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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.
Comparison of oral erythromycin formulations in the horse using pharmacokinetic profiles. The pharmacokinetic properties of four erythromycin formulations were compared in six adult horses after administration of single and multiple oral doses. Formulations of erythromycin administered were estolate and phosphate given 37.5 mg/kg every 12 h and 25 mg/kg every 8 h, and stearate and ethylsuccinate given 25 mg/kg every 8 h. Areas under the curve (AUC) and maximum plasma erythromycin concentrations (Cmax) were equal or greater (P > or = 0.05) following administration of erythromycin phosphate and stearate compared with those values following administration of erythromycin estolate or e...
Kinetic evaluation of muscle damage during exercise by calculation of amount of creatine kinase released. To quantify the extent of muscle alteration during prolonged exercise, the release rate of creatine kinase (CK) from striated muscle was measured in six horses during a rest period (6 h) and during three exercise tests (15, 30, and 60 km) at a constant speed of 200 m/min. CK clearance was measured after intravenous bolus administration (150 U/kg) of a CK solution obtained from horse muscle. The CK steady-state volume of distribution was 0.059 +/- 0.0215 l/kg, the terminal half-life was 123 +/- 28 min, and the plasma clearance was 0.36 +/- 0.10 ml.kg-1 x min-1. After an intramuscular CK adminis...
Adrenocortical carcinoma in a 12-year-old mare. A 12-year-old Dutch warmblood mare was examined because it had suffered colic intermittently for a few years and had lost weight in the previous two months. Palpation per rectum revealed a large firm mass in the left sublumbar region; the mass was classified post mortem as an adrenocortical carcinoma. The basal plasma cortisol concentration (at 10.00) of the mare was 94 nmol/litre, within the normal range. As in another case of adrenocortical neoplasm, a functional tumour could not be demonstrated. Only one of the 21 horses with a neoplasm of the pituitary-adrenocortical axis examined by the a...
Sedation of horses with romifidine and butorphanol. Combinations of romifidine and butorphanol were used to sedate 55 horses for a variety of surgical, therapeutic and diagnostic procedures. Eighteen of the horses were given the drugs separately, romifidine first followed by butorphanol four minutes later, and 37 were given the drugs together. The levels of sedation and ataxia were assessed and graded, and there were no statistically significant differences between the two methods of administration. The side effects were typical of the alpha-2 agonists, including bradycardia, heart block and some sweating. Box-walking was observed in one horse....
Prevalence and factors associated with development of laminitis in horses with duodenitis/proximal jejunitis: 33 cases (1985-1991). Medical records of 116 horses admitted to the Texas Veterinary Medical Center between Jan 1, 1984 and Dec 31, 1991 with duodenitis/proximal jejunitis (DPJ) were reviewed. The prevalence of laminitis was 28.4% (33/116; 95% confidence interval: 20.2 to 36.6%). The prevalence of DPJ and DPJ-associated laminitis did not appear to vary significantly by year during the study period. Anamnesis, physical examination, clinicopathologic data, and initial treatment recorded at the time of admission were reviewed to determine risk factors associated with development of laminitis associated with DPJ. A tre...
[An outbreak of equine arteritis virus infection in a riding school]. A major part of the residing horses and ponies of a riding school in Noord-Holland became affected by a febrile disorder that included anorexia, depression, conjunctivitis, urticaria, edema of the legs and laborious locomotion. All remaining horses fell ill within one week. Based on the clinical symptoms the disorder was diagnosed as vasculitis. With serology the causative agent of the disorder appeared to be equine arteritis virus.
Effect of oxytetracycline on metacarpophalangeal and distal interphalangeal joint angles in newborn foals. Thirty-five newborn foals were assigned to 1 of 3 groups and treated with 0.9% NaCl solution (saline; group 1; n = 12), oxytetracycline (44 mg/kg of body weight; group 2; n = 12), or 2-pyrrolidone (oxytetracycline vehicle; group 3; n = 11) in saline solution during the first 36 hours after birth. Serum biochemical analyses were performed on samples obtained from group-1 and group-2 foals before treatment and 24 and 96 hours after treatment. Lateral to medial radiographic views of the forelimbs were obtained before treatment and 24 and 96 hours after treatment in all foals. Metacarpophalangeal ...
Investigation of the metabolism of azaperone in the horse. Urine samples collected from a horse after intramuscular administration of 40 mg of azaperone were extracted at pH 10 before and after acid hydrolysis. The extracts were concentrated and analysed by LC-MS-MS. Two N-dealkylated metabolites, N-despyridinylazaperol and N-despyridinylazaperone, and a low concentration of azaperone were detected in the unhydrolysed urine. Six metabolites; hydroxyazaperol, two hydroxyazaperones, azaperol, N-despyridinylazaperol and N-despyridinylazaperone were detected in the hydrolysed urine extracts. Using XAD-2 resin extraction, three glucuronide conjugated azape...
Genetics of racing performance in the Japanese Thoroughbred horse:: II. Environmental variation of racing time on turf and dirt tracks and the influence of sex, age, and weight carried on racing time. Data collected by the Japan Racing Association (JRA) were individual horse racing times at eight racecourses (Hakodate, Fukushima, Niigata, Tokyo, Nakayama, Chukyo, Kyoto and Hanshin) and at five distances (1000 m, 1200 m, 1400 m, 1600 m, and 1800 m) from 1982 to 1990. Important sources of variation in racing time were examined using a nested model and expressing the variance components as percentages of the total on both turf and dirt. At all racecourses and at all distances where races were on both turf and dirt, racing times were less on turf than dirt. Differences were from 2.09s to 3.91s ...
Genetics of racing performance in the Japanese Thoroughbred horse:: I. Description of the data. The Japan Racing Association (JRA) operates 10 national racecourses with both turf and dirt tracks. JRA formulates the rules for horseracing; registers owners, colors, and horses using foal registration; and licenses all JRA trainers and jockeys. In 1990, at the 10 racecourses there were 288 racing days, 3,353 races, and some 38,397 horses. Horse breeding is concentrated in 7 locations with 93% of the Thoroughbreds foaled each year coming from Hokkaido. Thoroughbred flat racing comprise 92% of all races held. Two year olds race together and nearly 40% of their races are run at 1200 m. Some 39%...
Serum hypoxanthine and xanthine concentrations in horses heterozygous for combined immunodeficiency. A group of diseases termed combined immunodeficiency (CID) results in a severe form of immunodeficiency. While CID in humans has two genetics bases, in Arabian it is inherited in an autosomal recessive manner. Kettler et al. (1989) determined that uric acid was significantly (p 0.05) between carrier and non-carrier horse's serum levels of hypoxanthine or xanthine. These data, combined with our previous ones suggest that an enzymatic lesion in the purine salvage pathway may occur at the urate oxidase step. ZUSAMMENFASSUNG: Serum-Hypoxanthin- und -Xanthin-Spiegel in Pferden mit Heterozygotie fÃ...
Follicular fluid lipoproteins in the mare: evaluation of HDL transfer from plasma to follicular fluid. Using a density gradient ultracentrifugal procedure, we have separated equine plasma and follicular fluid high-density lipoproteins (HDL). The density distribution of the follicular fluid HDL was clearly displaced towards the highest densities in comparison with that of plasma HDL. Similarly, an analysis of size distributions showed a decrease in follicular fluid HDL diameters (4.2 to 9.2 nm) compared to plasma HDL (5.5 to 9.5 nm). HDL were isolated into three subfractions on the basis of the disposition of the Sudan Black stained bands in the centrifuge tubes. Concentrations of each subfracti...
Respiratory mechanics of the horse during the first year of life. This study investigated the developmental changes in the mechanical properties of the respiratory system in growing horses. Pulmonary mechanics and lung volumes were serially measured in anesthetized foals during the first year of life. Quasi-static pressure-volume curves were generated, and functional residual capacity (FRC) was measured using a closed nitrogen equilibration technique. At birth, chest wall compliance normalized to body weight was substantially less than that reported in other less precocious newborn species, while lung compliance normalized to body weight was similar to value...
Influence of intra-articular sodium hyaluronate and polysulphated glycosaminoglycans on the biochemical composition of equine articular surface repair tissue. The influence of repeated intra-articular injections of sodium hyaluronate and polysulphated glycosaminoglycan on the repair of full-thickness osteochondral defects was examined in the midcarpal joints of ponies. The study showed no significant difference between treated and control groups with regard to total collagen content, uronic acid content or the relative proportions of Type I and Type II collagen in the repair tissue, indicating that the drugs did not affect the biochemical composition of the repair tissue 11 weeks after defect induction.
Caffeine clearance in the horse. The pharmacokinetic properties of intravenously administered caffeine were studied in 10 horses using a commercially available automated enzyme immunoassay. The harmonic mean for the distribution half-life was 5.2 min (range 1.4-18.7). The harmonic mean for the elimination half-life was 10.18 h (range 6.82-20.92). The harmonic mean of the volume of distribution was 0.32 L/kg (range 0.22-0.53). There was no correlation between the dose of caffeine/kg body weight and the elimination half-life (Spearman's coefficient of rank correlation = 0.19).
Mechanisms of exercise-induced pulmonary hemorrhage in the equine athlete. This article discusses exercise-induced pulmonary hemorrhage (EIPH), a pathophysiological syndrome which occurs worldwide in the equine athlete. It reviews the history of EIPH, the incidence in performance horses, the etiology, studies performed on the treadmill to determine the mechanisms of EIPH, and the most likely causes of stress failure of the pulmonary capillaries.
Solitary osteochondroma of the nasal bone in a horse. A 3-year-old Appaloosa stallion with a 4 cm x 4 cm x 2.5 cm mass protruding from his nasal bone was evaluated. Radiographs revealed an osseous mass, with a radiopaque outer margin and several radiolucent areas within the body of the mass. The mass was surgically removed and evaluated histopathologically. The histopathological diagnosis was osteochondroma. This case represent the first reported occurrence of an osteochondroma arising from intramembraneous bone in the horse.
Measurements of urethral pressure profiles in the male horse. Urinary tract pressure profiles were evaluated in 6 clinically normal geldings over 3 consecutive days. This was performed by introducing a 1.3 m-long cuffed catheter into the urinary tract, under xylazine sedation (0.8 mg/kg, iv). The method was reproducible. The mean (+/- sd) intra-vesicular pressure (IVP) and maximal urethral closure pressures (MUCP) were 10.3 (+/- 1.7) and 129.8 (+/- 19.6) cmH2O, respectively, and the ratio between MUCP and IVP was 13.2 (+/- 2.5). A gelding with urinary incontinence showed a significantly lower MUCP (73.4 cmH2O), and an MUCP to IVP ratio of 8.0. It was con...
A herd outbreak of equine leukoencephalomalacia. Equine leukoencephalomalacia (ELEM) affected 6 of 10 pleasure horses in adjacent paddocks at a boarding facility. Four of the 6 affected horses died or were euthanized. Two of 3 horses presented for treatment survived with complete resolution of clinical signs. Treatment was primarily supportive. Dimethyl sulfoxide, dexamethasone, flunixin meglumine and thiamine were administered as anti-inflammatory agents and to decrease or prevent cerebral edema. Fusarium monileforme was cultured from ear corn fed the affected horses. Fumonisin B1, B2 and B3 were isolated.
The long-term influence of biotin supplementation on hoof horn quality in horses. The influence of dietary biotin in horses with brittle hoof horn and chipped hooves was investigated in a long-term study, which was performed over a period from one to six years. 97 horses received 5 mg of biotin per 100 to 150 kg of body weight, per os, daily; 11 horses were not supplemented with biotin and served as controls. The hooves of all horses were evaluated macroscopically every three to four months. Hoof horn specimens of the proximal wall were examined histologically and physically in 25 and 15 horses, respectively. The tensile strength of normal coronary horn was 60 N/mm2 or grea...
Ultrasonographic assessment of the proximal digital annular ligament in the equine forelimb. Ultrasonography was used with 6 normal cadaver forelimbs of Dutch Warmblood horses to delineate the ultrasonographic anatomy of the palmar pastern region, with emphasis on the proximal digital annular ligament. Using a 5.5 MHz sector scanner, the thin proximal digital annular ligament was not visible on offset sonograms. Only if the digital sheath in the normal limb was distended was the distal border of this ligament outlined. In all normal limbs the palmarodistal thickness of the combined skin-proximal digital annular ligament layer in the mid-pastern region was 2 mm. The flexor tendons and ...
Frusemide attenuates the exercise-induced rise in pulmonary capillary blood pressure in horses. Catheter mounted micro-tip-manometers (the signals from which were matched with fluid-filled pressure signals from same cardiovascular sites and zeroed at the point of the shoulder), were used to study pulmonary haemodynamics in 8 healthy sound horses at rest and during exercise performed at 8, 10, 12 and 14 m/s on a treadmill. Measurements were made without frusemide (control) and 4 h after iv administration of 250 mg frusemide. Post-frusemide data were also obtained on a separate day, and these observations were not significantly different from those made on the same day as controls. Pre-fru...
Large granular lymphocyte neoplasia in an aged mare. No abstract available
Inhibitory nerve distribution and mediation of NANC relaxation by nitric oxide in horse airways. The distribution of inhibitory nerves and the mediator of the inhibitory nonadrenergic noncholinergic (iN-ANC) nervous system were investigated in smooth muscle preparations from seven regions of equine airways. In tissues incubated with atropine and precontracted with histamine, electrical field stimulation produced frequency-dependent relaxation, and the magnitude of the relaxation decreased from trachea to central bronchi and was absent in peripheral airways. The degree of relaxation in bronchi was not simply a function of bronchial size or generation. Propranolol inhibited part of the rela...
