Topic:Thoroughbreds
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.
Equine ehrlichiosis in northern California: 49 cases (1968-1981). Case records of horses with equine ehrlichiosis (Ehrlichia equi) at the University of California Veterinary Medical Teaching Hospital and Ackerman Creek Large Animal Clinic were analyzed for evaluation of clinical signs, time of onset, hematologic values, response to treatment, and recovery. Equine ehrlichiosis was found to be seasonal in horses in the foothills of northern California, with higher incidence than reported previously. The horses developed fever, anorexia, depression, limb edema, icterus, and ataxia. Hematologic changes were leukopenia, thrombocytopenia, icterus, anemia, and incl...
Compression bone plating of a medial condylar fracture of the third metatarsal bone in a Thoroughbred filly. A medial condylar fracture of the third metatarsal bone in a 2-year-old Thoroughbred filly was repaired successfully by use of compression bone plating. At discharge from the hospital, thickening of the metatarsus was evident, and proliferative changes were associated with the site of bone plate application. It was expected that these changes would limit the filly's use as a racehorse, and a return to training was not recommended. Especially in horses that may return to racing, use of compression bone plating initially should not replace stall rest or lag screw fixation treatment of this type ...
Prevalence of internal parasites in horses in critical tests of activity of parasiticides over a 28-year period (1956-1983) in Kentucky. The prevalence and number of naturally acquired gastrointestinal parasites were compiled for horses used in critical tests of activity of parasiticides over a 28-year period (1956-1983). Data are presented as follows: n = number of horses examined; % = mean prevalence; number in parentheses after % = aggregate mean number of parasites in infected horses. Parasites found were: bots (n = 513) - Gasterophilus intestinalis, 2nd instar, 61%(58); 3rd instar, 94%(168); G. nasalis, 2nd instar, 36%(28); 3rd instar, 81%(51); stomach worms (n = 200) - Habronema muscae, 65%(179); Draschia megastoma, 29%(9...
Common internal parasites found in the stomach, large intestine, and cranial mesenteric artery of thoroughbreds in Kentucky at necropsy (1985 to 1986). A total of 278 Thoroughbreds (less than 1 to 31 years old) were examined at necropsy (July 9, 1985, to Feb 2, 1986) in Kentucky for various internal parasites. Examination was not made of all the horses for each of the parasites. Specific parasites recovered from the stomach of foals (n = 30) and yearlings and older horses (n = 96) and percentage (in parentheses) of each age category infected, respectively, were as follows: Gasterophilus intestinalis 2nd instar (53% and 32%) and 3rd instar (37% and 24%); G nasalis 2nd instar (7% and 8%) and 3rd instar (7% and 10%); Habronema spp immature (7% a...
Frequencies of plasma protease inhibitor alleles in Australian horse breeds and the recognition of two new alleles. Investigation of the plasma protease inhibitor system (Pi) in the Arabian and quarter horse breeds and re-examination of the standardbred breed resulted in the recognition of two new Pi alleles, designated E and L2. PiE is rare and has been found in only three quarter horses. In contrast, PiL2 is relatively common in the standardbred (0.107) and allowed subdivision of PiL into PiL and PiL2. Splitting of PiL resulted in an exclusion probability (PE) of 0.649 for the standardbred Pi system. Frequencies of the Pi genes have now been determined for four breeds (thoroughbred, standardbred, quarter ...
Formation of acetylcarnitine in muscle of horse during high intensity exercise. To study the changes in carnitine in muscle with spring exercise, two Thoroughbred horses performed two treadmill exercise tests. Biopsies of the middle gluteal were taken before, after exercise and after 12 min recovery. Resting mean muscle total carnitine content was 29.5 mmol.kg-1 dry muscle (d.m.). Approximately 88% was free carnitine, 7% acetylcarnitine and acylcarnitine was estimated at 5%. Exercise did not affect total carnitine, but resulted in a marked fall in free carnitine and almost equivalent rise in acetylcarnitine. The results are consistent with a role for carnitine in the regu...
Consequence of excess iodine supply in a Thoroughbred stud in southern Brazil. Excessive iodine supply of at least 700 mg inorganic iodine in foals and of more than 350 mg iodine in pregnant and lactating mares cause a high incidence of goitres in the newborn and disorders in the long leg bones of foals. Elevated phosphorus and alkaline phosphatase content in the blood may indicate a severe disturbance in the bone metabolism. Of 39 pregnant mares 17 aborted and some of the mares also showed goitres. After withdrawal of the iodine supply normalization took place. Foals born more than 6 weeks later showed normal conditions. The goitres in the mares and the high blood level...
Cardiopathology of sudden cardiac death in the race horse. Twenty thoroughbred race horses were selected for postmortem cardiopathological study of sudden cardiac death; ten of the twenty horses died suddenly. In order to define accurately the morphological changes observed in these ten hearts, ten other thoroughbred race horses considered to have normal hearts were selected as a control group and studied by postmortem coronary angiography. Of the ten horses that died suddenly, eight were witnessed to have died either during or shortly after training or racing. The death was instantaneous except in one horse, which showed ventricular tachycardia and d...
The carrier state in equine arteritis virus infection in the stallion with specific emphasis on the venereal mode of virus transmission. The carrier state has been confirmed virologically in Thoroughbred and non-Thoroughbred stallions naturally infected with equine arteritis virus (EAV). Short-term or convalescent and long-term carriers occur. The frequency rate of the long-term carrier state in Thoroughbreds was high, averaging 33.9% among the three groups of stallions under study. While the convalescent carrier state only lasted a few weeks after clinical recovery, the long-term carrier state could persist for years. There was evidence, however, that not all such carriers might remain persistently infected for life. Carrier s...
Characterization of equine plasma lipoproteins after separation by density gradient. 1. Plasma lipoproteins from six thoroughbred horses were separated by density gradient ultracentrifugation. For each sample, lipoprotein bands were visualized by means of a prestained plasma control and characterized by electrophoretic, chemical and morphological analysis. 2. Very low density lipoproteins (VLDL) were isolated at d less than 1.018 g/ml. 3. Two clearly resolved bands were detected in the low density lipoprotein fraction (LDL). The density limits were evaluated as follows: LDL1(1.028 less than d less than 1.045 g/ml) and LDL2(1.045 less than d less than 1.070 g/ml). Marked differ...
Induction of ovulation in anoestrous mares with a slow-release implant of a GnRH analogue (ICI 118 630). A total of 18 experimental pony and 136 commercial maiden, barren and foaling Thoroughbred mares in seasonal or lactation-related anoestrus were injected subcutaneously with 1 or 2 slow-release D,L-lactide-glycolide co-polymer implants impregnated with 0.9 or 1.8 mg of the potent GnRH analogue, ICI 118 630, to give a daily release of, respectively, 30 or 60 micrograms analogue for 28 days; 32 of the Thoroughbred mares were also given a daily oral dose of 27.5 mg allyl trenbolone for 5 days after injection of the implant. Thirteen pony (76%) and 120 Thoroughbred (88%) mares ovulated 3-18 days a...
Comparison of systemic and local respiratory tract cellular immunity in the neonatal foal. Blood neutrophils from 10 Thoroughbred and 2 Pony foals were evaluated using in-vitro cellular function tests of chemotaxis, chemiluminescence, phagocytosis and intracellular killing. A comparison of the functional capacities of these cells before and 2-4 days after the ingestion of colostrum indicated an improvement in blood neutrophil chemotaxis and chemiluminescence. Bronchopulmonary lavage was carried out on 9 Thoroughbred and 2 Pony 36-h-old foals. The technique used did not require sedation or anaesthesia. Pulmonary alveolar macrophages were the predominant cell type recovered. When comp...
Antithrombin III (ATIII) activity in plasmas from normal and diseased horses, and in normal canine, bovine and human plasmas. Plasma Antithrombin III (ATIII) activity was quantitated in 24 clinically normal Standardbred/Thoroughbred horses using a clotting time technique. ATIII activity ranged from 80 to 106% of the pooled reference standard plasma, with a mean of 94%. Horses presenting with impaction or spasmotic colic (n=17) had normal plasma ATIII activity, while 15 horses presenting with acute diarrhea/colitis had significantly lower plasma ATIII activity with a mean of only 74% of the reference plasma. Seven horses presenting with liver disease had significantly higher plasma ATIII activity with a range of 127 t...
Observations and management of fractures of the proximal phalanx in young Thoroughbreds. A retrospective study of 119 cases of fracture of the proximal phalanx is described. The short incomplete sagittal fracture (split pastern) was most common and carried a good prognosis for a return to racing following conservative treatment. Longer incomplete fractures also had a good prognosis but complete fractures, either through the lateral cortex of the proximal phalanx or through the bone into the proximal interphalangeal joint, required internal fixation. Careful assessment of these and comminuted fractures was essential before surgery was undertaken. Most comminuted fractures were trea...
Cervico-endometrial cytology and physiological aspects of the post-partum mare. After parturition, Thoroughbred mares were mated at the first post-partum oestrus (N = 24) or at a subsequent oestrus (N = 12). All mares were examined daily for: oestrous detection, palpation per rectum of the genital tract, vaginoscopic examination and cervico-endometrial cytology. Pregnancy diagnosis was carried out at Days 18, 35 and 45 after mating. An identical first service conception rate of 50% was found in both groups. The number of neutrophils followed a descending profile to only scattered cells at the first post-partum oestrus and in Group II mares remained at this very low level ...
Cellulitis associated with coagulase-positive staphylococci in racehorses: nine cases (1975-1984). Nine Thoroughbred racehorses were admitted with cellulitis (of one or more limbs) associated with coagulase-positive staphylococci. The right hindlimb was affected in 4 horses, the right forelimb in 2, the left hindlimb in 1, and both hindlimbs in 2. Typical abnormalities included high values for rectal temperature (9 horses) and heart rate (5 horses), hyperfibrinogenemia (7 horses), leukocytosis (7 horses), and neutrophilia (6 horses). The staphylococcal isolants were speciated in 3 horses and classified as Staphylococcus aureus. Complications included skin loss (5 horses), laminitis of the a...
The lack of effect of inoculation with equine influenza vaccine on theophylline pharmacokinetics in the horse. Several studies conducted during the past few years have shown that the pharmacokinetics of a variety of drugs may be altered following viral infection or vaccination. The elimination of drugs which are extensively metabolized, such as theophylline, may be prolonged, especially following exposure to RNA viruses such as Type A influenza or similar orthomyxoviruses. The purpose of this study was to determine whether vaccination of horses with equine influenza virus affected pharmacokinetic parameters describing the distribution and elimination of intravenously administered theophylline. Three th...
Equine laryngeal hemiplegia. Part V. Central nervous system pathology. Evidence of long central nerve fibre degeneration (axonal spheroids) in the lateral cuneate nuclei was found in all eight Thoroughbreds affected clinically and subclinically with equine laryngeal hemiplegia, but in only one of six control animals. It was considered that these spheroids may signify a central nervous component of the disease process of laryngeal hemiplegia although until further investigations are performed no firm conclusions regarding the relationship of these findings with laryngeal hemiplegia could be made. Examination of the left and right nucleus ambiguus of clinical and s...
Study of arterial blood pressure in newborn foals using an electronic sphygmomanometer. An electronic sphygmomanometer which functions on oscillometric principles, was used to measure arterial blood pressure in foals. Its accuracy was assessed by comparison with results obtained by direct measurement in anaesthetised pony foals, aged 34 to 64 days. Correlations between data obtained by the two methods were highly significant but the sphygmomanometric readings were consistently lower than those obtained by direct measurement. An equation was derived from the pooled values for mean, systolic and diastolic pressure measurements. This was used as a correction factor when the oscillom...
[Pregnancy diagnosis in thoroughbred mares using radioimmunoassay (RIA), enzyme immunoassay (kit) and ultrasound echography (scanning)]. On the basis of progesterone determination on plasma or blood after RIA and the kit method respectively and consecutive scanning performed on a total number of 31 mares the following features were demonstrated: The overall material shows that in 20 mares (64.5%) embryonic vesicles were demonstrated. Of these mares 16 have conceived after service in the 1st estrous cycle and 3 mares in the 2nd estrous cycle. 18 mares were scanned in the time interval 13th-26th day after the latest service, while 2 mares were scanned on day 46 and 41 respectively. A total of 14 scanning positive mares were exami...
Equine laryngeal hemiplegia. Part III. A teased fibre study of peripheral nerves. Individual nerve fibres were isolated from the recurrent laryngeal and some distal hindlimb nerves, in an investigation of equine laryngeal hemiplegia. One hundred teased fibres were obtained from each of three sampling sites on both left and right recurrent laryngeal nerves, from 15 Thoroughbred horses. These fibres were graded descriptively and internode lengths measured. A distal distribution of pathology was demonstrated in all groups studied, but was most severe in the clinical group of horses. The predominant change was one of short thinly myelinated internodes interspersed amongst norma...
Lactation in the horse: the mineral composition of mare milk. Changes in the mineral composition of mare milk during lactation were studied. Milk samples were obtained from five Thoroughbred mares one to three times weekly from the first to the eighth week of lactation and from two of the mares for an additional 8 wk. Samples averaging 500 mL were obtained after oxytocin was administered to the mares. Each sample was analyzed for total solids, ash, calcium, phosphorus, magnesium, sodium, potassium, copper and zinc. The concentration of all constituents except sodium and potassium decreased throughout lactation. The rates of decline of ash, calcium, phosp...
Chronic inflammatory and lymphoproliferative lesions of the equine small intestine. A retrospective study was made of 20 horses with severe and extensive chronic disease of the small intestine. Many of the animals had clinical evidence of malabsorption, with progressive loss of weight, hypoalbuminaemia and sometimes anaemia. All but two of the horses were Thoroughbreds. The pathology was diverse. Nine of the cases were alimentary lymphomas (Platt, 1986) and five had lymphocytic and eosinophilic infiltrations in the bowel wall which were considered to be probable reactions to parasitic invasion. One had acute thrombosis associated with partial occlusion of the anterior mesente...
Epidemiological features of 5009 cases of equine cryptorchism. Data from 16 North American veterinary university teaching facilities, 5009 cryptorchid horses, were analysed using relative risk methodology. In five breeds (Thoroughbred, Standardbred, Morgan, Tennessee Walking horse and Arabian), cryptorchism was diagnosed significantly (P less than 0.05) less frequently than expected by their representation in the hospital population. Three breeds, (Percheron, American Saddle horse and American Quarterhorse), plus ponies (as a group) and crossbred horses were significantly over-represented within the series. The over-representation of Quarter-horses was ev...
Efficacy of human chorionic gonadotrophin and gonadotrophin releasing hormone for hastening ovulation in thoroughbred mares. Plasma progesterone levels were measured daily to determine the accuracy of diagnosing ovulation by rectal palpation carried out every other day; 81.5 per cent mares injected with human chorionic gonadotrophin showed increases of progesterone more than 1 ng/ml by 72 h after injection compared with 65 per cent of mares injected with gonadotrophin releasing hormone (GnRH) or saline. Mating at ovulation achieved a 74 per cent pregnancy rate in mares given hCG compared with 50 per cent given GnRH and 45 per cent controls. Diagnosis of ovulation per rectum on the basis of a pit in the ovarian surfa...
Equine laryngeal hemiplegia. Part I. A light microscopic study of peripheral nerves. This light microscopic investigation of 15 Thoroughbred horses provided substantial evidence for the classification of equine laryngeal hemiplegia as a distal axonopathy. Morphologic and morphometric examinations were performed on resin embedded recurrent laryngeal nerves from control, subclinical and clinical laryngeal hemiplegic animals. In the latter group of animals some distal hindlimb nerves were also examined. A distally graded loss of myelinated fibres selectively affecting those of large diameter was demonstrated in both left and right recurrent laryngeal nerves. Morphologic evidence ...
Track condition and racing injuries in thoroughbred horses. 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.
Estimation of urinary flow rate in weanling and yearling horses. In an attempt to validate the use of urinary creatinine concentration as an index of urinary flow rate, a series of timed quantitative urine collections were done on several groups of weanling and yearling ponies and Thoroughbreds. A total of 411 urine samples were generated by 19 ponies and 12 Thoroughbreds. Urinary flow rates and urinary creatinine concentrations were measured. When all the data were examined, urinary flow rates were independent of creatinine concentrations. However, for any given animal, daily urinary creatinine excretion was constant over several days, and urinary creatini...