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Topic:Standardbred Horses
Standardbred horses are a breed known for their performance in harness racing, characterized by their ability to trot or pace at high speeds. This breed is distinguished by its well-muscled build, strong legs, and calm temperament. Standardbreds are primarily used in racing but are also versatile in other equestrian activities, including riding and driving. Their genetic lineage can be traced back to the late 18th century, with the establishment of the breed registry in the United States. This page compiles peer-reviewed research studies and scholarly articles that explore the genetics, physiology, and performance characteristics of Standardbred horses, as well as their management and health considerations in various equine disciplines.
Cardiovascular effects of submaximal aerobic training on a treadmill in Standardbred horses, using a standardized exercise test. Seven healthy, unexercised, previously trained, adult Standardbred horses were allotted to 2 groups and trained 78 days on a treadmill set at a 7 degree 30' angle. The groups were trained on different schedules, and the effects of training on heart rate, cardiac output, stroke volume, arteriovenous oxygen difference, systemic blood pressure, and venous lactic acid were determined. Measurements were made at rest, during exercise on the treadmill at rates of 55 m/min, 75 m/min, 100 m/min, and 154 m/min, and at 5 minutes after exercise (standardized exercise test). Heart rate and cardiac output d...
A study of the effects of lasering on chronic bowed tendons at Wheatley Hall Farm Limited, Canada, January, 1983. Chronic bowed tendons of horses have been lasered with an infrared 904-nm laser at Wheatley Hall Farm Limited since 1980. A sample of 42 single injury/single treatment standardbreds which were racing within 120 days of laser treatment and met certain criteria, were evaluated for final race times, last quarter race times, and class changes. Results indicate that a significant percent of the standardbreds raced with similar or improved times and classes. Lasering bowed tendons presents a safe and less expensive alternative to traditional treatment methods which often requires a year layoff for t...
Population studies on the ELA system in American standardbred and thoroughbred mares. 336 Standardbred mares and 334 Thoroughbred mares in the vicinity of Lexington, Kentucky, were lymphocyte typed for 11 allelic antigenic specificities of the equine lymphocyte antigen (ELA) system. The Standardbred mares were divided into a population of pacers and a population of trotters. Substantial differences in ELA gene frequencies were found between the 3 groups. When the distribution of antigens within populations were compared to Hardy-Weinberg equilibrium expectations, relatively good agreement was found.
The effect of exercise on blood parameters in standardbred and Finnish-bred horses. Serum enzyme activities, albumin, protein, urea, cholesterol, triglyceride, free fatty acid, glucose and lactate concentrations as well as hematocrit values were measured in standardbred and Finnish-bred horses at rest and after (i) a short controlled exercise and (ii) a trotting competition. There were no breed differences in the enzyme activities at rest and the 2 breeds responded in the same manner to the exercise. Only after the race proper significant increases in the enzyme activities were found. The activities rose more in the standardbred horses than in the Finnish-bred horses. Urea an...
Equine marker genes: polymorphism for plasminogen. Polymorphism for two autosomal alleles of equine plasminogen, PLG1 and PLG2, was demonstrated in plasma by isoelectric focusing and immunofixation, with a goat anti-human plasminogen antibody. The frequency of PLG2 was 0.16 in 150 Standardbreds, 0.20 in 96 Thoroughbreds, and 0.39 in 32 Shetland ponies. No evidence for linkage of PLG with any of 13 marker loci was found.
Linkage disequilibrium between the ELA and the A blood group systems in Standardbred horses. The linkage group formed by the ELA and A blood group system in horses was studied in American Standardbred horses. The distance between the ELA locus and the A blood group locus was measured as 1.61 centimorgans, observing only the haplotypes contributed by the sires. Strong linkage disequilibrium was found in pacing Standardbred horses for ELA-W1 with Aa, ELA-W5 with Ab and ELA-W10 with Ab. Linkage disequilibrium was apparent at both the population and family level. Among trotting Standardbred horses, linkage disequilibrium was found for ELA-W1 with Aa and for ELA-W10 with Ab. It was not pos...
Prevalence of anti-red blood cel antibodies in the serum and colostrum of mares and its relationship to neonatal isoerythrolysis. The sera of 390 pregnant Standardbred mares and 409 pregnant Thoroughbred mares were tested for anti-red blood cell (RBC) antibodies. Of the Standardbred mares and Thoroughbred mares, 20% and 10%, respectively, had anti-RBC antibodies detectable in hemolytic or saline agglutination tests. Most of the antibodies were specific for the CA blood-group antigen of horses. Other antibodies were specific for the Aa, Ab, Aa, Ab, Da, Df, Ka, Ua, or Qa blood-group antigens. The occurrence of these antibodies in the serum and colostrum was compared for 268 mares. With 3 exceptions, whenever antibodies wer...
Pleuritis secondary to pneumonia or lung abscessation in 90 horses. Of 122 horses with pleural effusion, 90 (73.8%) had pleuritis secondary to pneumonia or lung abscessation. Fifty-one horses died or were euthanatized. The highest prevalence was in Thoroughbred and Standardbred racehorses. Eleven (12.2%) horses were postsurgical patients and 22 (24.4%) horses had been transported over 500 miles. There was no relationship between final outcome and the age, sex, breed, hematologic values, or laboratory findings pertaining to pleural fluid except for the bacterial isolation of Escherichia coli from the pleural fluid, as this was more frequently associated with de...
Glutathione peroxidase and selenium in the blood of healthy horses and foals affected by muscular dystrophy. When blood selenium concentrations and glutathione peroxidase activity was measured in 30 standardbred horses a significant correlation was found (r = 0.97). A comparison between blood GSH-px activity in clinically healthy foals, foals affected by muscular dystrophy (MD) and their respective mares was also done. There was no difference in GSH-px activity between the healthy foals and the MD foals or between the corresponding mares.
Lymphocyte alloantigens of the horse. I. Serologic and genetic studies. A genetic system controlling lymphocyte alloantigens of the horse is described. Alloantisera to paternal histocompatibility antigens induced as a result of pregnancy in mares were used in an antibody-mediated complement-dependent microcytotoxicity assay to define 15 Equine Leukocyte Antigen (ELA) specificities using cluster analysis. In this study 369 sera were screened for alloantibody using lymphocytes from 10 randomly selected, unrelated horses. A high proportion (83%) of these sera were found to be positive for antibody to lymphocyte alloantigens. After initial cluster analysis, 120 of the...
Pulmonary haemorrhage in standardbred horses after racing. Endoscopic examinations of the upper respiratory tract were done on 92 of 314 Standardbred horses that raced one or more times at 4 consecutive, weekly race meetings. Although participation was voluntary, the characteristics of the population of horses examined were not statistically different from those of all horses that raced. No horse showed epistaxis, but 34 (32.4%) examinations of the trachea revealed blood that ranged from a trace in the tracheal mucus to large amounts scattered over the tracheal walls. Forty-four horses exhibited minor degrees of pharyngeal lymphoid hyperplasia, 2 had ...
The equine electrocardiogram with standardized body and limb positions. Eleven-lead electrocardiograms (ECGs) were recorded from 50 Thoroughbred (TB) and 50 Standard bred (SB) horses at rest with 40 tracings being selected from each group for more complete analysis. Incomplete atrioventricular block with dropped beats commonly reported in mature horses was recorded only in the TB (15%), while wandering of the atrial pacemaker (WAP) thought also to be associated with variations in tone of the autonomic nervous system was detected almost equally in both breeds (30%). In some horses (12.5%), the initial component of the P wave (P1) did not vary as seen with WAP but h...
Effect of induced back pain on gait and performance of trotting horses. Back pain was induced in Standardbred horses by multiple intramuscular injections of a concentrated lactic acid solution into the left longissimus dorsi muscle. The investigation was divided into 2 parts. In Stage 1, 2 trotters were exercised on a treadmill and filmed by high speed cinematography before and after the induction of back pain. No signs of hindlimb lameness were evident and no quantitative changes in the components of the gait resulted, but a noticeable reduction was seen in performance capacity. Stage 2 involved a more intensive clinical and cinematic analysis of 3 horses. In the...
[Derivation and use of a new physiological criterion in the evaluation of performance in horses]. The possibility of using the test for pulse-rate response to gradated load in the evaluation of the endurance component of horse performance (in other words, response to the degree of horse adaptation to load) is discussed in detail. A mathematic-statistical analysis of regression coefficients is performed in the equations of the dependence of pulse rate on speed obtained in 278 three years old horses in the period following the termination of the basic training (145 Bohemian Warm-Blooded horses, 115 Kladrub Black horses and 18 English Half-Breds). A ten-score scale is calculated on the basis ...
Genetics of Standardbred stallion reproductive performance. Reproductive performance of 10 Standardbred stallions was related to the probability that the embryo resulting from a given mating would be heterozygous for transferrin or plasma esterase. Fertility, measured by foaling rate per insemination or by foaling rate per year, showed a highly significant regression on the probability of offspring heterozygosity for transferrin and, to lesser extent, for esterase. Substantial differences between stallions in the slope of the regression line and no deficiency of foals homozygous for either protein suggests that the relationship to fertility is indirect...
Transuterine migration of the fetus in the mare between day 42 and parturition. A total of 2187 Thoroughbred and Standardbred mares was examined over a 4-year period to determine the location of the fetus at 42 days, the location of the previous fetus as determined by examination 5-15 days after foaling, and pregnancy location the next season. Maiden mares showed 44 and 56% of pregnancies in the left and right horns respectively. No transuterine migration was observed in 139 maiden mares examined after their first foal. Lactating mares showed 62% implantations and full-term pregnancies on one side of the uterus with the next season's pregnancy being in the opposite uterin...
The cause and prevention of sacroiliac arthrosis in the Standardbred horse: a theoretical study. Sacroiliac arthrosis is a major cause of "hiking" lameness (often, so-called "stifle lameness") in Standardbred horses. The cause of this arthrosis is found in the moment forces generated as horses negotiate unbanked and underbanked turns and in the forces generated on cambered racing surfaces. The prediction is that such lameness could be virtually eliminated if racetrack and training track turns were properly banked and camber held to a minimum.
Blood volume and rate of growth in Standardbred foals. Blood volume and parameters of body size were studied in 45 Standardbred foals during their first 400 days of life. Bodily dimensions, including body weight (bwt), depth of chest, girth and length (distance from point of shoulder to caudal aspect of croup), increased curvilinearly with age. There was a much faster growth rate noted for the first 100 days of life. Bwt could be predicted from girth and length much more precisely than from age alone. The total blood volume increased proportionately with age and, consequently, the plasma and red cell volumes as functions of bwt were high at birth ...
A field evaluation of pro-benzimidazole, benzimidazole, and non-benzimidazole anthelmintics in horses. The effectiveness of 1 pro-benzimidazole (pro-BZD) drug, 3 benzimidazole (BZD) drugs, and 3 non-benzimidazole (non-BZD) drugs in keeping fecal egg counts below 50 eggs per gram 2 and 4 weeks after treatment at 6-week intervals was compared in groups of brood mares and yearlings at 2 Standardbred farms. In a preliminary study (December 1978 to April 1979) as well as major study (April to November 1979), horses were kept in the same groups in the same areas. In the major study, treatments were arranged in a Latin square design. On farm 1, which had a history of repeated use of BZD drug since 196...
[Evaluation of the performance of horses using pulse rate loading dynamics after basic training]. On the basis of test results, regarding the pulse rate response to the increased load, obtained from 278 three-year-old horses after finishing their elementary training (145 Bohemian warm-blooded horses, 115 Kladrub Black horses and 18 English half-bred horses), a method was worked for the evaluation of their performance. As an evaluating criterion a velocity (v170) was chosen which was obtained from an experimentally determined regression dependence of velocity on the pulse rate at 170 pulses per minute. A set of v170 data were statistically processed and on the basis of quantiles of normal d...
Two equine true hermaphrodites with 64,XX/64,XY and 63,XO/64,XY chimerism. The karyotypes of a Welsh pony and a Standardbred were 64,XX/64,XY and 63,XO/64,XY respectively. Both intersexes were true hermaphrodites with bilateral ovotestes. Neither intersex showed stallion-like behaviour. Each one had an underdeveloped penis, bilateral seminal vesicles and uterine tissue. It would appear that the chimerism in these equine intersexes resulted from double fertilization or fusion of blastocysts. Mosaicism in the Standardbred is a possibility, resulting from loss of a Y chromosome by anaphase lag in an early embryonic XY cell.
Studies on the physiopathology of chronic obstructive pulmonary disease in the horse. IV. Blood gas and acid-base values at rest. Radiometer Blood Micro-system 2 was used in studies designed to, (a) compare the mean blood gas and acid-base values of 38 normal horses and 20 horses with chronic obstructive pulmonary disease (COPD), (b) determine the means and standard deviations of blood gas and acid-base values of Thoroughbred horses in training, and (c) investigate the relationships between clinical data, blood gas values, intracardiac and pulmonary arterial pressures in subjects with COPD. There were significant differences between the mean values for partial pressure of arterial oxygen (PaO2), arterial carbon dioxide (...
Equine congenital cutaneous papillomatosis: a report of 5 cases. Four cases of equine congenital cutaneous papillomatosis were found during a review of 555 cutaneous tumours received at the pathology department, Ontario Veterinary College, during a 10-year period. A fifth case received after that period was also included. Two of the tumours were found in Thoroughbreds, one in a Standardbred, one in an Arabian and in one case the breed was not specified. The anatomical locations were the rib cage, head, hind leg and 2 on the forehead.
Equine marker genes: Polymorphism for soluble erythrocyte malic enzyme. Polymorphism of equine erythrocyte malic enzyme is detactable on starch gel electrophoresis. The frequency of ME1S was 0.06 in 667 Standardbred and 0.09 in 85 Thoroughbred horses. No genetically determined electrophoretic variation in soluble malate dehydrogenase was detected.
Antigen-antibody crossed electrophoretic studies and quantitative comparisons of serum transferrin types in horses. Selected transferrin phenotypes from 14 horses were investigated by antigen-antibody crossed electrophoresis. Horse sera were subjected to starch gel electrophoresis followed by right angle electrophoresis in agarose gels containing rabbit produced anti-horse transferrin. This technique gave an additional zone in the front as compared with 2 transferrin zones seen after ordinary starch gel electrophoresis. Comparisons of transferrin concentrations in horse sera were performed by an immunodiffusion technique. Values were related to a chosen reference serum. A total of 372 horses (210 Norwegian ...
Histochemical properties of muscle fibres types and enzyme activities in skeletal muscles of Standardbred trotters of different ages. Fibre characteristics and enzyme activities were determined for the gluteus, semitendinosus, vastus lateralis and triceps brachii muscles of 55 Standardbred trotters of different ages. Four fibre types (I, IIA, IIB, IIC) were demonstrated by histochemical staining of myofibrillar adenosine triphosphatase after preincubation at different pH values. Type II fibres predominated in all the muscles and the type IIA/IIB ratio was higher in horses over 5 years than in younger horses, except in the vastus in which the IIA/IIB ratio did not change with age. The vastus had the highest proportion of type...
Effects of furosemide on cardiovascular function and performance when given prior to simulated races: a double-blind study. In a double-blind study under simulated racing conditions, six Standardbred horses, which had been trained for 12 weeks, were given 1 mg of furosemide/kg of body weight or saline solution IV 15 minutes before the first of two warm-up workouts (1.6 km at 60-minute intervals). Sixty minutes later, 135 minutes after drug or placebo injection, these horses were driven 1.6 km at maximum speed. Heart rate, respiratory rate, cardiac output, pulmonary trunk pressure, body temperature, PCV, arterial oxygen, and plasma lactic acid were recorded during and after the first warm-up workout and after a simu...
Comparison of muscle fiber types from 2-year-old fillies of the Belgian, Standardbred, Thoroughbred, Quarter horse and Welsh breeds. The percentages of three muscle fiber types in the biceps femoris and triceps brachii were determined in five breeds of horses: Belgians, Standardbreds, Thoroughbreds, Quarter Horses and Welsh ponies. Biopsies were taken from the two muscles from each of four 2-year-old untrained fillies of each breed. Percentages of red, white and intermediate fiber types were determined from tissues stained for succinic dehydrogenase activity. Intermediate fibers were the most numerous for all breeds. The difference between red and white fibers varied significantly with breed. Thoroughbreds had the highest p...
Thermography: a technique for subclinical diagnosis of osteoarthritis. Thermographic and radiographic evaluations of the tarsus (hock) were done on 20 Standardbred racehorses before and after exercise at three consecutive 6-week intervals. All horses were from the same stable and given the same care and training under identical schedules and conditions. Normal thermographic patterns were established before and after exercise. These patterns corresponded to the underlying tarsal vasculature. Postexercise thermal patterns indicated a warming trend, and the increases were uniform. Abnormal thermal patterns were more localized and did not conform to the normal underl...
