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.
Fortier J, Goachet AG, Julliand V, Deley G.In humans, cardiorespiratory responses are widely evaluated from field incremental exercise tests. On the contrary, equine exercise physiology faces a huge lack of oxygen consumption measurements (VO2) in field conditions due to technical concerns. The aim of this study was to test the effects of two incremental continuous field tests on cardiorespiratory responses in Standardbred trotters. The two protocols were realized at trot and ended when horses galloped. The tests started at 4.2 m/s (T1) and 6.4 m/s (T2), with speed increments of 1.4 m/s every 3 min for T1 and 0.8 m/s every 2 min for T2...
Abraham M, Reef VB, Sweeney RW, Navas de Solís C.Ultrasonographic appearance of the gastrointestinal (GI) tract of equine neonates has not been completely described. Objective: To describe (1) sonographic characteristics of the GI segments in normal nonsedated equine neonates, (2) intra- and interobserver variation in wall thickness, and (3) the sonographic appearance of asymptomatic intussusceptions, and (4) to compare age and sonographic findings of foals with and without asymptomatic intussusceptions. Methods: Eighteen healthy Standardbred foals ≤5 days of age. Methods: Prospective, cross-sectional blinded study. Gastrointestinal sonogr...
Jäderkvist K, Andersson LS, Johansson AM, Árnason T, Mikko S, Eriksson S, Andersson L, Lindgren G.In a previous study it was shown that a nonsense mutation in the DMRT3 gene alters the pattern of locomotion in horses and that this mutation has a strong positive impact on trotting performance of Standardbreds. One aim of this study was to test if racing performance and trotting technique in the Nordic (Coldblood) trotters are also influenced by the DMRT3 genotype. Another aim was to further investigate the effect of the mutation on performance in Standardbreds, by using a within-family analysis and genotype-phenotype correlations in a larger horse material than in the previous study. We gen...
Carmalt JL, Borg H, Näslund H, Waldner C.The aim of this study was to determine whether horses with a proximal palmar/plantar first phalangeal osteochondral fragment (POF) had comparable racing careers (prior to and following surgery) to horses without this fracture. A retrospective cohort study included 174 Swedish Standardbred trotters with osteochondral fragmentation in the palmar/plantar fetlock joint and 613 radiographically negative control horses presented for prepurchase examinations. Medical records and radiographs were examined for each horse. Racing data were retrieved from online Swedish Standardbred harness racing record...
Slack J, Boston RC, Soma LR, Reef VB.Cardiac arrhythmias are a recognised but poorly characterised problem in the Standardbred racehorse. Frequency data could aid the development of cardiac arrhythmia screening programmes. Objective: To characterise the occurrence of cardiac arrhythmias in Standardbreds prior to racing and in the late post race period using a handheld, noncontinuous recording device. Methods: Prospective, observational study, convenience sampling. Methods: Noncontinuous electrocardiographic recordings were obtained over a 12 week period from Standardbred horses competing at a single racetrack. Electrocardiograms ...
McCoy AM, Ralston SL, McCue ME.Osteochondrosis (OC) is commonly diagnosed in young Standardbred racehorses but its effect on performance when surgically treated at a young age is still incompletely understood. This is especially true for Standardbred pacers, which are underrepresented in the existing literature. Objective: To characterise the short- (2-year-old) and long-term (through 5-year-old) racing performance in Standardbred pacers and trotters after early surgical intervention (<17 months of age) for tarsal OC. Methods: Retrospective clinical study. Methods: The study population consisted of related, age-matched Stan...
Thomson PC, Hayek AR, Jones B, Evans DL, McGreevy PD.Significant proportions of horses leave the Australian Thoroughbred and Standardbred racing industries, which has ramifications for both the economic sustainability and the public perception of racing. The aim of this study was to quantify potential horse wastage, describe the destinations of exiting horses and identify risk factors for horses going to these destinations. Methods: Questionnaires were sent to 1258 selected Thoroughbred and 981 Standardbred trainers, with response rates of 30% and 32%, respectively. The survey investigated the role of various risk factors for wastage, including ...
Physick-Sheard P, Kraus M, Basrur P, McGurrin K, Kenney D, Schenkel F.To assess evidence for genetic contributions to atrial fibrillation (AF) in the Standardbred horse. Methods: Equine referrals to the Ontario Veterinary College Health Sciences Centre (OVCHSC) for 1985-2009, and age and gait matched breed registry controls. Methods: Breeds presenting ≥ 5 times annually were tabulated (admission year and diagnosis; total 40,039; AF 396; no AF 39,643), and breed and year effects examined. Heritability and inbreeding coefficients were determined for Standardbred AF cases and racing contemporaries, and odds ratios for AF were calculated for frequently occurring s...
Koenig TJ, Dart AJ, McIlwraith CW, Horadagoda N, Bell RJ, Perkins N, Dart C, Krockenberger M, Jeffcott LB, Little CB.To assess the effects of sodium pentosan polysulfate (PPS), N-acetyl glucosamine (NAG), and sodium hyaluronan (HA) in horses with induced osteoarthritis (OA). Methods: Experimental. Methods: Adult Standard bred horses (n = 16). Methods: OA was induced arthroscopically in 1 intercarpal joint; 8 horses were administered 3 mg/kg PPS, 4.8 mg/kg NAG, and 0.12 mg/kg HA (PGH), intravenously (IV), weekly and 8 horses were administered an equivalent volume of saline IV until study completion (day 70). Horses underwent a standardized treadmill exercise program. Clinical and radiographic findin...
Kristensen L, Buhl R, Nostell K, Bak L, Petersen E, Lindholm M, Jacobsen S.The purpose of the study was to investigate whether acute strenuous exercise (1600- to 2500-m race) would elicit an acute phase response (APR) in Standardbred trotters. Blood levels of several inflammatory markers [serum amyloid A (SAA), haptoglobin, fibrinogen, white blood cell count (WBC), and iron], muscle enzymes [creatinine kinase (CK) and aspartate transaminase (AST)], and hemoglobin were assessed in 58 Standardbred trotters before and after racing. Hemoglobin levels increased and iron levels decreased 12 to 14 h after racing and haptoglobin concentrations, white blood cell counts, and i...
Martinson KL, Coleman RC, Rendahl AK, Fang Z, McCue ME.Excessive BW has become a major health issue in the equine (Equus caballus) industry. The objectives were to determine if the addition of neck circumference and height improved existing BW estimation equations, to develop an equation for estimation of ideal BW, and to develop a method for assessing the likelihood of being overweight in adult equids. Six hundred and twenty-nine adult horses and ponies who met the following criteria were measured and weighed at 2 horse shows in September 2011 in Minnesota: age ≥ 3 yr, height ≥ 112 cm, and nonpregnant. Personnel assessed BCS on a scale of 1 t...
Hellings IR, Larsen S.Gastric ulceration is highly prevalent in horses, and there is a large commercial market for feed-additives and non-licenced products that claim effect for prevention and treatment of gastric ulceration. ImproWin® has been used as a feed additive in horses with anecdotal evidence that it may have some positive effects on gastric ulceration.The aim of this study was to investigate the effect of ImproWin® treatment on spontaneously occurring gastric ulcers of the squamous mucosa in Standardbred and Coldblooded trotting racehorses. The study was performed as a randomised, double-blinded, single...
Goachet AG, Harris P, Philippeau C, Julliand V.This study aimed at evaluating, in previously inactive Standardbreds horses, the effect of 5 weeks of an exercise training programme on nutrient digestibility and faecal fermentative parameters (FFPs). As an increase in digestibility had previously been reported in trained endurance horses, we hypothesized that similar results would be found in horses being trained for other types of exercise on a different type of diet. After 3 weeks of dietary adaptation, a digestibility trial (DT1) was undertaken, over 3 days, in eight untrained Standardbreds with a fresh faecal sample being collected on th...
Sutton GJ, Cawley A, Murphy C, Lau ML, Hibbert DB.Horse racing authorities impose a limit on the concentration of plasma 'total carbon dioxide' (TCO2), typically 36 mM with action taken above 37 mM, as measured by an electrochemical gas analyzer. It is of interest to understand the distribution of TCO2 in a 'normal' population of racehorses and determine probabilities of members of this population exceeding these current regulatory and action limits. TCO2 levels in equine plasma samples have been modelled for 12 months (2011-2012) of thoroughbred (3076 measurements) and standardbred (3788 measurements) data in Australia. The two populations h...
Padalino B, Zaccagnino P, Celi P.The aim of this study was to investigate the impacts of three different physical exercises on the physiological and behavioural patterns of Standardbred trotters housed in single stalls. Twelve racing mares were observed twice during each different exercise: daily training (DT) consisted of forty minutes at slow trot (4-5 m/s) in a small track; maximal exercise (ME) consisted of 1600 m run at maximal velocity; race (R) was a real race of 1600 m. The mares were examined at rest in their stall (Time I), soon after the completion of the exercise (Time II), one hour (Time III), and two hours...
Thomas KC, Hamilton NA, North KN, Houweling PJ.The sarcomeric α-actinins, encoded by the genes ACTN2 and ACTN3, are major structural components of the Z-line and have high sequence similarity. α-Actinin-2 is present in all skeletal muscle fibres, while α-actinin-3 has developed specialized expression in only type 2 (fast, glycolytic) fibres. A common single nucleotide polymorphism (SNP) in the human ACTN3 gene (R577X) has been found to influence muscle performance in elite athletes and the normal population. For this reason, equine ACTN3 (eACTN3) is considered to be a possible candidate that may influence horse performance. In this stud...
Bertuglia A, Bullone M, Rossotto F, Gasparini M.There is a substantial paucity of studies concerning musculoskeletal injuries in harness Standardbred racehorses. Specifically, little is known about the epidemiology of exercise-related musculoskeletal injuries. Most studies on this subject involve Thoroughbred racehorses, whose biomechanics and racing speed differ from Standardbred, making comparisons difficult. Here, a population of Standardbred racehorses trained at the same racecourse was studied over four years and a classification system for exercise-related musculoskeletal injuries was designed. The incidence rates of musculoskeletal i...
Khosravi AR, Nikaein D, Sharifzadeh A, Gharagozlou F.This study was carried out in order to isolate and identify the normal conjunctival fungal flora from Caspian miniature, Thoroughbred, Turkmen and Persian Arab breeds in Tehran, Iran. Methods: A total of seventy-two adult healthy horses were studied. Ocular samples were collected from right and left eyes by using sterile cotton swabs; samples were cultured on Sabouraud dextrose agar and incubated at 30°C for 7-10 days. Molds and yeasts were identified using macro and micro-morphological and physiological characteristics. Conclusions: Number of fungal colonies per eye varied between 0 and 123 ...
Goodrich LR, Nixon AJ, Conway JD, Morley PS, Bladon BM, Hogan PM.An in-depth review of dynamic compression plate (DCP) fixation of propagating medial condyle fractures of the third metacarpus or metatarsus has not been previously reported. Objective: To describe the technique, evaluate short-term outcome and long-term race performance of racehorses that underwent DCP fixation for repair of propagating or spiralling medial condylar fractures of the third metacarpal (McIII) or metatarsal (MtIII) bone. Methods: Retrospective case series. Methods: The surgical case records of 30 horses with propagating fractures of the medial condyle of McIII or MtIII were revi...
Rumpler MJ, Colahan P, Sams RA.The disposition of plasma glycopyrrolate (GLY) is characterized by a three-compartment pharmacokinetic model after a 1-mg bolus intravenous dose to Standardbred horses. The median (range) plasma clearance (Clp), volume of distribution of the central compartment (V1 ), volume of distribution at steady-state (Vss), and area under the plasma concentration-time curve (AUC0-inf ) were 16.7 (13.6-21.7) mL/min/kg, 0.167 (0.103-0.215) L/kg, 3.69 (0.640-38.73) L/kg, and 2.58 (2.28-2.88) ng*h/mL, respectively. Renal clearance of GLY was characterized by a median (range) of 2.65 (1.92-3.59) mL/min/k...
François I, Lalèyê FX, Micat M, Benredouane K, Portier K.Some controversy exists over whether or not horses' recovery and cardiopulmonary function are affected by suspension in slings. Objective: To measure arterial oxygen tension and pulmonary ventilation in anaesthetised horses placed in a standing position in an Anderson Sling (AS) after a period of right lateral recumbency (RLR). Methods: Randomised crossover experimental study. Methods: Six Standardbred horses were anaesthetised twice. Catheters were inserted into the right jugular vein and the left carotid artery. After premedication with romifidine, anaesthesia was induced with diazepam and k...
van Eps AW, Pollitt CC, Underwood C, Medina-Torres CE, Goodwin WA, Belknap JK.Prophylactic digital hypothermia reduces the severity of acute laminitis experimentally but there is no evidence for its efficacy as a treatment once lameness has already developed. Objective: To investigate the therapeutic effects of digital hypothermia, applied after the onset of lameness, in an experimental acute laminitis model. Methods: Randomised, controlled (within subject), blinded, experimental trial. Methods: Eight Standardbred horses underwent laminitis induction using the oligofructose model. Once lameness was detected at the walk, one forelimb was continuously cooled (CRYO), with ...
Mariella J, Pirrone A, Gentilini F, Castagnetti C.The purposes of this study were to determine physiological changes occurring in hematologic and biochemical parameters in mares between the last month of gestation and the first week after parturition. If a significant change was observed with respect to the reference interval of an adult horse, a further aim of the study was to establish different reference intervals. Blood samples were collected from 62 healthy pregnant Standardbred mares. Seventeen nonpregnant and nonlactating mares were used as a control group. In pregnant mares, blood sampling was conducted every three days from 1 month b...
Bamford NJ, Potter SJ, Harris PA, Bailey SR.Breed-related differences may occur in the innate insulin sensitivity (SI) of horses and ponies, an important factor believed to be associated with the risk of laminitis. The aim of this study was to measure the glucose and insulin responses of different breeds of horses and ponies in moderate body condition to a glucose-containing meal and to compare these responses with the indices of SI as determined by a frequently sampled intravenous glucose tolerance test (FSIGT). Eight Standardbred horses, 8 mixed-breed ponies, and 7 Andalusian-cross horses with a mean ± SEM BCS 5.0 ± 0.3 of 9 were us...
Arroyo LG, Ter Woort F, Baird JD, Tatiersky L, Delay J, van Dreumel T.This report describes 5 cases of fatal Lawsonia intracellularis-associated ulcerative and necro-hemorrhagic enteritis in weanling Thoroughbred and Standardbred foals. The lesions are similar to those of the L. intracellularis-associated ulcerative and necro-hemorrhagic enteritis syndrome in pigs. Two foals had concurrent severe typhlo-colitis as a result of a large burden of encysted cyathostomes. The clinical, diagnostic, and therapeutic challenges, and the potential complications encountered during the management of such cases are discussed. Entérite ulcérative et nécro-hémorragique asso...
de Laat MA, Clement CK, McGowan CM, Sillence MN, Pollitt CC, Lacombe VA.Equine laminitis, a disease of the lamellar structure of the horse's hoof, can be incited by numerous factors that include inflammatory and metabolic aetiologies. However, the role of inflammation in hyperinsulinaemic laminitis has not been adequately defined. Toll-like receptor (TLR) activation results in up-regulation of inflammatory pathways and the release of pro-inflammatory cytokines, including interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-α), and may be a pathogenic factor in laminitis. The aim of this study was to determine whether TLR4 expression and subsequent pro-infla...
Depecker M, Richard EA, Pitel PH, Fortier G, Leleu C, Couroucé-Malblanc A.The aim of this study was to determine whether the lung side being sampled would significantly influence bronchoalveolar lavage (BAL) cytological profiles and subsequent diagnosis in Standardbred racehorses. One hundred and thirty-eight French Trotters in active training and racing were included in a prospective observational study. BAL was performed using videoendoscopy in both right and left lungs during summer meetings in 2011 (64 horses) and 2012 (74 horses). Cytological data performed 24h later from right and left lungs were compared and specifically used to classify horses as affected wi...
Ruppin MP, Dennis MM, Smith CL, Vogelnest LJ.A 2-month-old Standardbred filly was presented for examination and treatment of extensive congenital skin lesions that had a linear distribution on the left front leg extending from the dorsal midline to the metacarpal region. The lesions were surgically excised under general anaesthesia. Surgical excision was curative and there were no signs of recurrence 6 weeks after surgery. The number and distribution of lesions were more extensive than in previously reported cases of congenital papillomas, which have also been described as epidermal growth abnormalities (naevi or hamartomas). Early repor...
Liburt NR, McKeever KH, Malinowski K, Smarsh DN, Geor RJ.This study tested the hypotheses that age-induced alteration in cortisol, ACTH, and glucose concentrations are due to differences in the response of the hypothalamic-pituitary-adrenal axis and that exercise training would attenuate these differences. Six old (22.0±0.7 yr; mean±SE) and 6 young (7.3±0.6 yr) unfit Standardbred mares ran 3 graded exercise tests (GXT): before (GXT1), after 8 wk of training (GXT2), and at study end at 15 wk (GXT3). Mares trained 3 d/wk at 60% maximum heart rate. Each mare underwent 5 endocrine stimulation tests pre- and posttraining: 1) control (CON), 2) adrenoco...
Lascola KM, O'Brien RT, Wilkins PA, Clark-Price SC, Hartman SK, Mitchell MA.To qualitatively describe lung CT images obtained from sedated healthy equine neonates (≤ 14 days of age), use quantitative analysis of CT images to characterize attenuation and distribution of gas and tissue volumes within the lungs, and identify differences between lung characteristics of foals ≤ 7 days of age and foals > 7 days of age. Methods: 10 Standardbred foals between 2.5 and 13 days of age. Methods: Foals were sedated with butorphanol, midazolam, and propofol and positioned in sternal recumbency for thoracic CT. Image analysis software was used to exclude lung from nonlung str...
Champion ZJ, Breier BH, Ewen WE, Tobin TT, Casey PJ.A survey of standardbred horses was conducted to build up a normal population profile for insulin like growth factor-I (IGF-I) concentrations in racing standardbreds and to ascertain how age, sex and geographic location affect IGF-I. Blood samples were drawn by jugular venepuncture from 202 racing standardbred horses aged one to eight years located in five different geographic regions of New Zealand. IGF-I concentrations were determined by insulin like growth factor-I binding protein (IGFBP)-blocked radioimmunoassay validated for the horse. As described in other species, age played a significa...
Diel de Amorim M, Montanholi Y, Morrison M, Lopez Rodriguez M, Card C.The ability to predict impending foaling is invaluable, as attending foaling improves mare and foal outcome during parturition; therefore, a comparison of foaling prediction technologies is warranted. The purpose of this study was to compare technologies to predict foaling. Forty Standardbred mares were monitored daily for parturition. Prefoaling mammary secretion was collected daily and evaluated using a: calcium titration method (Ca titration), calcium and magnesium strip (Ca and Mg), handheld digital pH device (pH digital), pH strip, and refractometer (Brix). In addition, a birth monitoring...
Carstensen H, Nissen SD, Saljic A, Hesselkilde EM, van Hunnik A, Hohl M, Sattler SM, Fløgstad C, Hopster-Iversen C, Verheule S, Böhm M, Schotten U....Atrial fibrillation (AF) is more prevalent in athletes, and currently, the mechanisms are not fully understood. Atrial fibrillation inducibility and stability was investigated in trained and untrained Standardbred racehorses. The horses underwent echocardiography for evaluation of atrial size. High-density mapping during AF was performed, and the presence of structural remodeling, as well as the expression of inflammatory and pro-inflammatory markers in the atria, was studied. Atrial fibrillation sustained significantly longer after tachypacing in the trained horses, whereas no difference in A...
Morris DD, Meirs DA, Merryman GS.A prospective study was performed to determine the incidence and associated maternal and managemental factors of failure of passive transfer (FPT) in foals on a breeding farm. The zinc sulfate turbidity test (ZSTT) and latex agglutination test (LAT) were compared for accuracy in estimating serum immunoglobulin (Ig)G of foals, as determined by single radial immunodiffusion (SRID). Complete past and present foaling histories of 136 Standardbred mares were obtained. All foalings were witnessed by farm attendants, and colostral samples were collected from mares within 2 hours after parturition. Fo...
Anderson BH, Kannegieter NJ, Goulden BE.An endoscopic survey of young race horses was performed to examine the prevalence and character of laryngeal movements during quiet respiration. The main aim was to determine whether those arytenoid movements which could possibly reflect the efficiency of left dorsal cricoarytenoid muscle function changed over a period of time. Of the 452 horses examined, 439 were Thoroughbreds and 23 were Standardbreds, 250 were less than 2 years of age (6-21 months), and 202 were 2 years old. One hundred and nine of these horses were examined again 16 months later. Arytenoid movements were given one of four ...
Latham CM, Fenger CK, White SH.Responses of equine skeletal muscle characteristics to growth and training have been shown to differ between breeds. These differential responses may arise in part because muscle fiber type and mitochondrial density differ between breeds, even in untrained racing-bred horses. However, it is not known when these breed-specific differences manifest. To test the hypothesis that weanling Standardbreds (SB) and Thoroughbreds (TB) would have higher mitochondrial measures than Quarter Horses (QH), gluteus medius samples were collected from SB (mean ± SD; 6.2 ± 1.0 mo; n = 10), TB (6.1 ± 0.5 mo; n ...
Beeler-Marfisi J, Arroyo L, Caswell JL, Delay J, Bienzle D.Hepatoblastoma (HB) is an uncommon pediatric liver tumor in humans and horses. In humans, HB is most frequently diagnosed in fetuses, neonates, and young children, whereas hepatocellular carcinoma (HCC) affects juvenile and adult humans. Hepatoblastoma in the horse is rare, with only 9 reported cases. Affected horses ranged in age from late-term aborted fetuses to 3 years. The current study describes 3 new cases of primary liver tumors in horses and reviews findings in relation to other reports on this condition. Tumors classified as HB were identified in a male Standardbred aborted fetus and ...
Beard WL, Bramlage LR, Schneider RK, Embertson RM.Medical records for 64 Thoroughbred and 45 Standardbred horses with osteochondrosis dissecans (OCD) of the tarsocrural joint that were treated by means of arthroscopic removal of the fragments before 2 years of age and before beginning racing were reviewed. Lesion site was recorded for all horses. The other foals from the dams of these surgically treated horses (siblings) were identified from mare progeny records. Racing data, including number of starts and money won during the 2- and 3-year-old racing years were obtained from the Jockey Club and the United States Trotting Association for affe...
Timoney PJ, McCollum WH.Further characterization of the carrier state in stallions infected with equine arteritis virus revealed that there is considerable variation in the frequency of its occurrence among breeds. The frequency ranged from 12.5% (Holsteiner stallions) to 72.7% (Dutch Warmblood stallions), with a mean occurrence of 40.8% in the seropositive stallions (n=561) examined. More than 70% of the virus shedders were Standardbred stallions. The carrier state was not confirmed in any of the stallions that had been vaccinated against equine viral arteritis nor was there any evidence of intermittent virus sheddi...
Dabbene I, Bullone M, Pagliara E, Gasparini M, Riccio B, Bertuglia A.Information on interference injuries in racehorses is lacking. Objective: To describe clinical findings and prognosis of palmar forelimb interference injuries in Standardbreds. Methods: Retrospective cohort study. Methods: Records of 74 racehorses sustaining palmar forelimb interference injuries were studied; 7 occurred during training and 67 during racing. The number of starts before injury, hind shoeing status, gait penalties and racing speeds in cases occurring during racing were compared with negative controls (67 age, sex and speed category matched horses) from the same races. The number ...
Gordon ME, McKeever KH, Bokman S, Betros CL, Manso-Filho H, Liburt N, Streltsova J.Horses in training tend to become inappetant; however, the mechanism responsible for this training-induced inappetance is not known. Objective: Training and/or ulcers alter the feed intake (FI) and hormonal and/or biochemical (active ghrelin, leptin, glucose, insulin and cortisol) responses to acute high intensity exercise. Methods: Eight Standardbred mares underwent 3 interval exercise tests (IET) and 3 parallel control tests (CON) before (IET1) and after 8 weeks of training (IET2) and after treatment for gastric ulcers (IET3). Plasma samples were taken before (0 min), during (last 10 sec of ...
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...
Pirrone F, Albertini M, Clement MG, Lafortuna CL.The aim of this study was to investigate and quantify respiratory mechanical dysfunctions in Standardbred horses with both poor performance and bronchoalveolar lavage fluid cytology characteristic of inflammatory airway disease (IAD). A control group of healthy Standardbred horses was compared. Respiratory mechanics and breathing pattern were examined at rest and during hyperventilation induced using a rebreathing method. At rest, respiratory mechanics and breathing pattern were superimposable in both groups. In IAD horses, rebreathing increased ventilation, with larger tidal volumes and lower...
Perez-Moreno CI, Couëtil LL, Pratt SM, Ochoa-Acuña HG, Raskin RE, Russell MA.The objective was to quantify the effect of furosemide and carbazochrome on exercise-induced pulmonary hemorrhage (EIPH) in Standardbred horses using red blood cell count and hemoglobin concentration in bronchoalveolar lavage (BAL) fluid. Six healthy Standardbred horses with prior evidence of EIPH performed a standardized treadmill test 4 h after administration of placebo, furosemide, or furosemide-carbazochrome combination. Red blood cell (RBC) counts and hemoglobin concentrations were determined on the BAL fluid. The RBC count in BAL ranges were (2903-26,025 cells/microL), (45-24,060 cells/m...
Ter Woort F, Caswell JL, Arroyo LG, Viel L.OBJECTIVE To describe histologic findings in the small airways during postmortem examination of actively racing horses and to quantify the degree of airway inflammation by use of a semiquantitative scoring system. SAMPLE Lung tissues obtained from 95 horses (Thoroughbreds, Standardbreds, and Quarter Horses) that had been actively racing or training. PROCEDURES 10 standardized lung sections were obtained during postmortem examination of 37 horses that had been actively racing or training, and 2 histologic sections of the caudodorsal lung lobes previously collected from each of 58 horses that di...
Niemelä TM, Tulamo RM, Carmona JU, López C.Inflammatory and degenerative activity inside the joint can be studied in vivo by analysis of synovial fluid biomarkers. In addition to pro-inflammatory mediators, several anabolic and anti-inflammatory substances are produced during the disease process. They counteract the catabolic effects of the pro-inflammatory cytokines and thus diminish the cartilage damage. The response of synovial fluid biomarkers after intra-articular hyaluronan injection, alone or in combination with other substances, has been examined only in a few equine studies. The effects of hyaluronan on some pro-inflammatory m...
Malikides N, Hughes KJ, Hodgson JL.To determine whether percentages of neutrophils in tracheal aspirate (TA) samples collected from racehorses are increased after exercise and whether interpretation of results from TA samples taken before and after exercise agree. Methods: Case series of 40 young Thoroughbred and Standardbred racehorses in race training presented for evaluation of poor performance. Methods: TA samples were collected endoscopically from racehorses presented for poor performance 24 h before and 1 to 2 h after high speed treadmill exercise testing. Aliquots of the retrieved fluid were cytocentrifuged and smears we...
Connysson M, Muhonen S, Jansson A.This study investigated the effects of transport and diet on metabolic response during a subsequent race-like test in Standardbred horses in training fed a forage-only diet and a 50:50 forage:oats diet. Six trained and raced Standardbred trotter mares were used. Two diets, 1 forage-only diet (FONLY) and 1 diet with 50% of DM intake from forage and 50% from oats (FOATS), were fed for two 29-d periods in a crossover design. At Day 21, the horses were subjected to transport for 100 km before and after they performed an exercise test (transport test [TT]). At Day 26, the horses performed a control...
Ronéus M.Biopsy samples were taken from the middle gluteal muscle in 107 health Standardbred horses. The horses were separated according to sex and divided into 4 age groups (1, 2, 3 and 4-6 years). The proportion of Type I fibres increased with age (from 16 to 20%), irrespective of sex. The proportions of Type IIA and IIB fibres varied with age and differed between stallions and mares. Type IIA fibres increased in mares from 37 to 47% and in stallions from 40 to 48% and Type IIB fibres decreased from 49 to 34% in mares, and from 43 to 30% in stallions. Mares and stallions did not differ in enzyme acti...
Weese JS, Sabino C.Antimicrobials had been administered to 38/55 (69%) racing standardbred and Thoroughbred horses with poor performance, subsequently diagnosed with nonseptic inflammatory airway disease. Horses with cough were more commonly treated (P = 0.02). In almost all cases, no clinical signs suggested that bacterial infection was present. Inappropriate use of antimicrobials was common. Des antimicrobiens ont été administrés à 38/55 (69 %) chevaux standardbreds et chevaux pursang affichant une piètre performance, diagnostiqués par la suite avec une maladie inflammatoire aseptique des voies respirat...
Little CB, Ghosh P, Rose R.Articular cartilage degeneration in the middle carpal joint is a common problem in racing horses. This study evaluated the effect of exercise on the in-vitro synthesis of the large aggregating proteoglycans (aggrecan) and two small proteoglycans, biglycan and decorin, in articular cartilage taken from three weight bearing regions of the third carpal bone of horses which were subjected to moderate or strenuous exercise. Twelve Standardbred horses free from clinical and radiographic disease of the middle carpal joint were subjected to an 8 week moderate exercise program. The horses were then ran...
van Ginneken MM, de Graaf-Roelfsema E, Keizer HA, van Dam KG, Wijnberg ID, van der Kolk JH, van Breda E.To investigate the effects of exercise on activation of mitogen-activated protein kinase (MAPK) signaling proteins in horses. Methods: 6 young trained Standardbred geldings. Methods: Horses performed a 20-minute bout of exercise on a treadmill at 80% of maximal heart rate. Muscle biopsy specimens were obtained from the vastus lateralis and pectoralis descendens muscles before and after exercise. Amount of expression and intracellular location of phosphospecific MAPK pathway intermediates were determined by use of western blotting and immunofluorescence staining. Results: Exercise resulted in a...
Demmers S, Johannisson A, Gröndahl G, Jensen-Waern M.The aim of this study was to investigate the phagocytic and killing capacities as well as expression of CD18 of neutrophils obtained from healthy foals from birth to age 8 months. Blood was taken from 6 Standardbred foals at 7 time-points between ages 2-56 days and thereafter once a month. For comparison, cells from 16 mature horses were evaluated. Neutrophil phagocytosis of yeast cells was assessed by flow cytometry after opsonisation with mature pooled serum, autologous serum or anti-yeast IgG. The killing capacity of the neutrophils, as indicated by the oxidative burst, was monitored by che...
Eagle RC, Font RL, Swerczek TW.An 18-month-old Standardbred filly had a large intraocular tumor involving the optic nerve. The tumor was a malignant medulloepithelioma, a rare intraocular neoplasm derived from the primitive medullary epithelium. By light microscopy the tumor had cords and lobules of primitive neuroepithelial cells that formed clefts and true rosettes. Electron microscopy of the rosettes showed a girdle of zonulae adherentes joining the apices of the cells as well as several basal bodies. This is the sixth report of equine intraocular medulloepithelioma, and, to the best of our knowledge, the first intraocul...
Morgan K, Funkquist P, Nyman G.The aim of this study was to study the physiological, especially thermoregulatory, responses during intense exercise in the clipped horse compared to the horse with winter coat. Six Standardbred trotters were studied before and after clipping. They performed an inclined incremental high intensity treadmill exercise test and were monitored during recovery. The clipped horse differed significantly (ANOVA) during exercise as compare to coated: less increase in central venous blood temperature, higher skin surface temperature, greater difference skin to ambient temperature and higher rate of nonev...
Koenig TJ, Dart AJ, McIlwraith CW, Horadagoda N, Bell RJ, Perkins N, Dart C, Krockenberger M, Jeffcott LB, Little CB.To assess the effects of sodium pentosan polysulfate (PPS), N-acetyl glucosamine (NAG), and sodium hyaluronan (HA) in horses with induced osteoarthritis (OA). Methods: Experimental. Methods: Adult Standard bred horses (n = 16). Methods: OA was induced arthroscopically in 1 intercarpal joint; 8 horses were administered 3 mg/kg PPS, 4.8 mg/kg NAG, and 0.12 mg/kg HA (PGH), intravenously (IV), weekly and 8 horses were administered an equivalent volume of saline IV until study completion (day 70). Horses underwent a standardized treadmill exercise program. Clinical and radiographic findin...
Connysson M, Rhodin M, Jansson A.This study examined the effects of two housing systems (free-range and box stalls) on recovery of energy balance after competition-like exercise in Standardbred horses. Eight adult geldings (mean age 11 years) were used. The study had a change-over design, with the box stall (BOX) and free-range group housing (FreeR) treatments each run for 21 days. The horses were fed forage ad libitum and performed two similar race-like exercise tests (ET), on day 7 and day 14 in each treatment. Forage intake was recorded during the last 6-7 days in each period. Blood samples were collected before, during, a...
Laws EG, Richardson DW, Ross MW, Moyer W.A retrospective study of 114 Standardbred horses diagnosed with osteochondrosis (OC) of the cranial intermediate ridge of the distal tibia was carried out, and their subsequent race records were compared with 456 control horses. Each OC-affected horse was compared with 4 horses randomly selected from a list of horses matched to it by year of birth, sex and sire. The horses with OC were treated by arthroscopic removal of osteochondral fragments (N = 58) or managed conservatively (N = 56). The clinical presentation of these two groups was similar, although joint effusion was a more common presen...
Lo Feudo CM, Stucchi L, Conturba B, Stancari G, Zucca E, Ferrucci F.Equine Gastric Ulcer Syndrome (EGUS) is a highly prevalent disorder in horses, which can be classified, based on the localization of the lesions, as Equine Squamous Gastric Disease (ESGD) or Equine Glandular Gastric Disease (EGGD). Although EGUS is recognized as a common cause of poor performance in racehorses, objective investigations about its relation with athletic capacity are lacking. Therefore, the present retrospective study aims to evaluate the associations between EGUS severity and some fitness parameters measured during an incremental treadmill test in Standardbred racehorses in trai...
Valentine BA, McDonough SP, Chang YF, Vonderchek AJ.Polysaccharide storage myopathy is an equine neuromuscular disorder characterized by accumulation of glycogen-related polysaccharide inclusions within skeletal muscle fibers. The pathologic criteria for diagnosis of this disorder are somewhat controversial; however, periodic acid-Schiff-positive, amylase-resistant inclusions are considered pathognomonic. Although these inclusions are most often found in affected horses related to the Quarter Horse, draft horse, and Warmblood breeds, this report describes these characteristic inclusions in muscle of five horses from nonrelated breeds (two Morga...
