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Topic:Animal Studies
Animal studies involving horses encompass a range of research focused on understanding equine biology, behavior, and health. These studies often investigate various aspects of horse physiology, genetics, nutrition, and disease pathology. Researchers utilize animal studies to explore the effects of different treatments, management practices, and environmental factors on horse welfare and performance. The findings from such studies contribute to the development of improved care strategies and health interventions. This page gathers peer-reviewed research studies and scholarly articles that explore the methodologies, findings, and implications of animal studies conducted on horses, providing insights into their application in advancing equine science.
Serum and liver lipid composition and lecithin: cholesterol acyltransferase in horses, Equus caballus. 1. The lipid composition of serum and liver and some properties of serum lecithin: cholesterol acyltransferase of the horse were investigated. 2. Phospholipids and cholesterol were the major components of serum lipids and the concentration of triglyceride was considerably low. The concentration of liver lipids was comparable with that of other mammals. 3. Fatty acid composition of serum cholesterol ester resembled that of the 2-position of lecithin, except palmitic acid. 4. The activity of serum cholesterol esterifying enzyme was found to be 0.03-0.09 mumol/hr per ml. There was an equimolar de...
Corticosteroid-potentiated vascular responses of the equine digit: a possible pharmacologic basis for laminitis. Spirally cut digital arteries and veins were mounted isotonically in organ baths containing oxygenated Krebs' Q-Henseleit solution. Twelve arterial and 12 venous preparations all contracted dose dependently when epinephrine, norepinephrine, serotonin, or histamine were added to the bathing fluid. Addition of hydrocortisone or betamethasone alone did not cause contractions in any of the tissues tested. However, when hydrocortisone or betamethasone was added to vessel strips that were partially contracted (40% to 60% maximal) by epinephrine, norepinephrine, or serotonin, each vessel strip invari...
Comparative studies on serum arginase and transaminases in hepatic necrosis in various species of domestic animals. Serum concentrations of arginase, glutamic pyruvic transaminase (SGPT) and glutamic oxaloacetic transaminase (SGOT) in dogs, cats, horses, cattle, sheep and pigs were determined before and after oral administration of CCl(4) at doses known to cause hepatic necrosis. Following CCl(4) administration, serum concentration of arginase and SGOT increased to a level of diagnostic significance in all animals. SGPT increased markedly in dogs and cats and marginally in 1 of 3 cattle and 2 of 3 pigs. In the surviving animals, the serum concentration of arginase returned to normal range much earlier than ...
Influence of exogenous testosterone on sperm production, seminal quality and libido of stallions. The effect of exogenous testosterone on sperm production, seminal quality and libido was studied in 24 stallions. Based on pretreatment data, a stallion was assigned to 1 of 3 groups each containing 8 animals. One member of each group received 0 (Group 1), 50 (Group 2), or 200 micrograms (Group 3) testosterone propionate per kg body weight every 2 days for 88 days. The lower dose of testosterone had no significant effect on most of the parameters studied: the higher dose depressed total scrotal width at Day 90 post-treatment (P less than 0.01), total spermatozoa ejaculated between Days 60 and ...
[Structure and topography of the nucleus intermediomedialis in the equine spinal cord]. In this paper, structure and position of the centers of the parasympathetic nervous system in the horse spinal cord were presented. Studies were carried out on 2 horse spinal cordis. After sampling, the material was dehydrated in alcohol, embedded in paraffin and cut into 15 micron thick sections. The sections were stained according to Nissl's method. Every third section was studied. Nucleus intermediomedialis in the horse spinal cord is an intermittent tract of nervous cells passing from the I cervical neuromere to the V sacral segment. The cells of this nucleus form round, horizontally--oval...
Fertility of prostaglandin-induced oestrus compared to normal post-partum oestrus. This study was undertaken to determine if fertility could be improved by increasing the interval from foaling to breeding. Forty-two mares, not bred during normal post-partum oestrus, were injected with a prostaglandin analogue on Day 6 or 7 following ovulation. Mares were mated artifically with antibiotic-treated semen during the resulting oestrus and, if necessary, for the following 4 cycles. Their fertility was compared, by cycles/pregnancy and rate of fetal loss, to mares bred by the same methods on 86 normal post-partum oestrous periods. The interval from foaling to the onset of breeding ...
Body composition of the horse. Seventeen horses were dissected and their organs and tissues weighed. The results of these dissections are presented together with comparisons of the data with that already available in the literature. Predictive equations for organs and tissue weights are also given which were derived by comparison of linear and allometric regression models using 4 different body weight indices.
Plasma progesterone concentrations derived from the administration of exogenous progesterone to ovariectomized mares. Six ovariectomized mares were divided into 3 groups to determine the effects of exogenous progesterone in oil and repositol progesterone on plasma progesterone concentrations. Progesterone in oil was administered in 7 daily injections in Exp. I. Progesterone concentrations were not maintained greater than 1.0 ng/ml for 24 h with 50 mg/day. However, they remained greater than 1.0 ng/ml during the last 4 days of 100 mg/day and greater than 1.5 ng/ml throughout the injection sequence of 200 mg/day. Repositol progesterone was administered on Days 1 and 7 in Exp. II. At 500 mg, progesterone concent...
Localization of gonadotrophin-releasing hormone (GnRH) in the hypothalamus of ovariectomized pony mares by season. Fifteen Pony mares, ovariectomized during the previous summer, were randomly assigned to three seasonal treatment groups, winter, spring and summer (N = 5). At the designated season, the animals were killed and hypothalamic areas were collected and assayed by radioimmunoassay for gonadotrophin-releasing hormone (GnRH) activity. The hypothalamic areas were sectioned into 54 5-mm cubes to determine the sites of GnRH storage. Maximum immunoreactive GnRH activity was located in an oblique pattern extending from the arcuate nucleus-median eminence area to the anterior hypothalamic area dorsally and...
Effects of age and frequency of ejaculation on sperm production and extragonadal sperm reserves in stallions. Extragonadal reserves totalled 89 X 10(9) spermatozoa for 5--16-year-old sexually rested stallions and 60 X 10(9) for 2--4-year-olds. Regardless of age, the cauda epididymidis contained 62% of the total reserves and the vas deferens, including the ampulla, contained 7% of the total reserves of spermatozoa. The caput plus corpus epididymidis from 5--16-year-old stallions (N = 41) contained 14.9 X 10(9) spermatozoa per side as compared (P less than 0.01) to 8.5 X 10(9) for 2--4-year olds (N = 30). Frequency of ejaculation did not influence the number of spermatozoa found in caput plus corpus epi...
Hybridization of bovine papilloma virus type 1 and type 2 DNA to DNA from virus-induced hamster tumors and naturally occurring equine tumors. DNAs from bovine papilloma virus(BPV)-induced hamster tumors and from equine connective tissue tumors of unknown etiology were examined for BPV DNA sequences by molecular hybridization. DNA from two distinct classes of BPV (type 1 and type 2) was labeled in vitro and used as probes. Analysis of DNA-DNA reassociation kinetics indicated that both virus types were capable of tumor induction in the hamster. DNA isolated from 6 of 7 equine tumors accelerated the reassociation of the BPV DNA probes. BPV type 1 or type 2 DNA hybridized extensively to DNA from 3 tumors, while 3 other tumors contained ...
[Myocardial changes following experimental protein sensitization]. Guinea pigs were sensitized by three subcutaneous injections of 0.1 ml native horse serum at 2-day intervals, 21 days after the third injection the animals developed marked sensitization to this antigen which was manifested by anaphylactic reaction to the subcutaneous challenge with this antigen. At this time, the myocardium of the sensitized animals showed signs of extra- and intracellular oedema, a sharp increase in the number of lysosomes, damage of their membranes, 2 1/2 months after sensitization the animals showed no anaphylactic reaction to the challenge dose of the antigen. There were ...
Isoelectric focusing of some enzymes from Echinococcus granulosus (horse and sheep strains) and E. multilocularis. Extracts of the horse and sheep strains of Echinococcus granulosus and E. multilocularis were compared on the basis of their isoenzyme patterns for 10 enzymes by means of isoelectric focusing in polyacrylamide gels. The enzymes examined were: acid phosphatase, lactate dehydrogenase, malate dehydrogenase, malic enzyme, phosphoglucoseisomerase, isocitrate dehydrogenase, adenylate kinase, aldolase and alpha-glycerophosphate dehydrogenase. Interspecific and intraspecific differences are apparent in the isoenzyme profiles of all the enzymes except adenylate kinase; the pattern and activity of adeny...
Ultrastructure of rat pinealocytes in vitro: influence of gonadotropic hormones and LH-RH. The influence of gonadotropic hormones on the ultrastructure of rat pinealocytesin short-term organ culture was studied. Human chorionic gonadotropin (HCG), as well as pregnant mare serum gonadotropin (PMSG), caused a marked activation of pinealocytes. An hypothesis is discussed implying the presence of a feedback mechanism between the pineal organ and the hypothalamo-hypophysial system.
Tendon and ligament from the horse: an ultrastructural study of collagen fibrils and elastic fibres as a function of age. A study has been made of the ultrastructural organization of the collagen fibrils and elastic fibres in tendons and ligaments from horses of ages ranging from 2 months premature to 19 years. Diameter distributions of the collagen fibrils in the common digital extensor tendon, the superficial flexor tendon and the suspensory ligament are unimodal in the foetal tissue and at birth, and at these stages of development the three collagenous tissues are virtually indistinguishable. However, at maturity, the ligament and flexor tendon have bimodal distributions similar to that found for rat-tail tend...
California encephalitis virus activity in mosquitoes and horses in southern Ontario, 1975. A study was undertaken in 1975 to determine California encephalitis virus activity in southern Ontario. Three thousand and sixty-one mosquitoes, primarily Aedes species, were divided into 104 pools and inoculated into suckling mice. Isolates of snowshoe hare virus were obtained from one pool each of Aedes fitchii and A. triseriatus mosquitoes collected in the Guelph area. Serological testing of horse sera revealed extensive virus activity in southern Ontario and indicated that horses may serve as excellent monitors for California encephalitis virus.
Differences in the histochemical properties of skeletal muscles of different breeds of horses and dogs. Histochemical profiles of individual muscle fibres were established using myosin adenosine triphosphatase (myosin ATPase), succinate dehydrogenase (SDHase), and glycogen phosphorylase (GPase) reactions in three muscles (semitendinosus, diaphragm, and pectoralis transversus) of the horse and dog. The major histochemical difference between fibres lies in their myosin ATPase activity; fibres can be subdivided into those with a high and those with a low activity. In horse muscle, all fibres have a high activity of GPase. In the diaphragm and pectoralis transversus, all fibres have a high SDHase ac...
Survey for infection with Onchocerca cervicalis in horses in eastern United States. This survey was performed to study the prevalence of infection with Onchocerca cervicalis in horses in the eastern United States. In the course of the survey, 121 horses, 1 mule and 1 donkey were examined. Microfilariae were recovered from 74 (61%) of the horses examined. All infected horses showed microfilariae of O cervicalis in the umbilical sample, 62 (84%) were infected in the eyelid and, in 36 (49%), microfilariae had invaded the eye. The mule was unifected and the donkey was infected with O cervicalis.
Swimming–a method to study the physiologic response of the horse to exercise. The literature on exercise physiology in the horse with special reference to swimming is briefly reviewed. The use of a pool for swimming horses is described and a technique discussed for the collection of haematologic and haemodynamic data using this form of exercise.
Shunting in intracranial microvasculature demonstrated by SEM of corrosion-casts. The use of methyl methacrylate corrosion-casts has made it possible to examine the intracranial microvasculature on a three-dimensional scale with the scanning electron microscope. By this means we have compared regions of four cerebral and cerebellar arteries among three domestic animal species. The results of this study suggest that there are from one to three different levels of interarteriolar anastomosis between branches of the same or adjacent vessels. In the horse and ox anastomoses were demonstrated (1) at the level of the precapillary arterioles, (2) along the arterioles, and (3) betw...
Ductuli efferentes in the epididymis of boar, goat, ram, bull, and stallion. Dutculi efferentes were studied by microdissection and histologic methods in 2 boar, 6 goat, 5 ram, 25 bull, and 19 stallion epididymides. On the basis of the present findings and the data of others and relating them to the total number of specimens examined in each species, an estimate (narrow range) was made of the minimal-maximal numbers of efferent ductules as follows: dog 13 to 15; cat 14 to 17; boar 14 to 16; goat 18 to 19; ram 17 to 20; bull 13 to 16; and stallion 14 to 17. The histologic appearance of the efferent ductules of the bull, including measurements of their diameter, lumen, a...
Myocardial perfusion and function during acute right ventricular systolic hypertension. Hemodynamics, myocardial function, and regional myocardial blood flow (MBF) were measured in 6 closed-chest ponies anesthetized with ketamine hydrochloride before (control) and after creation of acute right ventricular systolic hypertension (RVSH) during normoxia and isocapnic hypoxia. The right ventricular (RV) systolic pressure during each RVSH approached 90 mmHg. There were significant alterations in the pattern of total ventricular MBG distribution in favor of the RV. Because RV myocardium received proportionate increments to its endocardium as well as epicardium, it is concluded that auto...
