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.
Banks KL, Henson JB.A defect in lymphocyte function could be responsible for persistent infection by the equine infectious anemia virus. The number of lymphocytes bearing surface immunoglobulin, as detected by immunofluorescence, and lymphocyte response to mitogens were the same in uninfected and equine infectious anemia-infected animals. A defect in T or B lymphocyte numbers or ability to respond to stimuli was not detected in this chronic virus disease.
Ball BA.There are considerable differences between mammalian species in the distribution and activity of ciliated cells within the oviduct, and limited information is available concerning either the distribution or activity of cilia within the equine oviduct. Patterns of ciliary activity were characterized in the ampulla and isthmus of oviducts recovered at 2 d after ovulation from 10 mares, and scanning electron microscopy was used to examine regional differences in the distribution of cilia in oviducts from 3 of these mares. Based upon the motility of 15 microm latex microspheres, ciliary activity w...
Kniazev SP, Nikitin SV.Two polymorphic blood group systems (E and M) of the pig Sus scrofa L. and one blood group system (D) of the horse Equus caballus L. have been studied. On the basis of phenogroup analysis, models describing the formation of the complex allele spectra of these systems and reflecting the contributions of mutations and recombinations have been constructed. The complementary relationships between the antigens determined by the variants of supergenes within the systems, as ell as the probable number and relative positions of the subloci encoding individual groups of antigens in them, have been dete...
Valberg SJ.Movement disorders are defined as involuntary movements that are not due to a painful stimulus or associated with changes in consciousness or proprioception. Diagnosis involves ruling out any lameness and neurologic disease and characterizing the gait during walking backward and forward and trotting. Shivers causes abnormal hindlimb hypertonicity during walking backward and, when advanced, a few strides walking forward. Stringhalt causes consistent hyperflexion during walking forward and trotting and variable difficulty when walking backward. Classification and potential causes are discussed a...
Marqués FJ, Higgins S, Chapuis R, Waldner C.Circulating l-lactate concentration is commonly measured in hospitalized horses by sampling from indwelling intravenous (IV) catheters. However, there are no published evidence-based recommendations to prevent contamination by lactated Ringer's solution (LRS). Objective: Withdrawing 10 mL of blood from the LRS-containing extension set connected to the IV catheter before obtaining the sample for analysis should be adequate to obtain accurate measurement of blood lactate concentration (BLC). Methods: Thirty-three adult hospitalized horses receiving constant rate infusion of LRS. Methods: Immedia...
Suwannachot P, Joosten BJ, Klarenbeek A, Hofma J, Enzerink E, van Weeren PR, Everts ME.To investigate the effects of moderate short-term training on K+ regulation in plasma and erythrocytes during exercise and on skeletal muscle Na+,K(+)-ATPase concentration in young adult and middle-aged horses. Methods: Four 4- to 6-year-old and four 10- to 16-year-old Dutch Warmblood horses. Methods: The horses underwent a 6-minute exercise trial before and after 12 days of training. Skeletal muscle Na+,K(+)-ATPase concentration was analyzed in gluteus medius and semitendinosus muscle specimens before and after the 12-day training period. Blood samples were collected before and immediately af...
Nishita T, Deutsch HF.Equine muscle carbonic anhydrase (CA-III) behaves like ubiquitin in undergoing extensive acylation of N epsilon-lysine residues upon reacting with p-nitrophenyl esters. The enzyme undergoes extensive carbamoylation of lysine residues when reacted with carbamoyl phosphate. The modification of from 6 to 7 lysine residues results in the production of a series of more anodic electrophoretic components. The derivatization of the lysine residues leads to a marked decrease in the enzyme's ability to hydrate CO2. The equine CA-III possesses both acid and alkaline phosphatase activities in contrast to ...
Gauvreau GM, Young SS, Staempfli H, McCutcheon LJ, Wilson BA, McDonell WN.A valved gas collection system for horses was validated, then used to examine the relationship between the respiratory exchange ratio (RER), and plasma and muscle lactate in exercising horses. Four healthy Standardbred horses were trained to breathe through the apparatus while exercising on a treadmill. Comparisons of arterial blood gas tensions were made at 3 work levels for each horse, without (control), and with the gas collection system present. At the highest work level, the arterial oxygen tension (PaO2) was significantly lower (P < 0.05), and the arterial carbon dioxide tension (PaCO2) ...
Rupić V, Bacar-Huskić L, Lojkić M, Habe F, Ergotić N.Research was carried out into the effect that different quantities and compositions of concentrated portions of meal had on certain haematological properties and on the immune response of mares in the course of hyper-immune antitetanus sera production. The experiment involved 24 Nonius and Lipizzaner cross-bred mares divided into two groups of 12 animals each, a control group and a trial group. The experiment lasted 12 months, with haematological and immunological tests being carried out every 30 days. During the course of the experiment each mare was subjected to 11 immunisation cycles, and i...
Jaramillo C, Arias MP, Mosqueda D, Darby S, Renaud D, Gómez DE.This study aimed at describing selected hematological, biochemical, and acid-base variables of adult horses living at sea level and comparing them to those living at 5 different altitudes. One hundred and thirty-eight healthy Paso Fino horses > 2 years old were enrolled. Altitudes included the following: altitude A (0 to 50 m above sea level, masl; n = 23), B (1000 to 1050 masl; n = 25), C (1450 masl; n = 30), D (1950 to 2050 masl; n = 30), and E (2950 to 3100 masl; n = 30). A portable blood gas analyzer was used to determine selected biochemical and acid-base variab...
Wong KS, Cheung HW, Choi YC, To NS, Wan TSM, Ho ENM.Recombinant human follistatin (rhFST) is a potential performance-enhancing agent owing to its stimulating effect on muscle growth. Administration of rhFST to athletes is prohibited in human sports by the World Anti-Doping Agency (WADA) and in horseracing according to Article 6 of the International Agreement on Breeding, Racing and Wagering published by the International Federation of Horseracing Authorities (IFHA). For effective control of the potential misuse of rhFST in flat racing, methods for screening and confirmatory analysis are required. This paper describes the development and validat...
Harland MM, Fedele C, Berens v Rautenfeld D.Horses are highly susceptible to lymphedema. Knowledge of the morphological components of lymphatic collectors is therefore essential to understanding the function of the lymphatic system. A better knowledge of the lymphatic system allows the development of more effective treatments against lymphedema. The composition of hypodermal and deep lymphatic collectors was investigated with immunohistochemical staining, using antibodies against proteins of the collector walls from the skin in the hind limbs of 10 healthy horses. Lymphatic collectors can be subdivided into passive (elastic fibers) and ...
Ellison RS, Jacobs RM.The main purpose of this study was to ascertain whether isoelectric point determination of alkaline phosphatase (AP) using an isoelectric focusing technique on agarose gels could define the isoenzymes present in healthy equine serum. The isoelectric points of AP extracted from nine tissues ranged from pH 3.5 to 7.5 with all tissues having multiple bands. There was considerable similarity in band pattern among tissues, with only pancreatic and colostral AP having substantially different isoelectric points from the others. Sera contained thirteen bands with isoelectric points ranging from pH 3.5...
Suagee-Bedore JK, Hebrock S, Sundin O, Lengi AJ, Corl BA, Worth M.LinPro™ (LP) is a commercial dietary supplement marketed to increase hoof growth and quality. Ten mature (5-15 years) non-pregnant Quarter Horse mares without existing hoof quality issues were used to test the hypothesis that 32 weeks of daily supplementation with 113 g of LP would increase hoof growth rates as compared to non-supplemented controls. Hooves were trimmed at the start of the study and every 8 weeks thereafter. A mark was applied on the hoof wall surface at 2.5 cm below the junction of the hoof wall and coronary band. At each trimming, the distance between the mark and coronary ...
Dart AJ, Snyder JR, Julian D, Hinds DM.The microvascular circulation of the cecum was studied in 15 adult horses, using microangiography and light microscopy combined with gross studies and scanning electron microscopy of vascular replicas. After heparinization, the horses were euthanatized and the cecum was transected at the cecocolic junction. Blood was flushed free of the circulation with isotonic NaCl and the cecal lumen was slightly distended. In 6 horses, the vascular system was injected with a modified radiopaque medium and evaluated radiographically. Sections evaluated radiographically were also prepared for histologic exam...
Mancini RA, Suman SP, Konda MK, Ramanathan R, Joseph P, Beach CM.Research focused on determining the fundamental mechanisms by which lactate influences color stability has not considered a direct effect of lactate on myoglobin. Thus, the objective of this study was to use Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry to examine lactate adduction to myoglobin. Equine oxymyoglobin and equine carboxymyoglobin (0.15mM) were incubated with sodium lactate (200mM) at 4 degrees C, pH 5.6 in 50mM sodium citrate buffer or at 37 degrees C, pH 7.4 in 50mM sodium phosphate buffer, simulating typical meat storage and physiological condition...
Williamson JA, Dascanio JJ, Christmann U, Johnson JW, Rohleder B, Titus L.Simulation in veterinary education offers a solution for bridging the gap between observation and performance of clinical skills. An equine neck model was created that allows repetitive practice of jugular phlebotomy, intramuscular (IM) injection, and intravenous catheterization. The aim of this study was to validate the model for jugular phlebotomy and IM injection. We surveyed experienced veterinarians on the model's realism and the comprehensiveness of its features. In a randomized experimental study, we compared the learning outcomes of first-year veterinary students trained on the model (...
Tobin T, Blake JW, Sturma L, Arnett S.Procaine added to whole equine blood or diluted plasma was hydrolyzed with half times of approximately 9 and 12 minutes, respectively, at 37 C. This hydrolytic activity was sensitive to heating and physostigmine, but did not affect procainamide. At pharmacologic concentrations of procaine, the rate of the hydrolytic reaction depended directly on the concentrations of plasma or procaine in the system and was less in whole blood than in plasma. These properties are consistent with hydrolysis being due to plasma esterases operating at less than saturating procaine concentrations. These esterases ...
Aggarwal BB, Farmer SW, Papkoff H, Stewart F, Allen WR.Serum of the pregnant donkey, like that of the mare, contains a gonadotrophin of chorionic origin. The chorionic gonaditrophin of the donkey (dCG) has been isolated in purified form from the serum of pregnant donkeys using methodology previously employed for the purification of pregnant mare chorionic gonadotrophin (eCG). Unlike eCG, dCG is predominatly an LH in biological tests. In the in-vitro rat Leydig cell assay, dCG was as active as eCG, but in the in-vitro rat seminiferous tubule assay for FSH and in the augmentation assay, dCG was considerably less potent than eCG (1-10%). Specific rat...
Moore AB, Roesel OF, Fessler JF, Bottoms GD.The value of naloxone (1 mg/kg of body weight/hr for 4 hrs), a beta-endorphin antagonist, was assessed in the management of endotoxin-induced shock in ponies. Three groups of 5 ponies each were used: controls, ponies given Escherichia coli endotoxin put untreated, and ponies given endotoxin and then treated with naloxone. Endotoxin-induced changes in hemodynamics, blood chemical values, regional blood flow, plasma enzymes, and energy supplies were measured at selected times during the first 6 hours after endotoxin was given. There was no evidence that beta-endorphins released during shock were...
Clerbaux T, Serteyn D, Willems E, Brasseur L.The equine blood oxyhemoglobin dissociation curve has been traced in its entirety in standard conditions and the effects of temperature, pH and 2,3-diphosphoglycerate on this curve have been measured. When compared to that of human blood, the curve showed a higher oxygen affinity of hemoglobin (23.8 +/- 0.8 versus 26.6 mm Hg). The effect of the pH, expressed by d log P50/dpH, was found to be identical in man and horse (-0.47). The effect of temperature, however, expressed by d log P50/dT, proved to be lower in the horse (0.016 versus 0.024). The P50 showed an increase of 1 mm Hg each time 2,3-...
Aramaki S, Suzuki E, Ishidaka O, Momose A, Umemura K.The pharmacokinetics of caffeine (CAF) and its metabolites, dimethylxanthines, were examined in horses administered 2.5 mg/kg of CAF intravenously (i.v.), intramusculary (i.m.), or orally (p.o.). The plasma samples were extracted by Extrelut and the concentrations of CAF and metabolites were determined by high performance liquid chromatography (HPLC) with a short column. The pharmacokinetics of CAF after bolus i.v. injection were described by the assumption of a two-compartment model, and those of CAF after i.m. or p.o. administration were done by the assumption of a one-compartment model. The...
Calzone S, Wilkins C, Deckers I, Nankervis K.The EquiAmi Training Aid (ETA) is a popular training and rehabilitation tool, however knowledge about its effect on the equine gait is lacking. Understanding of its effects on equine kinematics, and the clinical relevance of these effects is vital to promote optimal use of training aids within training and rehabilitation programmes. Therefore, this study aimed to determine how the ETA influences horses' gait kinematics at walk and trot. Eight horses walked and trotted in-hand with and without the ETA. Optical motion capture was used to measure forelimb and hindlimb pro- and retraction angles, ...
Brommer H, Back W, Schamhardt HC, Rijkenhuizen AB, Barneveld A.To improve fracture treatment, in vitro experiments were performed to study the influence of a full limb cast and a walking cast on the loading regimen of bones in the distal portion of the equine forelimb. Methods: 6 forelimbs of 6 Shetland ponies. Methods: Loading of the third metacarpal bone was considered a representative measure for distal limb loading. Electrical resistance rosette strain gauges were attached to the dorsal, palmar, medial, and lateral surfaces of the midshaft of this bone in 6 forelimbs of 6 Shetland ponies. The limbs were tested in a pneumatic loading device to a maxima...
Dzierzęcka M, Jaworski M, Purzyc H, Barszcz K.The aim of the study was to analyse selected densitometric and geometric parameters in the third metacarpal bone along the long axis in horses. The densitometric parameters included the cortical and trabecular bone mineral density, while the geometric parameters included the cortical, trabecular, and total areas, strength strain index X, strength strain index Y, and the polar strength strain index. Methods: The parameters were analysed using eight sections from 10% to 80% of the length of the bone. Peripheral quantitative computed tomography was used in the study. Statistical analysis was carr...
Hyun SH, Ryew CC.The aim of this study was to investigate the motor ability of forelimb according to on- or off-riding during cadences (walk and trot) of horse. Horses and rider selected as subject consisted of total 37 heads of Jeju native horse and 1 female rider. The variables analyzed composed of 1 stride length, 1 step length, elapsed time of stance, elapsed time of swing, elapsed time of 1 step, and forward velocity (x-axis). Two-way analysis of variance of variables was employed for the statistical analysis with the level of significance set at 5% (P<0.05). Trot cadence showed significant difference ...
Shults T, Combie J, Dougherty J, Tobin T.An operant conditioning apparatus for studies in equine pharmacology was constructed. Horses interacted with this apparatus by breaking a light beam and were rewarded with 30 ml of oats. Horses readily learned to use this apparatus and were trained to respond on a variable-interval-60 schedule. With this schedule, there was no direct relationship between the rate of light beam breaking and the reward. Horses thus developed their own individual response rates (ie, light-beam breaking rates), and these rates remained stable at between 5 and 35 responses/min for each horse over a period of months...
Fulton IC, Derksen FJ, Stick JA, Robinson NE, Walshaw R.The efficacy of a nerve muscle pedicle (NMP) graft in restoring upper airway function was evaluated in exercising horses with induced left laryngeal hemiplegia. The NMP graft was created from the first cervical nerve and the omohyoideus muscle and transplanted into the left cricoarytenoideus dorsalis muscle. Seven adult Standardbreds were trained to exercise on a treadmill inclined at 6.38 degrees. With the horses at rest and exercising at 4.2 and 7.0 m/s, the following variables were recorded: peak inspiratory and expiratory transupper airway pressures (defined as the pressure difference betw...
Schuberth HJ, Hadam M, Leibold W.The determination of differentiation and transplantation antigens will be of growing importance in immune diagnosis for individual animals as well as for breeding purposes in populations. Differentiation antigens characterize subsets of cell populations and indicate their functional capacity while transplantation antigens represent markers of individuals of a species. Occurrence and significance of these antigenic systems are briefly reviewed.
Asperio RM, Marzola P, Sbarbati A, Osculati F, Addis F.To analyze the tendon of the deep digital flexor (TDDF) muscle of the forelimb in horses by use of a contrast radiographic agent (gadopentate dimeglumine [Gd-DTPA/Dimeg]) and magnetic resonance imaging (MRI) and to determine the concentration of water protons in the tendons by use of MRI. Methods: 8 TDDF harvested from the forelimbs of 6 horse cadavers. Methods: Examinations were performed on the same portion of each tendon. Tendons were examined by use of two techniques: MRI before and after treatment with Gd-DTPA/Dimeg as well as scanning electron microscopy. Results: Tendons did not have de...
Grandi D.An ultrastructural and immunohistochemical analysis was performed on the epiphysis of two species of mammals: mink and horse. These animals present a reproductive cycle that varies along the year according to the light exposition. The aim of the study was to define possible structural changes connected with the gonadal activity. Structural aspects in common emerged such as those in concern with the epiphysis cells, their immunocytochemical characteristics (NSE and Synaptophysin positivity of pinealocytes, as well as CFAP positivity of further cells), and those in concern with the general ultra...
