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.
Speirs VC, van Veenendaal JC, Harrison IW, Smyth GB, Anderson GA, Wilson DV, Gilbo B.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 ...
Fregin GF.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...
Jeffcott LB, Dalin G, Drevemo S, Fredricson I, Björne K, Bergquist A.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...
Kovár J.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 ...
Weitkamp LR, MacCluer JW, Guttormsen S, McKnight J, Wert N, Witmer J, Boyce P, Egloff J.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...
Pascoe RR.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...
Rooney JR.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.
Persson SG, Ullberg LE.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 ...
Herd RP, Miller TB, Gabel AA.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...
Kovár J, Kostelecká B.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...
Dunn HO, Smiley D, Duncan JR, McEntee K.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.
Littlejohn A, Bowles F.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 (...
Garma-Aviña A, Valli VE, Lumsden JH.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.
Guttormsen SA, Weitkamp LR.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.
Ek N.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 ...
Essén B, Lindholm A, Thornton J.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...
Stull CL, Albert WW.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...
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...
Milne DW, Gabel AA, Muir WW, Skarda RT, Hamlin RL, Pipers FS.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...
Vaden MF, Purohit RC, McCoy MD, Vaughan JT.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...
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...
Roberts MC, Kelly WR.Granulomatous enteritis was diagnosed in a 4-year-old Standarbred mare suffering from chronic weight loss, depression, dependent oedema but not diarrhoea. There was hypoproteinaemia (hypoalbuminaemia), lymphocytopaenia and neglibible carbohydrate absorption from the small intestine. Pathological changes in almost the entire small intestine included proprial infiltration resulting in partial villous atrophy, and granuloma formation beneath the muscularis which was most severe in the ileum. Slight infiltration occurred in the stomach and the colon. The cells were predominantly lymphocytes and hi...
Drevemo S, Fredricson I, Dalin G, Björne K.A high-speed cinematographic analysis of interlimb time and linear gait characteristics was carried out at racing speed (12.0 m/sec; 1:23.6 min/km) in 30 clinically sound Standard-bred trotters. In respect of the whole group of horses the racing trot was found to be a very regular and symmetric gait. The variation coefficient between different horses ranged from 8 to 21 per cent depending on the particular characteristic being investigated. The variations recorded in individual animals were about 60 per cent less than those found for the whole group. The most stable characteristics were the du...
Drevemo S, Dalin G, Fredricson I, Björne K.The reproducibility of certain gait characteristics was investigated in Standardbred trotters at a speed of 12.0 m/sec. Twenty-two horses were recorded twice on the same day and 4 of them on a third occasion 3 years later. The short-term reproducibility was shown to be very good. In the long-term study it was found that the stride length and duration of swing and stride had increased. This was interpreted as an effect of training.
Drevemo S, Dalin G, Fredricson I, Hjertén G.The movements of the individual limbs of 30 clinically sound Standardbred trotters were studied using high-speed cinematography. At a speed of 12 metres per second (m/sec; 1:23.6 min/km) the mean stride length was 545 cm and the mean duration of the stride was 455 milliseconds (msecs). The stance phase in the forelimbs was 100 msecs and 177 msecs in the hindlimbs. This difference was due to a longer restraint period in the hindlimbs and resulted in slightly shorter swing phases for the hindlimbs. The variations in any particular horse for stride length and for the duration of stride, stance, s...
McGuire TR, Weitkamp LR.The equine transferrin F variant is distinguishable into two types, F1 and F2, on alkaline polyacrylamide gel electrophoresis. Gene frequencies in 63 related Thoroughbreds are 0.39 and 0.19 for TfF1 and TfF2, respectively. In contrast the frequencies for these two alleles in 375 related Standardbreds is 0.00 and 0.59.
Lumsden JH, Rowe R, Mullen K.Reference hematology and biochemistry intervals are presented for a number of variables of clinical interest determined for blood samples obtained from 60 thoroughbred mares, 12 thoroughbred foals and 50 standardbred horses in training. The observations for each variable were examined for outliers and Gaussian distribution. Parametric analysis was used where the observations were Gaussian initially or after any of four transformations, otherwise nonparametric analysis was required for estimation of the 2.5 and 97.5 percentiles. Description of the sample collection procedures, laboratory method...
Gabel AA.A prospective study of the diagnostic results on 25 previously untreated, slightly lame Standardbred horses showed that manipulative tests are of some help in diagnosis. The lameness of each horse was diminished or the horse went lame on the opposite limb after being given an injection of anesthetic in the cunean bursa, and lameness improved more when local anesthetic was injected in the distal intertarsal and tarsometatarsal articulations. In four horses, lesions of the distal articulation of the hock were evident on radiography.
Gabel AA.During 1975 and 1976, 70 Standardbred horses with cunean bursitis-tarsitis were treated by cunean tenectomy or by more conservative approaches (rested, given corticosteroid injections in the cunean bursa and distal hock articulations, given an oral course of phenylbutazone, a combination of these) or were sold. In 1975, owners were urged to have cunean tenectomy done to horses that appeared to have potential to race well, and in 1976, the more conservative methods of management and treatment were recommended. Statistical analysis of racing performance data led to the conclusion that there was ...
Shearman JP, Hopkins WG.To evaluate the reliability of 2 time-trial protocols, 1 that involved use of a pacemaker and 1 that did not, for assessing performance of Standardbred racehorses. Methods: 3- to 7-year-old Standardbred maiden pacers. Methods: 11 Standardbred pacers were used to determine the reliability of a time-trial protocol that involved use of a galloping pacemaker. All tests were performed by a single driver. Horses were paced for an initial 1,600 m then raced and timed for the final 800 m. They were retested 9 days later. Twenty-two horses were used to determine the reliability of a time-trial protocol...
Carmalt JL, Johansson BC, Zetterström SM, McOnie RC.OBJECTIVE To determine factors affecting race speed in Swedish Standardbred horses undergoing surgery of the carpal flexor sheath (CFS), to investigate whether preoperative racing speed was associated with specific intraoperative findings and whether horses returned to racing, and to compare the performance of horses undergoing surgery of the CFS with that of age- and sex-matched control horses. ANIMALS 149 Swedish Standardbred trotters undergoing surgery of the CFS and 274 age- and sex-matched control horses. PROCEDURES Medical records of CFS horses were examined. Racing data for CFS and cont...
Schott HC, Bohart GV, Eberhart SW.Efflux of potassium (K+) and lactate (lac-) from active skeletal muscle during high intensity exercise leads to increased plasma [K+] and [lac-] in venous and arterial blood. The exercise-induced increases in these ions in human athletes is ameliorated, in part, by uptake by noncontracting tissue, reflected by an increase in the arteriovenous difference across these tissues from rest to exercise. To test the hypothesis that these ions are taken up by noncontracting tissue in strenuously exercising horses, plasma [K+] and [lac-] were measured in blood samples collected simultaneously from the c...
Delvescovo B, Mullen KR, Eicker SW, Ivanek R, Ainsworth DM.Previously we described a clustering of dysphagic foal cases on a Pennsylvania (PA) Standardbred farm which was associated with exposure of pregnant mares to high concentrations of polycyclic aromatic hydrocarbons (PAHs) in the well water. The effect of dysphagia on future athleticism was uncertain. Objective: To determine if, as adults, dysphagic foals were less likely to race and if athleticism (age of first race, Speed Index and Earnings Per Start Index) differed from that of healthy foals that raced as adults. Methods: Prospective cohort study. Methods: All foals born during the study peri...
Hinchcliff KW, McKeever KH.The effect of blood volume repletion after frusemide administration on the right atrial and pulmonary artery pressure responses of horses to exercise has not been reported. We examined right atrial and pulmonary artery pressure and plasma atrial natriuretic peptide concentration (ANP) responses to an incremental exercise test in 6 Standardbred mares. Horses were treated, in a 3 way cross over design, with isotonic saline, frusemide (1 mg/kg bwt, i.v.), and frusemide followed 3 h later by lactated Ringer's solution (12 ml/kg bwt, i.v.). Three and a half hours after saline or frusemide administr...
Baragli P, Ducci M, Gatta D, Gazzano A, Sighieri C.Catecholamines (CAT) play an important role in modulating the response to exercise. But the kinetics of CAT changes during exercise are difficult to study due to their short biological half-life. Objective: Learning about variations in plasma CAT levels during training could furnish new information regarding sweating, redistribution of blood flow and energy metabolism. Methods: Four untrained Standardbreds, adapted to treadmill work, were used to determine the influence of training on plasma adrenaline (A) and noradrenaline (NA) kinetics. Horses underwent a standardised exercise test (SET) on ...
Hyland JH, Langsford DA.Foetal death was induced in 10 Standardbred mares at day 45 of gestation by injecting 20 to 45 ml of hypertonic (24% W/V) saline into the conceptus at surgery. Ten mares underwent sham treatment and acted as controls. Blood and urine samples were collected every other day between days 30 and 45 post ovulation and at 0, 3 and 6 h relative to the infusion of saline in the treated mares, or sham treatment in control mares. Blood and urine samples were then collected daily between days 46 and 55 post ovulation. Urine oestrone sulphate (E1S) concentrations, measured by radioimmunoassay, increased b...
Van Eenoo P, Delbeke FT, Deprez P.Clenbuterol, a beta-adrenergic agonist, is used in the treatment of recurrent airway obstruction in horses. It is prohibited by horse racing authorities, because of its stimulating and growth-promoting properties. However, information on detection times of clenbuterol after administration by nebulization is lacking. In this study, a fast, sensitive quantitative GC-MS(2) method for the detection of clenbuterol in urine was developed. Alkaline liquid-liquid extraction was followed by derivatization to a cyclic methyl boronate derivative and analysis on a Finnigan MAT GCQ instrument. Method valid...
Baragli P, Tedeschi D, Gatta D, Martelli F, Sighieri C.The aim of the present study was to test a constant blood withdrawal method (CBWM) to collect blood samples from horses during treadmill exercise. CBWM was performed in 4 Standardbreds and 5 Haflinger horses. A peristaltic pump was used to control blood aspiration from an i.v. catheter via an extension line. Blood was collected using an automatic fractions collector, with a constant delay time between the drawing of blood and sample collection. Blood withdrawal using CBWM was made during a treadmill standardised exercise test (SET). A blood flow of 12 m/min was used and samples collected every...
Väihkönen LK, Ojala M, Pösö AR.In red blood cell membranes, the activity of the main lactate carrier, H+-monocarboxylate co-transporter (MCT), varies interindividually and its distribution is bimodal. To show the repeatability of MCT activity, 2 to 5 blood samples were taken, at an interval of approximately 1 year, from 51 Standardbred horses, age 2 weeks-8 years, for a total of 128 observations. The horses could be divided into low (LT) and high (HT) lactate transport activity groups. Age significantly affected (P<0.05) MCT activity such that activity was highest in foals, reached a nadir at 2-3 years, and tended to inc...
Davidson EJ, Ross MW, Parente EJ.Little information exists regarding talus fractures in the horse and there have been no previously published case series of racehorses diagnosed with incomplete sagittal fracture of the talus. Objective: To describe the diagnosis, treatment and post injury performance of horses with incomplete sagittal fracture of the talus. Methods: Medical records of 11 racehorses (8 Standardbreds and 3 Thoroughbreds) admitted between January 1992 and January 1999 were reviewed. Subject details, anamnesis, results of lameness examination, radiographs and nuclear scintigraphic findings were evaluated. Racing ...
Gottlieb-Vedi M, Lindholm A.The responses in heart rate, plasma lactate and rectal temperature of standardbred trotters to draught loaded interval exercise on a treadmill and a race track were studied. The horses were exercised with incrementally increasing trotting speeds for two-minute intervals with draught loads of 10, 20 and 30 kilopond (kp) in three different tests. Each trotting interval was followed by two-minute periods at a walk without a draught load. Measurements of heart rate and plasma lactate were made at the end of each interval and the rectal temperature was taken at the end of the exercise. The heart ra...
Heath E, Aire T, Fujiwara K.A microtubular mass (MM) defect was found in the spermatozoa of 7 Standardbred stallions; 3 stallions were sons of the same sire. Two of these 3 stallions and 2 other stallions (for a total of 4 out of the 7 stallions) were considered subfertile when the defect was first observed. Fertility improved with time, either during the first breeding season or when a given stallion was used less frequently; however, the MM defect persisted, consisting of tortuous arrays of small abnormal microtubules visible only by transmission electron microscopy. The MM probably contained the protein tubulin as ind...
Johnson AL.Four seasonally anestrous mares (Standardbred), housed under a nonstimulatory photoperiod of 8 hours light:16 hours dark, were administered gonadotropin-releasing hormone (GnRH) in a pulsatile pattern (50 or 250 micrograms of GnRH/hour) for 8 to 18 days during February and March 1985. Treatment with GnRH, irrespective of dose or month, induced an increase in serum luteinizing hormone from a mean pretreatment value typical of anestrus (0.58 +/- 0.02 ng/ml +/- SE) to 10.84 +/- 1.27 ng/ml on day 8 of GnRH treatment. Ovulation in the 4 mares occurred 8.8 +/- 0.7 days after the initiation of pulsat...
Kane AJ, Stover SM, Gardner IA, Case JT, Johnson BJ, O'Brien MJ, Read DH, Ardans AA.To develop a standard technique for evaluation of racehorse shoes, to assess homotypic variation (interlimb variation) in shoe characteristics, and to determine whether shoe characteristics varied with age and sex. Methods: Cross-sectional study. Methods: Thoroughbred racehorses (n = 201) that died or were euthanatized at California racetracks between August 1992 and July 1994. Methods: Shoe characteristics were measured on horses examined after death. Percentage of agreement was used to compare shoe characteristics between limbs (homotypic variation). Using chi 2 analysis, shoe characteristic...
Jansson A, Nyman S, Morgan K, Palmgren-Karlsson C, Lindholm A, Dahlborn K.In this study 4 Standardbred geldings (age 3-8 years, weight 431-531 kg) were used. The horses were fed a hay and oat diet and the total sodium intake was about 32 mg/kg bwt (690 mmol/day). An exercise test (ET) which contained 3 phases was performed. Phase I consisted of 23.5 min of mainly submaximal exercise, Phase 2 of 2 h of box rest and Phase 3 of 26 min of exercise including an intensive trot over 2600 m at 90% of VO2max. The ET was repeated 3 times: the first at 20 degrees C (30-40% RH), the second at 35 degrees C (30-40% RH) and the third at 35 degrees C (30-40% RH) after a nasogastric...
Holcombe SJ, Derksen FJ, Stick JA, Robinson NE.To determine the effect of bilateral tenectomy of the tensor veli palatini muscle on soft palate and nasopharyngeal function in exercising horses. Methods: 5 Standardbreds. Methods: Treadmill videoendoscopy was performed on 5 Standardbreds exercising at 50, 75, and 100% of the speed that produced maximum heart rate; tracheal and pharyngeal pressures were measured before and after surgery. Tenectomy of the tensor veli palatini muscle was performed bilaterally on each horse while under general anesthesia, using a transoral approach. Results: Peak inspiratory tracheal pressures were significantly...
Lumsden JM, Derksen FJ, Stick JA, Robinson NE, Nickels FA.The efficacy of partial arytenoidectomy was assessed in 6 Standardbred horses, with surgically induced laryngeal hemiplegia, at rest (Period A) and during exercise at speeds corresponding to maximum heart rate (Period C) and 75% of maximum heart rate (Period B). Peak expiratory and inspiratory airflow rate (PEF and PIF), and expiratory and inspiratory transupper airway pressure (PUE and PUI) were measured and expiratory and inspiratory impedance (ZE and ZI) were calculated. Simultaneously, tidal breathing flow-volume loops (TBFVL) were acquired using a respiratory function computer. Indices de...
Leach DH, Crawford WH.This paper describes the major areas that require investigation in equine locomotion and outlines a plan for such research in both the Thoroughbred and Standardbred. Fifteen topics for future investigation have been selected and given an order of priority. These topics deal with characteristics of normal locomotion, factors which influence locomotion, the epidemiology and economics of lameness and the clinical identification of lameness.
Weitkamp LR, Kenney RM, Bailey E, MacCluer JW, Brown JS, Blanchard TL, Sertich PL, Love CC, Hunt PR.Histological features of the endometrium, as assessed in biopsy samples, were related to Standardbred mare genotypes for transferrin, esterase (as a control) and equine leucocyte antigens (ELA). Pathological changes were found more frequently in each successively older age group of mares. Among mares aged 6-19 years, there were significant pathologic changes on first examination following an infertile breeding season for 46 of 90 (51%) of transferrin homozygotes and 50 of 146 (34%) of transferrin heterozygotes. The difference between the two groups was significant for the total data (chi 1(2) ...
Bailey SR, Forbes G, Selvadurai N, McLarney K, Jones S, Steel CM.The administration of alkalinising agents including bicarbonate is of concern to racing authorities because resultant alkalosis may enhance performance and interfere with the detection of drugs in post-race urine. A threshold for total carbon dioxide (TCO ) of 36.0 mmol/L in plasma (with action limit of 37.0 mmol/L) has been set. Serial dosing of sodium bicarbonate has gained popularity in human athletes but has not been studied in horses previously. Sodium bicarbonate (200 g per horse) and 60 g of an electrolyte-vitamin complex was administered in 2-L water via nasogastric intubation to five ...
Brown J, Physick-Sheard P, Greer A, Poljak Z.Horse movements are one of the most important factors for the spread of equine diseases, and past epidemics indicate that contact networks play an important role. Network analysis was used to describe the spatial and temporal characteristics of horse movements between Standardbred racetracks in Canada and the United States during 2019, and to characterize the network to provide a better understanding of the potential racetrack-to-racetrack spread of infectious disease within the network. Networks were constructed and analyzed as an overall network (the entire study period) and monthly networks...
Palmer SE.Lameness of the Standardbred racehorse is a function of rigorous training programs, year-round racing schedules, hard racetrack surfaces, and the draft load. In this article, principles of lameness diagnosis and treatment are reviewed, with emphasis upon common or unique problems of the trotter and pacer. The role of physical therapy as an adjunct to medical and surgical treatment of lameness is described. Options for management of chronic pain are discussed, and a limited glossary of descriptive terms that are unique to harness racing is provided.
Thomas AL, Schramme MC, Lepage OM, Segard EM.An awareness of magnetic susceptibility artifacts is important for interpreting prepurchase and postoperative magnetic resonance imaging (MRI) studies in horses. These artifacts occur when a metallic or a paramagnetic substance creates a local magnetic field deformity. Aims of the current experimental study were to determine prevalence of these artifacts after arthroscopy in a sample of nonlame horses, and to describe effects of time and type of pulse sequence on low-field MRI signal intensity and detection of the artifacts. Ten, nonlame Standardbred horses were prospectively recruited. All ho...
Wilkins PA, Boston RC, Gleed RD, Dobson A.To compare cardiac output measured in the pulmonary artery and a carotid artery by use of thermal and electrical impedance dilution. Animals-7 fit, clinically normal Standardbreds between 2 and 5 years of age. Methods: Transient changes in electrical impedance and temperature of blood were induced by bolus injections of ice-cold saline hypertonic (6% and 9% NaCl) solutions. Cardiac output was calculated by applying Stewart-Hamilton principles to the indicator dilution transients. Measurements were made during sequential exercise episodes on a level treadmill over approximately an 8-fold range ...
Wong JKY, Kwok WH, Chan GHM, Choi TLS, Ho ENM, Jaubert M, Bailly-Chouriberry L, Bonnaire Y, Cawley A, Ming Williams H, Keledjian J, Brooks L....Acadesine, 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside, commonly known as AICAR, is a naturally occurring adenosine monophosphate-activated protein kinase (AMPK) activator in many mammals, including humans and horses. AICAR has attracted considerable attention recently in the field of doping control because of a study showing the enhancement of endurance performance in unexercised or untrained mice, resulting in the term 'exercise pill'. Its use has been classified as gene doping by the World Anti-Doping Agency (WADA), and since it is endogenous, it may only be possible to control del...
Burns JJ, MacMillan KM, John EE.Atrial fibrillation (AF) is the most clinically relevant cardiac arrhythmia identified in the Standardbred racehorse. However, there is limited literature regarding athletic ability in Standardbred racehorses following AF conversion. To investigate this issue, the objectives of this review were to: i) determine the success rate in using quinidine sulphate to treat AF in a population of hospitalized equine patients in Atlantic Canada between January 2008 and December 2019; and ii) measure return to athletic ability (using racetrack earnings and top-3 finishes) following cardioversion with quini...
Kokkonen UM, Hackzell M, Räsänen LA.To study the exercise-induced changes in atrial natriuretic peptide (ANP), a hormone with cardiovascular and renal effects, an incremental submaximal exercise test on a high-speed treadmill was carried out with Standardbred and Finnhorse trotters, the former bred for speed and the latter originally for heavy work. Standardbreds performed the 2 min exercise intervals at speeds of 6, 7, 8, 9 m s-1 and Finnhorses, according to their training status, at 5, 6, 7, 8 m s-1, 4, 5, 6, 7 m s-1 or 5, 6, 7 m s-1. Steady-state heart rate (HR) was reached within each 2 min interval. The increase in HR was l...
Cahoreau C, Combarnous Y.A number of horse chorionic gonadotrophin (CG) preparations of different purities and from diverse sources have been compared in radioimmuno-, radioreceptor, in-vitro cell culture, and in-vivo assays. The relative activities of the great majority of the preparations tested were consistent in the 4 assay systems. Moreover, their relative activities in the 4 assays were consistent with those found for unfractionated plasmas. These preparations were therefore considered to represent the native form of hormone. The second International Reference Preparation (IRP2) was among the few preparations ex...
Murphy DJ, Kö-Peternelj V, Aleri JW.Superficial digital flexor tendon (SDFT) injury is common in racehorses and a significant cause of lost training days and wastage in the industry. Objective: To compare the post-injury performance of Thoroughbred and Standardbred racehorses diagnosed with SDFT tendonitis treated with intralesional bone marrow and superior check desmotomy or managed conservatively and further to compare this performance with that of uninjured racehorses. Methods: Retrospective and case-controlled. Methods: Medical and race records of racehorses treated surgically or managed conservatively for SDFT tendonitis we...
