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Topic:In Vivo
In vivo studies involving horses refer to research conducted within living organisms to understand various biological processes, disease mechanisms, and therapeutic interventions in equine species. These studies provide insights into the physiological and pathological responses of horses under natural conditions. In vivo research encompasses a range of investigations, including pharmacokinetics, disease modeling, and the evaluation of treatment efficacy. It often involves the use of controlled environments to simulate real-life scenarios while observing the effects of specific variables on equine health. This page gathers peer-reviewed research articles and scholarly studies that explore the methodologies, findings, and implications of in vivo research in horses, contributing to the advancement of equine science and veterinary medicine.
Plasma and liver copper values in horses with equine degenerative myeloencephalopathy. Equine degenerative myeloencephalopathy (EDM) is a common spinal cord disease in the horse. The etiology of EDM currently is unknown. In other species, there are similarities in the clinical signs and neuropathological changes observed in EDM and in copper deficiency. The objective of this study was to determine if horses affected with EDM had low levels of plasma or liver copper. Plasma copper values were determined in 25 EDM affected horses and 35 normal horses. Liver copper levels were determined on 13 EDM affected horses and 22 normal horses. Plasma and liver copper values were not signifi...
Effect of active immunization against estrogen on gonadotropin response to testosterone propionate treatment in ovariectomized pony mares. An experiment was conducted to determine whether partial neutralization of estrogens via active immunization alters testosterone propionate (TP)-induced increases in FSH secretion after GnRH administration in ovariectomized pony mares. Twenty mares were used in a 2 X 2 factorial arrangement of treatments (n = 5/group). Factor 1 was long-term active immunization against either bovine serum albumin (BSA) or estrone-17-oxime-BSA. Factor 2 was 11-d administration of either vehicle (vegetable oil) or TP (175 micrograms/kg BW). Plasma concentrations of FSH were not affected (P greater than .1) by ei...
T and B lymphocytes in horses persistently infected with equine infectious anaemia virus. The percentage of T and B lymphocytes in the peripheral blood of horses chronically infected with equine infectious anaemia (EIA) virus was determined and the results were compared with the percentage of these cells in healthy uninfected horses. Cells with membrane receptors for sheep erythrocytes (T and active T lymphocytes) were determined by E and A rosette techniques, while cells with receptors for the C3b component of complement and those with receptors for mouse erythrocytes (B lymphocytes), were determined by the EAC rosette method. The percentage of Fe positive cells was assayed by the...
Effects of distention and neostigmine on jejunal vascular resistance, oxygen uptake, and intraluminal pressure changes in ponies. The influence of distention (high baseline intraluminal pressure) and neostigmine methylsulfate on intestinal vascular resistance, oxygen uptake, and intraluminal pressure changes (rhythmic contractions) was studied in terminal jejunal segments, which were perfused at a constant rate, in 16 anesthetized ponies. When baseline intraluminal pressure was increased to 10 mm of Hg, the intestinal vascular resistance and amplitude of rhythmic contractions were increased. Neostigmine induced cyclic increases in amplitude of rhythmic contractions whether intraluminal pressure was 0 or 10 mm of Hg. Neos...
Purification of F(ab’)2 anti-snake venom by caprylic acid: a fast method for obtaining IgG fragments with high neutralization activity, purity and yield. Pooled horse plasma containing antibodies against Crotalus durissus terrificus whole venom were digested with pepsin at an enzyme-substrate ratio of 8:1, pH 3.1, for 40 min and the F(ab')2M fragments purified by adding 8.7% caprylic acid (pH 5.0). For comparison, F(ab')2B purified by precipitation with ammonium sulphate and uncleaved IgG purified with caprylic acid were also prepared. Fab' fragments were obtained by reduction and alkylation of F(ab')2B. The anti-whole C.d. terrificus venom titers, determined by Dot-Blot were 12,800 (IgG), 6400 [F(ab')2B], 4800 [F(ab')2M] and 3200 (Fab'B). Immu...
Contraception in mares heteroimmunized with pig zonae pellucidae. Ten fertile feral mares and 6 domestic horses (4 fertile mares, 1 infertile mare, 1 gelding) were immunized with heat-solubilized pig zonae pellucidae by 4 injections equivalent to 2000 or 5000 zonae each at 2-4-week intervals and a booster injection of 20,000 zonae 6-10 months after the last of the initial inoculations. The immune response was reflected by high antibody levels as measured by an enzyme-linked immunosorbent assay (ELISA) using immobilized pig zona antigen. In-vivo inhibition of fertility occurred in 12 (86%) of the 14 fertile mares studied and persisted for a minimum of 7 month...
Evaluation of two techniques for large intestinal resection and anastomosis in the horse. Six normal adult horses had large colon resections at the sternal and diaphragmatic flexures. Stainless steel staples were used to close the stumps of the dorsal and ventral colons in all six. Intestinal continuity was restored with a side-to-side anastomosis of the dorsal and ventral colons. Three of these anastomoses were performed with staples, and three with a double inverting suture pattern. After one month, the horses were surgically reevaluated, and the anastomotic sites were examined. There was no significant difference between the stoma sizes in the two groups. No complications were o...
[The early chemotactic reaction of the equine uterus to acute inflammatory stimulation]. The uteri of normal pony mares in oestrus were infected experimentally with Streptococcus zooepidemicus. Uterine contents were collected 30, 60, 120 or 240 minutes later and were tested for their chemotactic effect on equine-neutrophils both with a morphological assay based on neutrophil shape changes and with a modified Boyden chamber technique. By 30 minutes after infection the uterine contents were markedly chemotactic for isolated peripheral neutrophils and remained so at the 240-minute collection. Uterine contents from uninfected mares had minimal chemotactic properties. These results cou...
Comparative effects of cholera toxin, Salmonella typhimurium culture lysate, and viable Salmonella typhimurium in isolated colon segments in ponies. Isolated segments of left dorsal colon and a side-to-side colocolostomy (between the left ventral colon and left dorsal colon) were surgically created in 6 adult ponies. Four segments, each separated by an empty segment, were inoculated (20 ml) with 1 of the following 4 solutions: phosphate buffered saline solution (PBSS)/1% polyethylene glycol (PEG); purified cholera toxin in PBSS/1% PEG (5 micrograms cholera toxin/ml of PBSS/1% PEG); lyophilized Salmonella typhimurium UCD 1755 culture lysate, reconstituted in PBSS/1% PEG; and viable S typhimurium UCD 1755 (10(8) organisms/ml of PBSS/1% PEG)....
Kinetic and inhibitory characteristics of serum angiotensin-converting enzyme from nine mammalian species. 1. Serum angiotensin-converting enzyme activities were obtained from nine mammalian species: rat, mouse, horse, sheep, guinea pig, hamster, rabbit, dog and man. 2. Kinetic constants (Km and Vmax) using hippuryl-L-histidyl-L-leucine as substrate and inhibitory constants (I50 and Ki) for captopril were determined for the serum ACE of each species. 3. There were important differences in the kinetic and inhibitory constants (Kms went from 6.6 mM to 1.21 mM for hamster and guinea pig; I50 ranged from 2100 nM to 3 nM for mouse and sheep) as well as differences in enzyme activity of the different spe...
An hypothesis on the etio-pathogenesis of equine inflammatory joint disease. The role of oxygen-derived free radicals is considered critical to the etio-pathogenesis of equine inflammatory joint disease. In vivo, the superoxide radical in the joint may be derived either from activated polymorphonuclear leukocytes or from an ischemia/reperfusion cycle. In the presence of ferrous iron, it may generate the highly reactive hydroxyl radical (OH *). Predisposing factors may include synovitis, exercise-induced ischemia and minor traumatic injury to the joints. Unlike other inflammatory mediators, oxygen-derived free radicals may damage tissue directly and these reactive speci...
[Experimental equine fascioliasis: evolution of serologic, enzymatic and parasitic parameters]. Three, four, and one horses were respectively infected with 100, 1,000, and 5,000 metacercariae of Fasciola hepatica. Six of them were reinfected 38 weeks later with 1,000 metacercariae each. Specific antibodies assayed by counter-electrophoresis, passive hemagglutination and ELISA tests appeared three to six weeks post-infection and peaked 10 to 17 weeks post-infection. Horses infected by 1,000 metacercariae and more showed 17.6% of positive samples by counter-electrophoresis, 49.2% by ELISA, and 75.6% by passive hemagglutination. Plasma glutamate dehydrogenase and gamma-glutamyltransferase l...
Occlusion of the external carotid and maxillary arteries in the horse to prevent hemorrhage from guttural pouch mycosis. Balloon-tipped catheters were used to occlude the external carotid artery and its branches in nine horses with hemorrhage caused by guttural pouch mycosis. The internal carotid artery on the affected side was occluded simultaneously in four horses and had been occluded previously in two others. In three horses, a single balloon-tipped catheter was inserted in the external carotid artery beneath the floor of the guttural pouch and its tip was advanced blindly into distal branches. In one horse, the superficial temporal artery was occluded briefly during surgery by a balloon-tipped catheter so a...
Lipopigments in veterinary pathology: pathogenesis and terminology. The lipopigments are a heterogenous group of pigments whose pathogenesis and terminology is confused. Whereas there is epidemiological and observational evidence that ceroid is derived from degeneration and peroxidation of unsaturated lipid, the assumption that all so-called lipopigments are similarly formed, is questioned. In particular, recent studies have distanced the pathogenesis of the pigment found in the ceroid-lipofuscinoses from that perceived for ceroid. The importance of protein rather than lipid in the pathogenesis of the pigment of ceroid-lipofuscinosis and of age pigment from th...
Urogenital paraneurons in several mammals. Amines and/or peptide-producing cells, deserving to be called paraneurons, were demonstrated in the urethro-prostatic complex of the man, rabbit, buffalo and sheep and in the uterine horns of the pig, horse and mouse, by means of histochemical, immunohistochemical, immunofluorescent and double labeling immunofluorescent techniques. In particular, the urethro-prostatic complex of the sheep contains cells producing serotonin, chromogranin A and somatostatin. Often the amine and the "marker"-protein were colocalized in the same cells. Chromogranin A- and somatostatin-containing cells were found i...
[Histochemical changes in skeletal muscles of racehorses susceptible to rhabdomyolysis after exertion. II. Later myopathological and regeneration phenomena]. Needle biopsies from m. gluteus medius of 22 horses which had suffered from repeated attacks of exertional myopathy were studied at various times after an attack, to determine if metabolic alterations can be demonstrated by enzyme histochemistry. Morphological changes and activity of 25 enzymes were studied. Immediately after onset of an attack, some large rounded fibres with a defect of the oxidative phosphorylation were seen. After some hours these fibres lost their glycolytic enzyme activity, followed by disappearance of mitochondrial enzyme activity with accumulation of Ca2+-containing sub...
[The effect of a single dose of dexamethasone on the production of superoxide anion and on the chemotaxis of blood polynuclear neutrophils in the horse]. Chemotaxis and superoxide anion production of neutrophils in healthy horses were investigated before and 8 h after, a single injection of dexamethasone at a dose of 0.045 mg/kg. Chemotaxis was studied by the technique of migration under agarose and superoxyde production was measured by ferricytochrome c reduction. Superoxide anion production was not changed, but the chemotactic index, with zymosan activated horse serum, was increased. The FMLP chemoattractant effect, at 10(-4) M, was slightly enhanced.
Survival of day-4 embryos from young, normal mares and aged, subfertile mares after transfer to normal recipient mares. The estimated embryonic loss rate between Days 4 and 14 after ovulation for young, normal mares (9%) was significantly lower (P less than 0.01) than the estimated embryonic loss rate for aged subfertile mares (62%). Fertilization rates, which were based on the recovery of embryos at Day 4 after ovulation, were 96% and 81% (P less than 0.1) for normal and subfertile mares, respectively. Day-4 embryos were collected from the oviducts of normal and subfertile donors mares. These embryos were transferred to the uteri of synchronized, normal recipient mares to test the hypothesis that the high inci...
A comparative study on acetyl-CoA synthesising enzymes in spinal cord from cows, horses and pigs. 1. Comparative data are presented of the activities of pyruvate dehydrogenase complex and acetyl-CoA synthetase and of the acetate content in homogenates from ventral grey matter in spinal cord from cows and two non-ruminant species, pigs and horses. The methods used in the study are evaluated and discussed. 2. The total pyruvate dehydrogenase complex activity was 24.9-29.9 mU/mg protein and did not differ between the species. The part of the complex that was in active form at the sampling occasion was 60, 85 and 95% in cows, pigs and horses, respectively. 3. Acetyl-CoA synthetase activity dif...
Alterations in the cell cycle characteristics of granulosa cells during the periovulatory period: evidence of ovarian and oviductal influences. Granulosa cells at different stages of differentiation were collected from ovarian follicles and oviducts during the periovulatory period, and their nuclear DNA content was monitored by flow cytometry to establish their cell cycle characteristics (G0 + G1, S, G2 + M). The proportion of cells in the three phases of the cell cycle varied in characteristics patterns depending upon the time they were collected, before or following ovulation. Granulosa (cumulus) cells recovered from ovulated oocytes were mitotically inactive as shown by the large proportion of cells with a 2C amount of DNA and the ...
Hereditary junctional mechanobullous disease in a foal. Mechanobullous disease was diagnosed in a male Belgian foal that had sloughed hooves at 30 hours and at 6 and 12 days of age. Histologic and electron microscopic studies disclosed that lesions were the result of separation of the basal epithelial cell layer from the lamina densa of the basement membrane zone along the lamina lucida. Results of immunofluorescence on tissue specimens were negative for immunoglobulin deposition. The breeding history of the foal's dam indicated that the foal was produced from breeding of the mare to its full sibling stallion. This same mare had produced a female f...
Ultrasonography of umbilical structures in clinically normal foals. The umbilical arteries, urachus, and umbilical vein were scanned ultrasonographically in 13 clinically normal foals that ranged in age from 6 hours to 4 weeks. Sonograms were obtained using a 7.5-MHz sector scanner transducer placed across the midline of the ventral portion of the foal's abdominal wall. The umbilical vein was scanned from the umbilical stalk to its entrance into the hepatic parenchyma. The mean (+/- SD) diameter of the umbilical vein was 0.61 +/- 0.20 cm immediately cranial to the umbilical stalk, 0.52 +/- 0.19 cm midway between the umbilicus and liver, and 0.6 +/- 0.19 cm at ...
Biphasic disruption of fasting equine gut motility by dopamine–a preliminary study. Dopamine was infused intravenously (1, 5 and 10 micrograms/kg/min) for 60 min in three fasted ponies. A dose-dependent increase in heart rate occurred that was rapid in onset and termination at the start and end of the infusions, respectively. Dose-dependent changes in gastric and small intestinal motility were observed. An initial marked inhibition of gastric contraction amplitude was followed by a secondary prolonged period of activity. At the same time the small intestine showed a prolonged period of irregular activity (phase II) and a marked increase in the interval between successive phas...
Studies on the effect of short term, high dose praziquantel treatment against protoscoleces of ovine and equine Echinococcus granulosus within the cyst, and in vitro. Protoscoleces of Echinococcus granulosus were subjected to high concentrations of praziquantel (10-1000 micrograms/ml medium or cyst fluid) for a short, 10 min duration in vitro or in situ within cysts. Drug efficacy was then monitored either by in vitro culture in drug-free medium and/or by passage into rodents. The in vitro test of effectiveness suggested that ovine-derived protoscoleces were more sensitive than those of equine origin, and that the in vitro method of treatment was more successful than that performed in situ. However, the subsequent passage of treated protoscoleces, whether i...
Effectiveness of an ivermectin liquid formulation given by nasogastric tube against strongyles in horses. Twenty horses were treated with ivermectin either by nasogastric tube with a liquid formulation for sheep or per os with a paste formulation for horses at a dosage of 200 mug/kg of body weight. Fecal samples were collected from these horses and from ten untreated horses at the time of treatment and every 2 wk thereafter for up to 10 wk. The samples were examined for nematode eggs using the Cornell-McMaster dilution and the Cornell-Wisconsin Double Centrifugation procedures.There were no signs of toxicosis in horses treated with ivermectin. Strongyle eggs were found in the feces of all horses b...
In vivo activation of equine eosinophils and neutrophils by experimental Strongylus vulgaris infections. Eosinophils and neutrophils from ponies with Strongylus vulgaris-induced eosinophilia (eosinophilic ponies; activated eosinophils and neutrophils) were assayed in vitro for chemotactic and chemokinetic responses to zymosan-activated serum (ZAS) using the filter system in Boyden chambers, for Fc and complement (C) receptors using the EA and EAC-rosette assays, respectively, and for phagocytic and bactericidal activities using opsonized Escherichia coli and the acridine orange method. The responses of activated eosinophils and neutrophils in the above assays were compared with those of eosinophi...
Prokinetic effects of cisapride, naloxone and parasympathetic stimulation at the equine ileo-caeco-colonic junction. The electromyogram of the terminal ileum, the caecum and the proximal right ventral colon was recorded in fasted conscious ponies receiving intravenously equiactive doses of pilocarpine (0.05 mg/kg) and carbachol (0.01 mg/kg) as acetylcholine analogues; cisapride (0.1 mg/kg) and metoclopramide (2 mg/kg) facilitating acetylcholine release from myenteric neurones and naloxone (0.05 mg/kg) as an antagonist of the endogenous inhibitory opioid system. Both cisapride and naloxone induced typical migrating spike bursts in the colon associated with contractions of caecal body and caecal base. Both pil...
Pharmacokinetics, bioavailability, and in vitro antibacterial activity of rifampin in the horse. The pharmacokinetics and bioavailability of rifampin were determined after IV (10 mg/kg of body weight) and intragastric (20 mg/kg of body weight) administration to 6 healthy, adult horses. After IV administration, the disposition kinetics of rifampin were best described by a 2-compartment open model. A rapid distribution phase was followed by a slower elimination phase, with a half-life (t1/2[beta]) of 7.27 +/- 1.11 hours. The mean body clearance was 1.49 +/- 0.41 ml/min.kg, and the mean volume of distribution was 932 +/- 292 ml/kg, indicating that rifampin was widely distributed in the body....
Actions of the novel gastrointestinal prokinetic agent cisapride on equine bowel motility. The effect of cisapride was evaluated on the normal fasting bowel motility of four ponies with chronically implanted electromechanical transducers. Cisapride was infused over 60-min periods at 0.05 mg/kg (n = 4), 0.1 mg/kg (n = 5) and 0.25 mg/kg (n = 5). It produced marked and prolonged increases in electrical and mechanical activity at all sites examined. In the stomach there was increased total contraction activity with increased contraction amplitude and a slight reduction in rate. In the small intestine there was an increase in irregular (phase II) activity with an increase in number and a...
