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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.
Inhibitory effects of horse serum on immunoassay of horse ferritin. The effects of horse serum on the immunoassay of horse ferritin were investigated using two sandwich enzyme-linked immunosorbent assay (ELISA) systems. In System A, affinity-purified antibody to horse spleen ferritin and its conjugate with alkaline phosphatase were used as the first and second antibodies, respectively. In System B, whole antiserum and its conjugate with the enzyme were used. The recoveries of horse spleen ferritin added to horse sera were very low in either system (50-71% in System A; 42-79% in System B). However, heat treatment of the sera at 75 degrees C for 15 min improved ...
Tissue-specific gene expression as an indicator of epididymis-specific functional status in the boar, bull and stallion. cDNA probes derived from genes expressed specifically in the human epididymis were used to examine gene expression in the epididymides of boar, bull and stallion by Northern hybridization. Two probes for the HE1 and HE4 gene products were found to recognize tissue-specific transcripts in all three species, with a regionally differential distribution within the epididymis. Additionally, antibodies recognizing the HE4 protein were shown to react specifically in the epididymis of the boar and bull. An extensive study of the boar showed that, whereas mRNA for the HE1-homologue was up-regulated mar...
In vitro maturation of horse oocytes: characterization of chromatin configuration using fluorescence microscopy. The chromatin configuration of resting horse oocytes and the time course of in vitro oocyte maturation was characterized using a fluorescent, DNA-specific label. Oocytes were classified as having either compact (CP) or expanded (EX) cumuli at the time of collection. Centrifugation of oocytes was effective in allowing visualization of the germinal vesicle. Two main chromatin configurations were found in oocytes known to have a germinal vesicle: condensed chromatin (CC), in which the chromatin formed a dense mass surrounding the nucleolus; and fluorescing nucleus (FN), in which the entire nucleu...
Comparison of the ability to bind lipids of beta-lactoglobulin and serum albumin of milk from ruminant and non-ruminant species. The interaction of sheep, horse, pig, human and guinea-pig whey proteins with fatty acids has been studied. Using gel filtration and autoradiography, it was found that sheep beta-lactoglobulin and serum albumin from all species had the ability to bind fatty acids in vitro. Sheep beta-lactoglobulin, isolated from milk, had approximately 0.5 mol fatty acids bound per mol monomer protein, and albumin from sheep, horse and pig contained approximately 4.5, 2.9 and 4.7 mol fatty acids/mol protein respectively. However, beta-lactoglobulin from horse and pig milk had neither fatty acids physiologicall...
Thromboxane A2 receptors in equine monocytes: identification of a new subclass of TXA2 receptors. Thromboxane (TX) A2 has been implicated as an important pathophysiologic mediator of a variety of cardiovascular diseases. Monocytes synthesize TXA2 and it modulates their function. This study sought to characterize monocyte TXA2 receptors. Radioligand binding studies were performed on membranes prepared from equine peripheral blood monocytes using [125I]BOP, a TXA2 receptor agonist. [125I]BOP bound to a single class of binding sites (Kd = 1.0 +/- 0.3 nM and Bmax = 389 +/- 191 fmol/mg protein; n = 5). Several TXA2 receptor agonists and antagonists competed for binding with [125I]BOP. I-BOP pro...
Equine lutropin and chorionic gonadotropin bear oligosaccharides terminating with SO4-4-GalNAc and Sia alpha 2,3Gal, respectively. Equine chorionic gonadotropin (eCG) and lutropin (eLH) are heterodimeric glycoprotein hormones which are synthesized in the placenta and pituitary, respectively. The beta subunits of eCG and eLH, like their alpha subunits, arise from a single gene and have identical amino acid sequences. In contrast, the beta subunits of CG and LH in primates arise from different genes and differ in sequence. We have examined the structures of the Asn-linked oligosaccharides on eCG and eLH. eCG bears di- and tri-branched Asn-linked oligosaccharides terminating with Sia alpha 2,3 or 6Gal beta 1,4GlcNAc. In cont...
A comparative review of human and equine leucocyte differentiation antigens. Monoclonal antibody technology has allowed the recognition and study of numerous leucocyte antigens in man and laboratory animals for over a decade. Numerous advances in the understanding of immune responses and immunopathology have resulted. In recent years equine researchers have started to develop similar reagents, which now offer a powerful tool to investigators of equine immunology and disease.
Closed-circuit liquid injection isoflurane anesthesia in the horse. Six horses were administered isoflurane anesthesia by liquid injection into a closed breathing circuit according to the square root of time model. The unit dose (UD) was calculated using Lowe's formula to provide an end-tidal concentration of 1.3%, or the minimum alveolar concentration of isoflurane. The mean UD was 4.2 +/- 0.2 mL. The mean end-tidal isoflurane concentration (ETiso) for each interval after injection, and the peak and minimum concentrations for each injection interval, did not change beginning with the second injection, indicating that the square root of time model accurately p...
Relationship between locomotor forces, hoof position and joint motion during the support phase of the stride of galloping horses. Three methods were used simultaneously to determine the relationships between the vertical forces exerted on the hooves and the positions of the limbs and hooves at the times of peak vertical forces from 2 horses galloping on a track straightaway. Vertical forces were recorded from an instrumented shoe, fetlock joint motion was measured with an electrogoniometer and the angles of the carpus, fetlock and hoof were determined from slow-motion films. At hoof contact, the mean angles of the carpus and fetlock were 181-182 degrees and 199-206 degrees, respectively. Peak vertical forces on the heel ...
The estimation of factor VIII levels in horse, cattle, sheep and pig plasma by the use of synthetic chromogenic substrate. Factor VIII level in horse, cattle, sheep and pig plasma was estimated by the use of synthetic chromogenic substrate S-2222 (benzoyl-isoleucyl-glutamyl-glycyl-arginyl-p-nitronilide). The highest level of this factor was stated in pig, the lowest one in sheep plasma.
Surface strain on the dorsal metacarpus of thoroughbreds at different speeds and gaits. Stacked rectangular rosette strain gages were used to measure surface bone strain on the dorsomedial cortex of the third metacarpal bones in 6 adult Thoroughbred horses during treadmill exercise. The peak principal compressive and tensile strains, angle of the peak strains and strain rate during loading were calculated and compared with speed and gait. At speeds from 4 to 14 m/s loading on the metacarpus resulted in compression of the dorsomedial cortex. Tension only occurred consistently in 1 forelimb of 1 horse at the walk (2 m/s). The angle of peak compression was within 10 degrees of the l...
The effect of exploratory laparotomy on the serum and peritoneal haptoglobin concentrations of the pony. Serum haptoglobin concentration was used as an indicator of the acute phase response in ponies undergoing exploratory laparotomy. Preoperative, 1 h intraoperative, 3 h, 6 h, 12 h and 24 h postoperative blood samples and 48 h postoperative peritoneal fluid samples were obtained for haptoglobin analysis. A spectrophotometric assay based on cyanmethemoglobin binding capacity (CyanBC) was used to determine haptoglobin concentrations. The preoperative reference range for serum haptoglobin concentrations in these ponies was 25-60 mg CyanBC/dL. Intraoperative and 3 h postoperative blood samples had d...
Multi-body modelling and simulation of animal locomotion. Multi-body models of musculoskeletal systems can be used to determine internal forces from measured external forces and movements ('inverse dynamics') and to perform simulations of movements using muscle forces or activations as input ('direct dynamics'). Examples of 'direct' simulations of movements in the horse are presented. With a model of the equine hindlimb, the function of the 'passive stay apparatus' could be explained. A model of the forelimb was used to determine force distributions in the digital flexor tendons, and to experiment with various methods to change the force distribution...
Determination of the center of pressure of the hoofs of the forelimbs of horses standing on a flat level surface. The pressure exerted on a flat level surface by recently trimmed, unshod hoofs of the front limbs of 23 sound, adult horses was measured using pressure-sensitive film and a specially built cassette. The horses were tranquilized and stood with one foot on the 2.9-cm-thick cassette and the other on a block of equal height. The hoofs were observed for motion during the measurement, and the developed film was examined for improper alignment of the film or slipping of the hoof. The center of pressure was located using the method of weighted proportions of Barrey. This static measurement system with...
[Indications for ultrasonography in the diagnosis of surgical diseases]. Ultrasonography has established itself as an invaluable diagnostic aid in surgical diseases. In addition to the diagnosis of thoracic and abdominal disease, ultrasonography is increasing in importance in the examination of muscles, tendons and joints in small animals. In the horse, the application of the technique is being extended from tendon conditions to organ diseases. The optimal diagnostic information can only be achieved through the use of different scanner types.
Coronary arterial anatomy of the one-humped camel (Camelus dromedarius). The detailed coronary arterial anatomy of seven camels was studied and compared with that of horses and cattle. In camels, there is a bilateral coronary supply, the right coronary artery being the larger. The left coronary artery follows the same pattern as that in horses. The ramus collateralis proximalis in camels separates off some distance away from the origin of the ramus interventricularis paraconalis, as in horses, whereas it separates of very quickly in cattle. The ramus collateralis distalis has two branches in camels, whereas the left distal ventriculi ramus does not branch. The ramu...
In vivo tendon forces in the forelimb of ponies at the walk, validated by ground reaction force measurements. The load distribution over tendinous structures in the equine forelimb was studied by computing forces from in vivo signals of implanted liquid-metal strain gauges in 5 ponies. For validation, these tendon forces were converted to joint moments, which were summed and compared to the calculated joint moments caused by the ground reaction force. Mean peak forces per kilogram body weight (n = 5) amounted to 5.2 N/kg for the superficial digital flexor tendon, 3.8 N/kg for the deep digital flexor tendon, 7.3 N/kg for the distal accessory (check) ligament and 8.4 N/kg for the third interosseous musc...
A method for loading equine platelets with the fluorescent calcium indicator Fura-2: ADP induces a rise in the cytosolic free calcium ion concentration. Equine platelets in platelet-rich plasma were incubated with the fluorescent indicator dye, Fura-2-AM (Fura-2-acetoxymethyl ester) and the degree of loading of the cells with the dye and the extent of hydrolysis of the ester was assessed by quantitative fluorimetry and by thin-layer chromatography respectively. Under these conditions the cells loaded poorly with Fura-2 to a concentration of 4 microM. The technique was validated by demonstrating adequate loading of human platelets with Fura-2, to a concentration of 250-300 microM, using the same method. The removal of plasma from the extracellu...
[Hemolytic properties of bacteria belonging to the Acinetobacter genus]. Direct and intermediate hemolytic activity of 526 strains of Acinetobacter was investigated. Their ability to produce lipase and lecithinase was also studied. Measurements were performed parallely on human, horse, sheep and bovine erythrocytes. Direct hemolytic activity was exhibited by 16% of tested strains (17 out of 24 strains of A. haemolyticus). Human, sheep and bovine erythrocytes were useful for testing the hemolytic activity of Acinetobacter. The hemolysis was occurring faster and was visible more frequently during incubation at 37 degrees C. Indirect hemolytic activity was observed in...
Assay for endogenous heparin in plasma of livestock using a synthetic chromogenic substrate. The levels of endogenous heparin in the plasmas of horses, cows, sheep and pigs were determined with the use of synthetic chromogenic substrate benzoyl-isoleucyl-glutamyl-glycyl-arginyl-p-nitroanilide (S-2222). The lowest heparin concentrations were stated in cattle plasma, the highest ones in the plasma of pigs.
Shortening of the forelimb in the horse during the stance phase. Compressions in the forelimb of a horse trotting at 3.7 m/s were studied using high-speed cinematography. From a diagram of shortenings it has been concluded that successive loadings in the longitudinal direction from below signify longer impact time and smaller impact forces compared to a theoretically stiff limb. It is proposed that the limb takes up the impact force passively until the onset of loading at the elbow joint, i.e. 30 ms following first contact.
