Topic:Adult Horses
Adult horses encompass a category of equines that have reached maturity, typically considered to be around five years of age and older. This stage of life is characterized by full physical development and the potential for peak performance in various activities such as riding, racing, and work. Adult horses require specific nutritional, health, and management practices to maintain optimal condition and performance. The study of adult horses covers a range of topics, including physiology, behavior, and the impact of environmental factors on their well-being. This page compiles peer-reviewed research studies and scholarly articles that explore the physiology, health management, and performance aspects of adult horses.
Effects of xylazine and ketamine hydrochloride on the electroencephalogram and the electrocardiogram in the horse. A continuous series of electroencephalograms (EEG) was obtained from each of 6 mature horses which had been given xylazine and ketamine hydrochloride IV. Electrocardiograms and respiratory rates were also obtained. The EEG of the unsedated standing adult horse displayed a dominant fast activity in the range of 25-35 Hz, 5-30 microV superimposed over slower 1-4 Hz, 10-50 microV activity with occasional 10-14 Hz, 10-40 microV spindle-type activity. The xylazine-sedated horse displayed hypersynchronous EEG patterns, with the dominant activity being 1-3 Hz, 10-70 microV with overlying mixed freque...
Effects of etiocholanolone and prednisolone on intravascular granulocyte kinetics in horses. The functional capacity of the marrow granulocyte reserve (MGR) in 4 adult horses was studied, using 51Cr-labeled leukocytes. The mean increase in the peripheral granulocyte count following injections of etiocholanolone (0.3 mg/kg) was 870 granulocytes/mm3, and the mean increase following prednisolone administration (200 mg) was 5,880 granulocytes/mm3. Etiocholanolone failed to mobilize the MGR and decreased the rate of granulocyte egress from the blood. Prednisolone rapidly mobilized the MGR and markedly decreased the granulocyte specific activity during the first 3 hours after injection.
Aqueous procaine penicillin G in the horse: serum, synovial, peritoneal, and urine concentrations after single-dose intramuscular administration. Six adult mares were given a single dose of aqueous suspension procaine penicillin G (300,000 IU/ml) IM at a dosage of 22,000 IU/kg of body weight (15.4 mg of penicillin G/kg). Serum, synovial fluid, peritoneal fluid, and urine penicillin concentrations were measured serially over a 48-hour period. The mean peak serum penicillin concentration was 1.42 microgram/ml at 3 hours. Penicillin was detected in synovial fluid and peritoneal fluid, which obtained mean peak penicillin concentrations of 0.62 microgram/ml and 0.58 microgram/ml, at 4 hours and 3 hours, respectively. These concentrations ste...
Oxytetracycline hydrochloride in the horse: serum, synovial, peritoneal and urine concentrations after single dose intravenous administration. Six adult mares were given a single intravenous injection of oxytetracycline HCl (50 mg/ml) at a dosage of 5 mg/kg. Serum, synovial fluid, peritoneal fluid, and urine oxytetracycline concentrations were measured serially over a 48-h period. The highest measured serum oxytetracycline concentration was 8.01 mcg/ml at 1/2 h. Oxytetracycline was detected in synovial fluid and peritoneal fluid, which obtained mean peak oxytetracycline concentrations of 4.43 mcg/ml and 4.20 mcg/ml, at 1/2 h and 1 h, respectively. These concentrations steadily declined in parallel with serum concentrations and were n...
Cardiopulmonary effects of butorphanol tartrate in horses. The cardiopulmonary and behavioral effects of butorphanol were evaluated in pain-free adult horses. Butorphanol tartrate was administered IV in doses of 0.1, 0.2, and 0.4 mg/kg to the same horses on 3 separate occasions. There were no significant (P less than 0.05) changes in heart rate, mean and diastolic arterial pressure, mean and diastolic pulmonary arterial blood pressure, or cardiac output recorded in the horses given these doses. Systolic arterial blood pressure was significantly (P less than 0.05) increased in only the horses given the 0.2 mg/kg dose. Significant (P greater than 0.05) ...
Characterization of equine alkaline phosphatase isoenzymes based on their electrophoretic mobility by polyacrylamide gel disc electrophoresis. Alkaline phosphatase isoenzymes of equine tissues, peritoneal fluid, and serum were characterized by their electrophoretic mobilities, using polyacrylamide gel disc electrophoresis. The alkaline phosphatase isoenzymes in liver, kidney, spleen, small intestine, placenta, bone, small colon, and large colon tissue samples were extracted and separated by electrophoresis. The resulting isoenzyme mobilities and spectrophotometric scans were evaluated for their tissue specificity and for their possible use in determining the tissue contribution of alkaline phosphatase to serum and peritoneal fluid. T...
The effect of joint position on juxta-articular bone marrow pressure. Relation to intra-articular pressure and joint effusion–an experimental study on horses. Six metacarpo-phalangeal joints of adult horses were studied. Pressure measurements were made in the joint and the metacarpal bone with simultaneous measurement of the systemic arterial blood pressure. Investigations performed to study the effect of joint position on juxta-articular bone marrow pressure showed that an increase in joint flexion was always followed by a rise in intraosseous pressure with a significant increase at flexion above 60 degrees. Increase in intra-articular pressure which was achieved by injection of saline was always followed by a slower rise in intraosseous pressure. ...
Lymphocyte immunostimulation in the diagnosis of Corynebacterium equi pneumonia of foals. A lymphocyte stimulation test using antigens of Corynebacterium equi was used to compare the response of peripheral blood lymphocytes from foals with C equi pneumonia with those of clinically normal foals and adult horses. The test clearly distinguished infected foals from normal foals when tested in animals less than or equal to 2 months old. After the 2nd month, stimulation response from individual normal foals sometimes exceed those from infected foals, but mean stimulation response to C equi antigens was significantly (P less than 0.025) greater in 3- to 5-month-old infected foals when com...
Guaifenesin: cardiopulmonary effects and plasma concentrations in horses. We determined the cardiopulmonary changes in horses given guaifenesin alone and in the same horses given xylazine (IV) immediately before administration of guaifenesin. In addition, plasma guaifenesin concentrations were determined in horses and 2 pregnant mares and compared with previously published values in ponies. The dose of guaifenesin necessary to produce lateral recumbency in adult horses was 134 +/- 34 mg/kg (mean +/- SD). The administration of guaifenesin caused insignificant (P less than 0.05) changes in heart rate, respiratory rate, right atrial pressure, pulmonary arterial pressur...
Effect of pyrrolizidine alkaloid-induced hepatic disease on plasma amino acid patterns in the horse. Plasma amino acid patterns were studied in 6 clinically normal adult horses during the course of hepatic disease induced by feeding them plants containing pyrrolizidine alkaloids. At death, there were significant (P less than 0.01) increases in glutamine, proline, tyrosine, asparagine, lysine, histidine, alanine, phenylalanine, methionine, aspartic acid, and ornithine values. There were no significant changes in glycine, valine, isoleucine tryptophan, and arginine values. There were significant (P less than 0.01) decreases in citrulline. Ammonia increased 4-fold. Alpha-Aminoadipic acid and alp...
Hydatidosis in donkeys in Morocco. The lungs and livers of 429 adult donkeys from different parts of Morocco were examined for hydatid cysts; 4·2% of lungs were infected and 2·1% of livers. Most of the cysts were small and had very hard thick walls; 61% of the donkeys had only one hydatid cyst; 78·5% of them were sterile and 29% caseated or calcified.
Vascular supply of the equine stifle joint. The vascular supply of the equine stifle joint was investigated, using latex vascular injections of pelvic limbs from 3 adult horses and 6 ponies. Vessels were grossly dissected to the small arteriole level. The primary source of blood supply was the femoral artery and its branches which entered the joint on the caudal and medial surfaces. The superficial vasculature arose from the caudal branch of the deep circumflex iliac artery cranially and laterally, and from the saphenous and descending genicular arteries medially. The deep vasculature arose from the popliteal artery and its branches on ...
Digoxin pharmacokinetics, bioavailability, efficacy, and dosage regimens in the horse. The pharmacokinetics of IV administered digoxin and the bioavailability of intragastrically administered powdered digoxin tables suspended in water were investigated in 6 clinically normal adult horses by 125I radioimmunoassay. The effect of 3 to 5 sequential IV doses of 5 micrograms of digoxin/kg of body weight at 2-hour intervals on a left ventricular index of contractility (Vmax) was assessed in 5 clinically normal horses. Standard pharmacokinetic equations and mean pharmacokinetic variables were used to derive parenteral and oral (loading and maintenance) doses for digoxin in horses. The c...
Relationship between QRS-duration (heart score) and racing performance in trotters. Heart scores increased with age and training. Yearlings had average heart scores of approximately 90 milliseconds (msecs). This increased to approximately 110 msecs in 5-year-old horses, after which there was only slight further increase. In horses 4 years or older, regression analysis revealed a highly significant correlation between heart score and kilometre time. In younger horses the level of significance was less. There was a positive correlation between heart scores and earnings in races. Thus, horses with heart scores above 115 msecs had won considerably more than horses with lower hear...
Cardiopulmonary, behavioral, and pharmacokinetic effects of propoxyphene in horses. The acute behavioral cardiopulmonary and pharmacokinetic effects of propoxyphene hydrochloride were studied in seven adult horses. Each horse was given three different dosages of propoxyphene (0.5, 1.0, 2.2 mg/kg) IV. Fourteen days was allotted between each drug administration. The lower IV dosages of propoxyphene (0.5, 1.0 mg/kg) resulted in no changes in indices of cardiopulmonary function. Four horses demonstrated a transient period of muscle fasciculations when given 0.5 mg of propoxyphene/kg. Horses given 1.0 mg/kg demonstrated a brief period of euphoria, ataxia, and muscle fasciculations...
Toxicoinfectious botulism in foals and adult horses. Toxicoinfectious botulism was proved to be the cause of a neuromuscular paralytic syndrome in foals and adult horses. In eight successive cases, Clostridium botulinum type B was isolated at necropsy. Foals were either found dead without premonitory signs of illness or, most often, they had signs of progressive and symmetric motor paralysis. Stilted gait, muscular tremors, and the inability to stand longer than 4 to 5 minutes were the salient clinical signs. Other clinical manifestations included dysphagia, constipation, mydriasis, and frequent urination. As the disease progressed, dyspnea with...
[Pharmacokinetic model studies of sulfamerazine in domestic mammals. 1. Elimination of Mebacid 200 following intravenous administration to large animals]. Pharmacokinetic data of sulphamerazine were recorded from eight heads each of calf, adult cattle, horse, and sheep, following intravenous application of Mebacid 200, and mathematical implications were discussed. Exponential excretion was recorded from all species, according to the following equation: c = B x e-k2 x t The most favourable pharmacokinetic parameters were recorded from calf.
The immune response of horses to tetanus toxoid. An intramuscular injection of 8-16 Lf tetanus toxoid in water-in-oil emulsion protected adult horses against tetanus for at least 128 weeks. A booster dose of 8 Lf toxoid in aqueous solution protected them for a further period of at least 3 1/2 years. Colostral immunity protected foals for at least 10 weeks. An intramuscular injection of 8 Lf toxoid in water-in-oil emulsion given to foals from immune dams when they were 10-18 weeks old did not elicit any antibody response. They did respond, however, to a booster injection of 8 Lf toxoid in aqueous solution given 12 weeks after the first dose. ...
Enema in the horse. Distribution and rehydrating effect. In the first series of experiments enema containing a water soluble marker was given to two groups of horses fasted for 1 and 18 hours, respectively. The marker was only in 1 out of 14 experiments found orally of the pelvic flexure (Table II). Fasting seemed to facilitate the flow in oral direction. The results were discussed with the possible significance in the treatment of large intestinal impactions. In the second series the effect of enemas on water, electrolyte and acid-base status in the acute furosemide-dehydrated horse was studied. Moderate acidifying and hypokalemic effect was encoun...
A probable congenital diaphragmatic defect in an adult pony. The presenting signs exhibited by a pony with a large diaphragmatic defect of probable developmental origin are described. The results of clinical examination, laparotomy and post mortem examination are presented.
Studies on experimental enteric salmonellosis in ponies. Clinical, bacteriological, serological and haematological observations were made on 13 adult ponies orally inoculated with Salmonella typhimurium. The results were compared to two control ponies and four others infected by accidental transmission. The clinical responses in inoculated ponies included pyrexia lasting four days and neutropaenia during the first five days after inoculation followed by a neutrophilia. Pyrexia and neutropaenia was associated with maximal shedding of organisms in the rectal faeces. Changes in the character of the faeces occurred between one and two days after inocula...
Intracecal endotoxin and lactate during the onset of equine laminitis: a preliminary report. Cecal fluid from two adult horses was assayed by the limulus amebocyte lysate system for endotoxin before and after carbohydrate overload of the gastrointestinal tract. There were increases in cecal fluid endotoxin concentrations at the 3-, 6-, and 12-hour samplings when compared with base-line values. Concomitant cecal fluid lactate concentrations and pH values increased and decreased, respectively. Both horses subsequently developed clinical signs of acute laminitis.
A serological survey of Leptospira interrogans serotype pomona in Saskatchewan horses. Leptospira interrogans serotype pomona antibody titres of 1:100 or greater were detected in 12.8% of 408 adult horses from seven of eight sampled herds in Saskatchewan. The geographical distribution of the seropositive horses was widespread throughout the agricultural area of the province. The geographical distribution and the cumulative increase in prevalence with age suggested that serotype pomona is enzootic in the equine population of Saskatchewan.
Volume dilution of sodium thiocyanate as a measure of extracellular fluid volume in the horse. Volume dilution of sodium thiocyanate as a measure of extracellular fluid volume was determined in 24 normal adult horses and 4 ponies. The method employed yielded highly reproducible results on multiple determinations in individual horses. A highly significant (P less than .001) correlation between thiocyanate space and body weight was demonstrated.
An investigation of the action and haemolytic effect of glyceryl guaiacolate in the horse. Glyceryl guaiacolate (GGE) was found to be a useful and safe casting agent when given by rapid intravenous infusion. It was administered to premedicated horses under controlled conditions at various concentrations from 10 to 20 per cent GGE solution. The onset and degree of relaxation was dependent only on the speed of infusion. For casting adult horses 350 to 450 ml of 15 per cent solution must be given within 30 to 60 seconds. A slight transient hypoxaemia occurred which seemed to be related to the animal being in lateral recumbency rather than the depressive action of GGE on respiratory fun...