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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.
Non-invasive assessment of the incidences of pregnancy and pregnancy loss in the feral horses of Sable Island. Field observations of 400 totally unmanaged feral horses on Sable Island, Nova Scotia, were complemented by oestrogen determinations in faecal samples from 154 identified females over a 4-year period (454 mare-years). Of mares that were sampled throughout the year and subsequently produced foals, 92.1% exhibited elevated faecal oestrogens between 15 October and 30 March. The results confirm that faecal oestrogens are a useful indicator of pregnancy after approximately 120 days gestation. Distribution of foaling resembled that seen in other feral populations, with 95% of births occurring from A...
Metabolic changes in thoroughbred and pony foals during the first 24 h post partum. Metabolic rates, rectal temperatures and respiratory quotients (RQ) were determined during the first 24 h post partum in Thoroughbred and pony foals and in relation to environmental temperature. Both breeds had high metabolic rates (greater than 200 W/m2) during the first hour post partum when they were wet and shivering; by 4 to 24 h values were fairly steady at about 153 and 105 W/m2 for Thoroughbred and pony foals, respectively. At birth, rectal temperature was lower in Thoroughbred foals than in pony foals; values increased during the first hour, and then decreased. At 24 h of age, both br...
The effect of cryopreservation on the metabolic activity of day-6.5 horse embryos. The decrease in embryo viability caused by cryopreservation may be due, in part, to metabolic disturbances. To determine the effect of cryopreservation on metabolism, Day -6.5 horse embryos were either frozen and thawed using glycerol as the cryoprotectant, given only the glycerol treatment or washed an equal number of times in phosphate buffered saline (PBS). Before and after treatment, individual embryos were incubated with L-[14C(U)]-glutamine, to measure Krebs cycle activity, and D-[5-3H]-glucose, to measure Embden-Meyerhof pathway activity. Before treatment, glucose metabolism ranged from...
Effect of interval between doses on response of the pony to sodium bicarbonate. Three pony geldings were given sodium bicarbonate orally in order to study the effect on blood pH and bicarbonate and to determine if frequency of dosing influences the response. In a preliminary study, it appeared that a carry-over effect might occur if the interval between dosing was only 2 days. The ponies received 2 doses of sodium bicarbonate (400 mg/kg) 7 days apart in trial one and then in trial two they received 2 doses of sodium bicarbonate 4 days apart. The sodium bicarbonate was mixed with 2 liters of warm water and given through a nasogastric tube on each trial day. Blood samples w...
[Local structure of cytochrome c from horse heart in solution. Conformational analysis using data of two-dimensional nuclear Overhauser effect spectroscopy]. Using the earlier suggested method the calculation of the backbone conformations of horse heart cytochrome c in oxidized (ferricytochrome c) and reduced (ferrocytochrome c) states has been performed by the two-dimensional nuclear Overhauser effect spectroscopy data. For both protein forms the secondary structure elements have been revealed and the conformations of the irregular polypeptide chain segments have been analysed. The similarity of the secondary structures of ferri- and ferrocytochrome c in solution was established from the comparison of their conformations. Small differences between...
Relationship between circulating tri-iodothyronine and cortisol in the perinatal period in the foal. Pre- and post partum changes in plasma T3 have been examined in relation to plasma cortisol in 23 newborn foals (12 full term, 6 premature and 5 'twilight'), and in 5 fetuses catheterized in late gestation. Blood samples were collected daily from the fetuses and from the neonates at 30-min intervals for 2 h after birth; the plasma was assayed for T3 and cortisol by standard radioimmunoassay methods. In the full-term foals, plasma cortisol and T3 concentrations were high at birth (67.4 +/- 6.1 and 4.3 +/- 0.3 ng/ml respectively) and rose to a maximum during the following 2-h period to 141.0 +/-...
Effect of constant light exposure on circulating gonadotrophin levels and hypothalamic gonadotrophin-releasing hormone (GnRH) content in the ovariectomized pony mare. Melatonin is thought to play a role in relaying photic information to the central nervous system as part of the seasonal reproductive cycle of the mare. However, the mechanisms by which melatonin may act are unknown. Therefore, this study was designed to determine whether exposure to constant light would, by reducing circulating melatonin concentrations, have any effect on hypothalamic gonadotrophin-releasing hormone (GnRH) content and circulating levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Blood samples were collected for 12 h at 15-min intervals from 8 ovariect...
Trophoblastic vesicles and maternal recognition of pregnancy in mares. Research has indicated that trophoblastic vesicles (TV) formed from Day-14 equine conceptuses would prolong luteal maintenance in mares after surgical transfer to the uterus at Day 10 after ovulation. The current study assesses TV as a further model for maternal recognition of pregnancy in mares. The objectives of the study were to determine the ability of TV to prolong luteal maintenance in mares, their effect on endometrial production of prostaglandin F (PGF) in vitro, and their ability to secrete polypeptides in vitro. In contrast to our previous study (Ball et al., 1989b), transfer of TV f...
In vitro comparison of Thoroughbred and Standardbred racehorses with regard to local fatigue failure of the third metacarpal bone. In vitro local fatigue testing of the third metacarpal bone from Thoroughbred and Standardbred racehorses was performed, using fully reversed cyclic bending. Strain number of cycle data were accumulated and indicated that significant difference did not exist between the 2 breeds. It was concluded that the marked difference in the incidence of fatigue failure in the third metacarpal bone (bucked shins, dorsal metacarpal disease) seen in Thoroughbreds and Standardbreds was not related to any differences between the 2 breeds in mechanical properties of the bone.
Ultrastructure of the red pulp in spleen innervation in horse and pig. The innervation of the red pulp in the spleen of horse and pig was investigated by electron microscopy. In addition, the neurilemma was studied by immunohistochemistry specific for S-100 protein. In the pig, a large population of smooth-muscle cells extending from the smooth-muscle trabeculae was present in the red pulp. The cytoplasmic processes of reticular cells enwrapped the smooth-muscle cells, and nerve fibres were distributed between the smooth-muscle cells and the reticular cells. The nerve terminals clustered toward the facing of the smooth-muscle cells. Nerve fibres and terminals wer...
Parahost behavior of adult Gasterophilus intestinalis (Diptera: Gasterophilidae) in Delaware. Parahost behavior of adult Gasterophilus intestinalis (DeGeer) was observed during the summers of 1978 and 1979 near pastured horses on two farms near Newark, Del. Adult fly occurrence, although sparse in early summer, indicated a gradual increase, with three surges in emergence. In the laboratory, males lived 1-3 d and females 1-2 d. In the field, marked flies were not seen on days following their release. Adult behavior indicated an urgency in mating and oviposition dictated by a short life span. Male flight patterns were characterized by in-flight searches for females and intraspecific conf...
Phylogeny of immune recognition: processing and presentation of structurally defined proteins in channel catfish immune responses. This work was undertaken to investigate whether or not antigen processing and presentation are important in channel catfish in vitro secondary immune responses elicited with structurally defined proteins, namely, pigeon heart cytochrome C (pCytC), hen egg lysozyme, and horse myoglobin. The use of in vitro antigen-pulsed and fixed B cells or monocytes as antigen presenting cells (APC) resulted in autologous peripheral blood leukocytes (PBL) responding with vigorous proliferation and antibody production in vitro. In addition, several long-term catfish monocyte lines have been found to function a...
Correlation of myosin isoforms with anatomical divisions in equine musculus biceps brachii. The biceps brachii of horses is subdivided into a lateral and medial head. Electrophoresis of samples from the lateral head revealed three slow-migrating native myosin isoforms, including one that does not correspond to slow myosin isoforms described for other mammalian muscles. In contrast, the medial head contained a single slow isoform. Both the lateral and medial heads contained three fast-migrating isoforms corresponding with the FM-2, FM-3 and FM-4 isoforms reported for other mammalian fast-twitch muscle fibers. Electrophoresis of myosin heavy chains (MHCs) revealed only two MHC bands, o...
Experimental cutaneous free flap transfers in the horse. Equine limb wounds often heal slowly by epithelialization, and large scars are a frequent end result. In some ways, they resemble the wound associated with human tibial injuries. The literature indicates that previous investigators have failed to transfer free skin flaps successfully in the horse. In this paper, we review our experimental work with the deep circumflex iliac flap in the horse. Dissections of 20 cadavers confirmed the anatomical consistency of the flap. Four flaps survived well when elevated as island flaps, but five orthotopic and nine heterotopic free flap transfers all failed...
Effect of oral melatonin on the date of the first ovulation after ovarian inactivity in mares under artificial photoperiod. Two experiments tested the hypothesis that exogenous melatonin (12 mg) given 4 h before dusk (evening melatonin), or near dawn (morning melatonin), would mimic a prolongation of the night and suppress stimulation of the ovaries induced by long days. Experiment 1 consisted of a non-stimulated control group, a control group stimulated by 14.5 h of light, a treated group stimulated with 14.5 h of light plus evening melatonin, a control group given 17.5 h of light and a treatment group given 17.5 h of light plus morning melatonin. The mean (+/- s.e.m.) intervals from the start of treatment to the ...
Diurnal changes in lactic and pyruvic acid levels and pH values in foals during the first 13 weeks of their life and in their lactating mothers. 1. The diurnal changes in the levels of lactic (LA) and pyruvic (PA) acids and values of pH were studied in standard-bred mares and their foals, for 13 weeks of foal life, throughout 2 years. 2. The studies began when a foal was 7 days old and were repeated every 2 weeks until foals reached 13 weeks of age. 3. Blood samples were taken every 4 hr for one day, each second week. 4. In the LA, PA levels and pH values no diurnal rhythm was stated in lactating mares during study periods. 5. In foals the diurnal rhythm in LA and PA occurred in the 3rd month of their life, with the acrophase at night ...
Tissue glycogen and glucose 6-phosphatase levels in fetal and newborn foals. Glycogen and glucose 6-phosphatase levels were measured in a variety of tissues from fetal, newborn and adult pregnant mares. Hepatic and renal glucose 6-phosphatase activities increased with increasing gestational age and rose further in the 24 h after birth to values similar to those observed in maternal tissues. The glycogen content of fetal liver and skeletal muscle also increased in late gestation, whereas that of fetal lung and cardiac muscle decreased toward term. No significant change in renal glycogen content with fetal age was observed. The values of hepatic glycogen and glucose 6-ph...
Effect of oral melatonin treatment on the seasonal physiology of pony stallions. This study tested the role of melatonin in the regulation of seasonal physiological change in the pony stallion. Four 3-year-old, Welsh Mountain pony stallions were housed initially under the prevailing short-day photoperiod in December (8 of light [L]:16 h of darkness [D]) before being transferred to long days (16L:8D) on 13 January for the remaining 22 weeks of the study. On Day 76 (11 weeks later) the stallions began an 11-week period of daily melatonin treatment (20 mg orally, 8 h after lights on). Marked changes in mean plasma testosterone, beta-endorphin and cortisol concentrations occur...
Partial purification and characterization of rhinoceros gonadotropins, growth hormone, and prolactin: comparison with the horse and sheep. The rhinoceros is an endangered species related to the horse family. Little is known of its reproductive endocrinology. The objectives of this study were to partially purify rhinoceros pituitary hormones, determine which assays could be used for their assessment, and to ascertain whether rhinoceros LH possesses the intrinsic FSH activity of equine LH. A single pituitary each from a White (1.3 g) and a Black (1.2 g) Rhinoceros was homogenized and extracted (pH 9.5), then subjected to pH and salt fractionation, and ion-exchange chromatography (DEAE and Sephadex SP-C50) to yield partially purifie...
Pasture mating behaviour of donkeys (Equus asinus) at natural and induced oestrus. The mating behaviour of 2 jacks, each with 21 non-pregnant jennies, was studied when the jennies were in natural oestrus and simultaneously induced oestrus. The main observations were: efficient pasture breeding at natural and induced oestrus, a territorial sociosexual structure, prolonged pre-copulatory interaction, gradual increase of mating activity up to 2 days before ovulation, a copulatory sequence similar to that of horses, vocalization of the jack as a conspicuous behaviour initiating pre-copulatory interaction, frequent heterotypical behaviour of jennies and active involvement of jenn...
Portable data acquisition cart for equine transportation stress study. A remote data sampling cart has been designed and built for studying environmental factors that produce stress in horses during transportation. This dedicated sampling cart uses an XT-compatible mother board powered by a 12 V battery, with customized BIOS and ROM program. Sampling is performed using two digital and eight A/D (bipolar, differential) channels in burst mode at a frequency of 1 kHz. Digitized data are stored on magnetic tape for retrieval after the experiment. Configuration of sampling parameters is accomplished via a serial communications link to a host computer, and is stored in...
Effects of furosemide on ponies with recurrent airway obstruction. The effect of aerosol and intravenous administrations of furosemide was examined in ponies with recurrent obstructive pulmonary disease, commonly called 'heaves'. This recurrent airway disease bears many similarities to human asthma. Six ponies with the disease (principal animals) were studied during clinical remission and during an acute attack of airway obstruction precipitated by stabling and feeding dusty hay. Six control animals were also studied. Furosemide (1.0 mg/kg) or vehicle was administered by aerosol in the first study, and intravenously in a second study. In principal ponies with...
[The estimation of platelet factor 3 activity in horses, cattle, sheep and pigs by the use of synthetic chromogenic tripeptide substrates]. The aim of this study was to investigate the platelet factor 3 activity in platelet-rich plasma of horse, cattle, sheep and pig, by the use of chromogenic tripeptide substrate H-D-Phenylalanyl-Pipecolyl-Arginyl-p-nitroanilide. Among species examined the highest activity of this factor was stated in pig, the lowest one in sheep. Chromogenic substrate test was 10 times more sensitive that Stypven clotting time test. Thus, the use of chromogenic tripeptide substrate is fully valuable in platelet factor 3 activity estimation in domestic animals.
Influence of pregnancy on diurnal and seasonal changes in glucose level and activity of FDPA, AlAT and AspAT in mares. 1. The diurnal changes in the glucose level and in activity of FDPA, A1AT and AspAT in four pregnant standard-bred mares were studied. 2. As a control four barren mares, were kept and examined in the same conditions. 3. Blood samples were taken every 4 hr for one day, each month, throughout pregnancy, or one year. 4. A diurnal rhythm in activity of A1AT and AspAT in barren mares was found. The pregnancy masked diurnal rhythm in activities of both transaminases. 5. No diurnal rhythm in glucose level and FDPA activity in both groups of mares was observed. 6. Seasonal cyclicity was found in all i...
Galactosyltransferase activity is restricted to the plasma membranes of equine and bovine sperm. beta 1, 4-Galactosyltransferase (GalTase) is localized to the plasma membrane of mouse sperm, in which it mediates the binding of sperm to glycoconjugate residues in the egg zona pellucida. In this study, the presence of subcellular distribution of sperm GalTase were determined in two other mammalian species that yield sufficient sperm for subcellular fractionation. Equine and bovine semen were collected, and the plasma membranes (PM), outer acrosomal membranes (OAM), and inner acrosomal membranes (IAM) were sequentially removed. The purities of the isolated membrane preparations were determin...
Characterization of hydrophobic cores in apomyoglobin: a proton NMR spectroscopy study. A proton nuclear magnetic resonance spectroscopic study of horse apomyoglobin was undertaken in order to define the regions of myoglobin that are and that are not structurally affected by the binding of the prosthetic group. It was found that, in spite of the poor spectral resolution, a number of spin systems could be identified by using standard correlated methods. Four clusters consisting mostly of hydrophobic residues were detected by nuclear Overhauser spectroscopy, two of which involved the tryptophan side chains. Extensive similarities to nuclear Overhauser spectroscopy data collected on...
Haem binding to horse spleen ferritin. Horse spleen ferritin, a spherical protein shell of 24 subunits, contains no haem when extracted. This contrasts with ferritins isolated from bacterial sources which have the capacity to bind up to 24 haem groups [(1990) FEBS Lett. 271, 141-143] via two methionine residues [(1990) Nature 341, 771]. Here it is shown that horse spleen ferritin can bind between 15 and 17 haems per 24 subunits with an apparent association constant of 2.2-3.2 x 10(4) M-1. The strength of haem binding appears to be unaffected either by the presence of the core or by the oxidation state of the haem. The demonstration...
[Reference values for cortisol, T4 and T-uptake in different horse groups using the fluorescence polarization immunoassay (FPIA)]. Reference values for Cortisol, T4 and T-Uptake, determined with the Fluorescence-Polarization-Immunoassays (FPIAs) in blood-plasma of different horse groups were established. The highest Cortisol values were measured in blood samples from thoroughbred racehorses and riding horses taken between 7 and 8 a.m. (181 +/- 37 and 268 +/- 43 nmol/l), the lowest gained between 5 and 6 p.m. (69 +/- 45 and 85 +/- 32 nmol/l respectively). Peak values for T4 in riding horses were found in blood samples collected between 1 and 2 p.m. (28.2 +/- 5.7 nmol/l) followed by the samples taken at 5-6 p.m. and 7-8 a.m...
The triangle of Viborg (Trigonum viborgi) and its anatomical relationships in the normal standing horse. A detailed description is given of the structures forming the borders of Viborg's triangle and those structures contained within and adjacent to the triangle. Changes in the size, shape and prominence of these structures with changes of head and neck posture of the horse are also described.
Comparative anatomy of the tracheobronchial circulation. This review considers the similarities and difference between several animal species to determine which are most appropriate for studies of the human bronchial circulation in health and disease. The subgross anatomy of the sheep, cow, pig and horse appear to be similar to that of humans. These species have a major bronchial artery with a consistent location. In humans and other species, there is evidence of anastomoses between the bronchial and coronary circulations. The bronchial circulation provides nutrient supply to the neural structures of all species. The bronchial arteries themselves ar...
