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.
Cardiopulmonary effects of narcotic agonists and a partial agonist in horses. The cardiopulmonary effects of the narcotic agonists morphine, meperidine, oxymorphone, and methadone and of the partial agonist pentazocine were examined in the pain-free adult horse. The drugs produced dysphoric followed by euphoric effects. Increases in heart rate, arterial blood pressure, and cardiac output were observed in all horses with all drugs. Arterial blood pressure remained increased even after heart rate and cardiac output had returned to base-line values. Respiratory rate generally remained unchanged or increased shortly after drug administration and then decreased insignificant...
Evaluation of xylazine, guaifenesin, and ketamine hydrochloride for restraint in horses. A combination of intramuscular xylazine plus intravenous guaifenesin and ketamine hydrochloride was evaluated as a method for chemical restraint and casting of the adult horse. This drug combination provided safe and rapid induction of the horse and uneventful recovery from lateral recumbency. Cardiopulmonary function remained within base-line values for the adult horse, although cardiac output, arterial blood pressure, and arterial partial pressure of oxygen were decreased from base-line values. Xylazine, guaifenesin, and ketamine hydrochloride provided safe induction to general anesthesia wi...
Rate of change of halothane concentration in a large animal circle anesthetic system. The slow rate of change of inspired halothane concentration which results in a conventional large animal circle anesthetic delivery system when low carrier gas flow rates are used was confirmed, using a model system. To obtain a 63% change in inspired halothane concentration in the 32-L large animal circle anesthetic machine at fresh gas inflow rates of 3, 6, and 12 L/minute required 10.7, 5.3, and 2.7 minutes, respectively. At a given inflow rate, increasing the rebreathing bag size from 20 to 40 L prolonged the time for equilibration between the gas flowing into the anesthetic circuit and th...
Vasculature of the equine and canine iris. Methyl methacrylic casts were prepared and tissue was freshly collected for histologic examination to compare the vascular supply and the structure of the vessels of the iris in the adult horse with those of the dog. In the horse, ciliary blood vessels divided in the iris and formed a complete major arterial circle of the iris. In the dog, the ciliary blood vessels divided in the ciliary body and, by means of recurrent branches, formed a complete arterial circle. From this circle, radial arteries extended toward the pupillary margin. The radial vessels in the horse were nearly straight and joi...
Dystrophic myodegeneration in adult horses. Five horses with histories of colic developed signs of myocardial failure and skeletal muscle disease. Necropsy revealed pale areas in the cervical, pectoral, pelvic, and cardiac musculature; histologically, the lesions were indicative of dystrophic myodegeneration. Serum vitamin E concentrations were normal in 2 of the horses but serum selenium concentrations were normal in 2 of the horses, but serum selenium concentrations were low when compared with values obtained from clinically normal horses.
Coronary arterial anatomy of the small pony. Ventricular weights and coronary arterial distribution and diameters were determined in 10 small adult ponies (139 +/- 32 kg). Combined ventricular weights averaged 0.52% of the body weight, with an average of 77% of the total ventricular weight being the left ventricle. The pony is right coronary predominant, with the interventricular subsinusoidal branch of the right coronary artery and interventricular paraconal branch of the left coronary artery providing comparable blood supply to the left ventricular free wall and septum.
The arterial supply of the navicular bone and its variations in navicular disease. Macroscopic, microscopic and radiological examinations of the navicular bones of 83 horses and ponies showed that the navicular bone in the adult horse has 2 principal routes of blood supply. One supply is present at birth, the other develops within the first 2 to 3 years of life, in response to increasing activity. The size of the nutrient foramina, as seen on radiographs, is related to the type, frequency and regularity of work done by the horse. These foramina are normally conical in shape, alteration to a circular, or mushroom-shape being evidence of occlusive vascular disease in the navic...
Immature stages of Trichonema spp as a cause of diarrhoea in adult horses in spring. Several incidents of diarrhoea and loss of weight occurred in adult horses during the spring of 1976. Detailed investigation of one typical case suggested that maturation of inhibited larvae of Trichonema spp was responsible.
Evaluation of xylazine and ketamine hydrochloride for anesthesia in horses. The cardiopulmonary effects resulting from the combination of xylazine and ketamine hydrochloride were evaluated in the adult horse. Xylazine (1.1 mg mg/kg) administered intravenously prior to or simultaneously with ketamine hydrochloride (2.2 mg/kg; intravenous) provided excellent analgesia and light anesthesia in all horses. Cardiac output, arterial blood pressure, pulmonary arterial pressure, central venous pressure, and pulmonary arterial wedge pressure remained within normal limits for the adult horse. Evidence of respiratory acidosis developed with time during the anesthetic period. Indu...
Effects of training on resting and postexercise ECG in standardbred horses, using a standardized exercise test. Five healthy, mature, previously trained Standardbred horses were given no exercise (left in a stall) for 4 months, then jogged (slow exercise) for 3 weeks, and placed in a 6-week training period. Cardiac variables were measured at the beginning of training and after 14, 20, 35, and 42 days of training before and at 10, 15, 20, 25, and 30 minutes after a 1.8-km (in 3:12 +/- 2 seconds) standard, submaximal exercise test on a deep 0.53-km track. There was no significant change during the 6-week conditioning period in the following variables at rest or at any of the times observed during recovery...
Stimulation of food intake in horses by diazepam and promazine. In two adult horses doses of 0.02-0.03 mg/kg diazepam, intravenously, increased 1 hr intake 54-75% above control levels. Intake was stimulated when the diet was a high grain, calorically dense one and also when the diet was a high fiber, calorically dilute one. Two young rapidly growing weanling horses showed an even more pronounced stimulation of intake. Following diazepam 1 hr intake was increased 105-240% above control lelvels. Promazine at a dose of 0.5 mg/kg also stimulated intake in adult horses, but not as markedly as did diazepam. A transquilizer and a neuroleptic appear to have a stim...
The prevalence, relative abundance and site distribution of nematodes of the subfamily Cyathostominae in horses killed in Britain. A total of 21 species of Cyathostominae was found in the lumen of the large intestine of 86 mature horses of various ages and breeds killed in south-west England during 1972-1974. Cylicostephanus longibursatus, C. goldi, C. calicatus, Cyathostomum catinatum, C. coronatum and Cylicocyclus nassatus were found in over 80% of the horses, while 12 of the remaining species were detected in less than 30%. Quantitative studies on 55 horses showed the adult cyathostome burdens to rise to a sharp peak (average over 400,000/horse) in April-June and a lower one in November-December. Parallel fluctuations ...
Serum antibody to Escherichia coli heat-labile enterotoxin in cattle and swine. Antibody titers to Escherichia coli heat-labile enterotoxin (LT) were measured in serum samples collected from mature cows, butcher pigs, mature sows and adult sheep, horses, dogs, cats, turkeys, and chickens. The frequency of LT antitoxin titers was greatest in sows (94%) and less in cows (38%). Titers were higher in swine than in cattle. There were no LT antitoxin titers in serums from sheep, horses, dogs, cats, turkeys, and chickens. It was concluded that LT-producing Escherichia coli are prevalent in the swine population, but much less so in cattle and the other species examined.
Estimation of cardiac output in the horse by thermodilution techniques. An evaluation and comparison of thermodilution technique with dye dilution technique was made in the computation of cardiac output in 39 conscious adult horses (av body wt, 450 kg). Estimation of cardiac output by thermodilution was found to compare favorably with values obtained from dye dilution when a volume of 30 to 40 ml at a temperature of 0 C was used. Difficulties in obtaining accurate thermodilution curves in the horse seem predominantly associated with errors in mixing and observation.
Effects of training on biochemical values in standardbred horses. Effects of training at a regular, fixed, standard exercise load on venous lactic acid, mixed venous and arterial blood gases and pH, and serum muscle enzymes were determined on previously unconditioned, healthy, adult, Standardbred horses. Arterial and mixed venous blood gases, pH, and serum muscle enzymes did not change in a consistent manner during training. Venous lactic acid concentrations did increase significantly with training and may be of value for the biochemical evaluation of fitness in horses.
Pharmacological experiments as a basis for the administration of digoxin in the horse. It is shown that the concentration of ouabain necessary for 50 per cent inhibition of the Na+K activated membrane ATPase of red cells is similar in man and horse. This is taken to indicate that the two species have similar sensitivity towards cardiac glycosides in general. In five adult healthy horses plasma digoxin concentration was measured with a radioimmunoassay technique after a single intravenous injection of 1 mg/100 kg body weight digoxin. The half time of elimination was 23 h and the apparent volume of distribution 7.3 litres/kg. An approximate estimate of plasma protein binding of di...
Pulmonary arterial wedge pressures: blood gas tensions and pH in the resting horse. Blood pressure recordings were made from right atrium, right ventricle, pulmonary trunk, and pulmonary arterial "wedge" positions in the standing, resting, adult horse. Similarly, comparisons were made of blood samples collected from these vascular positions, as well as from jugular vein and carotid artery. A consistently lower partial pressure of carbon dioxide and a greater partial pressure of oxygen and pH were found in blood samples from pulmonary arterial wedge than from carotid artery. A technique for safe and rapid collection of pulmonary trunk and pulmonary arterial wedge blood gases, ...
Postnatal changes in total and free thyroxine and triiodothyronine in foal serum. Total tyhroxine (TT4), free thyroxine (FT4), total triiodothyronine (TT3) and free triiodothyronine (FT3) concentrations in foal umbilical cord blood were respectively 14, 5 7 and 3 times the concentrations of these hormones in adult horse blood. The TT4 levels in foals declined rapidly to reach adult concentrations by Day 16 and FT4 levels declined steadily during the first 3 months of life. Foal TT3 levels rose during the first 10 hr after birth and thereafter declined, although they were still X2-5 higher than adult levels at 3 months of age. Levels of FT3 similarly increased after birth be...
Activated coagulation test in normal and heparinized ponies and horses. Activated coagulation test (ACT) was performed in 37 adult ponies and 31 adult horses. The mean ACT time of all ponies and horses was 2 minutes 38 seconds, with a standard deviation (SD) of 29 seconds. The ACT was compared with the Lee-White clotting test in heparinized ponies. The correlation of ACT with the Lee-White test was 0.95. Anticoagulation heparinized ponies during prolonged cardiopulmonary bypass was successfully monitored with the ACT. The ACT is simple and reproducible, has a definite end point, and would seem to be an ideal screening test for hemorrhagic diathesis in equine anima...
[The cologne riding course for the blind. Original information on a didactic-methodical approach (author’s transl)]. Since November 1973 a riding course has been carried out with six blind adults. Due to the instructional methods the participants were able to ride independently, without an attendant, after only 30 hours. The effects of riding on the blind encompass coordination training and development of muscle strength. Furthermore, riding has a pronounced influence on the circulatory system. This attractive reaction activity provides the person who, as a result of his specific handicapping condition is limited in both the spatial and social fields, with an expansion of his living space and sphere of exper...
Renal clearance and excretion of endogenous substances in the small pony. Renal clearance and excretion of endogenous substances were studied in 13 small adult ponies (152 plus or minus 93 (standard deviation (SD)) kg). Normal data of serum and urinary concentrations, clearance, and excretion of creatinine, osmolality, free water, sodium, potassium, and chloride during a 12-hour period are presented. Significant linear regressions on body weight (BW) were obtained for creatinine clearance (Ccr (ml/hr) = 127.2 times BW (kg) - 1553), osmolar clearance (Cosm(ml/hr) = 1.81 times BW (kg) m0.3), and free water (CH2O(ml/hr) = - 1.43 BW (kg) - 25.0). Compared with renal exc...
Serum levels of the immunoglobulins IgG and IgG(T) in horses. Levels of the immunoglobulins IgG and IgG(T) in serum in Norwegian horses of the breeds “Døle” and “Fjord” were determined by the quantitative radial immunodiffusion test. No significant differences were apparent between the 2 Norwegian breeds. The immunoglobulin levels were approximately in the same range as previously reported for Shetland ponies. Immunoglobulins could not be detected in the newborn foal. As early as 24 hrs. after birth the mean immunoglobulin level was within the adult range. After a drop during the first month of life, the immunoglobulins increased. IgG(T) rose mo...