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Topic:Experimental Methods
Experimental methods in equine research encompass a variety of techniques and procedures used to investigate physiological, behavioral, and health-related aspects of horses. These methods are designed to collect data that can enhance the understanding of equine biology and inform veterinary practices. Common experimental approaches include controlled trials, observational studies, and laboratory-based experiments. Techniques may involve the use of non-invasive imaging, biochemical assays, and physiological monitoring to assess parameters such as metabolic function, locomotion, and disease progression. This page compiles peer-reviewed research studies and scholarly articles that explore the application, development, and evaluation of experimental methods in the study of equine science.
Measurement of gastric emptying of water in foals by impedance epigastrography. Impedance epigastrography was used to measure gastric emptying rates on two occasions in each of three foals. After smoothing of the raw data, emptying of water appeared to obey an exponential model. The mean emptying rate constant (SEM) was 0.171 +/- 0.038 min-1 (mean emptying half time 4.9 +/- 1.0 min).
Experimental transmission of eastern equine encephalitis virus by strains of Aedes albopictus and A. taeniorhynchus (Diptera: Culicidae). The vector competence of Aedes taeniorhynchus (Wiedemann) and four strains of Aedes albopictus (Skuse) was assessed for eastern equine encephalitis (EEE) virus isolated from Ae. albopictus collected in Polk County, Florida. Both species became infected with and transmitted EEE virus by bite after feeding on 1-d-old chicks that had been inoculated with EEE virus (viremia = 10(10.1) plaque-forming units [PFU] per ml of blood). However, when fed on an older chick with a lower viremia (viremia = 10(6.1) PFU per ml of blood), Ae. albopictus was significantly more susceptible to infection (90%, n = ...
Phenotype and biological activity of neonatal equine chondrocytes cultured in a three-dimensional fibrin matrix. Equine neonatal chondrocytes were cultured in three-dimensional fibrin matrices under conditions of immediate implantation or implantation following monolayer culture for 6 days, and 3 cell concentrations (1 x 10(5), 1 x 10(6), and 5 x 10(6) chondrocytes/cm3). Equine fibrinogen was collected by cryoprecipitation and polymerized by use of activated bovine thrombin. The fibrin implants were harvested and analyzed histologically and biochemically at 3, 7, and 14 days after the chondrocytes were implanted in fibrin. The differentiation ratio (ratio of rounded, chondrocyte-like cells to stellate, f...
[15N-flow after in sacco incubation and feeding of sheep and goats with untreated wheat straw or straw treated with 15N horse urine]. Chopped wheat straw was homogeneously mixed with urine of horses (5.75 gN per 1, 16.88 atom-% 15N-excess) and airtightly stored in plastic containers for 6 months. Three rumen fistulated sheep and goats each were fed with untreated or urine treated straw. Concentrate was added to straw. Untreated and urine treated straw were given in nylon bags and incubated in the rumen of sheep and goats for 1, 3, 6, 12, 24, 48 and 72 hours. A three compartment exponential function was used to fit the measurements of 15N-excess and 15N-amount of bag content. The curves and the calculated partial Y-values of ...
Secretagogue-induced [14C]aminopyrine uptake in isolated equine parietal cells. Equine oxyntic mucosal cells were obtained by sequential exposure to pronase and collagenase. Acid production by parietal cells was assessed by uptake of [14C]aminopyrine (AP), a weak base that accumulates in intracellular acidic spaces. Incubation for various times revealed a maximal AP uptake at 10 minutes for histamine and carbachol. Similar secretagogue responses were observed for parietal cells from the mucosal cell preparation or after enrichment by elutriation. Histamine and isobutyl-methylxanthine (IBMX) stimulated AP uptake with a dose-dependent response and maximal effective concentr...
Molecular cloning of an equine satellite-type DNA sequence and its chromosomal localization. We have molecularly cloned portions of equine satellite-type DNA and investigated the organization of the DNA sequence of the cloned segments. Sequence analysis and dot-blot analysis, using the cloned sequence (ES200) as a probe, indicate that the satellite-type DNA sequence consists mainly of 221-bp tandem repeats and represents 3.7-11% of the equine genome. Southern blot analysis further shows that (1) no sequences homologous to ES200 exist in the human, swine, and bovine genomes and that (2) the fragment pattern of the satellite-type DNA produced by ApaI cleavage shows a slight difference a...
Culture of equine embryos in media containing egg yolk, mare’s milk and saline: Preliminary results. A medium containing egg yolk, mare's milk and/or modified PBS was used to culture Day-8 to 8.5 equine blastocysts. Twenty-one variants of the medium containing different concentrations of the 3 components were prepared. Embryos were recovered nonsurgically and placed into the media at 37 degrees C for 24 h. A total of 45 embryos was cultured; of these 7 died in culture and 13 showed inadequate development at the onset, while 25 continued to grow in the media. It was established that embryos grew best in media containing 20 to 60% yolk, 20 to 60% mare's milk and/or 20 to 60% PBS. It was found e...
Use of gonadotropin-releasing hormone, estrogen, or a combination to increase releasable pituitary luteinizing hormone in early transitional mares. A lack of pituitary LH stores has been implicated as the cause of seasonal anestrus and failure to ovulate during the spring transition period in mares. In this experiment, 40 mares were used to study the effects of GnRH, estrogen, and an estrogen-GnRH combination on increasing releasable pituitary LH. Mares were stratified based on their ability to secrete LH in response to a 950-micrograms challenge of GnRH (n = 10 per group) and then assigned to one of four treatment groups: 1) controls, given no treatment; 2) 1 mg of estradiol-17 beta in oil i.m. daily for 8 d; 3) 200 micrograms of GnRH an...
The effect of added dietary soybean oil on vitamin E status of the horse. Fourteen 2-yr-old Quarter Horses and Quarter Horse x Thoroughbreds were randomly assigned to either a control (CTRL) diet or a diet supplemented with 6.4% soybean oil (SBO). The amounts of both diets that were fed met current NRC nutrient requirements and were isoenergetic with similar nutrient:energy ratios. Venous blood samples (20 mL) were taken at d 0, 30, 60, and 90 of the experiment and analyzed for serum alpha-tocopherol, serum cholesterol, and serum triglyceride. The sum of serum cholesterol and serum triglyceride values was used as an estimate of serum total lipid. The ratio of serum ...
Effects of exercise and polysulfated glycosaminoglycan on repair of articular cartilage defects in the equine carpus. Our aim was to determine if mild to moderate postoperative exercise and intra-articular polysulfated glycosaminoglycan result in improved repair of large, experimentally induced osteochondral defects in a weight-bearing surface of equine joints. Arthroscopic debridement was used to produce full-thickness defects in a weight-bearing area of the radial carpal bones in 18 ponies. The ponies were randomly assigned to two groups balanced for age: nine animals in the exercise and nine in the no exercise group. Six ponies in each group were medicated weekly for 5 weeks with an intra-articular injecti...
Pulsed magnetic fields improve osteoblast activity during the repair of an experimental osseous defect. The influence of pulsed low-frequency electromagnetic fields (PEMFs) on bone formation was investigated in studies of the healing process of transcortical holes, bored at the diaphyseal region of metacarpal bones of six adult horses, exposed for 30 days to PEMFs (28 G peak amplitude, 1.3 ms rise time, and 75 Hz repetition rate). A pair of Helmholtz coils, continuously powered by a pulse generator, was applied for 30 days to the left metacarpal bone, through which two holes, of equal diameter and depth, had been bored at the diaphyseal region. Two equal holes, bored at the same level in the rig...
[The immunogenic properties of a recombinant vaccinia virus with an incorporated DNA copy of the 26S RNA of the Venezuelan equine encephalomyelitis virus]. A recombinant strain of vaccinia virus (VR26) containing a DNA-copy of the subgenomic 26S RNA of Venezuelan equine encephalomyelitis virus (VEE) inserted into the coding region of thymidine kinase (TK) gene was produced. This subgenomic RNA contained the genes for all structural proteins of the VEE virus, the strain Trinidad donkey (TRD). VR26 effectively expressed VEE virus glycoproteins on the membranes of the infected cells. Blood sera of VR26-immunized animals were found to contain VEE virus-specific antibodies. VR26-immunized mice and rabbits showed a high level of resistance to subcutane...
Nucleation of the iron core occurs at the three-fold channels of horse spleen apoferritin: an EXAFS study on the native and chemically-modified protein. Extended X-ray absorbance fine structure measurements have been carried out on the initial Fe(III)-apoferritin complex at a Fe/subunit ratio of 2 in native and modified horse spleen apoferritin. Analysis of the data indicates that in the native protein the iron forms a protein-bound polynuclear cluster (Fe-Fe distance 3.4 A) with a first coordination sphere constituted by 5-6 low-Z atoms, e.g., nitrogen atoms, carboxylate-like ligands or oxo bridges between the iron atoms. Modification of Cys-126, a residue localized on the outer surface of the hydrophilic three-fold channels, with p-chloromer...
Oxidation of methionine residues in equine growth hormone by Chloramine-T. 1. Reactivity of methionine residues towards Chloramine-T was studied in the equine growth hormone. 2. With a 20.0-fold molar excess of reagent over methionine, full oxidation of the four residues of the protein is achieved. 3. Methionine 4 is the most reactive group, followed by methionines 72 and 178--methionine 123 being the less reactive residue. 4. As judged by circular dichroism spectra and binding assays, protein conformation and binding capacity to specific receptors remains unchanged even after full oxidation of all four methionine residues. 5. Results agree with data previously obtai...
Uterine transport of prostaglandin E(2)-releasing simulated embryonic vesicles in mares. Transrectal ultrasonography was used to test the hypothesis that prostaglandin E(2) (PGE(2)) would increase the uterine transport of simulated embryonic vesicles in mares. Uterine transport of PGE(2)-releasing (PGE) vesicles, vehicle-releasing (sham) vesicles, and equine embryos was contrasted on Day 12 or Day 13 post ovulation. In Experiment 1, there was no difference (P>0.10) in transport of PGE vesicles, sham vesicles, Day-12 embryos, and Day-12 embryos after cervical manipulation (n = 3 per group). In Experiments 2 and 3, respectively, transport of PGE and sham vesicles was contrasted with...
Effect of ranitidine on healing of experimentally induced gastric ulcers in ponies. Thirty young ponies were examined endoscopically for evidence of gastric ulceration. Seven ponies had noninduced gastric ulcers present at the initial examination and were eliminated from the study. In an attempt to induce gastric ulcers experimentally, flunixin meglumine (1.1 mg/kg of body weight, IM, q 8 h) was administered for 7 days to the 23 ponies with endoscopically normal gastric mucosa. During the 7 days of flunixin administration, 11 ponies developed gastric ulcers that were appropriate for study. The 11 ponies were randomly allotted to 2 groups. Group-A (n = 5) and group-B (n = 6) p...
Effect of polysulfated glycosaminoglycan on osteoarthritic equine articular cartilage in explant culture. Middle carpal cartilage explants from 4 horses with mild osteoarthritis involving that joint were maintained in tissue culture to test the effects of a polysulfated glycosaminoglycan (PSGAG) on proteoglycan synthesis and degradation. Cultures were exposed to 0.025 or 25 mg of PSGAG/ml for 48 hours, after which the medium was replaced with medium containing similar doses of PSGAG and 35S. Subsequently, the sulfated proteoglycan content of the medium and extracts of the explants was measured. Gel filtration chromatography was used to estimate the size and to purify the principal, large proteogly...
Relationship between onset of puberty and establishment of persistent infection with equine arteritis virus in the experimentally infected colt. The relationship between stage of reproductive tract maturity and susceptibility to the experimental establishment of persistent infection with equine arteritis virus (EAV) was investigated in 21 prepubertal and 15 peripubertal colts. Five of six prepubertal colts inoculated intranasally remained infected in the reproductive tract from post-challenge day 28 to 93 and two of six from post-challenge day 120 to 180. No virus was detected in five of these animals killed on post-challenge day 210. Each of two peripubertal colts remained infected in the reproductive tract at post-challenge day 60 an...
Structural relaxation and nonexponential kinetics of CO-binding to horse myoglobin. Multiple flash photolysis experiments. The geminate recombination kinetics of CO-myoglobin strongly deviates from single exponential behavior in contrast to what is expected for unimolecular reactions (1). At low temperatures, this result was attributed to slowly exchanging conformational states which differ substantially in barrier height for ligand binding. Above 160 K the kinetics apparently slow down with temperature increase. Agmon and Hopfield (2) explain this result in terms of structural relaxation perpendicular to the reaction coordinate, which enhances the activation energy. In their model, structural relaxation homogeniz...
Generalization of a tactile stimulus in horses. Using horses, we investigated the control of operant behavior by a tactile stimulus (the training stimulus) and the generalization of behavior to six other similar test stimuli. In a stall, the experimenters mounted a response panel in the doorway. Located on this panel were a response lever and a grain dispenser. The experimenters secured a tactile-stimulus belt to the horse's back. The stimulus belt was constructed by mounting seven solenoids along a piece of burlap in a manner that allowed each to provide the delivery of a tactile stimulus, a repetitive light tapping, at different locations...
Responses of ponies to equid herpesvirus-1 ISCOM vaccination and challenge with virus of the homologous strain. An experimental (ISCOM) vaccine previously shown to protect hamsters from lethal challenge with equid herpesvirus-1 (EHV-1), was tested in horses. Vaccination with EHV-1 ISCOMs induced serum antibodies to the major virus glycoproteins gp10, 13, 14, 17, 18 and 21/22a, whereas antibody responses to gp2 were weak or absent. High levels of virus neutralising antibody of long duration were induced, but did not prevent challenge infection with virus of the homologous strain. However, in the vaccinated ponies there was a significant reduction in clinical signs, nasal virus excretion and cell associat...
Effect of oestradiol on oxytocin-stimulated prostaglandin F2 alpha release in mares. The objective of this study was to clarify the role of oestradiol in luteal function by examining its effect on the oxytocin stimulation of 15-keto-13,14-dihydro-prostaglandin F2 alpha (PGFM) concentrations in cyclic mares. In the first experiment, three groups of mares (4 per group) were given a bolus injection of 17 alpha-oestradiol (1 mg), oestradiol (1 mg) or vehicle on days 7, 9, 11, 13 and 15 of the cycle. Six hours later the mares were challenged with 10 iu oxytocin intravenously and frequent blood samples were taken from 15 min before to 15 min after for measurement of PGFM. Results sh...
Administration of a receptor antagonist for platelet-activating factor during equine endotoxaemia. Platelet-activating factor (PAF) is an important mediator of endotoxaemia and various PAF receptor antagonists prevent many of the adverse effects of experimental endotoxaemia in laboratory animals. In this study a specific PAF receptor antagonist was used to investigate the role of PAF in equine endotoxaemia. At an interval of not greater than 10 days, 6 horses were each challenged with endotoxin and endotoxin with concurrent administration of SRI 63-441, a PAF receptor antagonist. The order of the treatments was randomised. Clinical signs, serum biochemical and coagulation profiles, and plat...
Immunoprecipitation of viral polypeptides of equid herpesvirus 1 and 4 by serum from experimentally infected ponies. Sera from two sibling groups of ponies experimentally infected with Equid herpesvirus 1 or 4 (EHV-1 or 4) were used to investigate which viral polypeptides (VPs) of EHV-1 and EHV-4 were recognised. Recognition was detected as early as 8 d.p.i. and thereafter. The polypeptides of EHV-1 (labelled with 35S-methionine) immunoprecipitated (IIP) by sera from both groups had Mr of 148, 138, 123, 117, 110, 77-79, 70, 55, 49-50, 47, 40 and 35-37 kDa respectively. Of these VP148K (VP9 nucleocapsid) gave the maximum precipitation, followed by 117 and 77-79 kDa. The latter were confirmed by monoclonal ant...
The effects of different types of syringes on equine spermatozoa. Control extender was incubated at 4 degrees C for 24 hours. Rubber or plastic syringe plungers were separately incubated in semen extender for 24 hours at 4 degrees C. Following incubation, the extender was stored at -20 degrees C until the time of semen collection. The treatments consisted of the following: Group A = equine semen plus control extender; Group B=equine semen plus extender incubated with rubber plungers and Group C=equine semen plus extender incubated in plastic plungers; Group D=equine semen plus control extended in rubber plunger syringes and Group E=equine semen plus control ...
Effects of intraarticular corticosteroid and sodium hyaluronate injections on synovial fluid production and synovial fluid content of sodium hyaluronate and proteoglycans in normal equine joints. Hyaluronate and cartilage proteoglycan fragments in synovial fluid from normal equine joints were determined after repeated intraarticular injections of beta-methasone, methylprednisolone, hyaluronate, saline and a combination of beta-methasone + hyaluronate and methylprednisolone + hyaluronate. The experimental intraarticular treatments were given at the beginning of the study and after one and two weeks. Synovial samples were obtained at the onset of the study and after 1, 2, 3, 4, 6, and 8 weeks. The synovial volume was determined and showed no significant changes after the repeated arthroc...
Technique for long-term right dorsal colon fistulization in ponies. Right dorsal colon fistulas, 2.5 cm in diameter, were created in 2 healthy ponies, using a 2-stage surgical procedure. The first stage consisted of resection of portions of the 16th and 17th ribs on the right side, followed by surgical creation of a 6- to 8-cm-diameter adhesion between the right dorsal colon and the body wall. Fistulas were created approximately 2 weeks after the first surgery by sharp dissection through the adhesion into the lumen of the colon. The fistulas have been satisfactorily maintained for > 2 years by de Pezzer catheters (45 F). Ponies with fistulas have been used ...
Detection of humoral antigen and antibody by enzyme-linked immunosorbent assay in horses with experimentally induced Ehrlichia equi infection. An enzyme-linked immunosorbent assay (ELISA) was used to detect antigen in plasma and antibody in serum of 3 horses inoculated with Ehrlichia equi. Clinical signs, including rectal temperature, were correlated with the antigen and antibody detection. ELISA was very efficient in detection of serum antibody. Antigen detection using monoclonal antibodies to E. equi and ELISA should be considered as a diagnostic method.
Diurnal variation in plasma ir-beta-endorphin levels and experimental pain thresholds in the horse. Diurnal variation in nociceptive sensitivity and plasma immunoreactive beta-endorphin (ir-BEND) concentrations was examined in eight healthy Thoroughbred horses. Pain thresholds, ir-BEND concentrations, rectal temperature, heart rate, respiratory rate and pupil diameter were measured over a 24 hour period. Nociceptive sensitivity was determined using two objective measures of pain: the skin-twitch reflex latency and the hoof withdrawal reflex latency. Significant variation in both nociceptive thresholds and ir-BEND concentrations were noted over the 24 hour period, with elevated pain threshold...
