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Topic:Veterinary Research
Veterinary research in horses encompasses the study of diseases, health management, and medical treatments specific to equine species. This field investigates various aspects of horse health, including infectious diseases, metabolic disorders, and musculoskeletal conditions. Researchers focus on understanding the pathophysiology of equine ailments, developing diagnostic tools, and evaluating therapeutic interventions. The study of horse health also involves examining preventive measures such as vaccination protocols and nutritional management to promote overall well-being. This page collects peer-reviewed research studies and scholarly articles that explore the diverse areas of veterinary science related to horses, providing insights into disease mechanisms, treatment strategies, and advancements in equine healthcare.
The effect of Strongylus vulgaris larvae on equine intestinal myoelectrical activity. The myoelectrical activity of the ileum, caecum and large colon was monitored from Ag-AgCl bipolar recording electrodes in four conscious 'parasite-naive' weanling foals. All foals were inoculated with 1000 infective 3rd-stage Strongylus vulgaris larvae and alterations to the myoelectrical activity observed. The frequencies of caecal and colonic spike bursts increased significantly in all post infection periods coinciding with assumed larval penetration into the intestinal mucosa and migration through the vasculature. Peaks in caecal and colonic activity occurred at Days 1 to 5 post infection....
Gastric ulcers in horses: a comparison of endoscopic findings in horses with and without clinical signs. Gastroendoscopic examinations were performed on 187 horses, ranging from one to 24 years. Eighty-seven horses had clinical problems including chronic, recurrent colic for seven or more days (25), one or more episodes of colic within the previous seven days (13), or acute colic (10), diminished appetite (53), poor bodily condition (40), and/or chronic diarrhoea (9). One hundred horses that had no signs of gastrointestinal problems were examined as part of a gastroendoscopic survey. Lesions observed in the squamous fundus, squamous mucosa adjacent to the margo plicatus along the greater curvatur...
Plasma endotoxin concentrations in experimental and clinical equine subjects. Endotoxin (LPS) was quantitated in experimental subjects and in horses with naturally occurring gastrointestinal strangulation obstruction and/or septicaemic diseases to establish the fate of LPS and the clinical usefulness of the Limulus amoebocyte lysate (LAL) assay. The assay was validated for sensitivity (10 pg/ml), recovery (90 to 106 per cent), intra-assay precision (CV = 5.5 per cent) inter-assay precision (CV = 11 per cent), and stability of diluted, heat treated, frozen samples (at least 90 days). Plasma concentrations of LPS after sublethal (3 micrograms/kg) jugular or portal vein bo...
Renal effects of dopamine infusion in conscious horses. An ultrasonic flow probe was implanted around a branch of the left renal artery in five horses. The effects of dopamine were studied in the unsedated horses 10 days after surgery. Three experiments, separated by at least two days, were performed in random order on each horse. In two experiments, dopamine was infused intravenously for 60 mins at either 2.5 and 5.0 micrograms/kg bodyweight (bwt)/min. Saline was infused for 60 mins before and after each infusion, and for 180 mins in the third experiment as a control. Renal blood flow increased during administration of dopamine at both dose rates ...
Xeroradiographic evaluation of the equine larynx. The normal radiographic anatomy of the equine larynx was determine by use of xeroradiography and dissection. The body and laminae of the thyroid cartilage, the muscular process of the arytenoid cartilages, and the dorsal lamina and arch of the cricoid cartilage had radiographic evidence of mineralization (calcification) and/or ossification in clinically normal horses. There was a significant (P less than 0.01) increase in the degree of mineralization of the thyroid and arytenoid cartilages with advancing age. Horses with diagnosis of arytenoid chondrosis (arytenoid chondral dysplasia, arytenoi...
Effect of xylazine treatment on equine proximal gastrointestinal tract myoelectrical activity. Five 5 to 6 month old horses were surgically prepared with silver electrodes sutured to the serosa of gastric antrum, duodenum and proximal portions of the jejunum. Normal migrating motility complex (MMC) periodicity was determined during daytime hours in horses that were fed and horses from which food was withheld for 24 hours. Periodicity was defined as time span from the end of one period of regular spike activity (RSA) to the end of the next RSA in the MMC. The periodicity was 120.5 +/- 9.5 (SEM) minutes in horses from which food was withheld, and was 125.7 +/- 20.3 minutes in horses fed h...
Serological response of experimental ponies orally infected with Ehrlichia risticii. Ten healthy, mature ponies were orally infected with Ehrlichia risticii using Ehrlichia-infected P388D1 mouse monocyte tissue culture cells. Seven developed signs of equine ehrlichial colitis including fever, depression, anorexia, reduced borborygmi, increased abdominal hyperresonance, and diarrhoea. Three remained clinically normal apart from early fever in one. Indirect fluorescent antibody titres were detected in the clinically affected ponies by Days 12 to 17 post infection and increased rapidly to high levels (1:640 to 1:5120) which were maintained until the end of the observation period ...
Electromyographic activity of cubital joint muscles in horses during locomotion. Electromyographic (EMG) activity of 4 muscles of the cubital joint and the strain of forelimb hooves were recorded telemetrically in 4 Thoroughbreds (with and without a rider) standing, walking, trotting, and cantering. Bipolar fine wire electrodes were inserted into the muscles, and strain gauges were attached to the hoof wall. Motion pictures (16 mm), synchronized with EMG tracings, were taken to obtain kinematic data. When horses were standing, the biceps brachii had tonic activity, but the brachialis and the caput longum and the caput laterale of the triceps brachii had no EMG activity. Th...
Identification and description of beta-structure in horse muscle acylphosphatase by nuclear magnetic resonance spectroscopy. Nuclear magnetic resonance spectra of acylphosphatase were searched for signs of beta-structure, i.e. characteristic nuclear Overhauser enhancement patterns displayed in the two-dimensional spectra, typical chemical shifts, coupling constants and slow 2H-H exchange. The results provided identification of the main-chain resonances of amino acid residues involved in the beta-structure. The full sequential assignment of this region was gained by identification of some amino acid spin systems and their alignment with the primary sequence. The assignment of the side-chains was virtually completed s...
Haematological changes in two thoroughbred horses in training with confirmed equine herpesvirus 1 infections. An outbreak of respiratory disease among thoroughbred horses in training in Hong Kong was caused by equine herpesvirus 1 (EHV-1) subtype 1 (abortion strain). Two of the horses affected by EHV-1 were serially blood sampled over a period of several weeks and their haematological values measured. There was an increase in monocyte count in the first few days which steadily decreased in one horse, but the other had a second monocyte peak after a period of exercise, thus demonstrating the importance of not working animals in the early stages of the disease.
Androgen synthesis and aromatization by equine corpus luteum microsomes. Whereas mare corpus luteum does not produce androgens or estrogens in vivo, the incubation of mare corpus luteum microsomes with progesterone and NADPH resulted in 17 alpha-hydroxyprogesterone and estrogen production with a small yield of androstenedione. In the presence of an aromatase inhibitor (4-hydroxyandrostenedione), 17 alpha-hydroxyprogesterone and androstenedione were accumulated. Aromatization of testosterone and androstenedione occurred via stereospecific loss of the 1 beta, 2 beta hydrogen atoms and was inhibited by MgCl2, KCl, and EDTA. The Km of estrogen synthetase from equine co...
Evolution of the ECG from Spanish bred foals during the post natal stage. A study of electrocardiograms recorded from foals during the first two weeks of life has been made in order to detect any changes of the cardiac activation and recuperation processes during this period. A stepwise discriminant analysis revealed significant differences between the first and second week of age, fundamentally on the basis of the T and P wave amplitudes which gave the lowest values at 14 days, and on the PQ segment duration that showed the highest values at the same age.
Forces loading the tarsal joint in the hind limb of the horse, determined from in vivo strain measurements of the third metatarsal bone. Strain gauge rosettes were bonded to the dorsal, lateral, medial, and plantar aspects of the third metatarsal bone in the hind limbs of 6 ponies. The maximal compressive principal strain was approximately -600 X 10(-6) m/m, and exceeded the amplitudes of the tensile strains at all aspects of the bone. After transformation, the shear strain and the principal strains parallel and perpendicular to the bone were obtained. The first peak in the bending strain was higher in the dorsal and lateral aspects, and the second peak was higher in the medial and plantar aspects. Young modulus of elasticity w...
Reproductive traits, lactation and foal growth in mares fed altrenogest. Lactating mares were assigned as controls or fed altrenogest (.044 mg.kg body wt-1.d-1) for 15 d after foaling. Mares (n = 6) fed altrenogest were inseminated during the first estrus after treatment and mares (n = 6) in the control group were inseminated during the second postpartum estrus. Ovulation during the estrus in which mares were inseminated occurred 26 +/- 1 d postpartum for treated mares and 36 +/- 1 d postpartum for control mares. The percentage of mares conceiving was not different for control (67%) and alternogest-treated (100%) mares. No differences were observed in tone and size...
Morphologic features of the aqueous humor drainage pathways in horses. The iridocorneal angle of the horse was anteriorly lined by a pectinate ligament, consisting of several layers of vertically oriented collagenous beams, that were interrupted by a network of extracellular spaces. The anterior chamber angle consisted mostly of a large uveal trabecular meshwork that was composed of widely-spaced, thick trabeculae. These trabeculae were attached in part posteriorly to extensions of the ciliary body musculature and anteriorly inserted into the prominent pectinate ligament. The corneoscleral trabecular meshwork was shaped hemiobovately and formed the external bound...
Temporal appearance of seasonal changes in numbers of Sertoli cells, Leydig cells, and germ cells in stallions. The temporal appearance of seasonal changes in numbers of Leydig, Sertoli, and germ cells was evaluated to determine if seasonally increased daily spermatozoan production might be preceded by changes in numbers of either of two somatic testicular cells. A significant increase in numbers of spermatogonia and Sertoli cells preceded the significant increase in number of Leydig cells in the approaching breeding season. Seasonal changes in parenchymal weight and in numbers of Sertoli cells, Leydig cells, and germ cells were maximal in May and June. Numbers of A or B spermatogonia in June were 2.4 t...
Tubuloreticular inclusions in equine connective tissue neoplasms. Abnormal irregularly branched and anastomosing tubules within cisternae of endoplasmic reticulum were observed by transmission electron microscopy in tumour cells comprising connective tissue neoplasms (sarcoids) from three horses and a mule. These tubuloreticular inclusions were also observed in cultured tumour cells from one of these horses examined, but were not detected in fibroblasts (fibrocytes), epidermis, or vascular endothelial cells in skin biopsy specimens from five clinically healthy horses, nor in one additional equine connective tissue neoplasm.
“Repair cells” in equine uterine cytologic and histologic specimens. Cells resembling those known as "repair cells" in gynecologic cytology specimens from women were identified in uterine cytology specimens from infertile mares treated with antibiotics using indwelling uterine catheters. This prompted a study of the effect on the equine uterus of indwelling catheterization without antibiotic infusion, using light microscopic examination of cytologic and biopsy specimens and electron microscopic examination of biopsy specimens. Cytologic and biopsy specimens had features within normal limits at the start of the study. Following five days of indwelling catheteriz...
Twin embryos in mares. I: From ovulation to fixation. Recent findings on the origin and development of twins from ovulation (Day 0) to fixation (mean: Day 16) are reviewed. Available data show that almost all twins originate from multiple ovulations. Results of recent ultrasound studies indicate that the number of days between double ovulations does not affect the conception rate per ovum or embryo survival during the first 16 days after each ovulation. Embryo reduction is the natural elimination of excess embryos so that only one embryo enters the foetal stage. In two studies, embryo reduction before or on the day of fixation was not considered ...
Pulmonary vascular reactivity of the newborn pony foal. Adult ponies develop pulmonary hypertension at altitude (Bisgard, Orr and Will 1975), but the neonatal response to acute hypoxaemia is unknown. Seven foals aged five days were instrumented with a systemic and a Swan-Ganz pulmonary artery catheter while anesthetised and intubated. Cardiac index, pulmonary (PAP) and systemic (SAP) vascular pressures were measured as the foals breathed gas mixtures with FI02 of 8 to 94 per cent. Because foramen ovale or ductus arteriosus shunts might have altered thermodilution cardiac index measurements in the stressed foals, the ratio, PAP/SAP was calculated to...
Observations on gamma-glutamyl transferase, 5′-nucleotidase and leucine aminopeptidase activities in the plasma of the horse. In 18 horses there was no effect of age or sex on plasma activities of gamma-glutamyl transferase (gamma-GT), 5'-nucleotidase (5'-NT) and leucine aminopeptidase (LAP). All the enzymes were equally stable after storage for one month at -20 degrees C and there was no significant difference between their activities in serum and plasma in clinically normal horses. The pattern of release of gamma-GT, 5'-NT and LAP into plasma was studied in 114 horses which had a variety of orthopaedic, gastrointestinal, cardiovascular and hepatic (necrosis, lipidosis, neoplasia and cirrhosis) conditions. A definit...
Changes in serum concentrations of luteinizing hormone and follicle-stimulating hormone following injection of gonadotropin-releasing hormone during pregnancy and after parturition in mares. High concentrations of estrogens in the peripheral circulation during late gestation inhibit synthesis of LH and markedly reduce pituitary content of LH at the end of pregnancy in most domestic species. Because blood concentrations of estrogen peak shortly before mid-gestation in the mare and then gradually decrease until parturition, we hypothesized that pituitary content of LH may increase during late gestation. To test this hypothesis 10 horse mares were challenged with a maximally stimulatory dose (2 micrograms/kg) of GnRH on d 240 and 320 of gestation and d 3 after parturition. A separate...
Multifactorial inheritance of white facial markings in the Arabian horse. The hypothesis was tested that white facial markings in the Arabian horse show multifactorial inheritance. The hypothesis assumes that (1) alleles at different loci acting in a cumulative manner influence the variation in white facial markings, (2) the amount of whiteness is correlated with the number of genes, and (3) interacting nongenetic factors influence the variation. The study was based on computerized data obtained from the Arabian Horse Registry of America, Inc. The facial region was divided into five areas, and each horse was given a score according to the number of areas with a whit...
(+)-[3H]-PN 200-110 binding to cell membranes and intact strips of portal vein smooth muscle: characterization and modulation by membrane potential and divalent cations. 1. Specific binding of the calcium-antagonist dihydropyridine derivative, (+)-[3H]-PN 200-110 (isradipine), to cell membranes of equine portal vein smooth muscle was compared with binding to intact strips isolated from rat portal veins. 2. Specific binding to vascular smooth muscle membranes was of high affinity, saturable and reversible. The dissociation constant obtained from association and dissociation kinetics of (+)-[3H]-PN 200-110 was similar to that obtained from equilibrium binding and competition experiments. 3. Specific binding of (+)-[3H]-PN 200-110 was completely displaced by unla...
Use of the cobra head bone plate for distal long bone fractures in large animals. A report of four cases. Four long bone fractures with a short distal fragment were repaired with a cobra head bone plate alone (2 cattle) or in combination with a straight, broad dynamic compression plate (2 horses). Three fractures were of the distal femur (1 horse, 2 cattle) and one was of the distal radius (1 horse). The long-term outcome of the three femoral fractures was soundness in one case and mild lameness in two. Although satisfactory bone healing progressed in the horse with the radial fracture, laminitis in the contralateral forelimb necessitated euthanasia at week 6.
Comparison of bronchodilators in alleviating clinical signs in horses with chronic obstructive pulmonary disease. A representative of each of 3 types of bronchodilators was given iv to horses with clinical signs of chronic obstructive pulmonary disease. We used atropine (0.01 mg/kg of body weight) as an anticholinergic, isoproterenol HCl as a beta-adrenergic, and aminophylline, the soluble salt of theophylline, as a methylxanthine. Response to these drugs was evaluated by measuring maximal change in intrathoracic pressures (delta Ppl) and observing clinical signs. Atropine caused a significant (P less than 0.01) reduction in delta Ppl, compared with that caused by aminophylline. Atropine caused the delta ...
