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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.
Ability of the vector tick Boophilus microplus to acquire and transmit Babesia equi following feeding on chronically infected horses with low-level parasitemia. The protozoan parasite Babesia equi replicates within erythrocytes. During the acute phase of infection, B. equi can reach high levels of parasitemia, resulting in a hemolytic crisis. Horses that recover from the acute phase of the disease remain chronically infected. Subsequent transmission is dependent upon the ability of vector ticks to acquire B. equi and, following development and replication, establishment of B. equi in the salivary glands. Although restriction of the movement of chronically infected horses with B. equi is based on the presumption that ticks can acquire and transmit the ...
Evaluation of a rebound tonometer for measuring intraocular pressure in dogs and horses. To compare intraocular pressure (IOP) measurements obtained with a rebound tonometer in dogs and horses with values obtained by means of applanation tonometry and direct manometry. Methods: Prospective study. Methods: 100 dogs and 35 horses with clinically normal eyes, 10 enucleated eyes from 5 dogs, and 6 enucleated eyes from 3 horses. Methods: In the enucleated eyes, IOP measured by means of direct manometry was sequentially increased from 5 to 80 mm Hg, and IOP was measured with the rebound tonometer. In the dogs and horses, results of rebound tonometry were compared with results of applana...
Establishment of cloned Anaplasma phagocytophilum and analysis of p44 gene conversion within an infected horse and infected SCID mice. Diverse p44 alleles at the p44 expression locus (p44Es) encoding surface-exposed major membrane proteins, P44s, of Anaplasma phagocytophilum were hypothesized to be garnered by recombination to enact antigenic variation. However, this hypothesis has not been proven so far, due to inability to clone this obligate intragranulocytic rickettsia. To define the p44E recombination, we developed a novel method to clone A. phagocytophilum. This isogenic cloned population containing a defined p44E was used to infect a naive horse and severe combined immunodeficiency (SCID) mice. During a 58-day infectio...
Sequence analysis of canine and equine ferritin H and L subunit cDNAs. Canine and equine ferritin H and L subunit cDNA clones were obtained using reverse transcriptase-polymerase chain reaction (RT-PCR) and TA cloning from various tissues. Canine liver and spleen ferritin H subunit cDNA clones contained an open reading frame for the same 182-amino acid protein as that reported in canine brain ferritin H subunit cDNA although there were substitutions in the 3'-noncoding regions. Ferritin L subunit cDNA clones from canine liver, spleen, and kidney showed identical coding sequences encoding the 174-amino acid protein except for a single nucleotide substitution in ki...
Host-feeding patterns of suspected West Nile virus mosquito vectors in Delaware, 2001-2002. Paucity of data on host-feeding patterns and behavior of 43 mosquito species that are reported as suspected West Nile virus (WN) vectors has limited full evaluation of their vectorial capacity. Recent studies addressing this issue need additional confirmation and should also be expanded to include collections of species or subpopulations attracted to humans. We used 4 types of collection methods to collect mosquitoes, including omnidirectional Fay-Prince traps, Centers for Disease Control-type light traps, gravid traps, and human-landing collections. Mosquitoes were collected during 2 full WN ...
The equine larynx. A series of landmark studies on the function of the equine larynx was conducted by a group of researchers at Massey University between 1970 and 1987. These studies commenced with investigations on the normal laryngeal anatomy and physiology (Goulden et al 1976a; Anderson et al 1980; Quinlan et al 1982), and progressed to a clinical appraisal of laryngeal hemiplegia, the most important clinical disease affecting the horse's larynx (Goulden and Anderson 198 lab, 1982). The studies concluded with a series of in-depth cytological and pathological studies of the intrinsic laryngeal muscles and nerv...
In vitro evaluation of the effect of the opioid antagonist N-methylnaltrexone on motility of the equine jejunum and pelvic flexure. Although potent analgesics, opioids decrease intestinal activity, leading to ileus in many species. N-methylnaltrexone (MNTX), an opioid antagonist which does not cross the blood-brain barrier and antagonises the morphine effect on the intestine, directly stimulates motility and restores function without affecting analgesic properties. While its use has been reported in human subjects, there is no information with regard to its usage in the horse. Objective: To determine whether MNTX has an effect on contractile activity of the equine jejunum and pelvic flexure. Methods: Using circular smooth ...
Risk factors for faecal sand excretion in Icelandic horses. Sandy soil is often mentioned as a risk factor in the development of sand-related gastrointestinal disease (SGID) in the horse. There are other variables, but few studies confirm any of these. Objective: To investigate soil type, pasture quality, feeding practice in the paddock, age, sex and body condition score as risk factors for sand intake in the horse. Methods: Faeces were collected from 211 Icelandic horses on 19 different studs in Denmark together with soil samples and other potential risk factors. Sand content in faeces determined by a sand sedimentation test was interpreted as evidenc...
Structure of myelin P2 protein from equine spinal cord. Equine P2 protein has been isolated from horse spinal cord and its structure determined to 2.1 A. Since equine myelin is a viable alternative to bovine tissue for large-scale preparations, characterization of the proteins from equine spinal cord myelin has been initiated. There is an unusually high amount of P2 protein in equine CNS myelin compared with other species. The structure was determined by molecular replacement and subsequently refined to an R value of 0.187 (Rfree=0.233). The structure contains a molecule of the detergent LDAO and HEPES buffer in the binding cavity and is otherwise ...
Effect of dexamethasone, feeding time, and insulin infusion on leptin concentrations in stallions. Three experiments tested the hypotheses that daily cortisol rhythm, feeding time, and/or insulin infusion affect(s) leptin secretion in stallions. Ten mature stallions received ad libitum hay and water and were fed a grain concentrate once daily at 0700. In Exp. 1, stallions received either a single injection of dexamethasone (125 microg/kg BW i.m.; n = 5) or vehicle (controls; n = 5) at 0700 on d -1. Starting 24 h later, blood samples were collected every 2 h for 36 h via jugular venipuncture. Cortisol in control stallions varied (P < 0.01) with time, with a morning peak and evening nadir;...
Ocular parameters related to drug delivery in the canine and equine eye: aqueous and vitreous humor volume and scleral surface area and thickness. To measure the ocular surface area, scleral thickness, and the aqueous and vitreous humor volumes in the canine and equine eye. Animals studied Fourteen canine and 16 equine cadaver eyes. Methods: Eyes were measured either fresh or following fixation in formalin. Ocular surface area was calculated using the fluid displacement method. Globes were hemisected and aqueous and vitreous humor were collected and quantitated. Scleral thickness was measured by digital caliper, by image projection, and by ultrasonic biomicroscopy (UBM). Results: Mean +/- standard deviation (SD) scleral surface areas in ...
Response of Tabanidae (Diptera) to natural and synthetic olfactory attractants. The attraction of female tabanids to Malaise traps and canopy traps baited with aged horse urine, 1-octen-3-ol, or a combination of aged horse urine and acetone was studied in the Kopacki rit Nature Park in Eastern Croatia. Malaise traps captured very few tabanids relative to canopy traps. The number of females of Tabanus tergestinus and Haematopotapluvialis collected from 1-octen-3-ol baited canopy traps differed significantly from traps baited with aged horse urine. However, the number of females of Tabanus bromius, Atylotus loewianus, and Tabanus maculicornis collected from canopy traps bai...
Ultrastructural immunolocalization of cartilage oligomeric matrix protein (COMP) in relation to collagen fibrils in the equine tendon. The structure and organisation of the extracellular matrix, and in particular the axial alignment of type I collagen fibrils, are essential for the tensile strength of tendons. The resident tenocytes synthesize and maintain the composition of the extracellular matrix, which changes with age and maturation. Other components of the extracellular matrix include less abundant collagen types II, III, V, VI, XII, proteoglycans and glycoproteins. Cartilage oligomeric matrix protein (COMP) is an abundant non-collagenous pentameric glycoprotein in the tendon, which can bind to collagen types I and II. ...
Osteon interfacial strength and histomorphometry of equine cortical bone. The interfacial strength of secondary osteons from the diaphysis of the Thoroughbred equine third metacarpal was evaluated using the fiber pushout test. The pushout was performed on 300-500 microm sections of 4x4x15 mm bone blocks machined from four anatomic regions of the cortex. Pushout strength was evaluated from proximal to distal location within the diaphysis on four osteon types classified under polarized light on adjacent histologic sections from each block. The shear strength of the interfaces were estimated from shear lag theory. Differences were found in the interfacial strength of o...
Factors associated with the wastage and achievements in competition of event horses registered in the United Kingdom. The aims of this study were to estimate the wastage of horses registered for eventing in Britain, to investigate the reasons for this wastage and to evaluate factors affecting the horses' achievement of grade I status (at least 61 points) while registered. An analysis of the database of the British Eventing register found that 33.7 per cent of horses registered for the first time in 1999 were not re-registered for eventing in subsequent years. By using multivariable logistic regression analysis, it was shown that horses that were kept at an event yard were more likely to be re-registered than ...
Assessment of a platelet function analyser in horses: reference range and influence of a platelet aggregation inhibitor. The objective of this study was to assess whether a new human platelet function analyser (the PFA-100) could be used to evaluate platelet function in horses and detect acetylsalicylic acid (ASA)-induced platelet dysfunctions. Citrated blood samples from 40 healthy horses were processed to obtain reference values for closure time (CT) using cartridges with collagen-ADP (CT-ADP) and collagen-epinephrine (CT-EPI) as platelet agonists. In addition, CT-ADP and CT-EPI were also measured before and 24 h after oral ASA administration in another 12 healthy horses. The sensitivity and specificity of the...
An in vitro study on spontaneous myometrial contractility in the mare during estrus and diestrus. Uterine smooth muscle specimens were collected from euthanatized mares in estrus and diestrus. Longitudinal and circular specimens were mounted in organ baths and the signals transcribed to a Grass polygraph. After equilibration time and 2 g preload, their physiologic isometric contractility was recorded for a continuous 2.0 h. Area under the curve, frequency and time occupied by contractions were studied. Differences between cycle phases, between muscle layers, and over the recorded time periods were statistically evaluated using linear mixed-effect models. In the mare, physiologic contractil...
Femoral asymmetry in the Thoroughbred racehorse. To investigate the occurrence of geometrical asymmetries in the macro-architecture of left and right femurs from Thoroughbred racehorses previously used in competitive training and racing in New South Wales, Australia. Methods: Detailed postmortem measurements were made of 37 characteristics of left and right femurs from eleven Thoroughbred racehorses euthanased for reasons unrelated to the study. Measurements focused on articulating surfaces and sites of attachment of muscles and ligaments known to be associated with hindlimb locomotion. Results: Five measurements were significantly larger in...
Adiponectin and leptin are related to fat mass in horses. Plasma concentrations of adiponectin and leptin were measured in 23 mature Standardbred mares (age: 10+/-3 years) and 12 weanling fillies (10 Quarter Horse/Belgian crossbreds and two Quarter Horses; aged: 4+/-3 months) to test the hypothesis that adipocytokines are proportional to adiposity in horses. Rump fat thickness was measured using B-mode ultrasound and percent body fat (% fat) calculated using a published formula for the estimation of fatness in horses. Plasma adiponectin and leptin were determined using radioimmunoassay. In the absence of purified equine adiponectin or leptin, results...
Interaction of saddle girth construction and tension on respiratory mechanics and gas exchange during supramaximal treadmill exercise in horses. To determine the effect of girth construction and tension on respiratory mechanics and gas exchange during supramaximal treadmill exercise in horses. Methods: Six healthy detrained Thoroughbred horses were exercised on a treadmill inclined at 10% at 110% VO2max. Horses were instrumented for respiratory mechanics and gas exchange studies, and data were recorded during incremental exercise tests. The animals were exercised for 2 min at 40% VO2max, and samples and measurements were collected at 1 min 45 sec. After 2 min, speed was increased to that estimated at 110% VO2max and data was collected ...
Role of endothelium and nitric oxide in modulating in vitro responses of colonic arterial and venous rings to vasodilatory neuropeptides in horses. The objective of this study was to determine and compare the in vitro responses of equine large colon arterial and venous rings to vasodilatory neuropeptides; calcitonin gene-related peptide (CGRP); substance P (SP); vasoactive intestinal polypeptide (VIP); and acetylcholine (ACh), a standard nonpeptide endothelium-dependent vasodilator. Responses of vessel rings to graded concentrations (10(-11) M to 10(-5) M) of each drug were determined in endothelium-intact, denuded, and Nomega-nitro-L-arginine methyl ester (L-NAME, 10(-5) M)-treated rings that were pre-contracted with norepinephrine. Perc...
Transmission of a Venezuelan equine encephalitis complex Alphavirus by Culex (Melanoconion) gnomatos (Diptera: Culicidae) in northeastern Peru. Venezuelan equine encephalitis (VEE) complex alphaviruses are serious health threats in the Americas and regularly infect humans living in or near Amazonian rain forests. As part of a larger surveillance program, we placed six hamster-baited mosquito traps in a disturbed white sand forest of northeastern Peru for 3 d. Virus isolations from hamster serum and trapped mosquito pools demonstrated that a VEE subtype IIIC alphavirus was transmitted to a hamster by the mosquito Culex (Melanoconion) gnomatos Sallum, Hutchings & Ferreira. This species, like the other seven proven VEE complex alphavirus...
Functional specialisation of pelvic limb anatomy in horses (Equus caballus). We provide quantitative anatomical data on the muscle-tendon units of the equine pelvic limb. Specifically, we recorded muscle mass, fascicle length, pennation angle, tendon mass and tendon rest length. Physiological cross sectional area was then determined and maximum isometric force estimated. There was proximal-to-distal reduction in muscle volume and fascicle length. Proximal limb tendons were few and, where present, were relatively short. By contrast, distal limb tendons were numerous and long in comparison to mean muscle fascicle length, increasing potential for elastic energy storage. W...
Effect of the in vitro maturation medium on equine oocytes: comparison of follicular fluid and oestrous mare serum. The present study evaluated the effect of supplementing the medium used to mature equine oocytes in vitro with oestrous mare serum (EMS) or horse follicular fluid (HFF). To this end, 144 ovaries were obtained from mares aged 16-21 months and transported to the laboratory in Dulbecco's phosphate buffered saline (D-PBS) at 30 degrees C. Oocytes were harvested from the ovaries by slicing, and then selected for in vitro maturation (IVM) according to the number of cumulus cell layers and the characteristics of the cytoplasm. The selected oocytes were washed three times in TCM199 medium plus HEPES (...
Attenuation of equine influenza viruses through truncations of the NS1 protein. Equine influenza is a common disease of the horse, causing significant morbidity worldwide. Here we describe the establishment of a plasmid-based reverse genetics system for equine influenza virus. Utilizing this system, we generated three mutant viruses encoding carboxy-terminally truncated NS1 proteins. We have previously shown that a recombinant human influenza virus lacking the NS1 gene (delNS1) could only replicate in interferon (IFN)-incompetent systems, suggesting that the NS1 protein is responsible for IFN antagonist activity. Contrary to previous findings with human influenza virus, w...
Meal-induced gastric relaxation and emptying in horses after ingestion of high-fat versus high-carbohydrate diets. To evaluate the effect of ingestion of a high-carbohydrate versus a high-fat meal on relaxation of the proximal portion of the stomach and subsequent gastric emptying in horses. Methods: 6 healthy adult horses. Methods: The study consisted of 2 phases. In phase I, horses were offered a high-fat (8% fat) or a high-carbohydrate (3% fat) pelleted meal (0.5 g/kg) of identical volume, caloric density, and protein content. In phase II, meals consisted of a commercial sweet feed meal (0.5 g/kg) or this meal supplemented with corn oil (12.3% fat) or an isocaloric amount of glucose (2.9% fat). Proximal...
Infestation of Werneckiella equi on Icelandic horses, characteristics of predilection sites and lice dermatitis. Lice infestations on horses caused by the lice Werneckiella (Damalinia) equi and Haematopinus equi are observed worldwide. In this study, the distribution and clinical manifestations of lice on Icelandic horses were examined. Thirty-eight out of 93 animals (40.86%) were identified as infested with W. equi. Sixty-eight animals (73.12%) presented dermatological lesions associated with lice infestation, while only 32 of these animals presented lice. Six animals had no clinical signs although of being lice-positive, and 19 animals (20.43%) showed neither lice nor clinical manifestations. Lice burd...
