Topic:Animal Models
Animal models in equine research refer to the use of horses or other species to study biological and disease processes relevant to equine health. These models facilitate the investigation of various physiological and pathological conditions, allowing researchers to explore disease mechanisms, test therapeutic interventions, and understand genetic influences on health outcomes. Horses themselves are often studied as models for human diseases due to certain physiological similarities. Additionally, other species may be used to model equine-specific conditions when direct study in horses is impractical. This page compiles peer-reviewed research studies and scholarly articles that explore the application, development, and findings of animal models in equine research.
Irregular transmissions in the acidic prealbumin (Pr) system of the horse. During the routine parentage control of Norwegian Trotter horses with 10 000 parent offspring combinations two irregular transmissions of Pr alleles were found. The allele products were provisionally named D1 and D2. They appeared in two stallions which were typed as D1I and D2N respectively. The first stallion transmitted PrD1 to seven out of 10 offspring and the second stallion PrD2 to two of four offspring. Photographs of seven new Pr phenotypes are presented.
Ventricular defibrillation with myocardial electrodes in the dog, calf, pony, and pig. The defibrillation effectiveness of 4-msec rectangular wave shocks was evaluated using myocardial electrodes with 25-kg dogs and (nominally) 100-kg calves, ponies, and pigs as part of an evaluation of the suitability of these animals as models for automatic implanted defibrillator research. The percent success of defibrillation attempts in dogs ranged from 44% with 4-A, 6-J shocks to 93% with 8-A, 16-J shocks. The success achieved in calves with scaled electrodes was uniformly lower and reached a maximum of 28% with 23-A, 107-J shocks. Pigs defibrillated with scaled electrodes at a success lev...
Effects of influenza, mumps, and western equine encephalitis viruses on fetal rhesus monkeys (Macaca mulatta). Pregnant Rhesus monkeys were infected via instillation of influenza, mumps and western equine encephalomyelitis viruses respectively into the amniotic sacs at approximately 90 days gestation to determine if fetal infections would occur. Virus was recovered from fetal tissues after seven days in 100% of the exposed animals. Thus, the viruses are capable of causing fetal infection. Rhesus monkey fetuses were inoculated with influenza, mumps and WEE viruses by the direct intracerebral route at approximately 90 days gestation to determine possible teratogenicity of the viruses. influenza virus cau...
A serological survey of Leptospira interrogans serotype pomona in Saskatchewan horses. Leptospira interrogans serotype pomona antibody titres of 1:100 or greater were detected in 12.8% of 408 adult horses from seven of eight sampled herds in Saskatchewan. The geographical distribution of the seropositive horses was widespread throughout the agricultural area of the province. The geographical distribution and the cumulative increase in prevalence with age suggested that serotype pomona is enzootic in the equine population of Saskatchewan.
Variability in erythrocyte deformability among various mammals. Deformability is an important aspect of erythrocyte physiology and has been extensively studied using human red cells. We have studied erythrocytes from 25 different animals using a viscometric technique. Erythrocyte diameters ranged from 3.3 microns in the goat to 11.4 microns for the elephant seal. Erythrocytes from most species deformed readily when a fluid shear stress was applied. A deformability index of the stressed cell defined as (length - width)/(length + width) correlated with cell size. The erythrocytes of four animals (pygmy goat, goat, Batanga horse, and miniature horse) deformed...
Lymphocyte specificity to protein antigens. II. Fine specificity of T-cell activation with cytochrome c and derived peptides as antigenic probes. Murine T-lymphocyte specificity was determined in a system of antigen driven in vitro T-cell proliferation using cytochrome c molecules from different species, their derived peptides and reconstituted hybrid proteins. It was observed that primed T cells could discriminate between peptide fragments which differed from each other at a single amino acid residue. These conclusions were substantiated by the pattern of cross-reactivity noted in the response of closely related cytochrome c proteins as well as when artificial hybrid molecules reconstituted by the covalent linkage of peptide fragments ...
The pony as a model for septic shock. This study was conducted to determine the feasibility of using alert, conscious ponies as a model for septic shock in man. Ten ponies were given 0.7-5 X 10(9) organisms/kg of body weight of live E coli intravenously over one hour. All ponies died and exhibited signs of low cardiac output septic shock. significant decreases were found in cardiac index to 3.15 +/- 0.1 liters/min/m2 (P less than 0.05), white blood cell count to 1,930 +/- 100 cells/m3 (P less than 0.05), preterminal blood glucose to 75 +/- 5 mg/dl (P less than 0.05), PaO2 to 75.7 +/- 5.7 mm Hg (P less than 0.05), and pH to 7.15 +/...
Congenital stationary night blindness: an animal model. Electroretinographic studies of myctalopic Appaloosa horses demonstrated photopic and scotopic abnormalities similar to those in humans with congenital stationary night blindness (CSNB) of the Schubert-Bornschein type. The phototopic abnormalities consisted of reduced b-wave amplitudes and slower than normal b-wave implict time. The dark-adapted ERG's consisted of a simple negative potential; the scotopic b-wave was nonrecordable. However, a normal c-wave was present in the dark-adapted response. Histologic studies demonstrated no structural abnormalities that could explain the functional defe...
Studies on cross protection induced in calves by rotaviruses of calves, children and foals. Inoculation at birth with a live attenuated strain of a bovine rotavirus isolated in the USA (scourvax-reo) induced protection in five gnotobiotic calves seven to 21 days later against a UK isolate of pathogenic bovine rotavirus. However, no protection was induced in three calves challenged three to five days after vaccination. There was a close antigenic relationship demonstrated between the two bovine rotavirus isolates. In contrast only one of three gnotobiotic calves inoculated with foal rotavirus, and one of three with human rotavirus, were protected against bovine rotavirus challenge. Pr...
Quantitative study of the decussating optic axons in the pony, cow, sheep, and pig. A quantitative study of optic axons in the optic tracts of several species was performed to determine the number and percentage of optic axons that decussate. Animals were prepared by unilateral ocular enucleation, and light microscopic techniques were employed to count the fibers. The mean number of fibers projecting from a single eye was 732,119 for the pony, 1,041,739 for the cow, 534,755 for the sheep, and 442,629 for the pig. The mean degree of crossover at the chiasm was 80.8% in ponies, 82.9% in cattle, 88.9% in sheep, and 87.8% in pigs.
Pathologic changes and pathogenesis of Parascaris equorum infection in parasite-free pony foals. Parasite-free pony foals (n = 10) were infected orally with 1000,000 Parascaris equorum embryonated eggs. One pony foal each was euthanatized on days 1, 3, 5, 7, 11, 16, 23, 27, 42, or 80 after infection. Foals infected for more than 7 days showed signs of coughing, anorexia, rough coat, and weight loss. Cellular changes in the blood were mild anemia, marked eosinophilia, and leukopenia. Gross postmortem lesions included hemorrhage, edema, and white-to-yellow necrotic foci (0.5 to 1.00 mm) in lungs, liver, and bronchial and hepatic lymph nodes. Microscopically, the liver was hemorrhagic and ha...
Inheritance of yellow dun and blue dun in the Icelandic toelter horse. The coat colors of 161 progeny from matings between 10 yellow dun and 6 blue dun stallions and mares of 8 different colors are described. The results confirm the previous hypothesis that a dominant dilution gene, D, converts bay to yellow dun with dark mane and tail, chestnut to yellow dun and dun mane and tail, and black to blue dun (mouse, grullo). The palomino gene, c cr, on the other hand, is hypostatic to black and blue dun. In heterozygous form, c cr converts bay to buckskin, and chestnut and sorrel to palomino, and results in blue-eyed white when homozygous. No particular effect of D is...
Selection of a strain of Culex tarsalis highly resistant to infection following ingestion of western equine encephalomyelitis virus. After prolonged selection, two hybrid strains of Culex tarsalis were evolved that were highly resistant to infection following ingestion of western equine encephalomyelitis virus. These strains were greater than 25,000-fold more resistant than the most susceptible parental strain when fed on viremic chicks. Resistance was associated with a mesenteronal barrier since both refractory and parental strains were equally susceptible to infection by intrathoracic inoculation. Susceptibility was dominant, possibly incompletely dominant, over resistance. Inheritance was probably polyfactorial but this ...
Enzootic and epizootic Venezuelan equine encephalomyelitis virus in horses infected by peripheral and intrathecal routes. Forty-five horses were infected peripherally or intrathecally with enzootic or epizootic strains of Venezuelan equine encephalomyelitis (VEE) virus. Low titers of virus appeared in cerebrospinal fluid (CSF) after peripheral inoculation of enzootic or epizootic VEE virus strains. Intrathecal infection with either epizootic or enzootic VEE virus produced higher titers of virus in CSF than did peripheral infection. In contrast to peripheral infections with enzootic strains, intrathecal infections with these strains caused death. The animals that died had widespread histopathologic changes and lar...
The mini-pig as a model for penetration of penicillins. To be active, antimicrobials must reach the bacteria in the infectious foci in adequate concentrations. Direct measurements of levels in the various foci are difficult to perform, but a number of animal models with artificial extravascular foci have been developed. In many ways, the physiology of pigs resemble that of humans. Consequently, it was thought that pigs might also parallel humans in the handling of penicillins. General pharmacokinetics of ampicillin and flucloxacillin and the penetration of the substances to subcutaneously implanted teflon tistisue chambers were investigated. Ampici...
Somatostatin-containing cells in the rat and horse pancreatic islets. Somatostatin-, glucagon- and insulin-containing cells in the rat and horse pancreatic islets were investigated by an indirect immunofluorescent technique using antibodies to insulin, glucagon and somatostatin. In the rat pancreatic islets, insulin-containing cells were located centrally, and glucagon and somatostatin or somatostatin-like substance (SLS)-containing cells were peripherally disposed and glucagon-containing cells were situated more peripherally as compared with distribution of somatostatin-containing cells. On the other hand, in the horse pancreatic islets, insulin-containing cell...
National individual identification of horses. Methods of equine identification including signalment, blood typing tattooing and freeze marking are discussed. A new system of individually identifying horses with an unalterable freeze mark is proposed. Unalterable numerical and alphabetical symbols have been developed to apply a registration number to the animal.
Phenylbutazone and the horse–a review. The clinical uses and side-effects of phenylbutazone in man, horses, and other animals are reviewed. The blood dyscrasias commonly described in man have not been reported in the horse, although several of the more minor side-effects have occasionally been seen (e.g. water retention, depression, transient staggering and phlebitis). Despite the lack of documented evidence, the toxicity of phenylbutazone in the horse is considered to be lower than that in man. This may be associated with the lower dose rates normally used, the more rapid plasma clearance rate and the comparatively younger age of ...
A comparative study of the mechanical properties in aging alveolar wall. Alveolar wall from the lung of aging humans shows a progressive decrease in maximal extensibility, which should follow an increase in resting tissue length rather than a reduction in maximal length. An increase in resting tissue length is compatible with the change in lung volumes and reduction in elastic recoil that occurs with time. A model of the lung was used to compare the effects of a change in resting tissue length in diminishing elastic recoil with that of a reduction in the volume density of the elastic elements (emphysema). Such differentiation is important in selecting an animal tha...
Physical optics of the equine eye. The equine eye was treated as a general lens system and calculations were done to determine image position in relation to the retina for objects at a distance of infinity, 100 m, and 1 m. The retina is 19.1 mm behind the posterior surface of the lens; therefore, the image appears 14.6 mm posterior to the retina at infinity and at 100 m, and 16.3 mm at 1-m distance on a horizontal axis. The animals studied were hyperopic. It is evident that the horse must move its head or eye, or both, for optimal visual acuity. At the same time, some objects in the total field of vision are imperceptible or in...
The activity of purine salvage pathway enzymes in murine and horse models of congenital and acquired dysimmunity. Previous studies of human congenital immunodeficiency states and in vitro observations of lymphocyte response to mitogens have implicated two purine salvage pathway enzymes, andenosine deaminase (ADA) and nucleoside phosphorylase (NP), as critical in the normal maturation and/or function of the immune system. Based on this information, ADA and NP activities were examined in a variety of congenital and acquired animal models of dysimmunity. The animals studied herein included: congenitally athymic (nude) mice; congenitally asplenic mice; congenitally athymic-asplenic mice; motheaten mice; New Z...