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.
Zebarth BJ, Sheard RW.The 2 dominant processes involved in the horse hoof-to-racing surface interaction are the shock loading of the horse's leg upon impact with the racing surface and rotation of the horse's hoof into the racing surface. These processes were measured as impact resistance (ie, the peak deceleration of a moving body upon impact with the test surface) and as resistance to shear. The objective of the present study was to measure physically (under a variety of conditions) those soil and turf factors related to the 2 processes. It was concluded that thatch accumulation and mowing height of the turf did ...
Soma LR, Sams R, Duer W, Tobin T, Woodward C, McDonald J.The plasma and serum concentrations of phenylbutazone (PBZ) and oxyphenbutazone were measured in 158 Thoroughbred horses after various doses of PBZ wer given. All horses were competing or training at racetracks in various parts of the country. All horses used in the study had not been given PBZ 24 hours before they were placed on a specific dosage schedule. Samples were collected 24 hours after the last PBZ administration. Four grams of PBZ were given daily by stomach tube, paste, or tablet for 3 days. On day 4, 24 hours before sample collection, an IV dose of 2 g of PBZ was given, regardless ...
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...
Markel MD, Richardson DW.In a retrospective study, we examined the case records for 69 horses with noncomminuted fractures of the proximal phalanx, excluding proximal chip fractures. Forty-nine of the horses sustained the fracture while racing or training for racing. Radiographic examination of all affected limbs was performed, and fractures were classified into 6 noncomminuted types: midsagittal fractures, including short incomplete midsagittal fractures, long incomplete midsagittal (LIMS) fractures, and complete midsagittal (CMS) fractures; dorsal frontal fractures; distal joint fractures; plantar process fractures;...
Burrell MH.A group of racehorses in training was examined on several occasions with a fibreoptic endoscope and monitored for viral infection. Only equine herpes virus-2 (EHV-2) infection was detected. Pharyngeal lymphoid hyperplasia (PLH) was present in all horses and decreased in severity with age. There was no association between PLH severity and antibody titres to EHV-1, or with the isolation of EHV-2. Finishing position in races was not affected by PLH severity. Exercise induced pulmonary haemorrhage (EIPH) was evident on 23 out of 49 (47 per cent) examinations after maximal speed training exercise. ...
Kent JE, Blackmore DJ.The turbidimetric analysis of IgG(T) in the serum of horses is described. Reference values are provided for 'worm-free' ponies (2.6 +/- 0.7 g/litre), stabled Thoroughbreds two years old and over (4.1 +/- 1.3 g/litre), grazing Thoroughbred broodmares (7.1 +/- 2.4 g/litre) and regularly wormed adult and young ponies grazing pasture contaminated with intestinal parasite eggs and larvae.
Saibene F, Cortili G, Gavazzi P, Sala A, Faina M, Sardella F.Blood lactate concentrations were determined in 16 horses (three Thoroughbreds, seven Standardbreds and six polo ponies) before and 5 mins after they galloped over distances of 200, 300 and 400 m at maximal speed. The highest net lactate concentration (delta Lamax) of 14 to 15 mmol/litre was attained by the polo ponies and the highest speed by the Thoroughbreds. The maximal rate of lactate production (delta Låmax) was about 35 mmol/litre X min for the polo ponies and 20 to 25 mmol/litre X min for the Standardbreds and the Thoroughbreds. Values for delta Lamax and delta Låmax were similar to ...
Lyons ET, Tolliver SC, Drudge JH, Swerczek TW, Crowe MW.A total of 89 Thoroughbreds, 14 to 333 days old (born in 1982), were examined at necropsy for certain internal parasites during a 1-year-period, Mar 1, 1982, to Feb 28, 1983. The eyes of 73 of the horses and the cranial mesenteric arteries of 71 were examined. Specific interest was on prevalence of parasites according to month of the year and age of the horses at necropsy. Parasites recovered (first month-last month infected horse found) were as follows: Thelazia lacrymalis (eyes) immature and mature (June - February); Habronema/Draschia (lungs) immature (May - September); Habronema muscae (st...
An outbreak of equine viral arteritis in the American state of Kentucky led to a temporary ban being imposed by France, Ireland and the UK on the importation of horses from the USA during 1984. Sporadic cases of influenza caused by the type 2 strain of the virus were confirmed in France throughout the year and cases of strangles in thoroughbred mares and foals were reported from all three countries. No cases of contagious equine metritis were confirmed among the thoroughbred breeding population, although a number of outbreaks of the abortion form of rhinopneumonitis occurred. A small number of...
Matsui K, Amada A, Sawazaki H.Electrocardiographic observation in 10 Thoroughbred horses has been carried out from fetal stages to 12 months after birth. In this observation a filly out of 10 foals at a resting state showed second-degree atrioventricular {A-V) block with sinus arrhythmia after 2.5 months of age. The number of dropped beats and the irregularity of sinus arrhythmia in these blocks were affected by the atrial rate, and several variations of Wenckebach phenomenon were shown under the influence of the artial rate. Electrocardiographic characteristics of second-degree A-V block in the present filly might be simi...
Rossdale PD, Hopes R, Digby NJ, offord K.An epidemiological study of wastage among racehorses was conducted in 1982 and 1983 among six stables, five of which were in Newmarket. The basis of the survey was the inability of horses to take part in cantering exercise as a result of injury or disease. The greatest number of days lost to training was caused by lameness (67.6 per cent) and respiratory problems (20.5 per cent). Conditions of the foot (19 pe cent), muscle (18 per cent), carpus (14 per cent), fetlock joints (14 per cent), tendons (10 per cent) and sore shins (9 per cent) were the major reasons for training days being lost in 1...
Glade MJ, Reimers TJ.The effects of meal ingestion on the circulating concentrations of the growth-regulating hormones thyroxine (T4), tri-iodothyronine (T3) and insulin were examined in weanling Thoroughbreds fed 70% (diet A), 100% (diet B) or 130% (diet C) of their energy and protein requirements. Peak insulin concentrations occurred 1, 2 and 3 h after the ingestion of diets C, B and A respectively. Increases in plasma glucose concentrations preceded the increases in serum insulin concentrations. Serum T4 concentrations increased after the ingestion of diets A and B and decreased after diet C. In contrast, serum...
Knezevic PF, Fessl L.Thrombosis of the aorta as the cause of intermittent claudication in the horse appears to be rare. Two cases out of about 10 000 horses 1973-1984 are discussed. There are various views on its aetiology, whereby haemodynamic factors and disturbances of coagulation have been mentioned as well as parasites. For treatment surgical methods should be explored in addition to medical procedures. History, diagnosis and the attempt of an aortic thrombectomy in a 12 year old thoroughbred mare are described in this paper. A standardbred stallion was left untreated on owners wish.
Trommershausen Bowling A, Clark RS.Gene frequencies at 20 blood group and protein polymorphism loci (A, C, D, K, P, Q, U, Al, Tf, Pi, Xk, Es, Gc, PGD, CA, Cat, PGM, AP, Hb and PHI) are given for seven horse breeds in the United States (Thoroughbred, Arabian, Standardbred, Morgan, Quarter Horse, Paso Fino and Peruvian Paso). These data are used to calculate that the battery of tests is at least 96% effective for recognizing incorrect paternity in these breeds. In addition to paternity testing, these tests can be applied to studies of breed relationships.
Magnuson NS, Perryman LE, Mason PH, Marta KM.A microassay requiring as few as 2 X 10(5) cells per assay was developed for systematic analysis of 9 purine enzymes in lymphocytes from equine peripheral blood, spleen, lymph node, thymus and bone marrow. The activities of adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), adenosine kinase (AK), deoxyadenosine kinase (dAK), deoxycytidine kinase (dCK), 5'-nucleotidase (5'-N), AMP deaminase, hypoxanthine-guanine phosphoribosyl transferase (HGPRT or HPRT), and adenine phosphoribosyl transferase (APRT) were measured by this microassay in lymphocytes from peripheral blood from four ...
Wooden GR, Crane CS, Beisel CG.The objective of this study was to determine the effect of Hesperidin Complex and Lemon Bioflavonoid Complex (HC/LBC) on the growth and development of thoroughbred horses. The trial involved twenty-four foals (12 colts, 12 fillies) allotted to treatment shortly after weaning. The study was conducted for a 342-d growing phase and a 153-d training phase, or a total of 495-d. The HC/LBC was included in the test diet at a level calculated to supply the compound at 55 mg X kg body weight-1 X d-1. During the growing phase, average daily gain of colts that received HC/LBC was higher (P less than .05)...
Chay S, Woods WE, Nugent TE, Weckman T, Houston T, Sprinkle F, Blake JW, Tobin T, Soma LR, Yocum J.Experiments to determine the residual plasma concentrations of phenylbutazone and its metabolites found in horses racing on a 'no-race day medication' or 24-h rule were carried out. One dosing schedule (oral-i.v.) consisted of 8.8 mg/kg (4 g/1000 lbs) orally for 3 days, followed by 4.4 mg/kg (2 g/1000 lbs) intravenously on day 4. A second schedule consisted of 4.4 mg/kg i.v. for 4 days. The experiments were carried out in Thoroughbred and Standardbred horses at pasture, half-bred horses at pasture, and in Thoroughbred horses in training. After administering the i.v. schedule for 4 days to Thor...
van Aarde MN, Littlejohn A, Van der Walt JJ.A method was developed for determining the ratio of cardiopulmonary blood volume to stroke volume, in horses. The radioisotope 99 Tc (technetium 99m pertechnetate) was injected into the jugular vein as a bolus, which was then detected in the right and left ventricles consecutively by a scanning device consisting of a Na I crystal, a collimator, an amplifier and a discriminator. The radiocardiogram (RCG) and the ECG were recorded simultaneously by a two-channel writing device. The ratio of cardiopulmonary blood volume to stroke volume (cardiopulmonary flow index = CPFI) was then determined from...
Richardson DW.Fifteen longitudinal fractures involving the medial condyle of the third metatarsal bone were diagnosed in racing Thoroughbreds and Standardbreds. Twelve were repaired surgically with lag screws placed through stab incisions. Two of the horses suffered catastrophic fracture of the third metatarsal bone during recovery from anesthesia, and 3 more sustained complete fractures within 4 days of the repair. Of 3 horses with fractures treated without surgery, 2 healed without complication. Preoperative radiography did not demonstrate a nonlongitudinal fracture component in any of the horses that sus...
Bailey E.Lymphocyte typing can be used to detect incorrectly identified parentage of horses. Efficacies of lymphocyte typing to solve paternity questions were calculated using gene frequency estimates of equine lymphocyte antigen (ELA) markers for Thoroughbreds and Standardbreds. Probabilities that ELA typing will detect an incorrectly assigned sire were 68.7% in Thoroughbreds, 67.9% in pacing Standardbreds, and 62.0% in trotting Standardbreds. These calculations demonstrate that ELA typing is among the most efficacious genetic systems for solving paternity questions in horses. Likewise, it could also ...
Mason DK, Collins EA, Watkins KL.An investigation into the incidence of exercise induced pulmonary haemorrhage (EIPH) in thoroughbreds in Hong Kong was carried out between the 1981 and 1983 racing seasons. A total of 1039 post race endoscopic examinations were performed in 1982-1983 and the results indicated that 46.8 per cent of runners had EIPH. This was not statistically different from the percentage of horses showing EIPH during 1981-82 (46.9 per cent). As it had been postulated that dust, especially from straw, could be implicated in lung haemorrhage a proportion of horses were bedded on paper in the 1982-83 season. No s...
Bertone AL, Powers BE, Turner AS.An aged Thoroughbred stallion was examined because of progressive lameness, carpal swelling, and weight loss. Radiography revealed a destructive lesion in the caudomedial, distal portion of the radius. Chondrosarcoma was diagnosed by tumor-core biopsy. Gross and histologic evaluation of the neoplasm after necropsy revealed a locally invasive chondrosarcoma at the distal end of the radius that infiltrated the radiocarpal joint capsule and invaded the carpal bones. The malignant nature of this tumor was evident by its invasiveness and histologic features of cell pleomorphism and presence of mito...
Glade MJ, Gupta S, Reimers TJ.Growth-related skeletal diseases in young horses have been associated with high planes of nutrition, although the mechanisms underlying such an association have not been determined. It is likely that nutrition-induced effects on growth rate or growth quality involve the endocrine system. Hormonal and metabolic responses to the ingestion of meals containing either 80% (diet A) or 160% (diet B) of National Research Council energy and protein recommendations were examined in eight Thoroughbred weanling horses after 3 wk of dietary adaptation. After 24 h fasts, prefeeding serum concentrations of t...
Bayly WM, Grant BD, Breeze RG.Arterial blood gas and acid-base values during maximal exercise over a 1.2 km distance were recorded in four Thoroughbred horses before and after the chemical induction of pharyngeal lymphoid hyperplasia (PLH). Samples were collected after galloping 0.8 km and 1.2 km, immediately upon stopping and 5 mins after exercising. In only one horse was any difference noted in the pre and post PLH induction results. The horse was more hypercapnoeic at the 1.2 km mark and also took much longer to complete the gallop when it had PLH. However, it also had signs of lower respiratory disease. In the other ho...
Amis TC, Pascoe JR, Hornof W.The regional distribution of ventilation to perfusion ratios (VA/Q) in the lungs of 8 healthy standing Thoroughbred geldings (4.4 +/- 1.5 years, 465.7 +/- 46.6 kg) was studied, using steady-state inhalation and IV infusion of the radioactive gas krypton-81m. The VA/Q was uniformly distributed within a vertical lung strip centered over the 9th rib on the right side. Ventilation per unit of alveolar volume (V/VA) assessed from the clearance of inhaled radioactive gas in 5 horses increased from 0.49 +/- 0.13 (arbitrary units) in nondependent lung zones to 1.45 +/- 0.16 in dependent lung zones. Se...
Hobo S, Hiraga A, Birks EK, Takahashi T, Hada T, Jones JH.A study was undertaken to find if the reason why horses hypoventilate when running is that they experience expiratory flow limitation due to dynamic airway closure. To test this hypothesis, we measured peak expiratory flows on a Thoroughbred galloping on a treadmill and hypoventilating and compared those flows with the peak dynamically-limited flow that the same horse could achieve during a forced expiratory flow-volume manoeuvre. At the approximate lung volumes at which the horse was ventilating while running, it did not appear to be mechanically limited and appeared to have reserve capacity ...
Collins EA.Four cases of equine lameness were treated with intra-articular polysulphated glycosaminoglycan. Two, two-year-old flat racers were treated conservatively after traumatic injury. They subsequently became lame owing to the formation of new bone and osteophytes. Two older steeplechasers were lame owing to degenerative joint disease. The four horses were treated with intra-articular injections of polysulphated glycosaminoglycans and, after three or four injections, they became clinically sound and were able to continue racing with varying degrees of success.
Pye J, Spriet M, Dow P, Katzman S, Murphy BG.To describe clinical, imaging, gross, and histopathological abnormalities associated with osteochondral necrosis of the femoral condyles in foals and identify features suggestive of a common pathogenesis. 8 Thoroughbred foals euthanized with a presumptive diagnosis of necrosis of the femoral condyles. Postmortem CT was performed on all distal femoral epiphyseal samples. The articular epiphyseal cartilage complex (AECC) of affected distal femurs was examined grossly and histologically, focusing on lesions of interest identified on CT images. 7 foals were between 9 and 23 days old at the time of...
Valdes-Martinez A, Eades SC, Strickland KN, Roberts ED.We describe the echocardiographic findings in a 4-day-old thoroughbred foal with an aortico-pulmonary septal defect. The foal had labored breathing, cyanotic mucous membranes and a continuous grade 5/6 heart murmur with point of maximal intensity over the base of the heart on the right side. Echocardiographically, there was a large communication between the aorta and the pulmonary artery just dorsal to the base of the heart. The cardiac anomaly seen during the echocardiographic exam was confirmed at necropsy where a large communication between the two great vessels was observed. These findings...
Lyons ET, Tolliver SC, Drudge JH, Swerczek TW, Crowe MW.From Mar 1, 1984, to Feb 28, 1985, both eyes from 189 one- to four-year-old Thoroughbreds (88 males, 90 females, and 11 geldings) in Kentucky were examined at necropsy for eyeworms. Thelazia lacrymalis was recovered from 45% of 1-year-old horses, 26% of 2-year-old horses, 45% of 3-year-old horses, and 50% of 4-year-old horses; overall, 43% of 1- to 4-year old horses were infected. Prevalence of eyeworms in horses in the present study was comparable with that in horses of similar ages examined at necropsy in Kentucky in 2 previous studies (1975 to 1976 and in 1979), except for the lower percent...
Wiemer P, Ugahary F.A 6-year-old trotter gelding presented with exercise intolerance and swelling of the left side of the head during exercise and grazing. The complaints were caused by a complete thrombosis of the left jugular vein. In this case report a surgical approach is described in which a bypass was created with a synthetic vascular graft. After treatment the horse was capable of racing at his former level. The patency of the synthetic graft was 11 months.
Gunn AJ.This study involves the case of a young Thoroughbred filly who exhibited symptoms like reluctance to stand and vulva hemorrhagic discharge. The physical examination revealed normal physiological parameters, but an […]
Chu KK, Cohen ND, Stanley SD, Wang N.To estimate the probability of concurrently exceeding thresholds for plasma concentration of furosemide and urine specific gravity after IV administration of furosemide in horses. Methods: 12 mature healthy Thoroughbred (n = 6) or Quarter Horse (6) mares. Methods: Venous blood was collected from each horse prior to and 0.25, 0.5, 0.75, 1, 2, 3, 4, 4.5, 5, and 6 hours after IV administration of 250 mg (first experiment) or 500 mg (second experiment) of furosemide. Urine was collected hourly between 1 and 6 hours after administration of furosemide at both doses. Concentrations of furosemide were...
Sugiyama F, Takahashi Y, Nomura M, Ebisuda Y, Mukai K, Yoshida T.We investigated the risk factors for epistaxis in Japanese flat races over a 20-year period. The veterinary records of horses identified as having epistaxis by endoscopy on the race day, and the official racing records of all flat races from April to September between 2001 and 2020, were reviewed. The racecourses (n = 10), surface type, surface condition, race class, race distance, race year, sex, age, two training centers, ambient temperature, and body weight on race days were assessed using multivariable logistic regression (p < 0.05). Of 475,709 race starts, 616 (1.30 cases per 1000 starts;...
Rapezzano G, Foote A, Petrini F, Pereira R, Marcatili M.A newborn Thoroughbred filly presented with a large mass located on the ventro-rostral aspect of the mandible. The mass was surgically removed under general anaesthesia. Upon gross examination, the mass was well circumscribed with a heterogeneous lobulated appearance. The results of histopathology and immunohistochemistry were consistent with a diagnosis of congenital fetal rhabdomyoma. On follow-up at six months post-surgical excision, no abnormalities were noted on clinical examination.
Watanabe M, Sato F, Innan H.We investigated the changes in inbreeding levels in Japanese Thoroughbred horses over the past 46 years. Our results show a significant increase in inbreeding over the past 30 years, primarily due to the influence of two sires, Northern Dancer and Sunday Silence. Northern Dancer's bloodline spread gradually through descendants like Northern Taste, leading to a slower increase in the inbreeding coefficient. In contrast, Sunday Silence was directly imported and became a leading sire, causing a rapid increase in his blood proportion and inbreeding coefficient. Our findings suggest that monitoring...
Katano Y, Imai S.The effects of dipyridamole on thromboxane A2 formation by horse platelet microsomes were studied in comparison with those of imidazole, a prototype inhibitor of TXA2 synthetase and nifedipine, a calcium antagonistic vasodilator. Thromboxane A2 was synthesized by incubating PGH2 with horse platelet microsomes and was assayed on the superfused rabbit aorta. Dipyridamole induced as strong an inhibition of TXA2 synthesis as imidazole, while nifedipine was without effects. The possible beneficial clinical outcomes of this effect of dipyridamole are discussed.
Ikeda Y, Kuroda T, Mita H, Tamura N, Ohta M.We compared the antihistamine effect of four new antihistamines with olopatadine, which is used to treat equine allergic diseases. Six healthy Thoroughbred horses received oral doses of olopatadine (50 mg), levocetirizine (50 mg), bilastine (200 mg), rupatadine (100 mg), and desloratadine (50 mg) at >2-week intervals. The effects were investigated by measurement of the wheal area induced by histamine intradermal injection, and inhibition rate was compared with positive and negative controls. The maximum wheal inhibition rate (mean ± SD) of olopatadine (85.3% ± 7.7%) was significantly higher ...
Schaaf KL, Kannegieter NJ, Lovell DK.A Thoroughbred horse with bilateral laryngeal dysfunction was treated by placement of a long term tracheal cannula in order to restore full athletic function. The horse initially presented with right-sided arytenoid dysfunction that was considered to be due to a congenital malformation of the laryngeal cartilage. This was corrected by a right-sided laryngoplasty and ventriculectomy. The horse re-presented 1 year later with idiopathic left laryngeal hemiplegia. The decision was made to place a long-term tracheal cannula due to the low success rate and high complication rate associated with othe...
Bozzola C, Stucchi L, Sala G, Schinardi L, Stancari G, Zucca E.Pulmonary Artery Stiffness (PAS) is a non-invasive echocardiographic index of pulmonary artery elasticity. In horses, PAS has been measured only from the right parasternal short-axis view, while the influence of alternative imaging windows remains unknown. Objective: To assess the repeatability and reproducibility of Acceleration Time (AT), Maximal Frequency Shift (MFS), and PAS measurements from the left parasternal angled view of the right ventricular inflow/outflow, and to compare these parameters with those obtained from the right parasternal short-axis view in Thoroughbred racehorses. Met...
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 ...
Díaz S, Dulout FN, Peral-García P.Genetic polymorphism was analyzed for five blood proteins: albumin - Al, esterase - Es, alpha(1)B-glycoprotein - Xk, transferrin - Tf and hemoglobin - Hb in 200 Thoroughbred (TB) and 124 Argentine Creole (AC) horses. Of the five systems examined, Tf and Hb were not in Hardy-Weinberg equilibrium in either breed and Es was not in equilibrium in the Creole breed. Genetic variability, estimated as average heterozygosity, was higher in AC (H = 0.585 +/- 0.131) than in TB (H = 0.353 +/- 0.065). The genetic differentiation between these two populations (F(ST)) was 0.109. Thus, of the total genetic di...
McClure JJ, Koch C, Powell M, McClure JR.Associations were sought between ELA A1-A10 and W11 antigens and the presence of laryngeal hemiplegia, arytenoid chondritis, umbilical hernias and cryptorchidism in Thoroughbreds and/or Quarter Horses. No significant associations were detected between laryngeal hemiplegia and any ELA antigen in Thoroughbreds. The association between arytenoid chondritis and A9 was significant with a relative risk (RR) of 15.6 and aetiologic fraction (EF) of 0.80 in Thoroughbreds. There were apparent associations based on RR between A4 and A5 in Quarter Horses with umbilical hernias (RR = 7.5 and 6.1 respective...
Andruskevich SM, Perry P, Houpt K, Houpt TR.The objectives were to measure changes in fluid balance of mares at parturition and relate those changes to the foals' acquisition of passive immunity. Twelve Thoroughbred mares and their foals were observed for suckling behavior for the first 12h post-partum. The mare's water intake, packed cell volume, plasma protein concentration, and plasma osmolality were measured pre- and post-partum. The foals' immunoglobulin concentrations were measured at birth and 24h later. The median increase from pre- to post-foaling in mares' packed cell volume was 4.0% (interquartile range=0.3-6.8). The median i...
Sharma S, Davies Morel MC, Dhaliwal GS, Dadarwal D.Ultrasonographic pregnancy records of 195 mares from six Thoroughbred stud farms, over a period of 7 years were retrospectively analysed to assess the effect of various factors on embryonic vesicle (EV) fixation pattern and pregnancy outcome. Of the total of 746 pregnancies analysed, significantly (p < 0.01) more EV fixations were evident in the right uterine horn than in the left (53.35% vs 46.65% respectively). There was no significant effect of either, the side of ovulation, or age of the mare, on the side of EV fixation. However, EV fixation, was significantly (p < 0.001) more likely...
Tulleners EP.Fifty-seven Standardbred and 44 Thoroughbred racehorses and 1 Thoroughbred polo mare with primary clinical signs of exercise intolerance or respiratory tract noise or combined exercise intolerance and respiratory tract noise were referred for laser correction of epiglottic entrapment. Significantly (P less than 0.001) more Standardbred than Thoroughbred racehorses were affected, compared with the observed hospital population during the same period. At referral, 14 horses did not have evident epiglottic entrapment and were returned to exercise without development of entrapment after treatment, ...
Knych HK, Arthur RM, Stanley SD, McKemie DS.In order to ensure the welfare of performance horses and riders as well as the integrity of the sport, the use of both therapeutic and illegal agents in horse racing is tightly regulated. While Dehydroepiandrosterone (DHEA) is not specifically banned from administration to racehorses in the United States and no screening limit or threshold concentration exists, the metabolic conversion of DHEA to testosterone make its presence in nutritional supplements a regulatory concern. The recommended regulatory threshold for total testosterone in urine is 55 and 20 ng/mL for mares and geldings, respec...
McKenzie RK, Gibson IR, Ritmeester A.Three weanling Thoroughbred fillies were presented during autumn with depression, muscle rigidity and, in one case, colic symptoms and cardiovascular shock. Results: All fillies had abnormal physical examinations that included elevated heart rates and respiratory rates coupled with muscle rigidity through the back and rump. Biochemistry revealed markedly elevated creatinine kinase and aspartate aminotransferase which indicated a myopathy. Methods: All three horses were diagnosed with presumptive equine atypical myopathy. The horses received supportive therapy as per the literature available at...
Deaton CM, Brown-Feltner H, Henley WE, Roberts CA, Lekeux P, Schroter RC, Marlin DJ.Pulmonary capillary stress failure, largely as a result of high pulmonary vascular pressures, has been implicated in the aetiology of EIPH. However, the role of the respiratory system in determining the magnitude of EIPH has received little attention. Objective: Horses breathing a gas of greater density than air will exhibit greater transmural pulmonary arterial pressures (TPAP) and more severe EIPH, and horses breathing a gas of lower density than air will exhibit lower TPAP and less severe EIPH, both compared with horses breathing air. Methods: Following a warm-up, 8 Thoroughbred horses were...
Smith HL, Rosenblatt AJ, Suen WW, Owen H, Ahern BJ.A 6-week-old Thoroughbred filly was presented for evaluation of an expansile mass overlying the right nasal passage and causing respiratory stertor. On skull radiographs, there was a loculated, soft tissue-opaque mass identified dorsal to the right upper premolars and effacing the right nasal cavity. Computed tomography (CT) revealed a locally extensive mass with relatively benign characteristics located centrally on the tooth root apices of the deciduous second premolar (506). The mass extended axially into the right nasal cavity, occluding the meatuses and causing displacement of the nasal s...
Staempfli SA, Saied A, Wakamatsu N, Serra V, Eades SC.A 5-day-old Thoroughbred colt was presented with profuse watery diarrhea, hypovolemic shock, and a patent urachus. Despite intensive medical therapy, the colt was euthanized 15 d later due to poor clinical response. Necropsy revealed a small intestinal structural abnormality that formed a closed jejunal ring. Although rare, intestinal malformations should be considered in neonatal foals with clinical signs resembling enteritis. Entérite septique résistante au traitement causée par une malformation jéjunale chez un poulain Thoroughbred âgé de 5 jours. Un poulain Thoroughbred âgé de 5 jo...
Tabar-Rodriguez JJ, Cruz AM, Monteith G, Gordon K, Hurtig MB.OBJECTIVE-To use quantitative ultrasonography to evaluate the association between the speed of sound (SOS) at 9 sites in the third metacarpal bone (MCIII) of racing Thoroughbreds with workload accumulation and the effect that MCIII failure has on this association. ANIMALS-Sixty-two 2- and 3-year-old Thoroughbreds in racing condition. PROCEDURES-Cumulative work index (CWI) was used to calculate total workload (CWI(total)) and also 3 independent CWIs for the various gaits (ie, trot [CWI(trot)], gallop [CWI(gallop)], and race [CWI(race)]) used during training and racing. Speed of sound was monito...
Arthur RM.Racetracks are ideal environments for the promotion of lower respiratory disease. The stabling is close and unclean, the population is nationally and internationally mobile, and the work the racehorse performs is traumatic to the respiratory tract. The running horse must complete a respiratory cycle with each stride. This relationship requires 130-150 breaths a minute in the running horse. Minute volume has been measured at 1300 L per minute and peak flow rates of 60 L/second in horses traveling at a modest 8 meters per second. As a comparison, the fastest running horse approaches 18 meters pe...
Moorthy AR, Spradbrow PB.Mycoplasmas were isolated from two of 43 nasal swabs taken from live horses, and from one of 28 tracheal swabs taken from slaughtered horses. The slaughtered horse that yielded mycoplasmas had no gross pathological changes in the respiratory tract, but the nasal isolations were made from horses with rhinitis. The three mycoplasmas could be distinguished by cultural characteristics, and probably they represent three different species.
