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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.
Electroacupuncture in the treatment of chronic lameness in horses and ponies: a controlled clinical trial. Electroacupuncture was used to treat lameness in horses and ponies with chronic laminitis (n = 10) or navicular disease (n = 10). A clinical trial was conducted with random allocation of equal numbers of animals to control and treatment groups. Acupuncture was performed three times per week for four consecutive weeks. The degree of lameness was assessed by 1) a grading scheme, 2) measurement of stride lengths and 3) analysis of weight distribution using a force plate. Although seven out of ten animals with chronic laminitis improved clinically during the trial, there were no statistically sign...
Urinary excretion of pentoxifylline and its metabolites by standardbred mares. The urinary excretion of a sustained-release formulation of pentoxifylline was studied in the horse after the oral administration of 4.0 grams of Trental tablets. Urine samples were collected for 24 hours after dosing and analyzed for pentoxifylline and its metabolites using high-performance liquid chromatography coupled with an ultraviolet detector. Six metabolites of pentoxifylline were identified in horse urine in addition to less than 0.2% of unchanged drug. Concomitant use of gas chromatography/mass spectrometry allowed for the elucidation of the chemical structures of the metabolites. Me...
Semen selenium content and sperm mitochondrial volume in human and some animal species. Selenium (Se) and glutathione peroxidase (GSH-Px) were determined from the seminal plasma samples and spermatozoa of human and four different animal species. The human sperm Se concentration was 1.8 +/- 0.8 micrograms/g dry weight, which was about half of that in the bull. Abnormal sperm morphology and motility correlated with low sperm Se content. The volume of sperm mitochondrial sheath in human, bull and stallion was measured using transmission electron microscopy. In these species the sperm Se content was highly correlated with the volume of mitochondria. Among the five species studied, th...
Basal and bile salt-stimulated bile flow and biliary lipid excretion in ponies. The role of bile salt in biliary lipid excretion was studied in 3 healthy ponies with chronic external biliary fistulas. After endogenous bile salt pool depletion, micelle-forming taurocholate or taurochenodeoxycholate was infused to replace excreted bile salt. Enterohepatic circulations were held open (total biliary diversion) throughout each study. Results indicated that biliary lipid excretion in ponies (113 +/- 21 nmol/min/kg of body weight) is approximately 10 times less than that reported in rodents. Although the lipid composition (4.4% cholesterol, 5.6% phospholipid, and 90% bile salt) ...
Clinical and pathological effects of flunixin meglumine administration to neonatal foals. The effects of daily intravenous administration of flunixin meglumine at dosages of 0.55, 1.1, 2.2 and 6.6 mg/kg for five days were examined in neonatal foals. Six two day old foals were used to evaluate the effect of each dosage. Foals were examined every day and blood samples collected on days 1, 3 and 6. All foals were euthanized after six days, necropsied and examined for lesions. The major clinical abnormality was diarrhea, but the incidence was not related to the dosage of flunixin meglumine administered. The foals receiving 6.6 mg/kg of flunixin meglumine had significantly more gastroin...
Attempts to restore abduction of the paralyzed equine arytenoid cartilage. I. Nerve-muscle pedicle transplants. The purpose of this project was to adapt a surgical technique from humans and dogs to horses in which a portion of an accessory muscle of respiration and its nerve supply is transplanted to a denervated dorsal cricoarytenoid muscle. Anatomical dissections in seven horses revealed two possible donor nerve-pedicle grafts: the omohyoid and the sternothyrohyoid, both innervated by a branch of the first and second cervical nerves. Histochemical evaluations in two ponies of the dorsal cricoarytenoid, omohyoid and sternothyrohyoid muscles revealed similar proportions of fiber types 1 and 2 in all thr...
Age-related changes in the fibre composition of equine peripheral nerve. Transverse sections of the lateral palmar nerve from a group of horses free from neuromuscular disease were assessed quantitatively, with emphasis on differences in the fibre population related to age. Morphometric analysis of the population of myelinated and unmyelinated fibres was performed. Changes were identified, there being a loss of larger myelinated fibres in older horses. The relationship of myelin thickness to axon diameter and the unmyelinated fibre population did not alter with age. The lateral palmar nerve is suitable for biopsy and electrophysiological study in the horse, but age...
A rapid, non-invasive method for measuring total respiratory impedance in the horse. Total respiratory impedance was measured rapidly and noninvasively in conscious horses over the frequency range 3 to 40 Hz by the forced random noise method. The shape of curve of impedance versus frequency in horses was markedly different from that of humans. Respiratory resistance was readily found as the real part of impedence and both its absolute value and frequency dependence are useful indices of pulmonary function. It was difficult to obtain meaningful results in intubated animals with the method because of the mechanical properties of the endotracheal tube itself.
Single-dose pharmacokinetics of detomidine in the horse and cow. The pharmacokinetics of detomidine, a novel analgesic sedative, was studied in the major target species after high (80 micrograms/kg) i.v. and i.m. doses. In addition, drug residues in some organs were determined. Concentrations were measured using a sensitive, detomidine-specific radio-immunoassay method. Rapid absorption following i.m. dosing occurred. Absorption half-lives were 0.15 h (horse) and 0.08 h (cattle). The mean peak concentration in the horse (51.3 ng/ml) was achieved in 0.5 h and in the cow (65.8 ng/ml) in 0.26 h. The areas under the concentration curve after i.m. dosing were 66...
Mechanism of exercise-induced hypoxemia in horses. Arterial hypoxemia has been reported in horses during heavy exercise, but its mechanism has not been determined. With the use of the multiple inert gas elimination technique, we studied five horses, each on two separate occasions, to determine the physiological basis of the hypoxemia that developed during horizontal treadmill exercise at speeds of 4, 10, 12, and 13-14 m/s. Mean, blood temperature-corrected, arterial PO2 fell from 89.4 Torr at rest to 80.7 and 72.1 Torr at 12 and 13-14 m/s, respectively, whereas corresponding PaCO2 values were 40.3, 40.3, and 39.2 Torr. Alveolar-arterial PO2 di...
Immunoglobulin lambda-light-chain-derived amyloidosis (A lambda) in two horses. Tumorous amyloid deposits in the nasal mucosa of two horses differed from generalized AA-amyloidosis with respect to clinical features, organ distribution, and resistance to KMnO4 treatment. Using a panel of antibodies directed against different human amyloid fibril proteins and employing the peroxidase-anti-peroxidase (PAP) technique, we showed the described equine amyloid to be A lambda-type, as demonstrated by immunohistochemical cross-reactivity. Consequently, we identified a second amyloid class in horses and showed that immunoglobulin light-chain-derived amyloid may also be present in an...
Vascular anatomy of the descending colon of the horse. The blood supply to the descending colon of the horse was studied by gross dissection and methyl methacrylate corrosion casts. The arterial supply is derived from the left colic artery and cranial rectal artery with the left colic artery supplying approximately the proximal three fourths. Each artery gives off four to eight arcuate arteries that form a series of anastomosing arcades. The arcade pattern continues to form a marginal artery that parallels the long axis of the colon. Small branches from the marginal artery anastomose with adjacent branches to form a secondary arcade. The secondary...
Myoelectric activity of the cecum and right ventral colon in female ponies. The myoelectric activity of the cecum and right ventral colon (RVC) was studied in 4 female ponies. Eight, bipolar Ag-AgCl electrodes were sequentially placed on the seromuscular layer of the cecum (6 electrodes) and RVC (2 electrodes), and recordings were begun 14 days after surgery. The myoelectric activity for each pony was recorded during 12, 60-minute recording sessions done during the interdigestive period (3 to 7 hours after the morning feeding). Coordinated series of spike bursts were recognized as independent motility patterns in the cecum and in the RVC. Local haustra-haustra myoelec...
Effects of ischemia and dimethyl sulfoxide on equine jejunal vascular resistance, oxygen consumption, intraluminal pressure, and potassium loss. Physiologic effects of 1 hour of ischemia and 1 hour of reperfusion on equine jejunum and protective effects of systemic administration of dimethyl sulfoxide (DMSO, 1 g/kg of body weight) were investigated in 18 ponies, using neurally intact segments of jejunum perfused at constant flow with heparinized blood. Ponies were allotted to 4 groups: group 1, saline solution administered (control, n = 3); group 2, DMSO administered (DMSO, n = 3); group 3, ischemia induced and saline solution administered (ischemia, n = 6); and group 4, ischemia induced and DMSO administered (ischemia-DMSO, n = 6). In...
Capillary tortuosity in skeletal muscles of mammals depends on muscle contraction. Capillary orientation (anisotropy) was compared in hindlimb muscles of mammals of different size and/or different aerobic capacity (dog, goat, pony, and calf). All muscles were fixed by vascular perfusion at sarcomere lengths ranging from 1.5 to 2.7 micron. The ratios of capillary counts per fiber cross-sectional area on two sets of sections (0 and 90 degrees) to the muscle fiber axis were used to estimate capillary anisotropy and the coefficient c(K,0) relating 1) capillary counts on transverse sections (a commonly used parameter to assess muscle capillarity) and 2) capillary length per volum...
Vasopressin in dehydrated and rehydrated ponies. Six pony mares deprived of water for 24 hours showed significant increases in plasma vasopressin (2.8 pg/ml) and osmolality (9 mosmol/kg). When water was made available the ponies drank rapidly (5 of 6 drank to satiety within 90 seconds) and corrected their fluid deficits precisely. Vasopressin did not return to predehydration levels until osmolality did after 15 minutes of access to water. The horse differs from rodents and humans, but is similar to pigs in that vasopressin levels do not fall before osmolality returns to normal. Oropharyngeal factors, therefore, may not be as important in vas...
Thyroid hormone periodicity in healthy adult geldings. Serum samples were collected from 10 healthy geldings every 4 h for three consecutive days and the triiodothyronine (T3) and thyroxine (T4) concentrations determined by radioimmunoassay. There were significant differences in the hormone concentrations related to time. The mean (+/- sd) T3 concentration peaked around 08.00 h at a level (54.06 +/- 14.02 ng/dl) significantly (P less than .001) higher than the lowest concentration (38.71 +/- 10.81 ng/dl) around midnight. Although the highest mean T3 level was 08.00 h, this value was not significantly different from the noon and 16.00 h levels. Lik...
An intersex horse with X chromosome trisomy. An X-trisomy has been detected in an intersexuality Spanish-bred horse by using G- and C-banding methods. The external characteristics and the behavioural and physiological irregularities of the horse are described. This is the first time that an association between an X-trisomy and a case of intersexuality has been reported in any domestic animal.
Effect of water vapor-saturated air therapy on bronchoalveolar lavage and tracheal mucus transport rate in clinically normal horses. Water vapor-saturated air was delivered to 12 healthy, housed horses for 2 hours daily for 5 days. Treatment had no effect on tracheal mucus transport rate, bronchoalveolar lavage total and differential cell counts, blood cell counts, or plasma fibrinogen concentration.
Energy uptake and utilization by limit- and ad libitum-fed growing horses. Eighteen weanling horses were assigned to two treatments: limited or ad libitum feed intake. Growth and feed utilization were evaluated over a 78-wk period. Ad libitum-fed horses gained 24% more (P less than .05) weight than limit-fed horses. Total BW was distributed into 57% fore and 43% hind weight and did not differ between groups regardless of dietary treatment or age. Net gain and ADG in wither height of ad libitum-fed horses exceeded (P less than .05) that of limit-fed horses over 78 wk. Ad libitum-fed horses consumed 19, 44 and 34% more digestible energy (DE) than indicated in 1978 NRC ...
A human minisatellite sequence reveals DNA polymorphism in the equine species. Southern blot analysis of equine DNA's digested with the restriction endonuclease Hinfl hybridized with a 32 PdCTP labeled human VNTR probe revealed a highly polymorphic pattern of restriction fragments upon autoradiography. The horses were unrelated individuals of the quarter horse breed. This heterologous probe can thus be used in the equine species for individual identification and pedigree analysis.
Effect of subchondral drilling on repair of partial-thickness cartilage defects of third carpal bones in horses. Arthrotomies of middle carpal joints were done on 13 horses, and a 1-cm partial thickness, round defect was made on the radial facet of both third carpal bones. In one joint, 1-mm diameter 1-cm deep holes were drilled within the defect, and one joint was used as a control. horses were assigned to 2 groups--group 1 (n = 6 horses), 5 drill holes; group 2 (n = 7 horses), 11 drill holes. At 1 and 3 weeks after surgery, differences between joints in synovial fluid total protein values, WBC counts, or results of mucin precipitate tests were not significant (P = 0.005). Physically and radiographicall...
Hepatotoxicity and renal toxicity in rats of corn samples associated with field cases of equine leukoencephalomalacia. Currently there is no convenient bioassay to determine the potential toxicity of corn naturally contaminated with Fusarium moniliforme. A short-term bioassay would be useful for future investigations aimed at isolating as yet unidentified toxins produced by this fungus. Two groups of five male Sprague-Dawley rats were each fed one of two F. moniliforme contaminated corn samples, designated CS-1 and CS-2, that were associated with separate field cases of equine leukoencephalomalacia (ELEM). A control group, also consisting of five male rats, was fed uncontaminated seed corn. All animals survive...
Relation of intrinsic heart rate and autonomic nervous tone to resting heart rate in the young and the adult of various domestic animals. Intrinsic heart rate (IHR) and autonomic nervous tone (ANT) were measured using the young and the adult of horses, cows, pigs, goats and chickens in order to elucidate species differences in a decrease of resting heart rate (RHR) with growth or age. The IHR and ANT were estimated from the changes in heart rate after the administration of atropine and/or propranolol. The IHR in all species decreased progressively with an increase in body weight from young to adult, and moreover the ANT altered toward the direction of parasympathetic predominance by a decrease in sympathetic tone and/or an incre...
Total muscle mitochondrial volume in relation to aerobic capacity of horses and steers. The relationship between maximal oxygen consumption rate (VO2max) and mitochondrial content of skeletal muscles was examined in horses and steers (n = 3 each). Samples of the heart left ventricle, diaphragm, m. vastus medialis, m. semitendinosus, m. cutaneous thoracicus and m. masseter, as well as samples of muscles collected in a whole-body sampling procedure, were analyzed by electron microscopy. VO2max per kilogram body mass was 2.7 x greater in horses than steers. This higher VO2max was in proportion to the higher total volume of mitochondria in horse versus steer muscle when analyzed from...
Identification and description of alpha-helical regions in horse muscle acylphosphatase by 1H nuclear magnetic resonance spectroscopy. It has been proposed that combination of intraresidue, sequential and longer range nuclear Overhauser enhancements occurring in 1H nuclear magnetic resonance spectra of protein chains folded in a helix show a regular characteristic pattern. As a test case the spectra of horse muscle acylphosphatase were searched for this pattern together with other typical signs of a helical conformation (i.e. chemical shift, coupling constants and slow 2H-H exchange). Two amino acid sequences complying with these requirements were found. Just a few amino acid spin system assignments were then sufficient to lo...
Embryo transfer in subfertile mares. Four subfertile mares (at least 2 barren years) were used as donors in an embryo transfer program. The embryo recovery rate was 50%, varying between 0-100. The transfer of 9 embryos resulted in the pregnancy rate of 44%. The efficiency of embryo transfer using subfertile mares is low. In this material 20% of flushings resulted in a pregnancy. Fyra subfertila ston (gatt galla i minst 2 är) användes som donatorer i ett program för embryot rans fer. Femtio procent av embryon tillvaratogs (varians 0–100%). Transfer av 9 embryon gav en dräktighetsresultat på 44%. Embryotransfer från subfert...
