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Topic:Horses
"Horses" is a broad topic that encompasses various aspects of equine biology, behavior, and management. This category includes studies on the anatomy, physiology, and genetics of horses, as well as their behavior, nutrition, and care. Research in this area may also cover the historical and cultural significance of horses, their roles in agriculture, sport, and therapy, and the challenges associated with their conservation and welfare. The page aggregates peer-reviewed research articles and scholarly studies that explore the multifaceted relationships between humans and horses, examining both scientific and socio-economic perspectives.
Implantation of a permanent transvenous pacing catheter in a horse with complete heart block and syncope. A permanent, transvenous, atrioventricular, sequential pacing system was implanted successfully in a 7-year-old Quarter Horse gelding with complete heart block. The transvenous atrial and ventricular electrodes were placed in their respective positions in the heart, using real-time, 2-dimensional echocardiography. The horse was able to return successfully to competition as a show horse.
Strongylid parasites of horses: experimental ecology of the free-living stages on the Canadian prairie. Each month for a 1-year period (October through September), equine fecal masses containing eggs of strongylid nematodes were placed outdoors on small grass plots in Saskatchewan, Canada. Thereafter, feces and grass from the plots were sampled after intervals of 1 week or longer, and the strongylid eggs and larvae recovered were counted. These observations were made over a 2-year period. Development of eggs to infective larvae occurred in all experiments, except those established in October, December, and January. Infective larvae from experiments set up in April through September survived that...
Normal motility of the cecum and right ventral colon in ponies. To study the normal motility of the cecum and right ventral colon (RVC) in 3 mature Shetland ponies, a 6-part, indwelling, intraluminal catheter system was used to measure intraluminal pressure changes. Three catheters were placed in the cecum at 10, 25, and 40 cm from the cecocolic orifice, and 3 catheters were placed in the RVC at 10, 20, and 30 cm from the cecocolic orifice. Recordings were made during the interdigestive period beginning 2 weeks after surgical operation was done. Frequent, low-amplitude peaks (0.35 +/- 0.13 coordinated peaks/min) were seen involving the cecal body and cauda...
Pharmacokinetics and body fluid and endometrial concentrations of cefoxitin in mares. Four healthy adult mares were each given a single injection of sodium cefoxitin (20 mg/kg of body weight, IV), and serum cefoxitin concentrations were measured serially during a 6-hour period. The mean elimination rate constant was 1.08/hour and the elimination half-life was 0.82 hour. The apparent volume of distribution (at steady state) and the clearance of the drug were estimated at 0.12 L/kg and 259 ml/hr/kg, respectively. Each mare and 2 additional mares were then given 4 consecutive IM injections of sodium cefoxitin (400 mg/ml) at a dosage of 20 mg/kg. Cefoxitin concentrations in serum, ...
[Effectiveness of ivermectin in Strongyloides westeri cases in foals]. Efficacy of Ivermectin in combating Strongyloides westeri infection of foal. The efficacy of Ivermectin and Mebendazol in combating spontaneous Strongyloides westeri infections in foals has been tested by examining faecal egg output reduction. Ivermectin as a paste formulation was given to sucking foals and pregnant mares in a single dosage of 200 micrograms/kg bodyweight by oral administration. A high efficacy of Ivermectin in combating patent Strongyloides westeri infection could be demonstrated; no side effects have been observed. Mebendazol at a dosage rate of 8 mg/kg did not yield satisfa...
Equine laminitis caused by distal displacement of the distal phalanx: 12 cases (1976-1985). Clinical data from 12 cases of equine laminitis characterized by distal displacement of the distal phalanx (P3) were reviewed. Clinical features of horses that survived the syndrome were compared with the nonsurvivors to obtain prognostic indicators. Animals affected included 8 Quarter Horses, 2 Welsh ponies, 1 Thoroughbred, and 1 Arabian. Eight of the animals were females (67%), 2 were stallions, and 2 were geldings. The mean age of affected animals was 8.6 years (2 to 14 years), and the mean body weight was 442 kg. The survivors weighed less than the nonsurvivors (384 kg vs 473 kg, respectiv...
Epidemiology and control of parasites in northern temperate regions. The serious and widespread problem of drug resistance has forced a re-thinking of basic philosophy regarding control of equine parasites. It has illustrated the dangers of total reliance on chemical control and stimulated the use of alternate strategies. Two new approaches are described. Prophylactic treatments in the spring and summer provide effective strongyle and colic control with less selection pressure for drug resistance. A nonchemical approach of pasture cleaning twice a week offers the same advantages with the added bonus of a 50 per cent increase in grazing area.
Pharmacokinetic disposition of dimethyl sulfoxide administered intravenously to horses. Dimethyl sulfoxide (DMSO) was administered IV to 6 Thoroughbred horses at 2 dosages: 1.0 g/kg and 0.1 g/kg. The pharmacokinetics seemed linear, with biological half-lives of 8.6 +/- 0.3 hours and 9.8 +/- 2.2 hours for the 1.0 g/kg and 0.1 g/kg dosages, respectively. This was further substantiated by mean residence times of 9.8 +/- 0.44 hours and 13.8 +/- 4.25 hours, areas under the curve of 12.55 +/- 1.42 mg/ml/hr and 1.63 +/- 0.49 mg/ml/hr, and the clearances of 0.081 +/- 0.009 L/kg/hr and 0.066 +/- 0.022 L/kg/hr for the large and small dosages, respectively. At 12 hours after 1.0 g/kg was ad...
Diagnostic laparoscopy in the horse. Laparoscopy was performed in 5 clinically normal horses. Abdominal fluid protein content and WBC count increased markedly in all horses. Necropsy findings were confined to an increased amount of slightly turbid abdominal fluid. Five examples of applications of laparoscopy in horses with abdominal problems indicated that laparoscopy can be a valuable diagnostic procedure in the horse.
Pharmacokinetics of metronidazole given to horses by intravenous and oral routes. Serum and peritoneal fluid concentrations of metronidazole were determined in 6 healthy adult horses given the drug (25 mg/kg) by IV or oral routes. The disposition of metronidazole in horses given the drug by the IV route conformed to a 2-compartment model with a distribution half-life of 0.16 hours, an elimination half-life of 2.9 hours, and a body clearance of 0.40 +/- 0.05 L/kg/hr. The oral absorption half-life was 0.40 hours, and the bioavailability, 85.0 +/- 18.6%. Peritoneal fluid concentrations were approximately equal to serum concentrations at all times, regardless of the route of ad...
Protozoal diseases. The clinical and pathologic findings of and therapy for such protozoal diseases as equine protozoal myeloencephalitis, toxoplasmosis, sarcocystosis, pneumocytosis, cryptosporidiosis, giardiasis, besnoitiosis, and klossiellosis are discussed. Emphasis is placed on disorders that occur with greater frequency in North America and on emerging protozoal diseases affecting horses.
Large strongyles. Recent advances. This review cites recent advances in the knowledge pertaining to infections of large strongyles in equids. Emphasis is placed on Strongylus vulgaris and attention is focused on pathogenesis of clinical manifestations of infections and treatment and control, including chemotherapy of migrating larvae and drug resistance.
Experimental Babesia equi infection in mature horses. Nine 4-year-old Arabian geldings were experimentally infected with Babesia equi of European origin. All horses developed detectable parasitemia an average of 30 days after they were inoculated, which was accompanied by a decrease in PCV. The infections were generally mild with no animal deaths. All horses became serologically positive by the indirect fluorescent antibody test within an average of 23 days after they were inoculated and by the complement-fixation test 30 days after they were inoculated.
The equine protease inhibitory system (Pi): abnormal expressions of PiF, PiL, and PiS1. Three cases of abnormal expression of the equine protease inhibitory alleles, Pi F, L, and S1, were observed following the examination of 30,000 plasma samples by one-dimensional acid (pH 4.6) polyacrylamide gel electrophoresis. Characterization of the abnormal proteins in terms of isoelectric point, molecular mass, inhibitory spectra, and sialic acid content was performed using one- and two-dimensional electrophoretic techniques. The Pi F and S1 abnormalities were postulated to be the result of amino acid substitutions causing alterations in the processing of the carbohydrate side chains. No ...
Other parasites. Recent advances. This article briefly reviews new information on trichostrongylid stomach worms, spirurid stomach worms, tapeworms, threadworms, pinworms, intestinal protozoa, lungworms, eye worms, and numerous other aberrant parasites as it relates to prevalence, pathogenesis of diseases, and treatments.
The effects of natural exposure to high levels of zinc and cadmium in the immature pony as a function of age. To study the effects of environmental exposure to zinc and cadmium in immature foals, five pregnant ponies were raised within 2.9 km of the New Jersey Zinc Smelter in Palmerton, Pennsylvania. The mares and their foals were kept outdoors on timothy hay and orchard grass. The foals were examined daily for signs of illness and blood samples were taken monthly for estimation of serum zinc, copper, and ceruloplasmin levels. The foals were sacrificed at 2.5, 4.5, 8.5, 13.5, and 18.5 months of age. Necropsy revealed generalized osteochondrosis in joints of the limbs and cervical vertebrae, lymphoid h...
Shoeing principles for the management of navicular disease in horses. Navicular disease was diagnosed in 36 horses. Each horse was treated, using shoeing as the only major means of treatment. Phenylbutazone was used initially for 10 days after shoeing. Shoeing was designed to correct preexisting problems, enhance physiologic function of the foot, and ease breakover of the foot. The horses were evaluated over a period ranging from 12 to 54 months. The lameness improved in all horses. Thirty-one of the 36 horses treated were not lame when last evaluated. Shoeing was most effective when performed within 8 months of the first signs of lameness. Also, horses used for...
Ascarids. Recent advances. P. equorum is a common and ubiquitous parasite that persists for many years in stables and on pasture in spite of good hygiene and anthelmintic control programs. Foals are usually infected early in life. During the migratory phase of the infection, clinical signs include coughing and a nasal discharge followed by depression and unthriftiness as the worms mature in the gut. Some foals die as a result of intestinal impaction or rupture. Patency is established around 3 months of age, and fecal egg counts may rise to very high levels. From 6 months of age onwards, the ascarid burden diminishes as ...
Clinicopathologic study of horses surviving pyrrolizidine alkaloid (Senecio vulgaris) toxicosis. Twenty horses of various ages had inadvertently ingested alfalfa hay contaminated with Senecio vulgaris. Among them, 4 died of liver disease. Blood was collected from affected horses at monthly intervals for 7 months and at the 9th and 14th months. The following serum enzymes and chemical items were assayed: aspartate aminotransferase, lactate dehydrogenase, alkaline phosphatase, gamma-glutamyl transferase, sorbitol dehydrogenase, total bilirubin, BUN, glucose, cholesterol, inorganic phosphate, calcium, total protein, and albumin. Amino acid profiles, conjugated bile acids, sulfobromophthalein...
Immunity and potential of vaccination. This article will focus on current information available on the equine immune response to helminth parasites as it relates to acquired resistance, hypersensitivity reactions, and vaccine development.
Ultrastructural study of the equine cecum during onset of laminitis. The morphologic and pathologic changes which occurred within the cecal mucosa of 4 horses during the onset of laminitis were determined from cecal biopsy materials obtained via a cecal fistula; the laminitis was induced with carbohydrate overload. The cecal epithelial mucosa specimens were obtained at 0 (base line), 24, 32, 48, and 72 hours after horses were given carbohydrate overload, and these were fixed and subsequently photographed. Changes in the cecal epithelium were examined by transmission electron and scanning electron microscopies. These histopathologic changes indicated that the mu...
Epidemiology and control of parasites in warm climates. The kind of parasites a horse acquires depends upon its environment. Because patterns of transmission vary greatly with climate and management, no one worming program has universal applications. This article discusses epidemiology and control of equine parasites in the southern United States, where climates vary from warm temperate to subtropical and from humid in the southeast to arid in the southwest.
Evaluation of androgenized mares as an estrus detection aid. Ten pony mares that had developed stallion-like sexual behavior as the result of anabolic steroid treatment (boldenone undecylenate, 0.55 mg/kg intramuscularly (i.m.), once weekly for 12 injections) were evaluated for ability to aid in detecting estrus in cycling mares. In across-the-fence estrus detection trials, androgenized mares failed to elicit signs of estrus or diestrus. In 10-min pasture trials, in which each androgenized mare was placed in a group of 10 cycling mares (six of which were estrous), seven of the 10 androgenized mares elicited estrous behavior from one or two mares. Observ...
Histochemical staining characteristics of normal horse skeletal muscle. The histologic and histochemical staining characteristics of the triceps brachii (long head), extensor carpi radialis, gluteus medius, vastus lateralis, biceps femoris, semimembranosus, semitendinosus, and extensor digitorum longus muscles of 8 Thoroughbreds, 2 Quarter Horses, 1 Arabian, 1 Paso Fino, and 1 Shetland Pony are described. Muscle fiber morphology, staining distribution and intensity, amount of IM connective tissue, number of IM blood vessels and IM nerves, calcium-activated adenosine triphosphatase activity (CaATPase), percentage of fibertype population, percentage of relative fibe...
Rupture of an aortic sinus aneurysm in a 15-year-old broodmare. A 15-year-old, Standardbred broodmare with an aortic sinus aneurysm developed rupture of the aneurysm with subsequent rupture of a tricuspid valve chorda tendinae, tricuspid regurgitation, acute right-sided congestive heart failure, and pulmonary thromboembolism. Shunting of blood from the aorta through the ruptured aneurysm into the right ventricle resulted in decreased renal perfusion and acute renal failure. Initially, treatment of the mare with analgesics, fluids, and digoxin resulted in clinical improvement, but the mare's condition deteriorated after 8 days and the mare was euthanatized ...
