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Topic:Veterinary Research
Veterinary research in horses encompasses the study of diseases, health management, and medical treatments specific to equine species. This field investigates various aspects of horse health, including infectious diseases, metabolic disorders, and musculoskeletal conditions. Researchers focus on understanding the pathophysiology of equine ailments, developing diagnostic tools, and evaluating therapeutic interventions. The study of horse health also involves examining preventive measures such as vaccination protocols and nutritional management to promote overall well-being. This page collects peer-reviewed research studies and scholarly articles that explore the diverse areas of veterinary science related to horses, providing insights into disease mechanisms, treatment strategies, and advancements in equine healthcare.
Chronic administration of therapeutic levels of clenbuterol acts as a repartitioning agent. The purpose of this study was to examine the effect of therapeutic levels of clenbuterol, with and without exercise training, on body composition. Twenty-three unfit Standardbred mares were divided into four experimental groups: clenbuterol (2.4 microg/kg body wt twice daily) plus exercise (ClenEx; 20 min at 50% maximal oxygen consumption 3 days/wk; n = 6), clenbuterol only (Clen; n = 6), exercise only (Ex; n = 5), and control (Con; n = 6). Rump fat thickness was measured at 2-wk intervals by using B-mode ultrasound, and percent body fat (%fat) was calculated by using previously published meth...
Detection of endophyte toxins in the imported perennial ryegrass straw. From 1997 to 1999, 29 cases of disorders were detected in cattle and horses that had been fed ryegrass straw imported from the U.S.A. These animals showed symptoms resembling ryegrass staggers and the clinical signs disappeared after removal of the straw. Endophytic hyphae were detected in the seeds of all straw samples that were responsible for the clinical cases. Lolitrem B concentrations in the straw ranged between 972 and 3740 ppb. Ergovaline concentrations were between 355 and 1300 ppb. Even though the concentrations of lolitrem B were lower than the toxic threshold proposed by Oregon Sta...
Endoscopic assessment of airway function as a predictor of racing performance in Thoroughbred yearlings: 427 cases (1997-2000). To compare endoscopic findings of the upper portion of the respiratory tract in Thoroughbred yearlings with their subsequent race records to determine whether subjective assessment of airway function may be used as a predictor of future racing performance. Methods: Retrospective study. Methods: 427 Thoroughbred yearlings. Methods: Endoscopic examination findings were obtained from the medical records and the videoendoscopic repository of the Keeneland 1996 September yearling sales. Racing records were requested for the yearlings through the end of their 4-year-old racing season (1997-2000). Tw...
Seroprevalence of antibodies against equine arteritis virus in horses residing in the United States and imported horses. To compare seroprevalence of antibodies against equine arteritis virus (EAV) in horses residing in the United States with that of imported horses. Methods: Serologic survey. Methods: Serum samples from 364 horses on 44 equine operations in California and 226 horses imported from various countries. Methods: Serum samples were collected from each imported horse and from up to 20 horses on each operation. For resident horses, the number of sampled horses on each operation was determined on the basis of the number of horses on the operation. Samples were tested for antibodies against EAV by use of...
Construction of chimeric arteriviruses reveals that the ectodomain of the major glycoprotein is not the main determinant of equine arteritis virus tropism in cell culture. The recent development of arterivirus full-length cDNA clones makes possible the construction of chimeric arteriviruses for fundamental and applied studies. Using an equine arteritis virus (EAV) infectious cDNA clone, we have engineered chimeras in which the ectodomains of the two major envelope proteins, the glycoprotein GP(5) and the membrane protein M, were replaced by sequences from envelope proteins of related and unrelated RNA viruses. Using immunofluorescence microscopy, we monitored the transport of the hybrid GP(5) and M proteins to the Golgi complex, which depends on their heterodime...
Peritonitis associated with Actinobacillus equuli in horses: 51 cases. To review the clinical findings, diagnosis and treatment of 51 horses with peritonitis attributed to Actinobacillus equuli. Methods: Retrospective study of clinical cases. Methods: Breed, age and gender of horse, history, physical examination findings, treatment and outcome were determined from the hospital records of 51 horses in which a diagnosis of peritonitis attributed to A. equuli was made between January 1993 and June 1999. Results of abdominal fluid cytology and bacteriology, antimicrobial sensitivity patterns, haematology and faecal egg counts, when performed, were also retrieved. Res...
Use of the flexion test of the distal forelimb in the sound horse: repeatability and effect of age, gender, weight, height and fetlock joint range of motion. The flexion test of the distal limb is a commonly used clinical tool in both lame and sound horses. In the latter use it is given some predictive value. In recent studies it has been shown that examiner-related factors (force, time) may strongly influence the outcome of the test. In the present study, the possible influences of a number of horse-related factors and short- and long-term repeatability were investigated. Flexion tests were performed by the same researcher in 100 clinically sound horses under standardized conditions. The outcome of the test was scored on a 9-point semiquantitative...
The action of mercury on cell membranes. The action of mercuric chloride and methyl mercuric chloride on the membrane lateral domain organization of bovine, equine, and canine erythrocytes was studied. Electron paramagnetic resonance (EPR) spectra of spin-labeled erythrocytes were analyzed with respect to their lateral domain structure. Continuous alteration of the membrane domain populations revealed that mercuric compounds affect the membrane via the evolution of toxic events in the cells.
Detection of equine herpesvirus type 2 (EHV-2) in horses with keratoconjunctivitis. The prevalence of EHV-2 in 27 horses with keratoconjunctivitis and 21 clinically healthy horses of different ages and stocks were analyzed. We demonstrated that EHV-2 was present in 12 keratoconjunctivitis cases as shown by nested PCR on ocular swabs. This is statistically more often than in the control group, where only two ocular swabs were EHV-2 positive. Cocultivation was successful on peripheral blood leukocytes of healthy and diseased horses but not on swabs. We isolated ten EHV-2 strains from diseased and nine from control horses, whereas 16 isolates showed different restriction enzyme ...
“Equine basal cell tumors: 6 cases (1985-1999)”. Basal cell tumors are rare benign tumors in horses. Over a 15-year period, 6 horses were diagnosed with basal cell tumors. The tumors were well-circumscribed. freely moveable, firm, raised papules, nodules, or masses that ranged from 0.6 to 5 cm in diameter. Five of the 6 tumors were ulcerated. Based on gross appearance, the tumors were diagnosed as sarcoids, and 1 was diagnosed as a melanoma. The range of age of affected horses was 6-26 years. The tumors were identified clinically 1 week to 3 years before excision. In 4 horses for which information was available, complete surgical excision wa...
Biochemical composition of equine carpal articular cartilage is influenced by short-term exercise in a site-specific manner. It was hypothesized that cartilage macro-molecular characteristics are influenced by exercise intensity and by location within a joint. Objective: To determine the macromolecular characteristics of carpal articular cartilage at common and uncommon sites of pathology in horses undergoing high or low intensity exercise, and to compare this composition between exercise groups. Methods: Twelve horses (19.3+/-0.9 years) were assigned to exercise groups. Each group underwent 19 weeks high-intensity treadmill training (N=6) or low-intensity exercise (N=6). Dorsal and palmar test sites were identified...
Toxicokinetics of ergovaline in the horse after an intravenous administration. The toxicokinetics of ergovaline (an ergopeptine mycotoxin present in some grasses infected with endophytic fungus of the genus Neotyphodium) were studied after intravenous administration of a single dose of 15 microg/kg bwt in four gelding horses. Plasma ergovaline concentrations were measured by high performance liquid chromatography, and the kinetic data were described by a three-compartment model. The elimination half-life and the total clearance of ergovaline were found to be 56.83 +/- 13.48 min and 0.020 +/- 0.004 L/min x kg, respectively. According to the toxicological data previously r...
Model formulation and determination of in vitro parameters of a noninvasive method to calculate flexor tendon forces in the equine forelimb. To describe a method to calculate flexor tendon forces on the basis of inverse dynamic analysis and an in vitro model of the equine forelimb and to quantify parameters for the model. Methods: 38 forelimbs of 23 horses that each had an estimated body mass of > or = 500 kg. Methods: Longitudinal limb sections were used to determine the lines of action of the tendons. Additionally, limb and tendon loading experiments were performed to determine mechanical properties of the flexor tendons. Results: The study quantified the parameters for a pulley model to describe the lines of action. Furthermo...
Calcium sensitivity of force production and myofibrillar ATPase activity in muscles from Thoroughbreds with recurrent exertional rhabdomyolysis. To determine whether the basis for recurrent exertional rhabdomyolysis (RER) in Thoroughbreds lies in an alteration in the activation and regulation of the myofibrillar contractile apparatus by ionized calcium. Methods: 4 Thoroughbred mares with RER and 4 clinically normal (control) Thoroughbreds. Methods: Single chemically-skinned type-I (slow-twitch) and type-II (fast-twitch) muscle fibers were obtained from punch biopsy specimens, mounted to a force transducer, and the tensions that developed in response to a series of calcium concentrations were measured. In addition, myofibril preparation...
Detection of Babesia equi (Laveran, 1901) by nested polymerase chain reaction. We describe a nested polymerase chain reaction (PCR) for the detection of Babesia equi in equine infected erythrocytes using oligonucleotides designed on the published sequence of a B. equi merozoite antigen gene (ema-1). A 102bp DNA fragment is specifically amplified from B. equi but not from Babesia caballi, Babesia bovis or Babesia bigemina DNA. In a mock infection we were able to detect down to six infected cells in 10(8) equine erythrocytes or to detect the parasite in blood with an equivalent parasitemia of 0.000006%. Furthermore, gene polymorphism was found by performing a PCR-RFLP (PCR...
Prevalence and incidence of trypanosomosis in horses and donkeys in the Gambia. In a study of the prevalence and incidence of trypanosomosis in horses and donkeys in two regions of the Gambia, surveys were carried out at Niamina east and Bansang south with a high and low to moderate tsetse challenge, respectively. Eleven horses and 67 donkeys were sampled monthly from August 1997 to September 1998. Blood samples were examined for trypanosomes using the buffy-coat (BC) method and polymerase chain reaction (PCR). Three primer sets were used, specific for either Trypanosoma vivax (TVW), Trypanosoma congolense (GOL) or Trypanosoma brucei (ORPHON5J). The BC results showed that...
Detection of North American West Nile virus in animal tissue by a reverse transcription-nested polymerase chain reaction assay. A traditional single-stage reverse transcription-polymerase chain reaction (RT-PCR) procedure is effective in determining West Nile (WN) virus in avian tissue and infected cell cultures. However, the procedure lacks the sensitivity to detect WN virus in equine tissue. We describe an RT-nested PCR (RT-nPCR) procedure that identifies the North American strain of WN virus directly in equine and avian tissues.
Prevalence of virulent Rhodococcus equi in isolates from soil collected from two horse farms in South Africa and restriction fragment length polymorphisms of virulence plasmids in the isolates from infected foals, a dog and a monkey. The prevalence of virulent Rhodococcus equi in soil isolates from two horse farms in South Africa and nine clinical isolates from six foals, a foal foetus, a dog, and a monkey was investigated. The isolates were tested for the presence of virulence plasmid DNA and 15- to 17-kDa antigens by immunoblotting. Rhodococcus equi was isolated from almost all of the soil samples obtained from the two farms with 5.0 x 10(1) to 3.3 x 10(4) colony forming units per gram of soil. Virulent R. equi was isolated from three soil samples from one of the farms and appeared in 3.8% (three of 80 isolates), but not...
The use of a neutralizing monoclonal antibody to detect infections of equine herpesvirus type 2 (EHV-2). A blocking enzyme-linked immunosorbent assay (ELISA) was developed to detect antibodies to equine herpesvirus 2 in serum samples of horses. By measuring the binding to a single epitope, this blocking ELISA gives a good picture of the antibody status in the animal. The test is based on a monoclonal antibody with neutralizing activity and had a sensitivity of 94% and a specificity of 100%. Antibodies due to newly acquired infection in foals were successfully detected with this blocking ELISA.
Mapping the sequences that mediate interaction of the equine herpesvirus 1 immediate-early protein and human TFIIB. The sole immediate-early (IE) gene of equine herpesvirus 1 encodes a 1,487-amino-acid (aa) regulatory phosphoprotein that independently activates expression of early viral genes. Coimmunoprecipitation assays demonstrated that the IE protein physically interacts with the general transcription factor TFIIB. Using a variety of protein-binding assays that employed a panel of IE truncation and deletion mutants expressed as in vitro-synthesized or glutathione S-transferase fusion proteins, we mapped a TFIIB-binding domain to aa 407 to 757 of the IE protein. IE mutants carrying internal deletions of ...
Influence of epidermal growth factor on mammalian oocyte maturation via tyrosine-kinase pathway. Epidermal growth factor (EGF) has been reported to promote different functions in mammalian ovaries, including oocyte maturation. The aim of the present study was to establish: that EGF influences oocyte maturation in ovine and equine, that a tyrosine kinase-dependent intracellular mechanism mediates EGF effect and, that EGF-R receptor is detectable in ovarian follicles by immunohistochemistry methods. Selected ovine and equine oocytes were aspirated from 2-5 mm (ovine) or 25 mm (equine) follicles and cultured in TCM 199 for 22 (ovine) or 36 hours (equine). They are then subjected to culture w...
Suppression of mosquito (Diptera: Culicidae) and black fly (Diptera: Simuliidae) blood feeding from Hereford cattle and ponies treated with permethrin. The blood feeding of mosquitoes and black flies from Hereford cattle and ponies treated with commercial formulations of permethrin was evaluated using an animal enclosure trap sample system that allowed comparison of insect blood-feeding levels between treated and nontreated animals. Blood feeding of both Aedes dorsalis Meigen and A. melanimon Dyar from heifers treated with pour-on concentrate and whole body spray treatments was reduced significantly by 79-88% at 4 d posttreatment, with apparent but not significant reductions of 61-68% at 11 d posttreatment. Simulium bivittatum Malloch and S. ...
Equine monocytic Ehrlichiosis (Potomac horse fever) in horses in Uruguay and southern Brazil. A disease named locally as churrío or churrido equino (i.e., equine scours) has occurred for at least 100 years in Uruguay and southern Brazil in farms along both shores of the Merín lake. This report describes cases of churrido equino and provides serologic, pathologic, and DNA-based evidence indicating that the disease is in fact equine monocytic ehrlichiosis (Potomac horse fever). Results of an epidemiological investigation conducted on an endemic farm are also presented. Clinical signs in 12 horses were fever, depression, diarrhea, dehydration, and sometimes colic and distal hind limb ed...
Influence of epidermal growth factor on mammalian oocyte maturation via tyrosine-kinase pathway. Epidermal growth factor (EGF) has been reported to promote different functions in mammalian ovaries, including oocyte maturation. The aim of the present study was to establish: that EGF influences oocyte maturation in ovine and equine, that a tyrosine kinase-dependent intracellular mechanism mediates EGF effect and, that EGF-R receptor is detectable in ovarian follicles by immunohistochemistry methods. Selected ovine and equine oocytes were aspirated from 2-5 mm (ovine) or 25 mm (equine) follicles and cultured in TCM 199 for 22 (ovine) or 36 hours (equine). They are then subjected to culture w...
Idiopathic systemic granulomatous disease and macrophage expression of PTHrP in a miniature pony. Idiopathic systemic granulomatous disease, which has been reported in horses, cattle and human beings, is characterized by perivascular granulomatous and lymphoplasmacytic inflammation in many organ systems. Diagnosis is based on the exclusion of possible viral, fungal or bacterial causes. The disease was identified in a miniature pony with widespread lymphoplasmacytic and granulomatous inflammation, special staining techniques having revealed no evidence of any aetiological agent. Skin lesions, which were severe, consisted of hyperkeratosis and serocellular crust formation, with inflammatory ...
Effect of two anaesthetic regimens on airway nitric oxide production in horses. There is evidence that halothane inhibits nitric oxide synthase in vitro, but the effect of intravenous anaesthetic agents is less clear. This study was undertaken to compare the rate of exhaled nitric oxide production (VNO) in spontaneously breathing horses anaesthetized with halothane or an intravenous regimen. Seven adult horses were studied twice in random order. After premedication with romifidine 100 microg kg(-1), anaesthesia was induced with ketamine 2.2 mg kg(-1) and maintained with halothane in oxygen (HA) or by an intravenous infusion of ketamine, guaiphenesin and romifidine (IV). I...
Administration of bovine, porcine and equine growth hormone to the horse: effect on insulin-like growth factor-I and selected IGF binding proteins. This study investigated the biochemical effects of administration of three types of recombinant growth hormone (GH; somatotropin) to the Thoroughbred horse. Equine or bovine or porcine GH was administered at a recommended dosage to 3-5-year old Thoroughbred geldings, for up to 21 days. It was shown that, in addition to equine GH, bovine and porcine GH were active in the horse; however, porcine GH caused injection-site reactions that were so serious that administration had to be terminated. The concentrations of a range of GH-related serum protein markers were determined before, during and afte...
The effects of ph, osmolarity and urine contamination on equine spermatozoal motility. Urospermia has been reported as a cause of infertility in numerous species. The detrimental effects of urine on spermatozoa are due, at least in part, to changes in pH and osmolarity. Semen was collected and subjected to conditions of varying pH (Experiment 1), of varying osmolarity (Experiment 2), and various quantities and concentrations of urine (Experiment 3) and effects on motility were recorded. Finally, semen was contaminated with urine and then either of 2 semen extenders was added, with or without centrifugation, in an attempt to alleviate the detrimental effect of urine on motility (...
Radiculomeningomyelitis due to Halicephalobus gingivalis in a horse. An adult horse was euthanatized following a clinical diagnosis of cauda equina neuritis. Significant gross postmortem and histopathologic findings were limited to the sacral spinal cord and cauda equina. The sacral spinal cord, meninges, and spinal nerve roots were expanded and partially effaced by sclerosing granulomatous inflammation with necrosis. The lesion contained numerous nematode larvae and fewer adults with a rhabditiform esophagus having a corpus, isthmus, and valved bulb. Female nematodes were amphidelphic and didelphic with reflexed ovaries. These morphologic features confirm Hali...
