nuclear scintigraphic examination. Horses were grade 3-4/5 lame. There was increased radiopharmaceutical uptake (IRU) in the distal cranial medial aspect of the humerus in one horse and along the caudal humeral cortex in the other three horses. Two of the four horses were affected bilaterally. Radiographic abnormalities consisted of thickening of the caudal cortex of the mid-diaphysis of the humerus but radiographic changes were not present in all horses. All horses were managed wi...
