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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.
Ultrastructure of schizonts and merozoites of Sarcocystis neurona. The ultrastructure of Sarcocystis neurona schizonts and merozoites was studied in specimens derived from cell culture and from the brains of infected mice. Schizonts and merozoites were located in the host cell cytoplasm without a parasitophorous vacuole at any stage of development. Merozoites divided by endopolygeny. Fully formed merozoites had a pellicle, numerous polysomes and ribosomes, smooth and rough endoplasmic reticulum, 22 subpellicular microtubules, 9-16 dense granules, 25-75 micronemes, a plastid, a Golgi complex, 1-3 mitochondria, a conoid, 2 apical rings, 2 polar rings, 0-6 lipid...
The hindlimb in walking horses: 1. Kinematics and ground reaction forces. The objective was to study associations between kinematics and ground reaction forces in the hindlimb of walking horses. Video (60 Hz) and force (2000 Hz) data were gathered for 8 strides from each of 5 sound horses during the walk. Sagittal plane kinematics were measured concurrently with the vertical and longitudinal ground reaction forces. The hindlimb showed rapid loading and braking in the initial 10% stride. The stifle, tarsal and coffin joints flexed and the fetlock joint extended during this period of rapid loading. The vertical ground reaction force showed 2 peaks separated by a dip; ...
Self-consciousness and animal suffering. Animals with relatively highly developed brains are likely to experience some degree of self-awareness and the ability to think. As well as being interesting in its own right, self-consciousness matters from an ethical point of view, since it can give rise to forms of suffering above and beyond the immediate physical sensations of pain or distress. This article surveys the evidence for animal self-consciousness and its implications for animal welfare.
Dietary fat supplementation effects on in vitro nutrient disappearance and in vivo nutrient intake and total tract digestibility by horses. Addition of fat to the diet of the equine is a popular method of increasing energy density of the diet while reducing feed intake. Reducing feed intake is of interest to race horse trainers because additional feed is seen as additional weight and, therefore, a hindrance to performance. Limited information is available regarding the interactions of fat with other dietary components, particularly fiber, in the equine digestive system. The effect of dietary fat on in vitro nutrient disappearance in equine cecal fluid was studied in Exp. 1 using a split-plot design within a 2 x 2 Latin square. Two...
Celiotomy closure via permanent implantation of polyamide in horses. Permanent implantation of nonabsorbable materials is appropriate in many surgical circumstances but is not commonly used to close equine celiotomies. This paper describes a simple method of continuous nonabsorbable implantation of polyamide suture used successfully to close 48 equine celiotomies. Forty-eight clean or clean-contaminated celiotomies were successfully performed over 5 years using this technique. The postsurgical survival observation period ranged from 1-6 years (median 3.5 years). There were 45 long-term survivors (93.75%). Only 2 minor implant complications (4.4%) were observed ...
West Nile encephalitis. WNV encephalitis in horses, previously reported in Africa, Asia, and Europe, occurred for the first time in the Western Hemisphere in 1999. The causative agent, WNV, is a flavivirus maintained in nature by a bird-mosquito cycle. The disease in horses is manifested primarily by ataxia of variable severity. Outbreaks of encephalitis may have a case fatality rate in excess of 40%, although this virus infection is inapparent in some horses. Early evidence indicates that WNV has overwintered in the northeastern United States and poses a threat for future disease occurrences in horses. No vaccine is...
Comparative studies in the promoter and exon 1 regions of tumour suppressor p53 in several mammalian species: absence of mutations in a panel of spontaneous domestic animal tumours. Tumour suppressor p53 is critical in a broad panel of tumour types in human, mouse and other mammals. Regions of the promoter and exon 1 play an important role in expression of p53. In the present study, the DNA sequences of promoter and exon 1 regions of four domestic animal species (dog, cat, horse and cattle) are determined and compared with experimental rodents (mouse, rat and hamster) and man. A broad panel of tumour types have been investigated for mutations in this regulatory area in 90 canine, 136 feline, 25 equine and 10 bovine patients. No mutation was detected in any of the tumours ...
Aggregation behavior and electrophoretic mobility of red blood cells in various mammalian species. Differences of red blood cell (RBC) aggregation among various mammalian species has been previously reported for whole blood, for RBC in autologous plasma, and for washed RBC re-suspended in polymer solutions. The latter observation implies the role of cellular factors, yet comparative studies of such factors are relatively limited. The present study thus investigated RBC aggregation and RBC electrophoretic mobility (EPM) for guinea pigs, rabbits, rats, humans and horses; RBC were re-suspended in isotonic 500 kDa dextran solutions for the EPM and aggregation measurements, with aggregation stud...
The distribution of intratubular dentine in equine incisors: a scanning electron microscopic study. The distribution of intratubular (peritubular) dentine was studied by scanning electron microscopy in 12 equine incisor teeth. High levels of intratubular dentine were found in the peripheral regions of the dentine. In these areas, a marked asymmetry occurred, as intratubular dentine was predominantly deposited onto the side of the dentinal tubular walls nearest to the dentino-enamel junction. The quantity and asymmetry of intratubular dentine were reduced towards the centre of the tooth. The significance of these variations in the amount and distribution of intratubular dentine between the di...
The hindlimb in walking horses: 2. Net joint moments and joint powers. The objective of the study was to describe net joint moments and joint powers in the equine hindlimb during walking. The subjects were 5 sound horses. Kinematic and force data were collected synchronously and combined with morphometric information to determine net joint moments at each hindlimb joint throughout stance and swing. The results showed that the net joint moment was on the caudal/plantar side of all hindlimb joints at the start of stance when the limb was being actively retracted. It moved to the cranial/dorsal side around 24% stride at the hip and stifle and in terminal stance at t...
Effect of a leukocyte-depleting filter in an extracorporeal circuit used for low-flow ischemia and reperfusion of equine jejunum. To determine effect of leukocyte depletion on hematologic, morphologic, and metabolic variables of equine jejunum after induction of arterial low-flow ischemia and reperfusion by use of an extracorporeal circuit. Methods: 14 healthy adult horses. Methods: A segment of jejunum was surgically removed and maintained in an isolated circuit for 3 hours (control group), arterial flow was reduced to 20% of baseline for 40 minutes followed by 1 hour of reperfusion (low-flow group), or leukocyte depletion was filter-induced, and low-flow ischemia and reperfusion were conducted as in the low-flow contro...
Cytogenetics of donkey chromosomes: nomenclature proposal based on GTG-banded chromosomes and depiction of NORs and telomeric sites. With the expansion of comparative genome analysis across different mammals, there is an increasing need to have well-defined banded karyotypes for the species chosen for investigation. In this context, the steadily growing gene mapping data in the donkey urgently require a framework whereby alignment/comparison of genetic information can be readily made with equids and other mammalian species. Hence a GTG-banded karyotype of the donkey (Equus asinus; EAS) is presented, along with schematic drawings and nomenclature of the banded chromosomes. In addition, the most characteristic features of ind...
Geophagia in horses: a short note on 13 cases. Recorded in several species including humans, geophagia or soil eating has been observed in both wild and domesticated horses and has generally been regarded as an indication of nutritional deficiency or "boredom". Studies of soils consumed by different species have led to several theories as to the identity of soil constituents that stimulate geophagia. In this study, geochemical analysis of 13 equine geophagic sites from different parts of Australia was undertaken. Significantly larger concentrations of iron and copper were found in soil samples from geophagic sites when compared to paired c...
Clenbuterol administration does not enhance the efficacy of furosemide in attenuating the exercise-induced pulmonary capillary hypertension in Thoroughbred horses. The stimulation of pulmonary beta2-adrenergic receptors causes a decrease in vascular resistance. Thus, the present study was carried out to examine whether concomitant administration of clenbuterol-a beta2-adrenergic receptor agonist, to horses premedicated with furosemide would attenuate the exercise-induced pulmonary capillary hypertension to a greater extent than furosemide alone, and in turn, affect the occurrence of exercise-induced pulmonary hemorrhage (EIPH). Experiments were carried out on six healthy, sound, exercise-trained Thoroughbred horses. All horses were studied in the control...
Heart rate and behavioural responses of crib-biting horses to two acute stressors. The heart rate and behaviour of 14 adult saddle horses, eight crib-biters and six normal controls, were investigated. Initially, the relationship between crib-biting and heart rate was investigated while the horses were undisturbed. The horses were tested when restrained with a lip twitch, and assessed when they were exposed suddenly to the rapid inflation of a balloon. The heart rate of the crib-biters during crib-biting was lower than during other behaviours. The crib-biters had a higher overall mean heart rate (P<0.05) suggesting that they may have had a higher basal sympathetic activity...
Absence of selective brain cooling in free-ranging zebras in their natural habitat. We used implanted miniature data loggers to measure brain and arterial blood temperatures in three free-ranging zebras (Equus burchelli) in their natural habitat, every 5 min for 9 days. The animals experienced globe temperatures exceeding 40 C, and radiant heat load of about 1000 W m-2. Arterial blood exhibited a moderate amplitude (1.7 C) nychthemeral rhythm, with an acrophase at 19.00 h and a nadir late in the morning, at 10.00 h. Brain temperature consistently exceeded blood temperature, on average by 0.2-0.4 C, and changes in brain temperature closely tracked changes in blood temperature....
Faecal excretion profile of moxidectin and ivermectin after oral administration in horses. A study was undertaken to evaluate and compare faecal excretion of moxidectin and ivermectin in horses after oral administration of commercially available preparations. Ten clinically healthy adult horses, weighing 390-446 kg body weight (b.w.), were allocated to two experimental groups. Group I was treated with an oral gel formulation of moxidectin at the manufacturer's recommended therapeutic dose of 0.4 mg/kg b.w. Group II was treated with an oral paste formulation of ivermectin at the recommended dose of 0.2 mg/kg b.w. Faecal samples were collected at different times between 1 and 75 days ...
Molecular cloning and sequencing of equine cDNA encoding serum amyloid A (SAA). The serum amyloid A (SAA) protein is a characteristic and sensitive acute phase reactant in all vertebrates investigated. We molecularly cloned the equine cDNA encoding SAA from the liver of a healthy horse by polymerase chain reaction (PCR). The cloned cDNA is 480 bases in length, and contains an open reading frame (ORF) of 387 nucleotides encoding a precursor SAA protein of 128 amino acids. The precursor of horse SAA seems to have an 18-residue signal peptide and differs from the reported amino acid sequences of the horse SAA by substitution of valine at residue 81. It shows high homology wi...
Expression and characterisation of equine interleukin 2 and interleukin 4. In the present study, we describe the expression of equine IL2 and IL4. The cDNA of equine IL2 or IL4 was cloned in a mammalian expression vector, containing c-terminal myc- and six histidines His(6)-epitopes for recognition and purification of equine cytokines. The vector constructs were used for transfection of chinese hamster ovary (CHO) cells. Purified equine cytokines were characterised by western blotting. Equine IL2 was secreted with a molecular weight of approximately 17.1kDa, whereas IL4 was expressed in three different sizes of 17.1, 19.6 and 22.1kDa, probably due to different glycos...
Effect of short-term feed restriction and calorie source on hormonal and metabolic responses in geldings receiving a small meal. The metabolic effects of short-term feed restriction and dietary calorie source were studied in horses receiving high-roughage or high-concentrate diets. Four Thoroughbred geldings were assigned to four treatment groups in a 4 x 4 Latin square experiment. The four treatments were 1) a nutritionally adequate high-roughage ration (70% roughage, 30% concentrate; AHR), 2) a nutritionally adequate high-concentrate ration (40% roughage, 60% concentrate; AHC), 3) 70% of the intake of the AHR diet (RHR), and 4) 70% of the intake of the AHC diet (RHC). Diets AHR and AHC were designed to meet the calori...
Changes in cardiac dimensions and indices of cardiac function during deconditioning in horses. To investigate the effects of deconditioning on cardiac dimensions and indices of cardiac function in horses. Methods: Thirteen 3-to 4-year-old Standardbred geldings. Methods: All horses had echocardiographic measurements performed at the conclusion of 9 months of intense training and at weeks 1.5, 4, 8, and 12 of deconditioning. Direct echocardiographic measurements included interventricular septal thickness, left ventricular internal dimensions, left ventricular freewall thickness, left atrial dimension, aortic diameter, diameter of the pulmonary artery, slopes of the mitral valve, heart rat...
Significance of plasmalemma disruption in bovine and equine spermatozoa. We have investigated fresh and cryopreserved bovine and equine spermatozoa using light and transmission soft X-ray microscopy. Spermatozoa were examined, in the presence or absence of semen, after using Percoll gradient centrifugation and re-suspending in medium. X-ray microscopy provided high resolution (30 nm) transmission images of whole cells in solution with high contrast, while retaining the simple preparation techniques used in light microscopy. We demonstrated translucent, membrane-bound vesicles in the acrosomal and midpiece regions that were similar in size and we noted their inciden...
Computed tomographic imaging of the equine head. The head from three horses euthanized due to diseases unrelated to the head and neck was imaged using computed tomography (CT). Gross cross-sectional slices of equine head #1 and skeleton of equine head #2 were compared with the CT images of the three equine heads to identify normal structures of the cranium, brain, paranasal sinuses, nasal cavity, and teeth. Labeled transverse CT images of the equine head are presented sequentially as a reference for normal anatomy.
Topography of ganglion cells in the retina of the horse. Topography of ganglion cells in the retina of the horse (Thoroughbred) was analyzed in the wholemount retina stained with cresyl violet, and a total number of ganglion cells were estimated. Sizes of ganglion cells were also measured and size spectra were analysed. The main results showed that: (1) a common point in 4 wholemount retinae, based on cell densities and retinal locations, was that a retina could be divided into 5 regions, namely visual streak, nasal, temporal, dorsal and ventral region to the visual streak. A maximum cell density of 4,000 cells/mm2 was found in the visual streak. An...
Cytogenetic localization of 44 new coding sequences in the horse. The purpose of this study was to increase the number of genes assigned by in situ hybridization to equine chromosomes and thus the number of links for comparative mapping with other species. Forty-four new sequences were added to the horse cytogenetic map by FISH mapping of BAC clones containing genes (35) or ESTs (9). Three approaches were developed: use of horse BAC clones screened with (i) horse EST primers, (ii) interspecific consensus intraexonic primers, and (iii) use of goat BAC containing genes previously localized on goat chromosomes. Present data suggest that the second approach is t...
Phenylephrine eyedrops as a diagnostic test in equine grass sickness. The effect of an ocular administration of the alpha-1 adrenergic agonist phenylephrine was studied in 23 cases of grass sickness and 12 control horses. In the horses with grass sickness there was a significantly greater mean increase in the size of the palpebral fissure, as measured by the change in the angle of the eyelashes to the head observed from a frontal view.
Comparative disposition of tripelennamine in horses and camels after intravenous administration. The pharmacokinetics of tripelennamine (T) was compared in horses (n = 6) and camels (n = 5) following intravenous (i.v.) administration of a dose of 0.5 mg/kg body weight. Furthermore, the metabolism and urinary detection time was studied in camels. The data obtained (median and range in brackets) in camels and horses, respectively, were as follows: the terminal elimination half-lives were 2.39 (1.91-6.54) and 2.08 (1.31-5.65) h, total body clearances were 0.97 (0.82-1.42) and 0.84 (0.64-1.17)L/h/kg. The volumes of distribution at steady state were 2.87 (1.59-6.67) and 1.69 (1.18-3.50) L/kg, ...
