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.
Watson ED, Zanecosky HG.Immunosuppressive substances which interfere with lymphocyte blastogenesis are released in vitro by embryos and endometrium from mares in early pregnancy. Immunosuppression was not evident when tissues were cultured in the presence of indomethacin (a prostaglandin-synthesis inhibitor). Various prostaglandins (PGs) were added to equine lymphocytes and lymphocyte proliferation was measured after the addition of concanavalin A (Con A) or phytohaemagglutinin A (PHA). PGE2 and PGF2 alpha inhibited Con A-induced blastogenesis down to final concentrations of 1.8 x 10(-9) M and 1.3 x 10(-6) M, respect...
Matthews AG.Distribution of the immunoglobulin (Ig) classes G, A and M within the anterior uvea of eight clinically normal equine eyes was examined using indirect immunoperoxidase labelling. Increased staining intensity of stromal IgG and IgA was observed within the ciliary processes, the iris stroma being relatively free of immunoglobulin. This may reflect anatomical variation in the permeability of the uveal microvasculature to lipid insoluble plasma macro-molecules. Intracellular IgG and IgA were observed within the non-pigmented ciliary epithelium in seven and four of the eight eyes respectively, alth...
Ebert M, Moore-Colyer MJS.The aim of this study was to estimate the energy requirements of Thoroughbred racehorses in active training for flat racing. Twenty-two Thoroughbred racehorses in England were measured over periods from 6 to 15 wk, which included periods of active race training and temporarily reduced training. Energy intake was determined by measuring daily feed consumption. Energy output was measured using heart rate monitors during 730 training sessions, relating heart rate (HR) to oxygen consumption (VO2) and converting VO2 to energy. Field maintenance requirements were calculated by deducting the marginal...
Barshick MR, Gonzalez ML, Busse NI, Helsel PJ, Johnson SE.Satellite cell (SC) activation is defined as the time frame during which the stem cell becomes poised to reenter G1 of the cell cycle. The growth factors and events leading to full mitotic activation in equine SCs remain largely unknown. Insulin-like growth factor I (IGF-I), hepatocyte growth factor (HGF), and fibroblast growth factor 2 (FGF2) are sequentially transcribed during the muscle repair and recovery period following strenuous exercise in adult horses. Expression of IGF-I occurs within 24 h of the postexercise recovery period suggesting it may affect early SC actions. As a first step,...
Rousselle JC, Gillet G, Fillion G.The solubilization of the serotonergic 5HT1 and 5HT3 sites was performed with digitonin and sodium cholate at 1% (final concentration). Two binding sites for [3H]5HT were observed on rat or horse brain synaptosomal membranes solubilized with these detergents. The corresponding dissociation constants (KD) were 1-3 nM and 13-30 nM respectively. These values were closely similar to those corresponding to 5HT1 and 5HT3 sites located in intact membranes. The solubilized sites specifically bound 5HT. The effect of GTP decreasing the binding to 5HT1 sites was lost on solubilized 5HT1 sites; it was re...
Forsell PK, Lindberg A, Karlsson S, Lindgren JA, Claesson HE.It has been demonstrated that equine neutrophils, but not eosinophils, require exogenous arachidonic acid for calcium ionophore A23187-induced leukotriene synthesis. Because cytosolic phospholipase A(2) (cPLA(2)) plays an essential role in leukotriene formation in leukocytes, we investigated the presence of a functional cPLA(2) in equine neutrophils. To determine whether cPLA(2) from neutrophils was catalytically active, we purified the enzyme >6,500 fold with 3% recovery from equine neutrophils. The full-length cDNA sequence encoded a 749-amino acid protein. The deduced amino acid sequence...
Ahern BJ, Lim YW, van Eps A, Franklin S.To determine the effect of a prototype dynamic laryngoplasty system (DLPS) on arytenoid abduction. Methods: In vitro experimental. Methods: Ten equine larynges. Methods: Dissected larynges were mounted, and the right arytenoid was maximally abducted for testing. A left-sided laryngoplasty (LP) was performed by using a strand of No. 2 FiberWire and a FASTakII anchor. Phase 1 involved tightening the suture, without the DLPS device in place, in 1-mm increments and acquiring a digital image of the rima glottidis at each increment. Phase 2 involved tying the suture with the DLPS in place at a left ...
Causey RC, Ginn PS, Katz BP, Hall BJ, Anderson KJ, LeBlanc MM.The aims of this study were to compare various staining and fixation techniques for endometrial biopsy samples and, thus, to investigate the mucociliary apparatus in endometrium from reproductively healthy mares and mares with delayed uterine clearance. Endometrial samples were collected from the left and right uterine horns of reproductively healthy mares (n=5) and mares with delayed uterine clearance (n=4) during anoestrus, transition, oestrus and dioestrus. Each sample of endometrium was fixed in either Bouin's fixative or formalin, and stained with alcian blue (pH 1.0 or 2.5), periodic aci...
Sukhova GS, Ignat'ev DA, Akhremenko AK, Levashova VG, Mikhaleva II, Sviriaev VI, Anufriev AI, Ziganshin RKh, Kramarova LI, Gnutov DIu.From tissues of hibernating and active long-tailed ground squirrels and from the brain of cold-adapted Yakut horses, low molecular peptide fractions were obtained which, after injection to albino mice, decreased oxygen consumption and rectal temperature in them. The same fractions exhibited negative chrono- and inotropic effects on isolated hearts of ectothermic and endothermic animals. Fractions from the brain of ground squirrels and the brain of horse exhibited similar pattern of the activity. The activity of fractions was subjected to seasonal changes and depended on the degree of their pur...
Masuda H, Shichijo S, Takeuchi M.1. Glycopeptides in the stomachs of eleven mammalian species, including human, rabbit, horse, cow, pig, goat, sheep, dog, cat, guinea pig and rat were assayed by determining the carbohydrate content of materials which remained after proteolysis. 2. The glycopeptide content was higher in the mucosa than in the muscular layer including serosa, especially in the porcine stomach and the fourth stomachs of the ruminants than in the stomachs of any other animals. 3. The glycopeptide, which was stained with both alcian blue and PAS, was absent or sparingly present in the mucosae of the human, rabbit,...
Norton NM, Santschi E, Fischer KJ.The etiology of subchondral bone cysts (SBCs) is not fully understood. Mechanical trauma and fluid pressure are two mechanisms believed to cause their formation and growth. The equine stifle joint provides a natural animal model for studying SBCs. Computed tomography images of an extended yearling cadaveric stifle joint were segmented using ScanIP to isolate bones and relevant soft tissues. Three model geometries were created to simulate cyst sizes of approximately 0.03 cm (C1), 0.5 cm (C2), and 1 cm (C3). A uniform pressure resulting in 3000 N force was applied at the proximal end of the fem...
Dusek J.Inbreeding was used in the regeneration process in the breeding of the Kladrub Black Horse. Inbreeding rate is realized in practice, as related to the manifestation of the selected characteristics of this unique horse population. The evaluation of the effect of inbreeding on conception rate and fertility did not demonstrate any differences between the group of inbred mares and non-inbred mares. The study was conducted in mares used for breeding for 10 years. The results provide evidence that inbreeding causes no depression in this characteristics in the Kladrub Black Horse which would otherwis...
Kojima AY, Kobayashi S, Acosta TJ, Kudo M, Miyamoto A, Takagi M, Miyazawa K, Sato K.Microdialysis System (MDS) is a novel technique used for investigation of molecule secretion between different cell populations. Local hormonal secretion at follicular wall has been still unclear. This MDS study was used to determine progesterone (P4), androstenedione (A4), estradiol-17beta (E2) and Prostaglandin F2alpha (PGF2alpha) release in mare pre-ovulatory follicles. Follicles larger than 30 mm were isolated from the ovary and follicular fluid aspirated for hormone assay. Follicular fluid collected from small, middle and large follicles were analyzed by EIA. The concentrations of P4 and ...
Tajima M, Araiso T, Koyama T, Fujinaga T, Otomo K, Koike T.The membrane viscosity of peripheral blood lymphocytes (PBLs) of equine, bovine and canine was measured by the use of time-resolved fluorescence depolarization technique with 1, 6-diphenyl-1,3,5-hexatriene (DPH). The viscosity values were 0.55, 0.59 and 0.50 poise for equine, bovine and canine PBLs, respectively. These values were compared with steady-state anisotropies and order parameters measured from electron spin resonance (ESR) of 5-doxyl stearic acid. Both values were increased with increase of viscosity. The fluid property of the membranes stimulated with phytohemagglutinin-P (PHA) was...
Komori M, Higami A, Imai Y, Imaoka S, Funae Y.A form of P450 [termed P450(h-1)] was purified from the liver microsomes of a male horse to electrophoretic homogeneity. The specific content of the final P450(h-1) preparation was 14.8 nmol/mg of protein and the recovery was 0.38% of the microsomal P450. The apparent molecular weight of P450(h-1) was 52,000 Da. The absorption spectra of P450(h-1) indicated that P450(h-1) was a low- and high-spin mixed type P450 in the oxidized form. The reconstituted system containing P450(h-1) could catalyze benzphetamine N-demethylation, 7-ethoxycoumarin O-deethylation, and testosterone 16 alpha-hydroxylati...
Sandersen C, Dmitrovic P, Dupont J, Cesarini C, Guyot H, Serteyn D, Kirsch K.Different blood gas analyzers are used in equine practice. Every machine needs to be validated, as they have not been designed for use in horses. The aim of this study was to compare the newly marketed GEM5000 machine to the formerly validated epoc machine for blood gas analysis in horses. In this prospective, non-blinded, comparative laboratory analyzer study, 43 equine blood samples were analyzed on both analyzers and values were compared between the two machines via Lin's concordance analysis, Passing-Bablok regression analysis and Bland-Altman plots. Duplicate measurements were conducted o...
Köhler H, Oberlojer HG, Schönbauer M.In the ampulla roof of the wave-like extending horse rectum the muscular coat is only weakly developed as a deltoid-shaped tuna muscularis area, thus forming a place of minor resistance. With regard to the degree of development of the muscular coat a rectal ampulla with a stable form and strong muscles can be distinguished from an ampulla with a labile form and weak muscles. The rupture of the intestinal wall in this region in the case of rupture-experiments as well as the frequent occurrence of diverticula reveals this area as being a place of minor resistance which requires extreme caution d...
Davies HM.The relationships were explored between measurements of bone quality, size (quantity) and shape, and strain data collected during treadmill exercise at 4 and 12 m/s from the third metacarpal bones of 6 yearling and 6 mature Thoroughbred racehorses. Peak strains in yearling and mature Thoroughbred horses during exercise were related to the size and shape of the third metacarpal bone. The peak strains were significantly lower in horses with a greater cross-sectional area of bone and with a greater proportion of the bone in the dorsal cortex. There was no consistent relationship between peak stra...
Jimenez Rihuete P, Villarino N, Pelisiak A, Rubio-Martinez LM.Refractometric determination of total protein (TP) in synovial fluid (SF) is commonly used for diagnosis and monitoring of synovial sepsis in horses. Previous studies have shown that elevated concentrations of certain anticoagulants may overestimate refractometric determination of TP concentration. Objective: The aim of the study was to evaluate the effect of different concentrations of dipotassium EDTA (KEDTA) and lithium heparin (LH) on TP determination by using a hand-held refractometer in equine synovial fluid. Methods: Cross-section observational study. Methods: Thirty samples of synovial...
Vincelette A.This article traces the characteristics, origin, distribution, and function of alternative lateral horse gaits, i.e., intermediate speed lateral-sequence gaits. Such alternative lateral gaits (running walk, rack, broken pace, hard pace, and broken trot) are prized by equestrians today for their comfort and have been found in select horse breeds for hundreds of years and even exhibited in fossil equid trackways. After exploring the evolution and development of alternative lateral gaits via fossil equid trackways, human art, and historical writings, the functional and genetic factors that led to...
Meintjes M, Graff KJ, Paccamonti D, Eilts BE, Paul JB, Thompson DL, Kearney MT, Godke RA.When aspirating ovarian follicles in pregnant mares to obtain oocytes for in vitro fertilisation (IVF), the effect of the manipulation on circulating concentrations of progesterone may be an important consideration in terms of the maintenance of pregnancy. The object of this study was to compare the effects of 3 different forms of transvaginal ultrasound-guided follicle aspiration (Treatment 1, no aspiration, n = 4; Treatment 2, aspirate only follicles > or =20 mm in diameter, n = 7; Treatment 3, aspirate all visible follicles, n = 7) on peripheral plasma progesterone concentrations between Da...
Muccioli G, Bellussi G, Ghé C, Pagnini G, Di Carlo R.The binding of 125I-labeled ovine prolactin (125I-oPRL) to membranes from different brain regions of pigeon, rabbit, rat, pig, calf, horse, and ewe was studied. The hypothalamus from rabbit, pig, horse, and pigeon showed a low but specific binding for 125I-oPRL clearly different from the other brain regions examined (cortex and cerebellum), whereas in the brain from rat, calf, and ewe the binding was very small and quite uniform in the various regions. Also the membranes from choroid plexus of rabbit, pig, calf, and horse showed an evident specific binding for prolactin. The binding of 125I-oP...
Heffron CJ, Baker GJ.Fibreoptic endoscopy was used to study the movements of the larynx and pharynx during nasal occlusion in 10 horses, which showed signs consistent with functional pharyngeal obstruction (FPO) on exercise. Cine-endoscopic films were made on 3 such horses. Consideration of the anatomy of the region indicates that FPO may best be regarded as a subluxation of the nasopharyngeal and larygneal airways and it was found that a constant component of the movements which brought about this subluxation was a marked caudal retraction of the larynx. It is suggested that this caudal retraction of the larynx o...
Numata M, Kondo T, Nambo Y, Yoshikawa Y, Watanabe K, Orino K.Antibody (immunoglobulin G (IgG), IgM or IgA) levels relative to ferritin in six foal sera (three male and three female) after birth (day 0 and 2, 6, 10, 20, 28, 36, 40, 52 and 56 weeks of age) were semi-quantitatively measured with normalization with antibody activity to ferritin in one adult horse serum. After addition of horse spleen ferritin to the serum sample, the complex formed between antibodies to ferritin in the serum and ferritin was co-immunoprecipitated using antibody to horse spleen ferritin. Antibody classes of the co-immnoprecipitate were detected with antibodies specific for h...
Ekman S, Skiöldebrand E, Heinegård D, Hultenby K.One of the most common causes of lameness in racehorses is osteoarthritis (OA). Pathogenesis is not clear and pathological processes of the different joint tissues interact in often progressive events. The interface between cartilage and newly synthesised bone has been shown to be particularly enriched in bone sialoprotein (BSP), a cell-binding matrix protein. Objective: To establish whether changes in the concentration of BSP may serve as a marker for early biochemical changes of the subchondral bone. Methods: Articular cartilage, cartilage/bone interface and subchondral bone of the proximal ...
Lawrence L.The National Research Council (NRC) published the Recommended Nutrient Allowances for Horses in 1949. The subsequent publication was renamed the Nutrient Requirements of Horses and the 6th revised edition was published in 2007. The document has increased in size and scope from the initial publication in 1949 that contained 29 pages to the most recent version with 341 pages. Several formats for expressing requirements (dietary concentrations or daily amounts) have been utilized. In addition, a variety of methods have been employed to determine the nutrient requirements of horses since 1949. Man...
Brasileiro LS, Segabinazzi LGTM, Menezes E, Salgueiro CC, Novello G, Scheeren VFDC, Alvarenga MA, Nunes JF.The aim of this study was to evaluate the effect of coconut water as a component of extender in different formulations for cooling equine sperm. One ejaculate of fourteen stallions was collected. Sperm was diluted to 50 × 10 sperm/mL using five different extenders: ACP-105: powdered coconut water extender (ACP-105, ACP Biotecnologia, Brazil); ACP-Milk: ACP-105 + 20 g/L of skimmed milk; ACP-EY 2.5%: ACP-105 + 2.5% of egg yolk; ACP-EY 5%: ACP-105 + 5% of egg yolk; and BotuSêmen (Botupharma, Botucatu, Brazil) and cooled in passive cooling device (BotuFlex, Botupharma, Botucatu, Brazil) at 5...
Dougherty DM, Lewis P.Using three horses we imvestigated responding on several concurrent variable-interval schedules. Each horse was first trained, using the method of successive approximations, to press a response lever with its upper lip. Following successful acquisition of the lip-press response, horses spent several days on pretraining schedules. These included a continuous reinforcement schedule and three variable-interval concurrent schedules: VI 15-sec VI 15-sec, VI 30-sec VI 30-sec, and VI 45-sec VI 45-sec. Horses were then exposed to the experimental sessions; sessions were conducted daily in the horse's ...
Laidler P, Cowan DA, Houghton E, Kicman AT, Marshall DE.Recognition by the legal authorities that growth hormones (GHs) may be abused to improve sporting performance and/or physique has led to the implementation of controls that make it an offence to produce, supply, possess or import and export GHs, with intent to supply, without the authority to do so. A method is described for the discriminatory analysis of human, equine, porcine and bovine GHs for forensic purposes. Peptide-mass mapping by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry following tryptic digestion gave sequence coverages of 97.4%, 93.7...
Hüthwohl H, Weiss R, Schmeer N, Schliesser T.Classification based on biochemical characteristics of 389 strains of plasma-coagulase-negative (plc-) staphylococci isolated from the genital tract of mares and stallions resulted in the following distribution of species: St. sciuri 130 (33.4%), St. equorum 42 (10.8%), St. xylosus 16 (4.1%), St. epidermidis 35 (9.0%), St. simulans 24 (6.2%), St. haemolyticus 33 (8.5%), St. warneri 18 (4.6%), St. lentus 12 (3.1%), St. hyicus 11 (2.8%). Strains of St. cohnii, St. capitis, St. gallinarum, St. saprophyticus and St. hominis have only been found sporadically (a. 1%). 48 (12.3%) strains could not be...
