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.
Rankin JS, Diesem CD.The hindlimbs of 3 ponies and 3 horses were dissected. The hip joint capsule was found to receive articular nerve fibers from the femoral, obturator, cranial gluteal, and sciatic nerves. The nerve fibers were distributed to the fibrous joint capsule and associated capsular ligaments. The stifle joint capsule was found to receive articular branches from the femoral, saphenous, obturator, common peroneal, and tibial nerves. The fibers terminated in the joint capsule, fat pad, patellar and collateral ligaments, and the internally situated meniscal and cruciate ligaments.
Cannon JH, Grant BD, Sande RD.Development of cysts in the equine paranasal sinuses is probably a congenital disease; however, signs may not appear for several years. In 4 cases, clinical signs were observed when fluid accumulation within the cysts resulted in nasal discharge or facial swelling, or when secondary infection occurred. Treatment required surgical removal of the lining membrane and other involved tissues. Postoperative care included lavage of the sinuses and systemic antibiotic therapy.
Wilbur DJ, Allerhand A.The titration behavior of individual tyrosine residues of myoglobins has been studied by observing the pH dependence of the chemical shifts of Czeta and Cgamma of these residues in natural abundance of 13C Fourier transform NMR spectra (at 15.18 MHz, in 20-mm sample tubes, at 37 degrees) of cyanoferrimyoglobins from sperm whale, horse, and red kangaroo. A comparison of the pH dependence of the spectra of the three proteins yielded specific assignments for the resonance of Tyr-151 (sperm whale) and Tyr-103 (sperm whale and horse). Selective proton decoupling yielded specific assignments for Cze...
Hillidge CJ, Lees P.Measurements of the rate of rise of left ventricular blood pressure (dP/dt) have been made in conscious and anaesthetised ponies. Concurrent measurements of heart rate, mean arterial pressure and left ventricular pressure were also made in order to assess their relationship to values of dP/dt. Thiopentone-halothane and thiopentone-ether anaesthesia reduced the maximal rate of rise of intraventricular pressure (dP/dt max) from conscious control levels. After correcting for variations in the loading conditions of the ventricle, the depressant effect of halothane was still apparent, but the actio...
Rance TA, Park BK, Rowe PH, Dean PD.A radioimmunoassay procedure was developed for the measurement of dehydroepiandrosterone (DHA) in peripheral serum in nonpregnant mares. The synthesis and conjugation of 3beta-hydroxy-5-androsten-19-al-17-one 19(0-carboxymethyl) oxime is described. Antisera were developed against this antigen and characterized. The most specific antiserum was used to measure DHA. Concentrations of DHA were greatest immediately before ovulation.
Reitnour CM, Salsbury RL.Protein digestion, nitrogen retention, plasma protein, plasma urea, and plasma-free amino acids were determined for ponies fed 3 different protein supplements. Substitution of casein, corn gluten meal, or corn gluten meal plus lysine for a portion of the cornstarch in a low-protein basal ration increased apparent digestion of protein. Substitution with either casein or corn gluten meal plus lysine produced a significant increase (P less than 0.05) in nitrogen retention, whereas the corn gluten meal substitution did not. Nitrogen retention, expressed as percentage of nitrogen absorbed, was incr...
Johnson HD, Vanjonack WJ.Recent data on various environmental stressors and blood hormone patterns are presented for lactating cattle. Known stressor effects of such factors as environmental temperature, air pollution, and noise on the plasma thyroxine, growth hormone, cortisol, prolactin, progesterone, luteinzing hormone, epinephrine, and norepinephrine of lactating cattle are discussed. Information on stressor effects is lacking on glucagon, insulin, vasopressin, calcitonin, oxytocin, thyrotrophic hormone, follicle stimulating hormone, melatonin, parathyroid hormone, and estrogens in the lactating cow. The importanc...
Carroll EJ, Lasmanis J, Schalm OW.A method is described for production of an equine anti-bovine leukocyte serum (EABLS). Leukocytes were harvested from the milk of cow's udders which had been irritated with endotoxin. The washed leukocytes as antigens were administered to 2 horses in a series of subcutaneous and intravenous injections. There was a variably progressive increase in total serum proteins and a decrease in albumin/blobulin ratios, but the most pronounced change was an increase in beta2-globulins. Accompanying these changes was an increase in the number of precipitin lines as shown by Ouchterlony analysis. Four old ...
Scott EA, Thrall DE, Sandler GA.Vascular supply of the equine forelimb was partially disrupted by ligation of the medial palmar and medial palmar digital arteries. Vascular architecture was evaluated before and after ligation by angiography. It was apparent from the present study that existing collaterals or newly formed collaterals, or both, were sufficient to maintain limb viability.
Sampaio MU, Galembeck F, Paiva AC, Prado ES.The kinetic constants for horse urinary kallikrein and trypsin hydrolysis of BAEE, TAME, bradykinin methyl ester and bradykinyl-Ser-Val-Gin-Val-Ser were determined. The values of the ratio kcat/Km show that (1) kallikrein is catalytically less efficient than trypsin for all the substrates (2) the three esters are equally good substrates for trypsin while horse urinary kallikrein is 100-fold more effective on bradykinin methyl ester than on the other substrates (3) for both enzymes the ester of bradykinin is a better substrate than the tetradecapeptide.
Sampaio CA, Prado ES.Ala-Phe-Lys-CH2-Cl is a chloromethylketone derivative which is able to promote the inhibition of several proteolytic enzymes. In this paper the inhibition of horse urinary and plasmatic kallikreins is described and this inhibition is compared to that produced in human plasma kallikrein. This compound was designed based upon the structure of bradykinin. This enzyme substrate system can provide a model for the study of the interactions between bradykinin and its receptor. The inhibition of the enzymes was achieved both for its esterase and kinin-releasing activities.
Garel JM, Barlet JP.The plasma concentrations of calcium, inorganic phosphorus, and magnesium were studied during the early postnatal period in a rodent (rats), in ruminants (lambs and calves), and in foals. Decreases in plasma calcium after birth were observed only in newborn rats and foals. In rats the postnatal fall in plasma calcium level was already evident 1 hr after cesarean section (9.20 mg/100 ml) as opposed to 11.90 mg/100 ml in utero) and reached a nadir within 6 hr (-4.05 mg/100 ml). Newborn foals showed a small decrease in plasma calcium (-0.73/100 ml) 48 hr after birth. In the four species plasma in...
Phillips AW, Woodrooffe JG, Courtenay JS, Whitaker AM, Thomas D, Woiwod AJ.Antibodies to cultured human lymphoblasts were raised in horses using a schedule employing both subcutaneous and intravenous routes of injection. Plasma from groups of horses was pooled and the IgG prepared from each pool was tested extensively for safety and immunosuppressive efficacy in vitro and in vivo. On the basis of the results of skin grafting in monkeys, only globulins derived from the first main bleeds were blended to produce a bulk for clinical use. One early pool of globulin was discarded because when undiluted, it was lethal in monkeys by the intravenous route, and another pool wa...
Holowka DA, Cathou RE.IgM antibodies specific for the fluorophore epsiolon-1-dimethylamino-5-naphthalenesulfonyl-L-lysine(DNS-lysine) were elicited in the horse and nurse shark by immunization with a DNS-lysine streptococcal conjugate; the antibodies were purified by specific adsorption with an immunoadsorbent followed by gel filtration to select the IgM class (molecular weight 900 000). About 90% of the equine anti-DNS was IgM.DNS-Lysine, when bound in the combining sites of a population of these anti-DNS IgM antigodies from horse and nurse shark, as well as from pig, exhibited a marked fluorescence enhancement an...
Nitschelm D, Van der Horst CJ.It has been shown that stimulation of the uterus of mares by the daily taking of biopsies can result in the occurrence of oestrous symptoms. This is accompanied by some follicular growth and a progesterone content in the blood often higher than 1 ng/ml. The following observations suggest that this progesterone originates in the uterus and not in the ovaries: (1) no active corpora lutea appeared to be present in the ovaries after ovariectomy, (2) ovariectomized mares showed the same oestrous symptoms in similar experiments and even mating took place, (3) in the uterine biopsies the concentratio...
Serrano L, Lees P, Hillidge CJ.Ponies were anaesthetized by administration of the ataractic, azaperone (0 · 2–0 · 8 mg/kg), in combination with the hypnotic, metomidate (3 · 5 mg/kg). Changes in blood biochemistry were measured during and following the course of action of these drugs. In control experiments, azaperone (0 · 4 and 0 · 8 mg/kg) was administered alone to other ponies. There were no significant changes in blood glucose concentration in either circumstance. Blood lactate and pyruvate concentrations and lactate/pyruvate ratio were not altered significantly by azaperone. However, moderate increases in lactat...
Saiatov MKh, Beĭsembaeva RU.Profiles of distribution of non-specific gamma-inhibitors of influenza A2/Victoria/35/72 in donkey and horse sera were established by gel chromatography in Sephadex G-200. High and low molecular inhibitors were found in 19S and 4S serum fractions. Highly purified preparations of a2-macroglobulin, transferrine and albumin were isolated by a combination of methods of salt precipitation, gel chromatography on Sephadex G-100, G-200 and ion exchange on DEAE-Sephadex A-50. Heating sera resulted in a considerable increase of the antiviral activity of a2-macroglobulin and transferrine and a reduction ...
Archibald AL.1. Serum isoamylases with alpha-glucosidase activity from cattle, sheep, horses, goats, red deer, pigs and dogs were compared to one another. 2. The isoamylases from cattle and pigs were polymorphic. 3. In agarose gel electrophoresis the isoamylases behaved as alpha-1-globulins but in starch gel electrophoresis they were differentially retarded by affinity effects. 4. Molecular weights were estimated: cattle (417,000); sheep (402,000); horses (420,000); goat (399,000); red deer (405,000); pigs (375,000) and dogs (390,000). 5. Isoelectric points were estimated: cattle, sheep, goat and red deer ...
Valeri CR, Valeri DA, Gray A, Contreras TJ, Lindberg JR.When equine RBC were frozen with 20% (w/v) glycerol and stored at -150 C for as long as 5 years, there were no adverse effects on freeze-thaw or freeze-thaw-wash recovery or oxygen transport function. The manner in which the glycerol was added to, and removed from, the equine RBC was shown to be an important consideration in ensuring optimal freeze-thaw-wash recovery values.
Dalefield RR, Palmer DN, Jolly RD.Lipofuscin accumulation and other histological changes in thyroid tissue, previously reported to be age-related, were studied in 31 horses aged up to 35 years. The number of lipofuscin granules relative to thyrocytes increased from birth to 5 years of age. There was a wide individual variation in the number of lipofuscin granules in thyrocytes in mature horses, but this was not directly related to age. Several abnormalities were identified in thyroid colloid. The prevalence of spherites, lipofuscin granules, nucleated cells and shreds of colloid increased with age, but the prevalence of calciu...
van der Linden LS, Bustamante-Filho IC, Souza APB, Lopes TN, da Silva AFT, Tomé LM, Timmers LFMS, Dos Santos SI, Neves AP.The protein disulphide isomerase A1 (PDIA1) is an important chaperone involved in protein quality control and redox regulation. Also, the ability of PDIA1 to bind to oestrogens suggests that it may play a role in epididymal maturation and male fertility. The goals of this study were to (a) verify the possible interaction between 17β-estradiol and equine PDIA1 using bioinformatics; (b) identify and quantify PDIA1 protein in equine cauda epididymis throughout peripuberty; and (c) determine whether the amounts of PDIA1 in equine seminal plasma and spermatozoa are associated with fertility. Using...
Rambags BP, Stout TA.An 18-year-old Friesian mare with a large intrauterine cyst was examined by transrectal ultrasonography. There were several small to moderately sized intraluminal endometrial cysts, one of which connected via the myometrium to a large subserosal cyst, thereby effectively forming a 'transmural' cyst complex. During a videohysteroscopy, the intraluminal part of this transmural cyst was removed by electrocoagulation via a polypectomy snare. It was then possible to drain the large subserosal part of the cyst into the uterine lumen by transrectal massage, thereby confirming the presence of the tran...
Colahan P, Lindsey E, Nunier C.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...
Squires EL, Cook NL.This article describes in detail the procedures for collection of equine oocytes using a transvaginal ultrasound probe. Success in obtaining oocytes from humans, bovines, and horses are presented. The effect of repeated follicular aspiration of both cattle and horses is reviewed.
May SA, Hooke RE, Lees P.Equine interleukin-1 has been produced from peripheral blood monocytes by stimulation with E. coli lipopolysaccharide. Sephacryl S200 gel filtration revealed a molecular weight of 17-18 kD. Chromatofocusing of the 17-18 kD peak identified four active fractions. Two major peaks were detected at pH 6.7 and pH 7, with smaller peaks at pH 6.3 and pH 5.9. The pI 7 molecule is probably the equine form of IL-1 beta.