"Horses" is a broad topic that encompasses various aspects of equine biology, behavior, and management. This category includes studies on the anatomy, physiology, and genetics of horses, as well as their behavior, nutrition, and care. Research in this area may also cover the historical and cultural significance of horses, their roles in agriculture, sport, and therapy, and the challenges associated with their conservation and welfare. The page aggregates peer-reviewed research articles and scholarly studies that explore the multifaceted relationships between humans and horses, examining both scientific and socio-economic perspectives.
Force L, Jortner BS, Scarrat K.Suchwann cells from a variety of nerves in two adult horses and one adult pony contained perinuclear intracytoplasmic inclusion complexes consisting of lipid droplets, variably electron-dense rounded to elongated bodies and rod-shaped multilamellar structures. The latter were characteristic of pi granules of Reich. There were no significant axonal or myelin alterations associated with these inclusions. It was concluded that the inclusions are a component of normal equine Schwann cells.
Bayly WM, Elfers RS, Liggitt HD, Brobst DF, Gavin PR, Reed SM.Acute renal failure was produced in 5 ponies which had received mercuric chloride (0.25 mg/kg) and potassium dichromate (3 mg/kg) intravenously each day for 5 days. Failure was due to acute nephrosis. This was indicated clinically by daily monitoring of the urine output, and B-mode ultrasonography of both kidneys after administering the fifth dose of the chemical agents. Euthanasia was performed after days 14, 9, 5, 8 and 5 respectively in each of the ponies, and the presence of renal disease confirmed by gross and microscopic post mortem examination. The nature of the kidney lesions observed ...
Bridges CG, Edington N.Intrinsic phagocytosis and killing of C. albicans by equine monocytes and polymorphonuclear leucocytes (PMN) was examined during Equid Herpesvirus 1 (EHV-1) (subtypes 1 or 2) and Adenovirus infections. Monocyte function increased during EHV-1 subtype 2 and Adenovirus infection. Conversely, there was an impairment of monocyte ingestion during EHV-1 subtype 1 infection which was ascribed to virus replication in peripheral blood mononuclear cells. PMN phagocytosis was not decreased in any of the infections studied. The raised levels of haemolytic complement in animals which subsequently developed...
McEwen SA, Hulland TJ.Thirteen horses with histories of exertional rhabdomyolysis were exercised for 20 minutes to induce clinical signs of lameness, elevated serum creatine kinase (CK), and aspartate aminotransferase (AST) activities and skeletal muscle morphologic lesions. The clinical signs exhibited by affected horses included trembling, sweating, increased rate of respiration, and restricted limb movement. Serum CK reached maximal activity between 4 and 8 hours after the exercise period and serum AST activity peaked between 24 and 48 hours. Histologically, the skeletal muscle lesions in muscle biopsies 24 hour...
Todhunter RJ, Erb HN, Roth L.The historical, clinical, laboratory, surgical and necropsy findings in 54 cases of gastric rupture in horses are described. Eleven per cent of the deaths of horses undergoing exploratory coeliotomy for colic during the period of the study were a result of gastric rupture. Comparison with all horses which had exploratory coeliotomies for colic over an eight year period did not show that horses with gastric rupture were different from these reference horses regarding age, breed or season. There were fewer stallions than expected in the gastric rupture group. Horses with histories of both acute ...
McCoy DJ, Beasley R.Hypercalcemia associated with malignancy was diagnosed in a 2-year-old Thoroughbred filly admitted because of weight loss and reduced exercise tolerance of approximately 2 months' duration. Laboratory findings included hypercalcemia, hypophosphatemia, anemia, marked neutrophilia with lymphopenia and eosinopenia, and normal immunoreactive parathyroid hormone concentration. At necropsy, a 53.6-kg tumor was located in the cranioventral aspect of the abdominal cavity. Gross renal lesions were not noticed. Bone tissue appeared to be normal on gross and histologic examinations. The parathyroid gland...
Baker H, Schor SM, Murphy BD, DeAngelis B, Feingold S, Frank O.Blood concentrations of thiamin, biotin, nicotinates, pantothenates, folates, riboflavin, vitamins A, B6, B12, C, E, beta-carotene and choline were analyzed in healthy animals (23 horses, 25 dogs, and 29 cats). B-Complex vitamins and choline also were analyzed in the liver of the dogs and cats. Vitamin concentrations in the blood and livers of dogs were similar; however, blood vitamin A and beta-carotene concentrations were lower in the cat than in the dog. Horses had a higher B12 blood concentration than did the dogs and cats. These data can be useful for detecting overt and hidden vitamin de...
Worthy K, Escreet R, Renton JP, Eckersall PD, Douglas TA, Flint DJ.Five pony mares were blood sampled during late pregnancy, foaling and early lactation. An homologous assay for horse prolactin was used to measure plasma prolactin concentrations in these samples. Regular estimates of cyclic activity were also made. Plasma prolactin concentrations rose markedly in the last week of pregnancy and remained high although variable in early lactation, before declining to basal levels by 1-2 months post partum. All mares showed a post-partum oestrus 7.0 +/- 0.9 days after parturition. One mare whose foal died shortly after birth showed a rapid decline in plasma prola...
Cordes DO, Perry BD, Rikihisa Y, Chickering WR.Potomac horse fever was reproduced in 15 ponies by transfusion of whole blood originally from two natural cases and subsequently from ponies infected by the transfusions. Incubation periods varied from 9 to 15 days. Affected ponies developed varying degrees of fever, diarrhea, anorexia, depression, and leukopenia. Eleven affected ponies were killed, three died in the acute phase of the disease, and one did not show clinical signs. The most consistent post-mortem findings were fluid contents in the cecum and large colon, and areas of hyperemia (of inconstant degree and distribution) in mucosae ...
Swanson CR, Muir WW.The influence of pharmacologic enhancement of cardiac output on the alveolar-to-arterial oxygen tension (difference (P[A-a]O2), physiologic right-to-left shunt fraction (Qs/Qt), and physiologic dead space-to-tidal volume ratio (VD/VT) ws studied in halothane-anesthetized horses in left lateral, right lateral, and dorsal recumbencies. Adult horses were anesthetized, using xylazine (2.2 mg/kg, IM), guaifenesin (50 mg/kg, IV), thiamylal (4.4 mg/kg, IV), and halothane (1.5% to 2% inspired) in 100% O2. Mechanical ventilation was controlled to maintain arterial eucapnia (PaCO2) 35 to 45 mm of Hg) fo...
Elfers RS, Bayly WM, Brobst DF, Reed SM, Liggitt HD, Hawker CD, Baylink DJ.The changes in serum and urinary levels of calcium and phosphorus and serum parathyroid hormone (PTH) were studied during controlled, chemically induced, acute renal disease in 4 ponies. There was an initial rise in daily urinary calcium and hydroxyproline excretion in 2 ponies which may have indicated increased bone resorption. Mild hypercalcemia, hypophosphatemia and elevated C-terminal PTH levels were associated with oliguria. Total daily urinary excretion of calcium and phosphorus decreased as oliguria developed. The levels of C-terminal PTH were increased in all four animals. This appears...
Powers BE, Stashak TS, Nixon AJ, Yovich JV, Norrdin RW.Specimens of ligamentum flavum, joint capsule, and dorsal lamina were collected at surgery or necropsy from 25 horses with cervical static stenosis. All horses had myelographic evidence of dorsal compression of the spinal cord caused by soft tissue and/or bone in the caudal cervical area, primarily at C6-7. Most horses also had radiographic evidence of degenerative joint disease of articular facets. Histologically 19 horses had osteosclerosis and cartilage retention in the dorsal lamina, and 24 horses had increased fibrocartilage at the ligamentum flavum attachment to dorsal lamina. The ligame...
Steenhaut M, Vlaminck K, Gasthuys F.RUPTURE of the stomach is a common complication of
gastric impaction and intestinal reflux or of gastric distention.
After rupture, the general condition of the horse deteriorates
and death follows within a few hours (Tennant, Wheat and
Meagher 1972; McIlwraith 1982).
Dietz and Wiesner (1982) state that partial rupture of the
stomach may result in severe blood loss with circulatory
collapse. In this report a partial rupture of the stomach was
surgically repaired during exploratory laparotomy.
Hammond CJ, Mason DK, Watkins KL.Routine post mortem examination of 195 Thoroughbreds in Hong Kong revealed that 66 per cent suffered from gastric ulceration. Racehorses killed straight out of training suffered a significantly greater incidence of ulceration (80 per cent) than those having been retired for a month or more (52 per cent). The macroscopic findings post mortem enabled a classification of equine gastric ulceration to be suggested (Types 1, 2, 3), according to severity. Severe lesions (Types 2 and 3) were present in 45 per cent of horses put down from training and 5 per cent of retired horses. This difference was s...
Edwards GB.Intraoperative techniques for assessing the viability of ischaemic bowel are discussed. Intravenous administration of sodium fluorescein appears useful but further investigation of the method is required. Methods of resection and anastomosis of small intestine are described and illustrated, including the use of automatic stapling instruments.
Edwards GB.During a 14 year period, 27 of 310 horses undergoing laparotomy because of abdominal pain were found to have an intussusception involving the small intestine (16 cases) or caecum (11 cases). The clinical signs, operative findings and techniques adopted to overcome the obstruction are described. An evaluation of possible predisposing factors provided further evidence of the important role of the tapeworm Anoplocephala perfoliata in initiating intussusception involving the ileum and caecum.
Mathisen SR, Wu HD, Sauvage LR, Walker MW.Because repeat sternotomies are becoming much more prevalent with repeat coronary bypass operations, prevention of direct adhesions of the heart and grafts to the back of the sternum by use of synthetic or xenograft material to close the pericardiotomy has become a matter for investigation. In this study bovine and equine glutaraldehyde-processed xenografts were implanted bilaterally in dogs for implant intervals of 6 weeks and 3, 6, 9, and 12 months. The bovine and equine xenografts both performed well in resisting the adhesion of the heart to their inner surfaces and less well in resisting a...
Alexander SL, Irvine CH.Luteinizing hormone release induced by a range of small (3.3-33 micrograms) and large (300-500 micrograms) i.v. doses of gonadotrophin-releasing hormone (GnRH) was measured in acyclic (n = 4), luteal phase (n = 3) and follicular phase (n = 5) mares and compared with endogenously generated LH pulses in the same reproductive states. Extrapolation from log-linear dose-response curves showed that an LH pulse comparable to an endogenous one would be simulated by i.v. injection of 7.0 (n = 4) and 4.1 (n = 6) micrograms GnRH in luteal and follicular phase mares respectively; a much smaller dose than ...
Riemersma DJ, De Bruyn P.The cross-sectional area, collagen content, dry weight as a percentage of the wet weight and the tendon fibre percentage of the cross-sectional area of the equine hindlimb were determined in the superficial and deep digital flexor tendons and the suspensory ligament at 10, 12 and six sites between tarsus and insertion respectively. The values of each of the four parameters varied between different sites in the same tendon, between different tendons within a horse and between analogous tendons of different horses. Within a tendon the cross-sectional area was inversely proportional to the collag...
Valpotić I, Kastelan M, Rudolf M, Gerencer M, Jukić B, Basić I.The percentage of T and B lymphocytes in the peripheral blood of horses chronically infected with equine infectious anaemia (EIA) virus was determined and the results were compared with the percentage of these cells in healthy uninfected horses. Cells with membrane receptors for sheep erythrocytes (T and active T lymphocytes) were determined by E and A rosette techniques, while cells with receptors for the C3b component of complement and those with receptors for mouse erythrocytes (B lymphocytes), were determined by the EAC rosette method. The percentage of Fe positive cells was assayed by the...
Zachar EK, Burgess HJ, Wobeser BK.Fine-needle aspiration (FNA) is commonly used to diagnose skin disease in companion animals, but its use in horses appears to be infrequent. Equine veterinarians in western Canada were surveyed to determine their opinions about FNA and 15 years of diagnostic submissions were used to compare the perceived to actual value of FNA in the diagnosis of skin disease in horses. Practitioners viewed FNA as quick, easy, economical, and minimally invasive. However, most veterinarians rarely chose to use FNA due to a perception that sample quality and diagnostic yield were poor and there was a narrow rang...
Allen WE, Clarke AR.Plasma concentrations of sodium benzylpenicillin following intrauterine infusion were increased by reducing the volume of solution and expelling air from the vagina after infusion. Instillation of 10 per cent Lugol's iodine solution into the uterus before penicillin infusion further increased the absorption rate, although peak plasma levels of penicillin were less than half those which resulted from intramuscular injection of the same dose.
Hejłasz Z, Nicpoń J, Czerw P.Sweat secretion was analyzed quantitatively and qualitatively in 20 horses after a 5 min. gallop at 450 m/min. The analysis revealed concentration of proteins 63.3 +/- 6.47 g/l, mainly albumins, a high level of sodium 254.43 +/- 62.84 mM/,l chloride 268.68 +/- 98.46 mM/l, potassium 98.95 +/- 49.62 mM/l and calcium 4.14 +/- 0.8 mM/l. A dependence was found between the protein concentration in serum and its quantity in sweat and between the level of potassium in sweat and its loss from the cells within a range 8.6 to 25.8 mM/l. The hypertonic horse sweat protects organism for excessive water los...
White NA, Moore JN, Douglas M.This paper describes the histological and scanning electron microscopical examinations of the right colic artery of eight ponies. Lesions all had large thrombi surrounding a larva or larvae, with arterial wall thickening. Endothelial shape change, degeneration and loss were present. Fibrin-platelet red blood cell aggregates were present on endothelial surfaces as well as on the surface of thrombi. Damage to the intima appeared to produce the conditions for progressive thrombus formation.
Barr AR, Sridhar B, Denny HR.Five horses with long incomplete longitudinal fractures of the third metacarpal bone and three horses with similar fractures of the third metatarsal bone were examined. In three of the metacarpal fractures a long incomplete fissure extended proximomedially, in association with the more common lateral condylar fracture of the third metacarpal bone, and in the other two cases the fracture originated from the medial aspect of the distal articular surface. In the three horses with fractures of the third metatarsal bone the fractures had a consistent spiral configuration.
Capik I, Ledecky V, Mihály M.Abnormalities of dental development such as hypoplasia of cementum, oligodontia, polydontia, enamel hypoplasia, brachygnathia, and prognathia are quite common in the horse. Abnormalities of eruption are less common and often associated with trauma. This case report describes the diagnosis and therapy for pre-eruption displacement of the maxillary left third and fourth premolar teeth resulting from previous facial trauma in a 1.5-year-old filly.
de Oliveira AC, Rosenbruch M, Schulz LC.The morphology of asteroid bodies in equine arteries is demonstrated by light microscopy as well as by scanning and transmission electron microscopy combined with chemical analysis. Asteroid bodies first occur in horses at four weeks of age in all investigated tissues except the esophagus and always are located in the subendothelial space. The number, shape, ultrastructure and chemical composition of asteroid bodies differ markedly--depending on the age of the horse. Asteroid bodies are round and smooth in foals, but are shaped irregularly and have several projections and marked stratified cal...
Pongratz MC, Junge HK, Riond B, Schwarzwald CC.To assess the accuracy and reliability of a point-of-care (POC) triglyceride analyzer and to establish reference intervals for blood ([TRIG]POC/WB ) and plasma triglyceride concentrations ([TRIG]POC/PL ) in horses, ponies, and donkeys. Methods: Prospective study. Methods: University teaching hospital. Methods: 120 adult healthy equids (78 horses and ponies, 42 donkeys) and 79 equids suffering from hypertriglyceridemia (73 horses and ponies, 6 donkeys). Methods: None. Results: [TRIG]POC/WB and [TRIG]POC/PL were measured using a POC analyzer and plasma triglyceride concentrations were measured u...
Vagnoni KE, Ginther OJ, Lunn DP.Chorionic girdle cells are a highly invasive subpopulation of trophoblastic cells of the horse conceptus that adhere to the uterine epithelium and begin to invade the endometrium on Days 34-36 (Day 0 = day of ovulation). Just prior to and during invasion (Days 32-36), chorionic girdle cells express high levels of major histocompatibility complex (MHC) I, but expression of this antigen decreases by Days 40-45 and is lost by Day 55. The mechanisms involved in the control of chorionic girdle cell invasion and altered MHCI expression over time are not known. The objective of this study, therefore,...
Steffey EP, Dunlop CI, Cullen LK, Hodgson DS, Giri SN, Willits N, Woliner MJ, Jarvis KA, Smith CM, Elliott AR.Cardiovascular and respiratory changes that accompany markedly long periods (12 hours) of halothane anesthesia were characterized. Eight spontaneously breathing horses were studied while they were positioned in left lateral recumbency and anesthetized only with halothane in oxygen maintained at a constant end-tidal concentration of 1.06% (equivalent to 1.2 times the minimal alveolar concentration for horses). Results of circulatory and respiratory measurements during the first 5 hours of constant conditions were similar to those previously reported from this laboratory (ie, a time-related sign...
Kim SW, Jo A, Im J, Lee HE, Kim HS.A microRNA (miRNA) is a small non-coding RNA (ncRNA) approximately 20 nucleotides long and it affects gene expression through mRNA cleavage or translational repression. Horses (Equus caballus) have been domesticated and bred to enhance their speed for racing. It has been studied extensively with genetic diversity, origins and evolution. We examined expression patterns of miR-221-3p and its target gene CDKN1C in various horse tissues. We used bioinformatic tools to examine target gene, seed region and evolutionary conservation of miR-221-3p. The expression patterns of miR-221-3p and its target ...
Bochsler PN, Slauson DO, Chandler SK, Suyemoto MM.The use of cultured tissue has not yet become widespread in research involving equine disease, and this may be attributable in part to the scarcity of published reports concerning tissue culture methods for this species. We report here the isolation of equine microvascular endothelium (EMVE) from fresh omental tissue of horses and ponies. Fresh donor tissue was minced, subjected to collagenase digestion, and filtered. Cells were layered on 5% bovine serum albumin for gravity sedimentation, the bottom layer was collected, and the cells were plated onto fibronectin-coated flasks. Medium consiste...
Chidambaram RM, Eades SC, Moore RM, Hosgood G, Venugopal CS.To characterize the in vitro response of equine cecal longitudinal smooth muscle (CLSM) to endothelin (ET)-1 and assess the role of ETA and ETB receptors in those ET-1-induced responses. Methods: 36 horses without gastrointestinal tract disease. Methods: To determine cumulative concentration-response relationships, CLSM strips were suspended in tissue baths containing graded concentrations of ET-1 (10(-9) to 10(-6)M) with or without BQ-123 (ETA receptor antagonist); with or without IRL-1038 (ETB receptor antagonist); or with both antagonists at concentrations of 10(-9), 10(-7), and 10(-5)M. To...