Omneity® Pellets
All-In-One Vitamin & Mineral Pellet
Topic:Physiology
The physiology of horses encompasses the study of the biological functions and processes that occur within the equine body. This includes the examination of various systems such as the cardiovascular, respiratory, musculoskeletal, digestive, and nervous systems. Understanding equine physiology is essential for comprehending how horses adapt to different environmental conditions, perform physical activities, and respond to health challenges. Research in this field often focuses on the mechanisms of energy metabolism, thermoregulation, and muscle function during exercise, as well as the physiological responses to stress and disease. This page compiles peer-reviewed research studies and scholarly articles that explore the diverse aspects of equine physiology, providing insights into the biological processes that support the health and performance of horses.
Potency of halothane-N20 in the horse. The minimal alveolar concentration (MAC) of halothane which just prevented purposeful movement in response to electrical stimulation was determined in 11 young, healthy, unpremedicated horses breathing oxygen (O2) or nitrous oxide (N2O) and O2. Ventilation was controlled during these MAC studies. The arterial PO2 was always greater than 90 mm of Hg and the average PaCO2. range was 36 to 40 mm of Hg. The MAC for halothane in O2 was 0.93 vol %. Alveolar N2O concentrations of 25% and 50% reduced the halothane MAC about 12% and 25%, respectively. In 8 of these horses, the cardiovascular effects of...
Haemodynamics in the horse: 1. Pressure pulse contours. Using a catheter with 2 transducers, one mounted at the tip and one 9 cm proximal to it, enabled transvalval pressure waveforms to be recorded in 8 horses. A simultaneous electrocardiogram acted as a time base. The changing waveforms produced in the chambers of the heart and great vessels are described and related to the events of the cardiac cycle. The effect of second degree AV block, ectopic beats, a pan diastolic murmur and chronic obstructive pulmonary disease are described.
Measurement of specific laryngeal muscle function by ultrasound. Ultrasonic dimension gauges were implanted in the crico-arytenoideus dorsalis muscle in a mature horse. Resting and contracted muscle length and average contraction rate were measured serially in the conscious state over a period of 25 days. Results suggest that specific laryngeal muscle function in the horse may be defined with this approach. Since man and horse are both known to suffer from laryngeal hemiplegia, this experimental preparation may help provide information of benefit to both species.
Pregnant mare’s serum gonadotropin. IV. Induction of premature labor by pregnant mare’s serum gonadotropin and its prevention by using clomiphene or indomethacin. The administration of pregnant mare's serum gonadotropin (PMSG), 30 IU on day 18 of pregnancy, resulted in premature labor in rats. However, this abortifacient efficacy of PMSG was not demonstrable when a simultaneous injection of progesterone, clomiphene, or indomethacin was scheduled, thus suggesting that the action of PMSG is medicated by the estrogen-stimulated release of prostaglandin. The termination of pseudopregnancy in bilaterally hysterectomized rats by PMSG and its reversal by indomethacin revealed that the inhibition of luteal function by PMSG does not require the presence of a ute...
Analysis of mechanisms regulating the expression of parental alleles at the GPD locus in mule erythrocytes. Erythrocyte glucose-6-phosphate dehydrogenase (G6PD) was examined by 13% starch gel electrophoresis in 74 mules (42 females and 32 males), 35 donkeys, and ten horses. The quantitative expression of the parental alleles at the Gpd locus varies greatly in female mules from the hemizygous expression of the maternal allele to that of the paternal. The data obtained indicate that the X chromosomes are randomly inactivated in females mules. No selective advantage of a cell population with a maternally (or paternally) derived X active was found in female mule erythrocytes. It is suggested that the ph...
The effects of exercise and adrenaline infusion upon the blood levels of propranolol and antipyrine in the horse. There are now several examples showing that experimentally induced changes in hepatic blood flow can have a marked effect upon the elimination of certain high clearance drugs. Changes in hepatic blood flow produced by exercise might therefore be expected to influence the clearance of these drugs. There was an increase of up to 100%, compound to control values, in the plasma levels of propranolol in horses given either d- or dl-propranolol, 0.2 mg/kg b.wt., and then subjected to sustained exercise for 30 minutes. There was, however, no similar increase with exercise in the plasma levels of anti...
Pregnant mare’s serum gonadotropin: V. Indomethacin or cortisone and the reversal of antifertility efficacy of pregnant mare’s serum gonadotropin. Pregnant mare's serum gonadotropin (PMSG) of 10 IU on day 5 of pregnancy induced luteal demise and consequently an absolute resorption of fetuses and placentae resulted on day 16 of pregnancy. Simultaneous regimen of PMSG and indomethacin or cortisone was found to be consistently effective in preventing the luteolytic effect of PMSG. The growth of the fetuses, placentae as well as corpora lutea was found to be parallel to controls. Similarly, shortening of the duration of pseudopregnancy to 10--12 days in the bilaterally hysterectomized rat by PMSG and its retaining the normal duration of 18--...
Plasma volume and extracellular fluid volume in horses at rest and following exercise. Plasma volume and extracellular fluid volume were determined in horses at rest and immediately after a standardized exercise test. Exercising during training demonstrated no detectable effect on plasma or extracellular fluid volume determinations when compared with resting values. An explanation of this finding and an argument for the proper analysis of plasma and extravascular fluid volumes are presented.
[The interaction between phosphate and protein, and the respiration of the llama, the human fetus and the horse (author’s transl)]. The sequence analysis of llama (Lama glama, Camelidae) hemoglobin is described. The chains were separated, cleaved by trypsin as previously described, quantitatively characterized and sequenced in the sequenator. The llama hemoglobin differs from the human hemoglobin in that it has 25 different amino acids in the alpha chain and 24 different amino acids in the beta chain. The interaction between protein and phosphate is discussed. The earlier finding that the O2 affinity of the llama hemoglobin is dependent on its content of 2, 3-bisphosphoglycerate is interpreted here as a mutation of the 2, ...
Testosterone and progesterone in peripheral plasma during the oestrous cycle of the mare. Measurements every day or every other day showed that testosterone levels ranging from 15 to 70 pg/ml were higher at oestrus in 4 of the 6 mares studied. In these 4 mares, another testosterone peak occurred 11--13 days before the next oestrus either before (3 mares) or after the fall in progesterone levels.
Species of differences in postganglionic motor transmission to the retractor penis muscle. 1 Graded motor responses were elicited in isolated, desheathed, thin strips of dog, horse, pig and sheep retractor penis (RP) muscles by field stimulation with trains of 0.2 ms pulses at 10 hertz. These twitches were shown to be neurogenic in all four species, by their prompt extinction in tetrodotoxin.2 alpha-Adrenoceptor blocking drugs abolished the contractile response to noradrenaline and to tyramine in all four species.3 Motor transmission was wholly adrenergic in the horse as in the dog RP because phentolamine rapidly abolished the electrically induced twitches in both these species; but...
Specific reaction of aloe extract with serum proteins of various animals. We found that aloe extract contains a lectin-like substance which reacts with serum proteins of various animals. Furthermore, in human serum 2 proteins, alpha2-macroglobulin and alpha1-antitrypsin, were shown to be reactive with aloe extract.
A case of spermatic arteriovenous anastomosis in the horse. A large anastomosis of the spermatic artery and vein is described. This was found while surgically removing an abdominal testis. Before surgery the animal wanted to rear after exercise and could not stand on 3 legs for any length of time while being shod. This unusual behaviour disappeared after removal of the mass. The performance and conformation of the horse has also greatly improved.
A phonocardiographic study of equine heart sounds. The occurrence and timing of heart sounds were examined from phonocardiograms taken from the mitral, aortic and tricupsid recording areas in each of 18 horses. 10 sound events could be identified with each cardiac cycle. Atrial contraction produced up to 3 sound events. The first heart sound consisted of 4 components whereas the second sound was single. Two sound events were associated with the 3rd heart sound in early diastole. The occurrence of third and fourth heart sound components varied between horses and between recording areas. The mitral recording area was considered most satisfactory...
