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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.
Pharmacokinetics of phenobarbital in the horse. Pharmacokinetics of phenobarbital was examined in 6 mature horses after 12 mg of phenobarbital/kg of body weight was infused over 20 minutes. Biexponential decrease in serum phenobarbital concentrations was observed with a distribution-phase half-life of 0.101 +/- 0.086 hour (mean +/- SD) and a terminal-phase elimination half-life of 18.3 +/- 3.65 hours. The volume of distribution at steady state was 0.803 +/- 0.070 L/kg. Total body clearance of phenobarbital was 30.8 +/- 6.2 ml/h/kg. The high clearance in the horse seems to explain the markedly shorter half-life of phenobarbital in this speci...
Absorption of neomycin from the equine uterus: effect of stage of oestrous cycle and volume of vehicle. Plasma concentrations of neomycin were measured following intrauterine infusion of 3.3 mg/kg bodyweight neomycin sulphate. Mares in oestrus absorbed approximately 6 per cent of neomycin infused whereas mares in a luteal phase absorbed 56 per cent. The volume of infusate also affected absorption as increased volume resulted in decreased absorption. The decreased absorption both during oestrus and when large volumes were used was probably due to reflux of antibiotic through the cervix.
Factors influencing morbidity and outcome of equine ocular squamous cell carcinoma. A retrospective review of 41 cases of equine ocular squamous cell carcinoma with follow up information for 33 horses is presented. An apparent prevalence in heavy horse breeds was identified. Age and sex distribution were similar to those previously reported. High recurrence (42.4 per cent) and low metastasis (6 per cent) rates were seen. Initial tumour location, primary treatment used, or patient case history had no apparent influence on final outcome. The willingness of owners to pursue with continuous treatment correlated with a high degree of success.
Elective inversion of the distal ileal stump into the caecum of the horse. The distal 30 to 40 cm of the ileum cannot be exteriorized through a midline laparotomy incision because of its close anatomical association with the base of the caecum. A method was developed to deal with those cases where this segment of small intestine was involved in an avascular, necrotic process and therefore required resection. The technique involves inverting the distal stump of ileum into the lumen of the caecum and then performing a routine ileocaecal or jejunocaecal anastomosis. This avoids the risk of peritonitis if a Parker-Kerr oversew of the necrotic ileal stump should dehisce. ...
Acute renal failure in six horses resulting from haemodynamic causes. Six horses had been admitted to the hospital because of illness other than renal failure; diarrhoea, myositis, abdominal pain and/or suspected bacterial sepsis. Hypotension and disseminated intravascular coagulopathy were frequent findings in the horses. Abnormally high serum creatinine concentration and urine specific gravity of less than 1.022 were found in the horses with acute renal failure. Hyponatraemia and hypochloraemia were the most common abnormal electrolyte findings. Pronounced hyperkalaemia was not found. Variable degrees of tubular necrosis were seen in three of the four horses t...
Regulation of equine herpesvirus type 1 gene expression: characterization of immediate early, early, and late transcription. The regulation of equine herpesvirus type 1 (EHV-1) transcription was examined in infected rabbit kidney cells using metabolic inhibitors. In order to map EHV-1 immediate early, early, and late transcripts, viral RNA was 32P-labeled in vivo and hybridized to EHV-1 DNA restriction fragments immobilized on nitrocellulose filters. Immediate early viral RNA was mapped to one region of the viral genome within the inverted repeat DNA sequences (map units 0.78-0.83 and 0.95-1.0). Northern blot hybridization analysis using a 32P-labeled cloned DNA probe from this region identified a single immediate e...
Pelvic fractures in horses: 19 cases (1974-1984). The clinical features of 19 horses with pelvic fractures were reviewed. The most common problem was a grade III or IV unilateral hind limb lameness. The prevalence of fractures was greater in females and horses less than 4 years old. All horses were treated with a combination of analgesic administration and stall rest for 2 to 6 months. Seven of 11 horses (64%) available for long-term follow-up evaluation recovered and 4 of 11 (36%) had no lameness when being ridden. Five of seven (71%) horses with fractures that involved the acetabulum recovered, and 4 (57%) had complete resolution of lamenes...
Development of an enzyme-linked immunosorbent assay for the detection of phenothiazine tranquillisers in horses. An acepromazine (ACP) hapten was synthesised, coupled to bovine serum albumin and injected into a horse to produce antibodies to the drug. A competitive ELISA was developed whereby ACP attached to the solid phase via lysozyme competed with free ACP present in phosphate buffered saline, horse serum or horse urine for limiting amounts of antibody. The assay could detect the presence of ACP and, or, some of its metabolites in horse urine for at least 25 hours after intravenous injection of 0.1 mg kg-1 ACP maleate, but because of non-specific interference, horse serum could not be used. As little ...
Genomic heterogeneity of equine betaherpesviruses. The genomes of 51 isolates of slowly cytopathic equine herpesviruses were examined by digestion with restriction endonucleases. Forty-seven of the isolates showed considerable fragment pattern heterogeneity although common fragments were evident, especially when any two isolates were compared or when they were digested with SalI. Fifteen of the 47 viruses, selected for their diverse fragment patterns, showed a high degree of homology in Southern blot hybridization. In contrast, four viruses, representing three epidemiologically distinct isolations, shared few, if any, comigrating fragments wit...
Congenital sinus cyst in a foal. Radiography and endoscopy of a 17-day-old Standardbred foal that had right-sided facial swelling and dyspnea since birth revealed a soft tissue mass in the right nasal passage and right maxillary and frontal sinuses. A bone flap was used to expose the mass, and a fluid-filled structure was removed surgically. After surgery, the dyspnea was alleviated. The facial deformity resolved by the time the foal was 6 months old. The upper airway obstruction was absent clinically and endoscopically by the time the foal was 17 months old.
Arterial blood gas tensions in the horse during recovery from anesthesia. The effects of body position and postoperative oxygen supplementation on arterial blood gas tensions (PaO2 and PaCO2) and pH were examined in clinically normal adult horses during recovery from halothane anesthesia. Hypoxemia developed during recovery from anesthesia in spite of adequate alveolar ventilation in horses without postanesthetic oxygen supplementation. Hypoxemia developed in horses positioned in left lateral or right lateral recumbency, and in horses that were rolled to the opposite side during the recovery period. Arterial blood gas tensions were not significantly (P greater than ...
Polymorphism of the acetylcholine receptor in the horse. A cDNA probe to the alpha subunit of the murine acetylcholine receptor was used to demonstrate restriction fragment length polymorphism in an acetylcholine receptor gene in the horse. Three different patterns of polymorphism have been observed with fragment sizes of 4.3 and 2.9 kilobases (kb) (pattern 1), 4.3 and 2.5 kb (pattern 2) and 4.3, 2.9 and 2.5 kb (pattern 1,2). Analysis of a three generation pedigree has suggested that patterns 1 and 2 represent two allelic forms of the gene encoding the alpha subunit of the acetylcholine receptor. These data provide a basis for the examination of the...
Running and shipping elevate plasma levels of beta-endorphin-like substance (B-END-LI) in thoroughbred horses. A specific RIA for beta-endorphin (B-END) was developed to measure horse plasma levels of B-END-like material (B-END-LI) during exercises and shipping. Three exercise speeds and durations were: trot at 260-300 m/min for 10 min; slow gallop at 390-420 m/min for 5 min and fast gallop at 700-800 m/min for 2 min. Blood samples were taken from 4 horses before, immediately after, 30 and 60 min after exercise. Trotting increased plasma B-END-LI from a basal level of 109 +/- 7 pg/ml to 172 +/- 22 at the end of exercise and returned to 127 +/- 17 and 107 +/- 10 pg/ml at 30 and 60 min after exercise. Si...
Radioimmunoassay of detomidine, a new benzylimidazole drug with analgesic sedation properties. A sensitive and specific radioimmunoassay was developed for detomidine, 4(5)-(2,3-dimethylbenzyl)imidazole. The antibodies were raised in rabbits against a conjugate of detomidine and bovine thyroglobulin prepared by diazo reaction. Detomidine was iodinated with chloramine-T and immunoreactive tracer was purified in cation exchange chromatography. The sensitivity of the RIA was 1.6 fmol/tube allowing direct detomidine measurements from minute serum and urine samples (0.1-0.2 microliter) as well as tissue homogenates (10 microliters). For concentrations below 16 pmol/ml chloroform extraction wa...
Right atrioventricular atresia and ventricular septal defect in a foal. Right atrioventricular atresia with a ventricular septal defect, a rare congenital cardiac anomaly of either animals or man, was diagnosed in a one week old Arabian foal. The foal had been weak and cyanotic since birth, sometimes becoming dyspneic when stressed. Necropsy revealed a dilated and hypertrophied left ventricle with the right ventricle being small. The right atrioventricular valve was absent. The right and left ventricles communicated via a septal defect which was located immediately adjacent to the aortic valve.
Isolation of Legionella pneumophila from calves and the prevalence of antibodies in cattle, sheep, horses, antelopes, buffaloes and rabbits. The lungs of 139 calves presented for autopsy and 29 healthy slaughtered calves were examined for Legionella by culture and by direct immunofluorescence (DIF) with fluorescein-conjugated antisera. About 17% of the cadaver lungs and 4% of lungs from slaughtered animals were positive by DIF. Legionella organisms were only isolated from the lungs of two cadavers (L. pneumophila, serogroup 1). In a prevalence study of antibodies to Legionella in domestic and wild animals of various species, titers of greater than or equal to 64 were demonstrated by indirect immunofluorescence in sera of 10% of dai...
Group C streptococcal arthritis. A case report of equine transmission. Presented is the third known case of a group C streptococcal arthritis, this case documented in a healthy 42-year-old horse trainer, apparently transmitted by a mare. After a delayed diagnosis, the patient responded favorably to surgical drainage and parenteral penicillin G, but required a manipulation of his knee under general anesthesia. Although rare, group C streptococcal arthritis can occur in hosts with no apparent predisposing factors. Frequent exposure to farm animals may increase the risk.
Serum triiodothyronine and thyroxine concentrations in weanling horses fed carbohydrate by direct gastric infusion. Plasma glucose and serum insulin, thyroxine, and triiodothyronine concentrations were monitored in 6 weanling Thoroughbreds after direct gastric infusion of solutions containing sucrose or casein. Neither plasma glucose nor serum hormone concentrations were affected by infusions of water or by infusions of 326 or 424 g of casein/250 kg of body weight. However, glucose and hormone concentrations increased significantly (P less than 0.001) after infusions of 649 or 844 g of sucrose/250 kg. Initial rates of increase were more rapid and increases were subsequently reversed more rapidly when 844 g ...
Cardiovascular drugs. Their pharmacology and use in horses. Knowledge of the dosage, rate and route of administration, and potential side effects of drugs used to treat cardiac disease in horses has been refined. The judicious use of these drugs can increase exercise capacity, improve health, and potentially prolong life. Currently, antiarrhythmics (quinidine, lidocaine), positive inotropies (digoxin), and diuretics (furosemide) are the primary agents used to treat cardiovascular disease in horses. The development of newer drugs (verapamil, milrinone, bumetanide) and their usefulness in therapy for horses with cardiovascular disease require further inv...
Enteroliths in horses. Many cases of enteroliths were reported in the nineteenth century but the number greatly decreased in the early twentieth century. However, in recent years the number of cases in certain parts of the United States such as California has greatly increased. The reasons for the increase are obscure. The intake of nitrogen, magnesium and phosphorus (the primary components of enteroliths) from water and food is likely to be a factor. Arabians may be more likely to develop enteroliths than horses of other breeds. A nidus such as a small stone is needed because a nidus has been found in every enterol...
The bioavailability of phenylbutazone in the horse. [phenyl-14C]-Phenylbutazone was administered to 2 horses p.o. and i.v. on separate occasions. Plasma levels and urinary and faecal elimination of 14C were monitored for up to 7 days after dosing. Phenylbutazone was rapidly and extensively absorbed after oral administration, and its bioavailability was 91% assessed by comparison of plasma AUCs of unchanged drug after p.o. and i.v. administration. The plasma elimination half-life of phenylbutazone was 9.7 h and this was independent of the route of administration. The pattern of elimination of phenylbutazone was independent of the route of admini...
Drug therapy of respiratory disorders. The emphasis of this article is on the clinical application of drugs in therapy for treatment of disorders of the lower respiratory tract. Medications discussed include those used to enhance clearance of secretions and those employed to prevent and/or alleviate bronchoconstriction. Antimicrobial agents and respiratory stimulants are briefly mentioned.
Seasonal changes in density and tissue distribution of Onchocerca cervicalis microfilariae in ponies and related changes in Culicoides variipennis populations in Louisiana. Seasonal changes in density and spatial distribution of Onchocerca cervicalis microfilariae were studied in ventral-midline skin of 15 infected pony mares in southern Louisiana. Triple running mean analysis of data over a 13-mo period indicated that a distinct pattern exists in total microfilariae population density and in microfilariae occurrence in different levels of the dermis. Microfilariae density reaches peak levels in the spring followed by a 58% decrease in the summer, a 19% increase in the fall, and a decrease to the lowest numbers in the winter. Microfilariae were found in all level...
