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Topic:Equine Health
Equine health encompasses the study and management of diseases, disorders, and overall well-being of horses. It involves understanding various physiological systems, preventive care, and treatment strategies to maintain optimal health in equine populations. Common areas of focus include nutrition, infectious diseases, orthopedic conditions, and reproductive health. Research in equine health aims to advance knowledge on diagnostic methods, therapeutic interventions, and management practices that improve horse welfare and performance. This page collects peer-reviewed research studies and scholarly articles that explore the diverse aspects of equine health, offering insights into current findings and advancements in the field.
Effect of a set stabled environmental control on pulmonary function and airway reactivity of COPD affected horses. The aim of this study was to evaluate the respiratory function of horses affected with chronic obstructive pulmonary disease (COPD) when maintained in a barn on wood shavings and fed grass silage for a period of 6 weeks. The mechanics of breathing, blood gas analysis and bronchial reactivity were examined on five horses with COPD at the end of the environment-controlled period (Period B) and the results compared with values obtained after 2 months at pasture (Period A) and after the onset of clinical signs of acute crisis (Period C). The results showed that clinical and functional parameters w...
Effect of bilateral blockade of the pharyngeal branch of the vagus nerve on soft palate function in horses. To determine the effect of bilateral blockade of the pharyngeal branch of the vagus nerve on soft palate function in horses. Methods: 5 Standardbreds. Methods: Peak tracheal inspiratory and expiratory pressures and airflow were measured while horses exercised at the speeds corresponding to 75 and 100% of the speed that resulted in maximal heart rate, with and without pharyngeal branch of the vagus nerve blockade. Respiratory frequency-to-stride frequency coupling ratio was measured by correlating foot fall measurements with respiratory frequency. The pharyngeal branch of the vagus nerve was bl...
Vascular and transsynovial forces of the isolated stationary equine joint. To provide quantitative assessment of forces affecting filtration of synovial fluid in response to incremental changes in arterial and venous hemodynamics. Methods: 7 clinically normal adult horses. Methods: Using a stationary, isolated metacarpophalangeal joint preparation, blood flow (Qa[cir]), tissue perfusion, arterial pressure (Pa[cir]), venous pressure (Pv[cir]), transsynovial fluid flow, total vascular resistance, vascular compliance, and tissue compliance were evaluated before and after arterial and venous pressure manipulations. At isogravimetric conditions, pre- and postcapillary res...
Changes in plasma atrial natriuretic peptide concentration in exercising horses in relation to hydration status and exercise intensity. To investigate effects of hydration status and exercise intensity on plasma atrial natriuretic peptide (ANP) concentration in exercising horses. Methods: 4 trained Standardbreds. Methods: Horses performed a 40-minute exercise test at 65 to 70% maximal heart rate (HRmax; no incline) and a 12-minute test at approximately 90% HRmax (3.5 degrees incline). The 40-minute test was performed with ad libitum access to drinking water (normohydration), after water had been withheld for 24 hours (dehydration), and 30 minutes after 12 L of water at body temperature had been given via nasogastric tube (hype...
Atrial fibrillation associated with central nervous symptoms and colic in a horse: a case of equine cardiomyopathy. A 18-year-old Dutch Warmblood mare was referred for colic. Upon arrival, lethargy, blindness, head pressing, ataxia, and circling were the main clinical signs. On rectal examination a hard mass and oedema around the cranial mesenteric artery were palpated. Plasma liver enzyme activities and the ammonia level were elevated. Atrial fibrillation with a pulse frequency of 36-52 beats per minute was noticed. On both sides a holosystolic murmer with the maximum intensity on the right side could be auscultated. Postmortem examination revealed eccentric hypertrophy of the right atrium and a pale spott...
Catecholamine and cortisol responses of horses to incremental exertion. The responses of the plasma concentrations of catecholamines and cortisol in horses to varied relative intensities of exertion were examined. The plasma concentrations of cortisol, epinephrine and norepinephrine increased significantly (p < 0.05) with exertion. The plasma cortisol concentrations at relative work intensities of 48.3% +/- 1.4%, 82.3% +/- 2.0% and 99.6% +/- 0.4% of VO2max were 114%, 124%, and 126%, respectively, of those at rest, whereas the plasma epinephrine concentrations were 239%, 772% and 3483%, and the norepinephrine concentrations were 138%, 255%, and 1121% of the valu...
Evaluation of platelet activation and platelet-neutrophil aggregates in Thoroughbreds undergoing near-maximal treadmill exercise. To determine whether platelets become activated and form platelet-neutrophil aggregates during near-maximal treadmill exercise in horses. Methods: 4 Thoroughbreds. Methods: Horses were subjected to 4 standardized exercise tests on a treadmill, and blood samples were collected before exercise, at treadmill speed of 12 m/s, and 5 minutes after exercise. Flow cytometric techniques were used to identify activated platelets, and flow cytometric and microscopic techniques were used to identify platelet-neutrophil aggregates. Results: Platelet-neutrophil aggregates increased from 2.8 +/- 0.4% at rest...
Pharmacokinetics of cefepime and comparison with those of ceftiofur in horses. To determine pharmacokinetics of i.v., i.m., and oral administration of cefepime in horses and to compare pharmacokinetics of i.m. administration of cefepime with those of ceftiofur sodium. Methods: 6 clinically normal adult horses. Methods: Horses received 3 doses of cefepime (11 mg/kg of body weight, PO; 2.2 mg/kg, i.v.; and 2.2 mg/kg, i.m.) and 1 dose of ceftiofur (2.2 mg/kg, i.m.). Two horses also received L-arginine, p.o. and i.v., at doses identical to those contained in the cefepime dihydrochloride-L-arginine preparations previously administered. Blood samples were collected for 24 hour...
CD8 dimer usage on alpha beta and gama delta T lymphocytes from equine lymphoid tissues. Eight murine monoclonal antibodies (mAb) were used to identify the equine CD8 alpha or CD8 beta chains and to define the expression of these chains on lymphocytes from various lymphoid tissues. CD8 alpha was a 39 kDa protein and CD8 beta was a 32 kDa protein. Both chains were expressed on most of the CD8+ T lymphocytes in the peripheral blood, spleen, thymus, mesenteric lymph nodes and ileal intraepithelial lymphocytes (IEL), however, in each lymphoid compartment a percentage of lymphocytes expressed only the CD8 alpha chain. The largest percentage of CD8 alpha alpha expressing T lymphocytes w...
Influence of atipamezole on effects of midsacral subarachnoidally administered detomidine in mares. To examine effects of atipamezole on detomidine midsacral subarachnoidally-induced analgesia, cardiovascular and respiratory activity, head ptosis, and position of pelvic limbs in healthy mares. Methods: 10 healthy mares. Methods: Using a randomized, blinded, crossover study design, mares received detomidine (0.03 mg/kg of body weight, diluted in 3 ml of CSF) midsacral subarachnoidally, followed by atipamezole (0.1 mg/kg [test]) or sterile saline (0.9% NaCl) solution (control), i.v. 61 minutes later and saline solution (3 ml, midsacral subarachnoidally) on a separate occasion, at least 2 weeks...
The effect of dietary protein on reproduction in the mare. IV. Serum progestagen, FSH, LH and melatonin concentrations during the anovulatory, transitional and ovulatory periods in the non-pregnant mare. The effect of total protein intake and protein quality on the serum concentrations of certain reproductive hormones during the anovulatory, transitional and ovulatory periods were studied in 36 Anglo-Arab mares. High-quality protein stimulated FSH and LH production during the late transitional period. Serum progestagen and melatonin concentrations were unaffected by the quality of protein nutrition during the anovulatory period. Mares receiving high-quality protein exhibited a 10-14-day cyclical pattern of FSH release approximately 4-6 weeks earlier than the mares fed the lower-quality protein...
Fluid and electrolyte balance in endurance horses. In horses, fluid losses of 10L to 15L per hour can occur during endurance exercise under hot environmental conditions. The horse's sweat is hypertonic with respect to plasma, and large amounts of sodium, chloride and potassium are lost during prolonged exercise. Horses that reach exhaustive syndrome often show pronounced increases in plasma protein concentration. This could be an indication of failure of the compensatory fluid shift from the intracellular compartment caused by severe dehydration. Thorough physical examination by the ride veterinarian allows early recognition of dehydration and...
Treatments affecting fluid and electrolyte status during exercise. A number of feeding and management practices, dietary electrolyte supplements, and medications may affect fluid and electrolyte status in resting and exercising horses. The contents of the gastrointestinal tract of the equine athlete, unlike its human counterpart, are responsible for more than 10% of body weight. Although ingesta traditionally has been considered dead weight for the sprinting horse, it is a valuable reservoir of fluid and electrolytes that may be used during endurance exercise. Numerous strategies for hyperhydration of the equine athlete and for replacement of fluid and electr...
Fluid, electrolyte, and acid-base balances in three-day, combined-training horses. Horses competing in 3-day, combined-training events develop a metabolic acidosis that is partially compensated for by a respiratory alkalosis immediately after phases B and D. By the end of phase C and 30 minutes to 2 hours after phase D, the acidosis is resolved by the oxidation of lactate, and a metabolic alkalosis prevails. A reduction in TBW and cation content occurs, which often is not replenished 12 to 24 hours after the event, even though the serum or plasma concentration of various constituents may be within normal limits. Hypochloremia and hypocalcemia, however, may persist 12 or more...
Fluid, electrolyte, and acid-base responses to exercise in racehorses. During both high-intensity and short-distance exercise, the high rate of expended energy is met by anaerobic oxidation of glucose to lactic acid; this is the main cause of metabolic acidosis observed during racing. In addition, plasma volume decreases because water moves from the vasculature to the intracellular and interstitial spaces at the onset of intense exercise. These fluid shifts, together with active ion-exchange between blood and tissue, cause marked changes in electrolyte concentrations. This article reviews the mechanisms of acid-base disturbances, fluid shifts, and electrolyte cha...
Thermoregulatory adaptations associated with training and heat acclimation. The large metabolic heat load generated as a consequence of muscular work requires activation of thermoregulatory mechanisms in order to prevent an excessive and potentially dangerous rise in body temperature during exercise. Although the horse has highly efficient heat dissipatory mechanisms, there are a number of circumstances in which the thermoregulatory system may be overwhelmed, resulting in the development of critical hyperthermia. The risk for development of life-threatening hyperthermia is greatest when (1) the horse is inadequately conditioned for the required level of physical perfo...
Thermoregulation. Base mechanisms and hyperthermia. Metabolic HP is extremely high during exercise in horses. Thermoregulation in horses is primarily dependent on evaporative heat loss from sweating in particular. Under thermoneutral conditions, these mechanisms are sufficient to allow horses to perform high-intensity exercise for long periods. Under thermally stressful conditions, particularly in high ambient humidity, the efficiency of evaporative heat loss mechanisms is compromised and may result in horses developing hyperthermia. Early recognition and vigorous treatment are essential to limit the consequences of heat stress in horses. Metic...
An aspartic proteinase expressed in the equine placenta. This manuscript describes the cloning of a novel aspartic proteinase expressed in the placenta of the horse (order Perrisodactyla). Evidence for similar genes in the cat (Carnivora) and ruminants (Artiodactyla), indicates that these molecules have been conserved within widely divergent species with distinct types of placentation. Since ePAG is produced by the outer cell layer (trophoblast) of the placenta, it can tentatively be grouped with the pregnancy-associated glycoproteins (PAG) of cattle, sheep, and pig. The high sequence identity that ePAG shares with pepsinogens as well as the PAG, in...
Effect of exercise on acid-base status of horses. Exercise in horses is associated with a wide variety of physiological changes in fluid, electrolyte and acid base balance. The integration of physiologic and physiochemical mechanisms acts to minimize alterations in pH and enhance removal of carbon dioxide produced by exercising muscles. This article provides a description of the changes that take place during exercise and how these changes affect acid-base balance in the horse.
Sweating. Fluid and ion losses and replacement. In the horse, sweat is produced by apocrine glands which are present over most haired and nonhaired skin. Although sweat secretion is initiated under a number of circumstances, the central drive for sweating in response to a thermal stimulus is the primary mechanism for its production. Sweating is an essential and primary mechanism for heat dissipation during exercise or exposure to hot ambient conditions. The rate of sweat production will reflect the interaction of numerous factors, including exercise intensity, ambient conditions, state of hydration, and the training or heat acclimation stat...
Experimental cyathostome challenge of ponies maintained with or without benefit of daily pyrantel tartrate feed additive: comparison of parasite burdens, immunity and colonic pathology. Eighteen mixed-breed, naturally infected ponies ranging in age from 1 to 16 yr and four cyathostome-naïve ponies reared and maintained under parasite-free conditions ranging in age from 1 to 4 yr were used in this study. Naturally-infected ponies were treated with 1 dose of ivermectin (IVM) at 200 micrograms kg-1, followed by a 5-day regimen of oxibendazole (OBZ) at 20 mg kg-1 to remove existing cyathostome burdens; cyathostome-naïve control ponies were treated with IVM alone. The naturally infected ponies were matched on age and gender, then randomly assigned to one of three treatment group...
Physiology of body fluids in the horse. This article presents a brief overview of the physiology of homeostasis in the horse and discusses the units of measurement by which dissolved electrolytes are assessed. Differences in electrolyte composition between compartments of the body and the manner in which water is exchanged between them are reviewed. The mechanisms by which alterations in osmolality and effective circulating volume are detected and the physiological responses to those alterations are presented.
An epizoological study of wastage in thoroughbred racehorses in Gauteng, South Africa. Wastage is the term used to describe the phenomenon of the loss of racehorses from conception to adulthood due to death or injuries (i.e. they never reach a race-track), or the days lost by racehorses due to not training or being withdrawn from a race. This epizoological study was conducted to investigate wastage in Thoroughbred horses used for flat racing in the Gauteng Province of South Africa. Data from 6 racing stables were recorded from 1 March 1993 to 28 February 1994. Each trainer completed a daily training record of the horses in his stable. This questionnaire included reasons why a ho...
C-cell adenoma containing variously sized thyroid follicles in a horse. A thyroid gland tumor, showing unusual histology, was identified in a 13-year-old male Andalusian horse. Microscopically, the tumor consisted of neoplastic proliferation of C-cell (parafollicular cell) with cytoplasmic fine granules, containing diffusely distributed, variously sized colloid-containing follicles. Immunohistochemically, the neoplastic C-cell were positive for calcitonin and follicleforming epithelial cells showed a positive reaction for thyroglobulin. Ultrastructurally, membrane-bound secretory granules up to 250 nm in diameter were found in the cytoplasm of the parafollicular c...
Results of quantitative cultures of urine by free catch and catheterization from healthy adult horses. Quantitative urine cultures were performed on 11 male and 11 female healthy adult horses. Urine was collected by free catch and catheterization using standard methods. Results showed that all samples collected by free catch contained less than 20,000 colony-forming units (CFU)/mL. All samples collected by catheterization contained 500 CFU/mL or less. A significant difference was found between collection methods (P < .005), with catheterization having less contamination. In samples collected by free catch, females had significantly greater contamination than did males (P < .03). Predominant bac...
Treatment of exercise-induced dehydration. One of the most common consequences of prolonged exercise is fluid and electrolyte depletion. Fluid and electrolyte losses during exercise may limit the horse's performance and, in extreme cases, jeopardize its health. To avoid or treat the deleterious effects of dehydration, fluid and electrolyte supplementation is essential. This article provides recommendations for fluid and electrolyte supplementation for horses involved in endurance-related events.
The exhausted horse syndrome. Exhaustion occurs in most equestrian sports, but it is more frequent in events that require sustained endurance work such as endurance racing, three-day eventing, trial riding, and hunting. Exhaustion is also more likely when an unfit, unacclimatized, or unsound horse is exercised. Mechanisms that contribute to exhaustion include heat retention, fluid and electrolyte loss, acid-base imbalance, and intramuscular glycogen depletion. Clinical signs include elevated temperature, pulse, and respiratory rate; depression; anorexia; unwillingness to continue to exercise; dehydration; weakness; stiffne...
Effect of exercise on fluid balance and renal function in horses. Exercise places large demands on the equine cardiovascular system which are further complicated by environmental factors. In many respects, performance is limited by fluid and electrolyte stores and the ability to maintain cardiovascular and thermoregulatory stability in the face of severe sweat losses. Studies in the exercising horse have been primarily descriptive or associative, with only a limited number seeking to identify physiologic mechanisms associated with the control of fluid and electrolyte balance. More mechanistic studies are needed to fully understand the integration of the card...
