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Topic:Veterinary Medicine
Veterinary medicine for horses encompasses the study and application of medical practices to diagnose, treat, and prevent diseases in equine species. This field involves a comprehensive understanding of equine anatomy, physiology, pathology, and pharmacology. Veterinary practitioners employ a range of diagnostic tools and therapeutic interventions to address health issues in horses, including lameness, gastrointestinal disorders, respiratory conditions, and infectious diseases. Preventative care, such as vaccination and deworming programs, is also a significant aspect of equine veterinary medicine. This page gathers peer-reviewed research studies and scholarly articles that explore various aspects of veterinary medicine as it pertains to horses, including advancements in diagnostic techniques, treatment protocols, and preventive health strategies.
Vascular response of the equine radius to cerclage devices. The arterial blood supply to the diaphysis of the radius, and the vascular reaction when three cerclage devices (cerclage wire, Parham-Martin band, and a partially contacting band) were applied 2 cm apart, were studied in six adult ponies. The opposite radial diaphysis served as the control. Ponies were euthanatized at weeks 4 and 8. A centrifugal blood flow pattern was demonstrated by microangiography. Larger numbers of medullary arteries exist in equine than in canine and human long bones. Changes in centrifugal blood supply were not identified beneath any of the cerclage devices.
NaCl transport across equine proximal colon and the effect of endogenous prostanoids. In contrast to in vivo findings, the equine proximal colon fails to demonstrate significant net absorption of Na+ and Cl- under in vitro conditions. The present study was undertaken to determine if endogenous prostanoids are responsible for this apparent lack of ion transport. Proximal colonic tissues from ponies were preincubated in either normal Ringer solution or in Ringer containing 1 microM indomethacin and studied in Ussing chambers containing these solutions. Untreated colonic mucosa demonstrated negligible Na(+)-Cl- absorption in the basal state. In contrast, indomethacin-treated colon...
Haemodynamic effects of small volume hypertonic saline in experimentally induced haemorrhagic shock. A comparison of the haemodynamic benefits of small volume hypertonic saline (2,400 mOsm/litre) versus isotonic saline (300 mOsm/litre) was conducted in 12 adult horses using a haemorrhagic shock model. The horses were anaesthetised and intravascular catheters placed for the measurement of haemodynamic data. Mean systemic arterial pressure was then reduced to 50 to 60 mmHg by controlled haemorrhage and maintained at that level for 40 mins. Cardiac output, stroke volume, mean systemic arterial pressure, plasma volume and urine production decreased significantly following blood loss. Hypertonic o...
Antigenic assay for protein C determination in horses. An antigenic assay was developed for determination of protein C in horses. Protein C, a natural, vitamin K-dependent anticoagulant component in blood, was isolated from equine plasma, a specific antibody was produced in goats, and a rocket electroimmunophoresis assay was established. Tests were performed to verify the identity of the isolated protein C and to determine the purity of the antibody. Protein C antigen was measured in plasma from 34 clinically normal horses, and values were compared with amidolytic function values. The mean (+/- SD) values for the 2 test methods were similar (antig...
Association between muscle acetyl-CoA and acetylcarnitine levels in the exercising horse. Treadmill exercise of 2-min duration and increasing intensity resulted in increased formation of acetyl-CoA and acetylcarnitine in working muscle of Thoroughbred horses. At high work intensities a plateau was reached for both acetyl-CoA (approximately 50 mumols/kg dry muscle) and acetylcarnitine (approximately 20 mmol/kg dry muscle). Postexercise concentrations were significantly (P less than 0.001) correlated; [acetylcarnitine] = 349.[acetyl-CoA] + 2.4. The results indicate that approximately 350 mumols acetylcarnitine were accumulated for every 1 mumol acetyl-CoA. Under the conditions of exe...
Effect of hypertonic vs isotonic saline solution on responses to sublethal Escherichia coli endotoxemia in horses. Cardiovascular responses to sublethal endotoxin infusion (Escherichia coli, 50 micrograms/ml in lactated Ringer solution at 100 ml/h until pulmonary arterial pressure increased by 10 mm of Hg) were measured 2 times in 5 standing horses. In a 2-period crossover experimental design, horses were either administered hypertonic (2,400 mosm/kg of body weight, IV) or isotonic (300 mosm/kg, IV) NaCl solution after endotoxin challenges. Each solution was administered at a dose of 5 ml/kg (infusion rate, 80 ml/min). Complete data sets (mean arterial, central venous, and pulmonary arterial pressures, pul...
Neuroaxonal dystrophy associated with vitamin E deficiency in two Haflinger horses. Neuroaxonal dystrophy and minimal diffuse degenerative myelopathy was diagnosed in two female full sibling, 1- and 2-year-old, Haflinger horses. Both animals developed slowly progressive ataxia from the age of 4 months. Clinical signs, which were more prominent in the hind legs, included hypermetria and dysmetria. Histological examination revealed neuroaxonal dystrophy characterized by spheroid formation, vacuolation, astrogliosis and lipofuscin pigment deposition in macrophages and neuronal perikarya. These changes were restricted to the gracilis and cuneate nuclei, nucleus of the solitary tr...
Overo lethal white foal syndrome: equine model of aganglionic megacolon (Hirschsprung disease). The lethal white foal syndrome (LWFS) is a congenital abnormality of overo spotted horses which is a model for human aganglionic megacolon or Hirschsprung disease. Foals with LWFS have an all white, or nearly all white, coat. They also present clinically with an intestinal obstruction that proves fatal within the first few days of life. The LWFS involves both melanocytes and intestinal ganglion cells, and appears to result from a genetic defect involving neural crest cells. This report describes pathologic studies of two recent cases of LWFS. Two different hypothetical models of inheritance of...
Effects of allopurinol on endotoxin-induced increase in serum xanthine oxidase in the horse. Using a modified bovine milk enzyme kinetic assay, xanthine oxidase activity of serum collected from 34 adult, healthy horses of both sexes was determined. Enzyme activity varied from 0 to 126 mU litre-1 with a mean of 44.95 +/- 21.05 mU litre-1. The optimal pH and temperature for maximal activity were 7.8 and 28 degrees C, respectively. Freezing the serum for four days at -70 degrees C did not destroy the enzyme activity. Various doses (25, 50 and 75 micrograms kg-1, intraperitoneally) of endotoxin (lipopolysaccharide D1 Escherichia coli O26:B6) previously known to have caused moderate to sev...
Uterine contractile activity in mares during the estrous cycle and early pregnancy. Transrectal ultrasonography was used to quantitate uterine contractile activity during the estrous cycle and early pregnancy in pony mares (nonbred, n = 9; pregnant, n = 16). Continuous 1-min scans of longitudinal sections of the uterine body were videotaped, and uterine activity scores (1=minimal activity, 5=maximal activity) were assigned to each tape segment. There was a tendency (P<0.06) for a main effect of reproductive status (nonbred versus pregnant), a main effect of day (P<0.0001), and a reproductive status by day interaction (P<0.006). Uterine activity scores were higher (P&...
EGF receptor-binding activity in the urine of normal horses and horses affected by chronic laminitis. A heterologous radioreceptor binding assay (RRA) has been developed capable of detecting nanogram amounts of epidermal growth factor (EGF) receptor-binding activity in equine urine. The binding parameters of [125I]mEGF (murine EGF) to EGF receptors on equine plasma membranes are in good agreement with values from other EGF-RRA systems. The dissociation constant estimated from equilibrium methods (KD = 4 X 10(-10) M) is in reasonable agreement with that determined from the rate constants (KD = 6 X 10(-10) M) and is in good agreement with values determined in other species. The assay is specific...
The effects of phenylbutazone on the morphology and prostaglandin concentrations of the pyloric mucosa of the equine stomach. Phenylbutazone, a nonsteroidal anti-inflammatory drug known to produce gastric ulcers, was administered intravenously (13.46 mg/kg body weight) daily to 12 horses. Horses were euthanatized daily after 24, 48, 72, and 96 hours following the initial injection. Eight untreated horses served as controls. Small multifocal pyloric erosions were seen after 24 hours and then progressed in severity over time. The erosions were characterized by sloughing of the surface epithelium, subepithelial bleb formation, necrosis of the lamina propria, degeneration of the walls of subsurface capillaries, and micro...
Characterisation of Chlamydia psittaci isolated from a horse. This paper describes the isolation and characterisation of a strain of Chlamydia psittaci obtained from a nasal swab taken from a horse with serous nasal discharge. Initial isolation was achieved in cycloheximide-treated McCoy cell monolayers. Chlamydial inclusions stained by immunofluorescence either with a rabbit antiserum raised against C. psittaci or with a monoclonal antibody directed against the genus-specific lipopolysaccharide antigen were single and compact. They did not stain with iodine or with a monoclonal antibody reactive against Chlamydia trachomatis. The agent was re-isolated i...
Specific immunotherapy in the treatment of Culicoides hypersensitive horses: a double-blind study. Fourteen privately owned horses completed a six month, controlled, double-blind trial to assess the efficacy of immunotherapy using an aqueous extract of whole, unfed Culicoides variipennis in the treatment of Culicoides hypersensitivity. Selected horses had a history of a seasonal, pruritic dermatitis, clinical signs and distribution compatible with Culicoides hypersensitivity, failed to improve in response to ivermectin therapy, and reacted to several dilutions of Culicoides extracts without significant reactivity to other possible allergens including insects, moulds and feeds. One horse fro...
Equine synovial tendon sheaths and bursae: an histological and scanning electron microscopical study. The structure of equine synovial tendon sheaths and bursae has been examined by light and scanning electron microscopy. Tissue samples were obtained from horses of various types and ages with no clinical evidence of sheath or bursal disorders. The interior of both structures was lined by a cellular layer superimposed on a vascular zone supported by a fibrous layer. The pattern of cell distribution of the lining varied from site to site within the same structure depending on the nature of the underlying tissue and on the amount of movement to which the structure was subjected. The cellular laye...
Partial pressures of oxygen and carbon dioxide, pH, and concentrations of bicarbonate, lactate, and glucose in pleural fluid from horses. Samples of pleural fluid from 20 horses with effusive pleural diseases of various causes were evaluated; samples from 19 horses were used for the study. There were differences for pH (P = 0.001) and partial pressure of oxygen (PO2) between arterial blood and nonseptic pleural fluid (P = 0.0491), but there were no differences for pH, PO2, partial pressure of carbon dioxide (PCO2), and concentrations of bicarbonate (HCO3-), lactate, and glucose between venous blood and nonseptic pleural fluid. Paired comparisons of venous blood and nonseptic pleural fluid from the same horse indicated no differe...
Endoscopy of the digital flexor tendon sheath in horses. An arthroscopic procedure for examination of the digital flexor tendons and tendon sheath was developed in 16 equine limbs and 12 horses. Distension of the tendon sheath and insertion of the arthroscope was accomplished through a cul-de-sac on the palmar or plantar surface of the tendon sheath 1 to 2 cm palmar or plantar to the digital neurovascular structures and between the annular ligament and proximal digital annular ligament. A single arthroscope entry point allowed examination of all regions of the tendon sheath cavity and most surfaces of the digital flexor tendons within the sheath. Di...
[Determination of cortisol, T4, T3 and T-uptake in serum and plasma of horses using fluorescence polarization immunoassays (FIPAs)]. The influence of duration and temperature of storage on hormone levels of whole blood, plasma and serum of horses was investigated. Using FPIAs cortisol, T4 and T-uptake could be measured while the T3-FPIA did not work appropriately. Serum and Plasma stored under the same conditions did not show any difference in cortisol, T4 and T-uptake values. In frozen heparinized plasma samples analysed on different days the cortisol and T4 concentrations fluctuated markedly. The T-uptake values were rather stable. The smallest day by day changes of cortisol and T4 in plasma were found when storing the sa...
Fumonisin B1 levels associated with an epizootic of equine leukoencephalomalacia. During the fall of 1989, an episode of equine leukoencephalomalacia involved 18 of 66 purebred Arabian horses at a breeding/training stable in Arizona. Of the 18 horses affected, the condition was fatal in 14. These horses, as well as 48 unaffected horses, had been fed a diet containing a substantial amount of white corn screenings. Gross pathologic findings included liquefactive necrosis in parts of the cerebral white matter and hemorrhagic foci of various sizes in the brain stem. Histopathologic findings included rarefied white matter with pyknotic nuclei and eosinophilic cytoplasm. Thin-lay...
Effects of three anthelmintic schedules on the incidence of colic in horses. Four privately owned herds (25 to 49 animals per herd) were used in a five-year trial designed to evaluate the effect of anthelmintic schedules on the incidence of colic. These herds had been treated bi-monthly with non-ivermectin, non-benzimidazole drugs for two years before the trial. Prior parasitological studies showed that they had substantial pre-treatment faecal egg counts (900 to 2200 eggs per gramme), and that they were infected with benzimidazole-resistant cyathostomes. In Years 1 and 2 of the trial, all herds (A, B, C, D) were treated bi-monthly with non-ivermectin anthelmintics (Sc...
Separation of equine bronchopulmonary lavage cells by density gradient centrifugation and expression of procoagulant activity in unpurified cells and cell subpopulations. Bronchopulmonary lavage was performed in 10 healthy horses and in 39 horses with chronic pulmonary disease. The predominant cell types were macrophages in healthy horses and neutrophils in severely diseased horses. Procoagulant activity (PCA) was detected in all 32 cell-free supernatants examined and in all 49 unpurified cell suspensions. Cells were separated by centrifugation on discontinuous gradients prepared either with Percoll or with Metrizamide. Macrophages were enriched in subpopulations of low density. Neutrophils could not be purified by density gradient centrifugation using either g...
Evaluation of 25%, 50%, and 67% nitrous oxide with halothane-oxygen for general anesthesia in horses. Twenty-five percent, 50%, and 67% nitrous oxide was administered to 12 horses anesthetized with halothane and oxygen. Compared to halothane-oxygen alone, there was no significant difference in heart rate, systolic, diastolic, or mean blood pressure values, arterial pH, PaCO2, or plasma bicarbonate values when nitrous oxide was included. A significant linear reduction in PaO2 values could be correlated with N2O:O2 concentrations. The halothane level required to maintain surgical anesthesia was reduced when nitrous oxide was administered, but it was not affected by changing the nitrous oxide con...
