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.
Lumsden HJ, Valli VE, McSherry BJ, Robinson GA, Claxton MJ.The hematological response to acetylphenylhydrazine hemolytic anemia was studied in three standardbred horses. The lifespan of erythrocytes produced during the most severe phase of the anemia were measured with 75-selenomethionine and found to be 144 days as compared to the 139 day lifespan in response to hemorrhagic anemia or 155 days in normal standardbred horses measured previously using the same technique. The erythrocyte counts returned to initial values in 42 days (37, 34 and 54 days) a mean erythrocyte production of 6.4 times 10-12 erythrocytes/day. The mean hemoglobin production was 0....
Carter EI, Valli VE, McSherry BJ, Milne FJ, Robinson GA, Lumsden JH.Three Standardbred horses were given 0.2 mg (1 mCi) of (75)selenomethionine intravenously and a second group of three were given 10 mCi of tritiated diisopropylfluorophosphate (0.5 mg) intravenously. Observations on labeled cells were continued for 250 days after radioselenium injection and 160 days after tritium injection. The lifespan of erythrocytes using (75)selenmethionine was 155 +/- 10 days and 148 +/- 7.8 days using tritiated diisopropylfluorophosphate. There was no significant difference at the 10% level between the lifespans, using these labels. The uptake of radioselenium into eryth...
Lindholm A, Johansson HE, Kjaersgaard P.LINDHOLM, A., H.-E. JOHANSSON & P. KJÆRSGAARD: Acute rhabdomyolysis (“tying-up”) in standardbred horses. A morphological and biochemical study. Acta vet. scand. 1974, 15, 325–339. — Morphological, biochemical and histochemical changes were studied in muscle needle biopsy specimens (gluteus medius) from 59 standardbred trotters with acute clinical symptoms of the “tying-up” disease. All horses had increased levels of serum enzymes SGOT and SCPK. The biopsy specimens were taken at various intervals after onset of clinical symptoms (1–4 hrs., 18–24 hrs. and 2–20 days). Ry light...
Carter EI, Valli VE, McSherry BJ.The peripheral blood cells from Standard bred horses were subjected to procedures which will separate equine peripheral blood cells with good precision and efficiency into red cell, leukocyte, and platelet fractions. The separated cells have normal morphology and the differential count of the separated granulocytes and lymphocytes is unchanged from that of the original sample.
Lindholm A, Piehl K.LINDHOLM, ARNE and KARIN PIEHL: Acta vet. scand. 1974, , 287–309. — Measurements of metabolites, electrolytes, water, RNA and protein concentrations, the activity of certain muscle enzymes (SDH and PFK) and muscle fibre composition were made on biopsy specimens from the gluteus medius muscle of 68 standardbred horses, ½ to 8 years old. The muscle fibres were classified in 3 major categories, slow twitch (ST), fast twitch and high oxidative (FTH) and fast twitch (FT) fibres. The percentage of FTH fibres was higher after the age of 4 years, averaging 54 %. ST fibres comprised 24 % and this...
Lindholm A, Saltin B.LINDHOLM, ARNE and BENGT SALTIN: The physiological and biochemical response of standardbred horses to exercise of varying speed and duration. Acta vet. scand. 1974, 15, 310–324. — Welltrained standardbred horses were studied to examine the metabolic response to excercise of various speeds and duration. Comparisons between interval (400, 700, 1,000 and 2,000 m) and continuous trotting (1 hr., 2 hrs.) and racing were made. Muscle and rectal temperatures were recorded before and immediately after each work bout. Heart rate was linearly related to trotting speed, and maximal heart rate (240 be...
Warm-season grasses (WSG) incorporated into traditional cool-season rotational grazing systems to increase summer yields are typically established in monoculture in separate pasture areas. Few studies have evaluated alternative interseeded establishment of WSG, despite potential benefits for improving biodiversity and land-use efficiency. The objective of this study was to determine the impact of establishment method (monoculture vs. interseeded) on crabgrass pasture forage yield, nutritive value, and preference under equine grazing. Three adult standardbred mares grazed two main plots on two ...
Osteochondrosis (OC) develops in growing horses due to disturbed differentiation and maturation of cartilage, particularly at the predilection sites of the fetlock, hock and stifle joints. Horses with osteochondrotic lesions are at a high risk of developing orthopaedic problems later in life. This article briefly reviews the published heritability estimates for OC and offers perspectives for selection in the horse industry. Heritabilities for OC in Warmblood and Standardbred horses have been estimated at 0.1-0.4 in animal threshold models. Whole genome scans using microsatellites have identifi...
Norton AM, Rosanowski SM, O'Brien T.Epiglottic entrapment (EE) is a common cause of poor performance in racing standardbreds (STBs) and thoroughbreds (TBs). There is limited information published on the condition in STB racehorses and limited information on factors associated with return to racing available for either breed. Unassigned: This study investigated and compared the pre surgical findings, post-surgical complications and racing performance in STBs and TBs undergoing surgery for correction of EE. Associations between signalment and pre-surgical findings, and the presence of complications and racing post-surgery were com...
Rossi HS, Hyytiäinen HK, Junnila JJT, Rajamäki MM, Mykkänen AK.Pneumonia is a common condition in ailing neonatal foals, and it remains an important cause of morbidity and mortality in this veterinary patient group. Factors affecting the survival of young foals with pneumonia have not been thoroughly investigated. The aim of this study was to explore the potential prognostic factors associated with survival of these foals. Fifty foals under one month of age with pneumonia were included in this retrospective clinical study. The foals were divided into groups based on survival (survived to discharge or died/euthanised during hospitalisation). Multiple clini...
Berglund P, Andonov S, Jansson A, Olsson C, Lundqvist T, Strandberg E, Eriksson S.In equine sports, shoes are used to protect the hooves from wear and tear. In Swedish trotting races, pulling off the shoes to race barefoot is popular because it improves racing time. Good hoof quality is essential for high-performance horses, but not all trotting horses have hooves that tolerate barefoot racing. The ability to race barefoot is a complex trait that is known to be influenced by environmental factors, but the genetic basis of this trait has not been studied. The aim of this study was to estimate genetic parameters and correlations between estimated breeding values for three nov...
MacMillan KM, Burns JJ, John E, Clancey N, Stull JW.Decreased total T4 (tT4) concentrations are frequently observed in racing Standardbred horses lacking clinical evidence of hypothyroidism. This poses a diagnostic challenge as primary hypothyroidism is reported to be rare in adult horses. Despite this, owners frequently wish to administer thyroid supplementation to horses having low tT4 concentrations. Forty racing Standardbred horses were sampled. Baseline tT4 concentrations were determined using human-based (equine) and canine-based chemiluminescent assays. Dynamic evaluation of tT4 was performed using a thyrotropin-releasing hormone (TRH) s...
Jimenez C, Hogan P, Belaghi R, Curtiss A.Epiglottitis is an uncommon upper airway pathology manifested endoscopically by mucosal oedema, reddening and thickening of the epiglottic mucosa. Literature on epiglottitis in horses is sparse. Objective: To describe the diagnosis, treatment and outcome of Thoroughbred and Standardbred racehorses diagnosed with epiglottitis at a single centre. A secondary objective is to demonstrate the efficacy of inhaled and topical anti-inflammatories for this condition. Methods: Retrospective case series. Methods: Medical records (2009-2023) were reviewed for racehorses treated for epiglottitis. Data coll...
Renaudin CD, Picandet V, Kass PH.Using the equation of Hartwig et al. and the table established for light breed horses, day of gestation was predicted in 108 Warmblood (WB) and 59 racehorses (Thoroughbred [TB] and Standardbred [STB]) pregnant mares. In WB, gestational ages were predicted within 2 weeks from 100 to 200 days of gestation using biparietal diameter (BPD), aortic diameter (AortD) or femur length (FL); within 2 weeks from 100 to 250 days using BPD or AortD; within 2 weeks from 100 to 300 days using BPD alone; and within 3 weeks from 100 to 350 days using eye approximated volume (EyV) alone. In the ...
Boshuizen B, De Maré L, Oosterlinck M, Van Immerseel F, Eeckhaut V, De Meeus C, Devisscher L, Vidal Moreno de Vega C, Willems M, De Oliveira JE....Aleurone, derived from the bran layer of grains like wheat and barley, has demonstrated positive effects on energy metabolism in pigs, mice, and untrained horses, influencing glucose-insulin dynamics and gut microbiome composition. Training itself enhances insulin sensitivity in horses, similar to the improvements in performance capacity observed in human athletes. This study aimed to investigate whether aleurone supplementation provides additional benefits to training by modulating insulin metabolism and gut microbiota in Standardbred mares. Unassigned: Sixteen Standardbred mares (aged 3-5 ye...
Connysson M, Jansson A.It is generally accepted that plasma muscle enzyme activity of creatine kinase (CK) and aspartate aminotransferase (AST) may increase in racehorses after exercise and racing, indicating muscle fibre damage and/or increased leakage from muscle fibres. However, other studies suggest that starch intake might influence plasma muscle enzyme activity reported postexercise. This study aimed to evaluate the effect of different starch allowances on plasma muscle enzyme activity in Standardbred trotters in professional training. Seventy-six horses from five professional trainers were sampled pre- and po...
Cravana C, Medica P, Fazio E, Satué K, Brancato G, La Fauci D, Bruschetta G.The hypothalamic-pituitary-adrenal (HPA) axis is a neuroendocrine system involved in the coping response to stressful challenges during exercise stimuli. Exercise represents a significant disruptor of homeostasis, inducing an ACTH-cortisol co-secretion, based on different characteristics of exercise in sport horses. Based on this statement, the aim of this study is to evaluate the circulating adrenocorticotropin and cortisol changes in Standardbred trotters, after training and racing sessions, considering the different age and sex. In particular, the aim is to determine to what extent the leve...
Ruspi BD, Bramlage LR, Ruggles AJ, Slone SA.To report the rate of survival, rate of return to racing, and quality of racing performance following surgical fixation of medial condylar fractures. Methods: Retrospective study. Methods: A total of 150 Thoroughbred and Standardbred racehorses surgically treated for medial condylar fracture (100 lag screw fixation, 50 plate fixation). Methods: Medical records, radiographs, and racing databases (2000-2020) were reviewed to collect signalment, fracture characteristics, fixation methods, survival rate, and complication rate. Change in racing performance was assessed using Wilcoxon rank sum tests...
Strand E, Vermedal H, Olsen HMB, Fjordbakk CT, Fretheim-Kelly ZL.Clinical evaluation of alar fold (AF) collapse is presently based upon subjective evaluation of improvement in breathing and respiratory noise after suturing the AFs dorsally. Objective: To evaluate use of nasopharyngeal airway pressure (NAP) as an objective method of assessing for the presence of AF collapse during exercise. NAPs should also potentially provide a precise means to grade the degree of airway obstruction present and response to surgical treatment. Methods: Prospective clinical study of actively racing Standardbred horses. Methods: Standardbreds undergoing this test were outfitte...
Avila F, Esdaile E, Bellone RR. Standardbreds, a breed of horses used in harness racing at either the trot or the pace, established a closed studbook in 1973. Concerns about genetic diversity within the breed led the United States Trotting Association (USTA) to establish a limit of mares bred per stallion (i.e., a studbook cap) in 2009. Here, we aimed to evaluate the impact of the breeding restrictions on genetic diversity between and among subpopulations. : Sixteen short tandem repeats (STRs) were analyzed across a dataset of 176,424 Standardbreds foaled in the United States between 1998 and 2021. We examined allelic richn...
Burns JJ, MacMillan KM.The Standardbred racing industry plays an important role in the North American economy and is expected to continue operating and growing. However, public perception is often unfavorable, with increasing concern about the health and welfare of Standardbred racehorses. Despite this, limited research has examined Standardbred well-being. To address this gap, a survey of equine trainers on Prince Edward Island (PEI) was conducted to evaluate key health and welfare issues during racing careers. Results showed that over one quarter of respondents had at least one horse displaying stereotypic behavio...
Alexeenko V, Tavanaeimanesh H, Stein F, Gold J, Hughes L, McCue M, Marr C, Durward-Akhurst S, Jeevaratnam K.Cardiac arrhythmias are common in healthy athletic horses and may lead to poor athletic performance or exercise-associated sudden death. Early detection of high-risk horses is an important goal of cardiovascular diagnostics. We hypothesised that non-linear analysis of electrocardiogram disorderliness can be used to identify horses exhibiting intermittent ectopic atrial and ventricular heart rhythm abnormalities at exercise using brief, artifact-free recordings of normal sinus rhythm electrocardiograms collected at submaximal heart rates. In a convenience prospective cross-sectional study, ambu...
Cuervo-Arango J.The objective of this study was to compare the fertility of diestrous mares with a follicle ≥ 30 mm in diameter treated with prostaglandin F2α (PGF) (PGF group) or left untreated for 7 days (SP group). Standardbred mares (n = 46) were assigned randomly to the SP (n = 23) and PGF groups (n = 23) when they were identified with a corpus luteum (CL) of unknown age and a follicle ≥ 30 mm in diameter (Day 0). The most frequent outcome in the PGF group was estrus and ovulation of the dominant follicle (74 %), while the outcomes of the SP mares 7 days after Day 0 were more variable: estrus and fo...
Bertin FR, van Eps AW, de Tonnerre DJ, Kulp JC, Stefanovski D.Dexamethasone is used to experimentally induce insulin resistance; however, its impact on insulin secretion is unclear. This study aimed to assess the responses to oral carbohydrate challenges in dexamethasone-treated horses. Unassigned: 8 healthy Standardbreds received 0.08 mg/kg of dexamethasone IM every 48 hours for 14 days in June 2022 (winter in the Southern hemisphere). Oral glucose tests (OGT) were conducted before treatment (day 1) and on days 8 and 15. Glucose, insulin, triglycerides, total and active glucagon-like peptide-1 (tGLP-1 and aGLP-1) and glucose-dependent insulinotropic pol...
Schwochow D, Alameddine A, Spörndly-Nees E, Montigny M, Naboulsi R, Jansson A, Niazi A, Lindgren G.Racing without protective shoes is common in the Swedish harness racing industry, as it can enhance horses' performance on the track. Trainers typically decide whether a horse will race barefoot based on practical experience rather than objective measures. However, this practice can sometimes lead to excessive hoof wear, posing potential welfare concerns for racing horses. Gene expression differences may help reveal the underlying genetic mechanisms associated with different phenotypic traits. To explore an objective measure for assessing which horses are best suited for barefoot racing, we co...
Avison A, Goderre BG, Pyle WG, Physick-Sheard PW.Sudden cardiac death is common in racehorses. Factors associated with the QT interval that could predispose to fatal cardiac arrhythmias are unknown. Cardiac restitution, expressed as a ratio of QT/TQ, has been used in humans to assess arrhythmia risk but has not been described in horses during maximal intensity exercise. Objective: Describe factors associated with the QT interval and cardiac restitution ratio (CRR) in clinically normal Standardbred racehorses under race-day conditions. Methods: Archival electrocardiograms from 42 Standardbred horses during live racing in Ontario. Methods: Obs...
Berglund P, Andonov S, Strandberg E, Eriksson S.Harness racing is popular in several parts of the world, and the ability to race barefoot is an important trait for success because of its effect on racing time. Barefoot racing is also discussed in terms of animal welfare because not all horses have hooves that tolerate racing without shoes. In Swedish Standardbred trotters (SB) and Swedish-Norwegian Coldblooded trotters (CB), the proportion of barefoot races and the probability to race barefoot in any given race (barefoot status) have low-to-moderate heritability (h = 0.07-0.28). However, the genetic correlation between the ability to race...
Kuroda T, Knych HK, Noble GK, Minamijima Y, Leung GN, Nomura M, Mizobe F, Ishikawa Y, Kusano K, Toutain PL.Flunixin meglumine is widely used to manage pain and inflammation in horses, and its regulation requires robust pharmacokinetic analysis for harmonization. In this study, we conducted a meta-analysis of flunixin disposition using plasma and urine concentration data from 65 horses across four countries to robustly estimate pharmacokinetic parameters in setting screening limits (SLs) for controlling medications in horses. A population (POP) model was developed using nonlinear mixed-effects model analysis. The irrelevant plasma concentration (IPC) and irrelevant urine concentration (IUC) were det...
Aarts RM, Smit IH, Ferraz GC, Rhodin M, Serra Braganca FM, Hernlund E.Assessment of equine metabolic and locomotory responses to quantified levels of physical exercise is needed to support the creation of tailored protocols for optimal training adaptation. The locomotory response to exercise in horses is not fully understood. Objective: To investigate the effect of a standardised exercise test (SET) on upper-body and limb kinematics and stride-to-stride variability in Standardbred Warmblood trotters. Methods: Experimental repeated-measures field study. Methods: Thirteen Standardbred trotters, equipped with nine inertial measurement units (IMUs), performed an inc...
Rhodes AD, McCoy AM, Stewart MC, Gutierrez-Nibeyro SD.To evaluate postoperative racing performance of a population of Standardbred racehorses following arthroscopic removal of an osteochondrosis dissecans (OCD) lesion of the femoropatellar joint. Methods: Retrospective study. Methods: A total of 45 client-owned Standardbred racehorses. Methods: OCD lesions were measured and graded using the length of the subchondral bone defect from preoperative radiographs. Postoperative racing results were obtained from the United States Trotting Association, and follow-up owner surveys were conducted. A control group of contemporaneous paternal siblings free o...
Pilger F, Aurich C, Aurich JE.The early career start of racehorses, the pretraining of two-year-old Warmblood stallions for licensing, and individual housing of young horses increasingly raise animal welfare concerns. Objective: Assess pretraining practices and the opinion of trainers on housing of young horses, minimum age to commence training and pretraining injuries. Methods: Qualitative interviews with trainers of Warmblood stallions and Thoroughbred and Trotter racehorses (n = 10 each). Results: Pretraining of Thoroughbreds and Trotters began at 18 months, whereas licensing preparation of Warmblood stallions began at ...
Palmisano MG, Tukdarian CR, Hopster K, Nolen-Walston RD.This report describes an 8-day-old foal diagnosed with acute respiratory distress syndrome (ARDS) successfully managed using a novel approach of intratracheal oxygen delivery. Methods: An 8-day-old Standardbred filly presented for an acute onset of respiratory distress. Given the acute onset, known risk factors, bilateral diffuse infiltrate on thoracic radiographs, and low PaO:FiO ratio of 170.5, the foal was diagnosed with acute respiratory distress syndrome. Initial treatment consisted of antimicrobial therapy (minocycline and metronidazole), nonsteroidal anti-inflammatories (flunixin meglum...
McCoy AM, Lopp-Schurter CT, Bishop RC, Narotsky A, Grogger K, Kemper AM.To determine the natural progression of tarsal osteochondrosis (OC) in a cohort of Standardbred foals and assess the impact of gait preference (trotting vs. pacing). Methods: Longitudinal observational cohort study. Methods: Client-owned Standardbred foals (n = 148). Methods: Tarsal radiographs were taken every 2 months from 2 to 12 months of age and foals were video monitored to document time spent pacing or trotting. Differences between groups were assessed using χ analysis. Survival analysis was used to determine if lesion healing differed between groups over time. Results: Of 148 ...
Baird JD, Arroyo LG, Lumsden JH.The objective of this study was to determine the effect of either oral supplementation of sodium selenite and alpha-tocopherol or intramuscular administration of a commercial preparation of selenium (Se) and vitamin E to Standardbred broodmares with low (21.0 ± 18.1 IU/g Hb) whole blood glutathione peroxidase (GPx) activity. Ten mares received 3 weekly intramuscular (IM) doses, whereas 9 mares were orally supplemented daily for 10 wk. Blood samples were collected jugular venipuncture and the whole blood GPx activity was measured at each sampling time for the 32-week period. Both oral and int...
Bertuglia A, Cantatore F, Pallante M, Manassero L, Bergamini L, Riccio B, Pagliara E.To report the incidence, and clinical and pathological findings of developmental lateral patellar luxation in Standardbred yearlings diagnosed with femoropatellar dysplasia (FPD) and demonstrate that osteochondral lesions in the lateral trochlear ridge (LTR) of the femur observed in the affected horses are osteochondral lesions related to patellar maltracking.Retrospective case series. Medical records were retrospectively reviewed for Standardbreds <12 months of age diagnosed with FPD between 2017 and 2023.A total of 10 Standardbred yearlings developed FPD (incidence 6.4 cases per 1,000 foals)...
