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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.
Pathophysiology of airway obstruction in horses: a review. Obstruction of the upper and lower airways is common in horses. In the upper airway, paresis of abductor muscles of the nares and larynx allows inspiratory collapse of soft tissues, which is accentuated by factors increasing upper airway resistance and by high inspiratory flow rates. Intrapulmonary airway obstruction occurs due to accumulation of secretions, release of chemical mediators in response to a variety of stimuli, and parasympathetic stimulation of airways. Obstruction of large airways increases the work of breathing, whereas obstruction of small airways may cause no measurable incre...
Occurrence and distribution of western equine encephalomyelitis in Florida. Research and surveillance programs relating to the occurrence and distribution of western equine encephalomyelitis virus in Florida, conducted between 1955 and 1976, suggest that the virus is (1) an endemic arbordae, (2) transmitted in a continuous cycle throughout the year by Culiseta melanura mosquitoes, and (3) restricted to fresh water swamps and waterways in central, north, and northwest Florida.
Role of horse flies in transmission of wquine infectious anemia from carrier ponies. Equine infectious anemia virus was transmitted from an acutely ill and an inapparently infected pony to uninfected ponies by the interrupted feeding of horse flies (tabanids). Transmission from acutely ill ponies was not accomplished following: (1) the interrupted feeding of a single horse fly, (2) bites of horse flies that had fed on an acutely affected pony 24 hours earlier, (3) bites of horse flies that had oviposited after feeding on an acutely affected pony, or (4) the inoculation of larval material derived from horse flies that had fed to repletion. It was concluded that horse fly transm...
Role of intracranial [H+] receptor in physiologic regulation of ventilation in ponies. Numerous studies have demonstrated the existence of an intracranial [H+] chemoreceptor mechanism capable of stimulating ventilation. 1 Supposedly, this chemoreceptor is located 0.2 mm below the surface of the ventrolateral side of the medulla and is responsive to [H+] in the surrounding cerebral extracellular fluid (ECF). During chronic conditions, ECF [H+] is supposedly in equilibrium with CSF [H+]; hence, stimulus level can be established through sampling and analysis of CSF. In this presentation, we summarize data from studies on spontaneously breathing, unanesthetized ponies which suggests...
Immunoglobulins and secretory component in the external secretions of foals with combined immunodeficiency. Nasal washings and tears were collected from seven Arabian foals with combined immunodeficiency and nine normal foals. The major immunoglobulin in the external secretions of normal foals over 2 months of age was secretory immunoglobulin A, whereas foals with combined immunodeficiency lacked this immunoglobulin. The external secretions of both normal and immunodeficient foals contained free secretory component at birth.
Blood glutathione peroxidase activity in horses in relation to muscular dystrophy and selenium nutrition. The activity of glutathione peroxidase, a selenium containing enzyme, was measured in the blood of horses to determine its usefulness as an indicator of selenium status. In 15 horses the enzyme activity was positively related to the blood selenium concentration (P less than .001, r-0.98) over the range of enzyme activities of 8.2 to 140 units (mumoles NADP-oxidised/min/gHb) and selenium concentrations of 0.24 to 2.74 mumol/l. In a group of 8 horses which 2 foals had died with lesions of muscular dystrophy the enzyme activity increased from a mean of 11.8 units before treatment with selenium to...
Eastern equine encephalitis in Massachusetts, 1957-1976. A prospective study centered upon analyses of mosquitoes. Reappearance of eastern equine encephalitis (EEE) in Massachusetts residents in the 1970's provided an opportunity to assess the predictive value of data on rainfall, EEE in horses, and carriage of EEE virus (EEEV) by mosquitoes, factors which had been studied annually since the last EEE outbreak in 1955-1956. The cycle of multiple cases during 1973-1975 started in a second consecutive year of rainfall that exceeded the annual mean by more than 20 cm, conditions recapitulating the 1955-1956 experience. In 1973, widespread EEE fatalities in horses presaged human cases, another recapitulation of...
Calcium metabolism, body composition, and sweat losses of exercised horses. The effect of exercise on the pathways of metabolism of 40Ca and 47Ca was studied in 4 yearling Standardbred horses in 4 consecutive treatment periods: (1) no exercise, (2) trotting 16 km/day, (3) trotting 10 km/day, and (4) no exercise. Metabolic balance studies and studies of 47Ca kinetics were conducted during the final week of each month-long treatment period. The urinary excretion of 40Ca and 47Ca decreased 50% to 75% during the exercise periods. Retention of 47Ca increased during the exercise periods, but the retention of dietary Ca (40Ca) did not change. The efficiency of Ca absorption ...
Clinical signs and chemical confirmation of 4-aminopyridine poisoning in horses. 4-Aminopyridine poisoning in horses was diagnosed. Specific methods, utilizing thin-layer and high-performance liquid chromatography, were developed for determining the compound in stomach contents and corn bait. The lethal dose was estimated at 2 to 3 mg/kg of body weight.
Circular dichroic properties and conformation of thionicotinamide dinucleotides bound to horse-liver alcohol dehydrogenase. The interaction between horse liver alcohol dehydrogenase and the oxidized and reduced forms of the 3-thionicotinamide--adenine dinucleotide coenzyme analogues (sNAD and sNADH) has been investigated by ultraviolet absorption, fluorescence and circular dichroism. The fluorescence of sNADH is enhanced when bound to the enzyme, and the protein fluorescence is quenched by both sNADH (60--65%) and sNAD (65%). The possible origin of the larger quenching produced by sNAD with respect to that of NAD is discussed. Coenzyme dissociation constants have been determined by monitoring the quenching of the p...
Clinically important structures of the equine hock. A study method has been devised to review clinically important structures of the equine hock joint on a fresh specimen. The review can be done alone; dissection takes about 2 hours; special tools or materials are not required.
Listeriosis in an Arabian foal with combined immunodeficiency. A 1-month-old Arabian foal with signs of central nervous system disease was found to have combined (B- and T-lymphocyte) immunodeficiency. The foal died in spite of intensive antibiotic therapy. At necropsy, generalized lymphoid hypoplasia and acute necrotizing and granulomatous inflammation of the brain, heart, and adrenal glands were found. In addition, there were spinal meningitis and focal hepatic necrosis. Listeria monocytogenes was isolated on primary culture from the brain.
Equine myositis and septicemia caused by Acinetobacter calcoaceticus infection. Myositis and septicemia caused by Acinetobacter calcoaceticus were diagnosed in a mare. The infection was characterized clinically by ventral swelling and edema, diarrhea, listlessness, and rectal temperature of 39.4 C. The mare was treated symptomatically for 2 days but died on the 3rd day. Conditions seen at necropsy were myositis, enteritis, typhlitis, colitis, and hepatitis. Lymph nodes were moderately enlarged throughout the body. Gross lesions in musculature were edema, scarring, petechiae, and an occasional exxhymosis. The enteritis was catarrhal, with excessive mucus and moderate hyper...
Interruption of aortic arch in two foals. Two foals with a history of normalcy at birth developed a lack of exercise tolerance and weakness in the first few days of life. Weakness, inability to rise, and reluctance to suckle were common complaints. Physical examination of both foals revealed a cardiovascular abnormality, with a loud systolic murmur audible over both thoracic walls. Additional diagnostic techniques were blood gas analysis, radiography, cardiovascular catheterization, and necropsy. Necropsy findings were ventricular septal defect, atrial septal defect, patent ductus arteriosus, and congenital absence of the aortic arch....
Microculture method for mixed lymphocyte cultures in the horse. A miniaturized method for the mixed lymphocyte culture test in the horse is described. The test is performed in either round- or flat-bottom microtitration tissue culture plates. Concentrations of responsing and stimulating cells are varied, depening on the experiment. Significant discrimination between isogeneic and allogenic mixtures is possible after 120 hours' culture when cells are labeled ([3H]thymidine) for the last 16 to 18 hours of the test.
Epiglottic entrapment by arytenoepiglottic folds in the horse. An abnormality of the epiglottis and arytenoepiglottic folds that caused epiglottic entrapment was diagnosed in 21 horses. Until recently, this entrapment was poorly understood. Definitive diagnosis of epiglottic entrapment can be made only by endoscopic examination of the epiglottis, arytenoepiglottic folds, and soft palate to differentiate the abnormality from dorsal displacement of the soft palate. Dorsal displacement of the soft palate is often associated with entrapped epiglottis. Epiglottic deformity, especially hypoplasia, is often associated with the entrapment. The abnormality was det...
Scanning electron microscopy of Gasterophilus intestinalis lesions of the equine stomach. The lesions caused by larvae of Gasterophilus intestinalis in the cardiac region of the equine stomach were funnel-shaped ulcers surrounded by a rim of hyperplastic epithelial cells. Bacteria were commonly seen on the rim of epithelial cells, at the base of some ulcers, and within the cavities produced by the hooks of the larvae. Cellular debris and mucus were within the ulcer.
[Immunochemical investigations on the gene expression of horse serum carboxylesterase (author’s transl)]. Immunochemical and enzymatic analyses of horse serum carboxylesterase were carried out with respect to the existence of a silent gene. Sera with positive phenotypic expression of esterase, both heterozygotes and presumed homozygotes, were compared with:--sera with positive phenotypic expression but genotypically +/O;--sera with a negative phenotypic expression, i. e. genotypically O/O;--sera of natural +/O "hemi-zygotes": mules (donkey lacking the esterase);--positive sera heated at 60 degrees C;--positive sera after specific inhibition of enzymatic activity. Titration by immunocompetition has...
Prevalence and epizootiology of equine salmonellosis. Feces from 1,451 horses entering a veterinary hospital over a 13-month period were cultured for salmonella. A total of 46 horses (3.2%) yielded 1 or more salmonella-positive fecal cultures. Twenty horses were found to be excreting salmonella in the feces on admission, and 5 of these later had severe diarrhea associated with enteric salmonellosis. Abdominal surgery and other severe stresses were associated with all cases of severe enteric salmonellosis. Serotypes of salmonella isolated included Salmonella agona (15), S anatum (14), S typhimurium (7), S typhimurium var copenhagen (4), S infantis...
Retrospective study of 350 cases of equine cryptorchidism. Equine cryptorchidism was examined by a review of the literature and a retrospective study of 350 horses over a 14-year period. The incidence of left vs right testis retention was nearly equal. On the left side, 75.2% of the retained testes were retained abdominally and 24.8% inguinally; on the right side, 41.8% of the retained testes were retained abdominally and 58.2% inguinally. Preoperative diagnosis by rectal palpation of the vaginal rings was considered a valuable technique, with 87.9% accuracy in 190 horses. Invasive and nonivasive surgical techniques for abdominal cryptorchidectomy and...
