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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.
Incorporation of fresh and cryopreserved bone in osteochondral autografts in the horse. The structural integrity of subchondral bone in fresh and frozen osteochondral autografts was investigated at month 3 in 10 horses. Two osteochondral autografts were harvested from the lateral aspect of the lateral trochlear ridge of the left talus in each of 10 anesthetized horses. Grafts were frozen in 7.5% DMSO. After 14 days, the thawed grafts were press-fitted into drill holes in the trochlear ridges of the right stifles. A fresh graft from the right hock was implanted in each left stifle. To control for the effects of surgery, a fresh graft was transferred from the right stifle to the le...
Equine synovial tendon sheaths and bursae: a transmission electron microscope study. A transmission electron microscope study was undertaken to investigate the details of the synovial tendon sheath and bursal lining in horses. The lining cells appeared to be fibroblasts and were buried in a finely granular ground substance. Generally these cells had poor cytoplasmic organelles, sparse short profiles of rough endoplasmic reticulum (RER), few scattered ribosomes and, occasionally, a poorly developed Golgi complex. However, a few lining cells appeared more active, having pronounced RER with dilated cisternane. The surface of the lining cells, particularly those with dilated RER, ...
Heterotopic transfer of fresh and cryopreserved autogenous articular cartilage in the horse. Two 10 mm thick osteochondral grafts were harvested from the lateral aspect of the lateral trochlear ridge of the left talus in each of 10 anesthetized horses. The grafts were frozen in a 7.5% DMSO solution and stored in liquid nitrogen. The horses were anesthetized again on day 14 and the thawed grafts were press-fitted into drill holes in the trochlear ridges of the right stifle. A fresh graft was transferred from the right hock to the left stifle. To control for the effects of surgery, another fresh graft was transferred from the right stifle to the left stifle. The result was two grafts in...
Measurement of cardiac dimensions with two-dimensional echocardiography in the living horse. Two-dimensional echocardiography (2DE) was performed on 22 unsedated Thoroughbred and part Thoroughbred horses weighing between 411 and 650 kg to establish normal reference values for 2DE measurements. Animals stood during examinations performed with a 3.5 MHz mechanical sector transducer using various transducer positions and tomographic planes. Right ventricular diameter (RVD), ventricular septal thickness (VSTh), aortic diameter (AoD), area of the chordal lumen of the left ventricle (CTA), left ventricular diameter (LVD) and left atrial diameter (LAD) were determined at ventricular end-dias...
Stability of equine lysozyme. I. Thermal unfolding behaviour. The thermal denaturation of Ca(2+)- and apo-forms of equine lysozyme was followed by using far and near UV circular dichroism and intrinsic fluorescence methods. The difference found between the temperature dependence of the ellipticity at 222 nm and 287 nm, which show two stages in the thermal transition, and those at 228 nm and 294 nm, which indicate only one stage over a wide range of temperatures reflects that different subdivisions of the protein molecule are characterized by a different stability, cooperativity and pathway of denaturation. The first transition, reflected in the increase ...
The influence of detomidine and epinephrine on heart rate, arterial blood pressure, and cardiac arrhythmia in horses. Detomidine (10 micrograms/kg and 20 micrograms/kg) was administered to seven horses with and without epinephrine infusion (0.1 microgram/kg/min) from 5 minutes before to 5 minutes after detomidine injection. One or more single supraventricular premature heartbeats were observed in three horses after detomidine administration. Epinephrine infusion did not modify the incidence of cardiac arrhythmias in detomidine-treated horses at the doses tested. Relatively high momentary peak systolic pressures were registered in some horses after detomidine administration during epinephrine infusion. The hig...
Endoscopic examination of normal paranasal sinuses in horses. The frontal, caudal maxillary, and rostral maxillary sinuses of 10 equine cadavers were examined endoscopically, and the findings were confirmed by sinusotomy. Similar endoscopic examinations were performed in five conscious, adult horses by using sedation and local anesthesia. Useful portals of entry for the arthroscope in adult horses were: for the frontal sinus, 60% of the distance in a lateral direction from midline to the medial canthus and 0.5 cm caudal to the medial canthus; for the caudal maxillary sinus, 2 cm rostral and 2 cm ventral to the medial canthus; and for the rostral maxillar...
The isolated perfused equine skin flap. Preparation and metabolic parameters. A model for the study of equine cutaneous physiology, pharmacology, and toxicology was developed. Four 4 x 12 cm and twenty-one 6 x 12 cm single-pedicle axial pattern skin flaps based on the caudal superficial epigastric artery, and eight 6 x 12 cm flaps based on the saphenous artery and medial saphenous vein, were raised and sutured in a tubed configuration. On day 2, each flap was removed, the artery was cannulated, and the flap was perfused with a modified Krebs-Ringer's albumin-based medium for at least 6 hours. Flap viability was assessed by glucose use, lactate production, and histologic...
Co-culture of day-5 to day-7 equine embryos in medium with oviductal tissue. Oviductal and uterine embryos were collected from mares at 5 to 7 days following ovulation 1) to evaluate the effects of oviductal tissue explants on in vitro growth and development of equine embryos and 2) to study the morphologic development of equine embryos in culture. Embryos were incubated for 5 days in a medium (control group) or in medium supplemented with oviductal tissue explants (co-culture group). Embryos were evaluated and the media changed daily. Following 5 days in culture, 10 10 (100%) control embryos and 27 29 (93%) co-cultured embryos had doubled in diameter. All embryos that...
Investigating equine ingestive, maternal, and sexual behavior in the field and in the laboratory. Some of the techniques that may be used to study social, reproductive, and ingestive behavior in horses are described in this paper. One of the aspects of equine social behavior is the dominance hierarchy or patterns of agonistic behavior. Paired or group feeding from a single food source may be used to determine dominance hierarchies quickly. Focal animal studies of undisturbed groups of horses may also be used; this method takes longer, but may reveal affiliative as well as agonistic relationships among the horses. Reproductive behavior includes flehmen, the functional significance of which ...
Coprophagy in animals: a review. Coprophagy is performed by rodents and lagomorphs and to a lesser degree by piglets, foals, dogs and nonhuman primates. Due to the construction of the digestive system of rodents and rabbits, coprophagy is necessary to supply many essential nutrients. Bacterial synthesis of nutrients occurs in the lower gastrointestinal tract in these animals where little absorption is realized. The eating of their feces provides a method for obtaining these nutrients.
Relationships between lymphoid nodules and lymph sinuses in lymph nodes: a study in horses. Secondary lymphoid nodules in lymph nodes of the horse are surrounded by a network of lymph sinuses, including the subcapsular sinus and its extensions around tabeculae, tubular and tubule-like sinuses deeper in the cortex, and sinuses between cord-like projections of cortical tissue. The precise role of this close association between sinuses and nodules in the transport of immune complexes, cells and cytokines is not known.
Horse and marmoset monkey sperm bind to the zona pellucida of salt-stored human oocytes. The present study demonstrates that horse and marmoset monkey sperm can bind to the human zona of salt-stored oocytes that failed to fertilize in vitro. Marmoset monkey sperm are also able to penetrate the salt-stored human zona. In contrast, human sperm do not bind to the zona of either horse or marmoset monkey oocytes. These results suggest that human sperm binding to the zona pellucida is more strictly species-specific than it is for horse and marmoset monkey sperm. In contrast, horse and marmoset monkey sperm contain receptors recognized by the human zona.
Use of nonimaging nuclear medicine techniques to assess the effect of flunixin meglumine on effective renal plasma flow and effective renal blood flow in healthy horses. The effect of flunixin meglumine on renal function was studied in 6 healthy horses by use of nonimaging nuclear medicine techniques. Effective renal plasma flow (ERPF) and effective renal blood flow (ERBF) were determined by plasma clearance of 131I-orthoiodohippuric acid before and after administration of flunixin meglumine. Mean ERPF and ERBF was 6.03 ml/min/kg and 10.7 ml/min/kg, respectively, before treatment and was 5.7 ml/min/kg and 9.7 ml/min/kg, respectively, after treatment. Although ERPF and ERBF decreased after flunixin meglumine administration, the difference was not statistically ...
Effects of carbohydrates on the pharmacokinetics and biological activity of equine chorionic gonadotropin in vivo. The sialylation of eCG was examined to determine its influence on the in vivo metabolism and biological activity of the molecule. Sialic acid was decrementally removed from eCG by incubation with agarose-linked neuraminidase for varying time periods. Pharmacokinetic parameters for the disappearance of 4,000 IU (267 micrograms) of three desialylated eCG preparations (20%, 53%, and 80% sialic acid removed) and control eCG were determined in sheep. The clearance rate of eCG increased (p less than 0.05) with each decrement of sialic acid. The removal of 53% sialic acid enhanced the distribution of...
Participation of H1-receptors in histamine-induced contraction and relaxation of horse coronary artery in vitro. The mechanisms of histamine-induced contraction and relaxation were investigated in rings isolated from a middle part of the left descending coronary arteries of horses. Intact and endothelium-denuded preparations were compared. Rings of horse coronary arteries contracted in response to histamine in a concentration dependent manner, but some of them relaxed with lower concentrations and contracted with higher concentrations. Removal of the endothelium abolished the relaxation and potentiated the contraction. The pD2 values were 4.70 +/- 0.08 in the rings with intact endothelium and 4.95 +/- 0....
Influence of polysulfated glycosaminoglycan on equine articular cartilage in explant culture. Articular cartilage explants from 3 horses were maintained in tissue culture to test the effects of a polysulfated glycosaminoglycan on proteoglycan biosynthesis. Cultures were exposed to concentrations of 0, 50, or 200 micrograms of the drug/ml for either 2 days or 6 days, and labeled with 35S, before measuring the content of sulfated proteoglycan in the culture media and in extracts of cartilage. In a second experiment, the explants were incubated with the isotope and subsequently exposed to the same concentrations of the polysulfated glycosaminoglycan for 4 days. Subsequently, the amount of...
Effect of whole-body potassium depletion on plasma, erythrocyte, and middle gluteal muscle potassium concentration of healthy, adult horses. The effects of whole-body potassium depletion induced by food deprivation on plasma, erythrocyte, and middle gluteal muscle K concentrations was quantified in 16 healthy, adult horses before, during, and at the end of a 7-day period of food deprivation during which water and sodium chloride were available ad libitum. Potassium concentrations were determined by atomic absorption spectroscopy. Plasma K concentration remained constant (3.49 +/- 0.09 mM K/L of plasma; mean +/- SEM) throughout the study. Erythrocyte potassium concentration decreased from 93.10 +/- 1.94 mM K/L of erythrocytes on day...
Effects of coronary occlusion duration on reactive hyperemia in conscious dogs and ponies. Coronary reactive hyperemia duration (RHD) and coronary blood flow debt repayment (BFDR) were compared in conscious dogs and ponies instrumented with coronary artery Doppler flow probes and pneumatic occluders. Additional ponies were instrumented with pacing electrodes. With the use of a Latin square design, eight animals of each species were subjected to a randomized series of nine coronary occlusions ranging from 5 s to 2 min in duration. In both species, postocclusion blood flow velocity rose rapidly and plateaued at similar peak levels relative to control, but in ponies this plateau lasted...
Intake, digestion and gastrointestinal transit time in resting donkeys and ponies and exercised donkeys given ad libitum hay and straw diets. Four donkeys and four ponies maintained in climate rooms, were provided with meadow hay or barley straw supplemented with minerals and vitamins ad libitum. Both diets were given to all animals for periods of 21 days. Measurements were made during the last seven days following single doses of two non-absorbable markers (Cr-fibre and Co-EDTA). After six weeks the donkeys repeated the trial, walking 14 km and ascending 260 m five days per week. At rest ponies ate more than donkeys, however the donkeys showed a higher digestibility of dry matter (DM), organic matter (OM) and acid detergent fibre (...
Oestrogen production by the preimplantation donkey conceptus compared with that of the horse and the effect of between-species embryo transfer. Aromatase distribution in membranes of preimplantation horse and donkey conceptuses was compared by measuring the incorporation of [3H]androstenedione into oestrone and oestradiol-17 beta. In the donkey conceptus, aromatase activity was similar in all the tissues examined (yolk sac, chorionic girdle and allantochorion), whereas in the horse it was generally lower and showed the relationship chorionic girdle greater than yolk sac greater than allantochorion. A higher proportion of labelled precursor was incorporated into oestradiol-17 beta by extra-embryonic tissues of the donkey compared with ...
Genomic distribution of heterochromatic sequences in equids: implications to rapid chromosomal evolution. We describe a molecular model for rapid chromosomal evolution that proposes tandemly repeated DNA sequences as a driving force. A prediction of this model is that when extensive rearrangements of euchromatin have been facilitated by heterochromatin, genomes will be characterized by tandemly repeated sequences that have actively changed chromosomal fields by intragenomic movement. Alternatively, it is proposed that in conservative chromosomal lineage each class of tandemly repeated sequences will be restricted to a specific chromosomal field. To provide baseline data to test this model we exami...
Relaxant effects of theophylline and clenbuterol on tracheal smooth muscle from horse and rat in vitro. A comparison between the relaxant effects of clenbuterol and theophylline on horse tracheal smooth muscle has been made in vitro. Rat tracheal smooth muscle was also investigated as a reference. The tracheal preparations were initially contracted with carbachol since the smooth muscle did not spontaneously develop tone. The response of the carbachol-contracted preparations to theophylline was the same in the two species. The response to clenbuterol varied. In only five out of eleven horses were the tracheal smooth muscles sensitive to clenbuterol (mean pD2 = 7.92 M). In the remaining six horse...
[A liposomal form of diamidine: reduced toxicity]. The cultures of Nuttalia eque mainly develop in the reticuloendothelial organs and so in treatment of nuttaliosis in horses and the Nuttalia carriers diamidine, an analog of imidocarb or imidozoline, was used encapsulated in liposomes. The liposomes were prepared with a modification of the phase inversion method (the lipids were dissolved in a mixture of freon-11 and chloroform). The content of the organic solvents in the preparation, as evidenced by gas liquid chromatography, was less than 0.2 per cent. The main fraction consisted of particles 1.5 to 2.5 microns in diameter. The tests on anim...
A preliminary study of the tolerance of healthy foals to a low residue enteral feeding solution. After a three day acclimatization period, six healthy, young (aged 4 to 20 days) orphan foals of mixed breeding were fed 100 per cent of their caloric needs (estimated at 523 kjoules/kg bodyweight [bwt] or 125 kcal/kg bwt/day) as a low residue isotonic feeding solution (LRF) for seven days. The solution provided 4.18 kjoules (1 kcal/ml) and was fortified with minerals and protein to meet estimated foal requirements. The solution was fed through an indwelling 12 French feeding tube. Five of the six foals completed the study; the loss of the sixth foal apparently was unrelated to the feeding pro...
Unilateral hypoxic pulmonary vasoconstriction in the dog, pony and miniature swine. The hypoxic pulmonary vasoconstrictor response to unilateral hypoxia was analyzed in pentobarbital anesthetized dogs (n = 5), miniature swine (n = 5), and ponies (n = 5). The left and right lungs (LL, RL) were separately ventilated with the LL exposed to inspired oxygen concentrations (CIO2) of 100%, 12%, 8% or 4%, while the RL always received a CIO2 = 100%. Pulmonary blood flow distribution was measured using 15 microns radioactive microspheres. LL PAO2, and percent pulmonary blood flow diversion (%FD) were calculated at each CIO2. At CIO2 of 4% there were significant differences (P greater t...
Season but not age affects Sertoli cell number in adult stallions. To evaluate the effect of age and season on Sertoli cell number per paired testes, ratio of germ cells per Sertoli cell, and daily sperm production, testes were obtained from 184 adult (4-20 yr) stallions at slaughter throughout one year. Numbers of Sertoli cells or germ cells were derived from nuclear volume density, volume of individual nuclei, and parenchymal volume. Germ cell to Sertoli cell ratios were calculated from cell numbers. Regression analysis was used to detect age-related differences in the breeding season (May-Jul) or throughout the year. A two-way analysis of variance was used...
Contribution of renal medullary mitochondrial density to urinary concentrating ability in mammals. In mammals, the length of the loops of Henle increases with increasing body size without a concomitant rise in urinary concentrating ability. Because mass-specific metabolic rate falls with increasing body mass, this study sought to determine the extent to which this decline in metabolic rate could explain the low urinary concentrating ability of large mammals with long loops of Henle. Mitochondrial ultrastructural parameters were measured in the medullary thick ascending limbs (mTALs) of a series of nine mammalian genera ranging in body mass from 0.011 kg (bats) to approximately 400 kg (horse...
