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.
Schenkman KA, Marble DR, Burns DH, Feigl EO.Multiwavelength optical spectroscopy was used to determine the oxygen-binding characteristics for equine myoglobin. Oxygen-binding relationships as a function of oxygen tension were determined for temperatures of 10, 25, 35, 37, and 40 degrees C, at pH 7.0. In addition, dissociation curves were determined at 37 degrees C for pH 6.5, 7.0, and 7.5. Equilibration was achieved with a myoglobin solution, at the desired temperature and pH, and 16 oxygen-nitrogen gas mixtures of known oxygen fraction. Correction for the inevitable presence of metmyoglobin was made by using a three-component least squ...
Smith JM, Meyers KM, Barbee DD, Schott H, Bayly WM.To determine whether plasma von Willebrand factor (vWf) concentration changes in horses during and after treadmill exercise. Methods: 5 mature, fit Thoroughbreds. Methods: A blood sampling catheter was placed in the right jugular vein. A warm-up period was followed by a 3-minute rest period. Horses were galloped at racing pace until fatigued (about 2 minutes). Blood samples were collected prior to warm-up, during the postwarm-up rest period, 1 minute into the run, at cessation of the run, and 5 to 120 minutes after cessation of the run. vWf activity was measured by ELISA and corrected for plas...
Hermanson JW.The extensor carpi radialis muscle of the horse is deceptive at first appearance. It has a fusiform shape similar to other forearm extensor muscles. The fiber arrangement also appears long and relatively parallel. However, it may contain two or more compartments that correlate with differing functional roles. Histochemical and immunocytochemical analysis of proximal and distal regions of the muscle (n = 9) demonstrate that the proximal portion of the muscle is composed of a mean of 13% type I, presumed slow twitch, and 61% type IIb, presumed fast twitch fibers. In contrast, the distal compartm...
Herholz C, Tschudi P, Gerber H, Moens Y, Straub R.A new computerised ultrasound-based spirometry system according to Buess et al. (1995) modified by a double flow measurement facility was used to study pulmonary function in healthy horses and horses affected with subclinical and manifest chronic bronchiolitis (CB). The horses were first evaluated at rest without any medication. On another occasion all horses were tested following i.v. administration of xylazine (0.4 mg/kg) and following i.v. administration of lobeline hydrochloride (l.hy.; 0.2 mg/kg) to evaluate the effect of xylazine and l.hy. on different spirometric variables. Ultrasound-b...
Proudman CJ, Holmes MA, Sheoran AS, Edwards SE, Trees AJ.The equine intestinal cestode Anoplocephala perfoliata has been the subject of recent epidemiological and immunological studies because of its suspected association with intestinal disease in the horse. We have previously shown that the IgG(T) subtype antibody response to the 12/13 kDa component of the parasite excretory/secretory (E/S) antigen is positively correlated with parasite intensity. In this study, we utilize that correlation to examine the changes in natural infection intensity with age. Infection intensity based on IgG(T) responses showed a triphasic age-dependency pattern with pea...
Miteva MA, Kossekova GP, Villoutreix BO, Atanasov BP.The present work shows the application of an optical label pyridoxal phosphate (PLP) for the experimental determination of local electrostatic potentials in singly substituted cytochromes c modified by pyridoxal phosphate at Lys 79 (PLP-Lys-79-cyt.c) or at Lys 86 (PLP-Lys-86-cyt.c). PLP has also been used to calculate the pKa values of all ionizable groups and the electrostatic potentials in the modified proteins and to analyse their properties. The experimental pKa values for the pyridine nitrogen and phenolic hydroxyl of the bound label were obtained from pH-dependent absorbance and fluoresc...
Mulligan RS, Livesey JH, Evans MJ, Ellis MJ, Donald RA.It has been suggested that atrial natriuretic peptide (ANP) is the long-sought inhibitor of corticotropin (ACTH) secretion, but the evidence is conflicting. We have examined the effect of ANP and C-type natriuretic peptide (CNP) on the secretion of ACTH by perifused equine pituitary cells in an in vitro milieu intended to mimic the in vivo milieu in the horse. Corticotropin-releasing hormone (20 pM) and cortisol (0 or 100 nM) were perifused continuously and 7 pulses of arginine vasopressin (AVP; 10 nM) applied for 5 min at 30-min intervals. ANP (1 nM) or CNP (1 nM) were perifused continuously ...
Sharp DC, Thatcher MJ, Salute ME, Fuchs AR.The effect of transcervical endometrial biopsy on the concentrations of plasma immunoreactive oxytocin and 15-keto-13,14-dihydro-prostaglandin F2 alpha (PGFM) was studied in 18 pony mares on days 8, 12 and 14 after ovulation, days 12 and 14 of early pregnancy and at oestrus. Five biopsy specimens were taken within 15 min and consecutive specimens from each mare were pooled two (A) and three (B) together for measurement of the number of oxytocin receptors. Blood samples were collected at intervals of 5 min for 15 min beginning just before the initial biopsy. Biopsy procedure elicited prompt oxy...
Añor S, Espadaler JM, Monreal L, Mayhew IG.The electrically induced blink reflex was studied electromyographically in 21 healthy adult, detomidine-sedated horses. Using surface electrodes, the supraorbital nerve was electrically stimulated at the supraorbital foramen. The responses were recorded from the ipsilateral and contralateral orbicularis oculi muscles with concentric needle electrodes inserted in the lateral aspect of the ventral eyelids. Ipsilateral and contralateral recordings were made on successive stimulations of the same side of the face, maintaining a constant stimulus intensity. The electromyographically recorded respon...
Bousfield GR, Butnev VY, Gotschall RR, Baker VL, Moore WT.There are two species for which both pituitary and placental gonadotropins are readily available, humans and horses. The human gonadotropins are better characterized than equine gonadotropins. Nevertheless, the latter are very interesting because they provide exceptions to some of the general structure-function principles derived from studies on human and other mammalian gonadotropins. For example, separate genes encode the hLH beta and hCG beta subunits while a single gene encodes eLH beta and eCG beta. Thus, eCG and eLH differ only in their oligosaccharide moieties and eLH is the only LH tha...
Reinert M, Calvete JJ, Sanz L, Mann K, Töpfer-Petersen E.The primary-structure of HSP-7, a 14-kDa protein isolated from stallion seminal plasma, has been determined, HSP-7 belongs to the spermadhesin protein family, shares 98% sequence identity with the boar seminal plasma protein AWN, and, like its boar homolog, displays zona-pellucida-binding activity. Despite these conserved structural and functional features, the equine and porcine spermadhesins differ in their topography on spermatozoa.
Gentry PA, Zareie M, Liptrap RM.The amounts of total protein, albumin, fibronectin, alpha 2-macroglobulin (alpha 2-M), immunoglobulin G, ceruloplasmin and antithrombin were determined in fluids collected from 53 preovulatory equine follicles and compared with the contents of estradiol-17 beta, progesterone and androstenedione, with follicle size and the amounts of the equivalent proteins in normal equine plasma. The concentration of fibronectin and the fibronectin/albumin ratios increased significantly with follicle size and with follicular estradiol levels. The alpha 2-M levels and alpha 2-M/albumin ratios correlated with f...
Izumisawa Y, Yamaguchi M, Bertone AL, Tangkawattana P, Masty J, Yamashita K, Kotani T.The structural arrangement and cellular distribution of endothelial and lining cells of the synovial villi were studied in the equine palmar/plantar recess of the metacarpo- and metatarsophalangeal joints by light microscopy and electron microscopy. The extent and distribution of blood vessels varied with villous shape and length. The majority of vessels formed concentric circles in cross and longitudinal sections and probably are arranged in a convoluted, spiral or helical pattern. The villi do not contain smooth muscle cells or typical capillaries as observed in other organs. Under the elect...
Hendrickson DA.The determination of poor performance in the young or unproven horse can be a difficult experience for the practitioner. This article describes an incremental exercise test that may be helpful in determining the cause of poor performance in horses when a complete physical examination and a lameness examination fail to elucidate the causes of poor performance. Included are values from normal yearling and 2-year-old horses that have undergone the incremental exercise test.
Parente EJ.The many testing methods available and the increasing sophistication of diagnostic equipment have enhanced greatly our capabilities to diagnose causes of exercise intolerance in the equine athlete during the last several years. High-speed treadmill examination has become the focus of this form of evaluation. Not all clinicians perform or have access to high-speed treadmill examinations. Testing methods that require the use of the high-speed treadmill, as well as methods that do not, are discussed.
Young LE, Blissitt KJ, Bartram DH, Clutton RE, Molony V, Jones RS.In order to determine if transoesophageal Doppler echocardiography could be used to estimate cardiac output in anaesthetized horses, we have compared the technique with estimations of cardiac output by thermodilution in eight healthy adult thoroughbreds. Measurements of aortic blood flow velocity were made by high pulse repetition frequency (HPRF) and continuous wave (CW) Doppler echocardiography from a 3.5-MHz transoesophageal probe. Cardiac output was increased during the study by administration of dobutamine, providing a range of cardiac output measurements by thermodilution from 15.0 to 64...
van den Berg IS.An apparatus for collection of free-flow urine from female horses is described. This apparatus is a modification of a similar device described previously. It allows the collection of voided urine from adult female horses without confining them to metabolic stables or resorting to invasive procedures like bladder catheterisation. It is relatively easy to use after a short adaptation period.
Klaus AM, Hapke HJ.This review compromises data about endogenous cortisol and its physiological variations in horses. The influence of synthetic glucocorticoids on the endogenous cortisol concentrations is discussed as well. The second part of the review summarizes detection times of therapeutically used glucocorticoids (dexamethasone, betamethasone, triamcinolone, prednisone, prednisolone, methylprednisolone and hydrocortisone) in the horse and their implication for doping control.
Kobluk CN, Gross GM.This article deals with the presenting histories, clinical examinations, and therapies of the causes of poor performance and exercise intolerance in the western performance horse and the sprint racehorse. The veterinarian's ability to diagnose and treat various pathophysiologic conditions that affect these horses is crucial to the major goals of a return to optimal performance and a long athletic career. Although these horses are a significant portion of most veterinary practices, there exists a minimal amount of information on their clinical evaluation and treatment. This article intends to f...
Conley KE, Jones C.We test the hypothesis that myoglobin is important for O2 supply near the oxidative capacity of muscle. This hypothesis is evaluated with a simple model that incorporates the properties of heart and skeletal muscle tissue taken from steers and horses exercising at their maximum O2 consumption rate. These tissue samples allowed us to set the bounds on oxidative demand and O2 flux from red blood cells to the core of the muscle fiber, to estimate the blood and tissue capacities for O2 diffusion, and to define the capillary blood PO2 driving this O2 flux. A model combining blood convection with ti...
Gonzales DS, Jones JM, Pinyopummintr T, Carnevale EM, Ginther OJ, Shapiro SS, Bavister BD.The behaviour of bovine, equine and human blastocysts was studied in vitro by time-lapse videomicrography and computer imaging. This study revealed that cytoplasmic extensions of the trophectoderm ['trophectoderm projections' (TEP)] were expressed by embryos of all three species, prior to or during zona escape. Bovine and human blastocysts escaped their zonae with a combination of blastocoele expansion, collapse and re-expansion coupled with the penetration of the zona pellucida by TEP. In equine embryos, after several cycles of blastocoele expansion and collapse, trophectoderm ruptured the zo...
MacDonald MH, Benton HP.To determine the influence of activated equine neutrophils on sulfated glycosaminoglycan metabolism of equine articular cartilage in vitro. Methods: Articular cartilage explants harvested from the metacarpophalangeal joints of 7 horses. Methods: Proteoglycan degradation and synthesis were measured by release of glycosaminoglycan from the explants, and incorporation of [35S]sulfate into newly synthesized glycosaminoglycan. Results: Activated equine neutrophils significantly increased the release of glycosaminoglycan from explant matrix and the magnitude of that response was influenced by durati...
Gottlieb-Vedi M, Essén-Gustavsson B, Lindholm A.Five Standardbred trotters performed treadmill exercise with incrementally increasing trotting velocities for 2 min intervals in three different tests until fatigue. Each test was performed with draught loads of either 10, 20 or 30 kilopond (kp). Each trotting interval was followed by 2 min periods at a walk without draught load. Recordings were made of heart rate (HR), respiratory rate (RR), plasma lactate (PLA) and stride frequency (SF) at the end of each trotting interval. The HR increased to average values of 191 +/- 10,203 +/- 10 and 214 +/- 7 bpm and PLA increased to 3.8 +/- 0.7, 7.3 +/-...
Foreman JH.Metabolic causes of exercise intolerance can be subtle and difficult to document in horses. Because of increased metabolic rate in exercising muscle, most metabolic causes of exercise intolerance are clinically manifested by muscle abnormalities such as ER. Newer causes of ER are being documented by current research and are summarized in the article on muscular causes of equine exercise intolerance. Endocrine causes of exercise intolerance have been poorly documented, but recent work has shown the detrimental effects of hypothyroidism on exercise tolerance in horses. Many metabolic manifestati...
Still J, Serteyn D, van der Merwe CA.Anaesthesia was induced in horses (n = 6) with a mixture of thiopentone and guaiphenesin and maintained by mechanical ventilation with a mixture of oxygen, air and isoflurane. Inspiratory and end-expiratory concentrations of oxygen, carbon dioxide and isoflurane were measured. Electrocardiography was used to evaluate heart rate and rhythm. Mean systemic arterial pressure (SAPm), pulmonary artery pressure (PAPm), right atrial pressure (RAPm) and pulmonary capillary wedge pressure (PCWP) were measured directly. Cardiac output was determined using the thermodilution method. Microcirculation in th...
Sheoran AS, Holmes MA.Equine IgG possesses four well-defined subisotypes, designated IgGa, IgGb, IgGc and IgG(T) on the basis of their increasing anodal mobility in electrophoresis. However, the preparation of IgGa and IgGb reference proteins has not previously been reported. Certain bacterial cell wall proteins, termed protein A and protein G, have been used for purification of IgG subisotypes from the serum of domestic animals which, combined with other techniques utilising differences in the physico-chemical properties of the proteins, has allowed the purification of Ig isotypes. This paper describes purificatio...
Singh S, McDonell WN, Young SS, Dyson DH.To assess the usefulness of glycopyrrolate (GLY) in preventing the decrease in cardiac index (CI) usually caused by xylazine (XYL)/ketamine (KET)-induced anesthesia in horses. Methods: 6 healthy horses. Methods: Horses were treated with saline solution or 2.5 micrograms of GLY/kg of body weight, administered i.v. 15 minutes later, XYL (1 mg/kg) was administered i.v., followed 5 minutes later by KET (2 mg/kg) administration. The horses were positioned in left lateral recumbency, insufflated with 15 L of oxygen/min, and maintained for 30 minutes on the infusion of 0.05 mg of XYL and 0.1 mg of KE...
Gaughan EM.Skeletal origins of exercise intolerance and performance failure can reside in multiple tissues. Diagnosis of injury that results in an ability to continue to exercise, yet inefficiently do so, requires familiarity with evaluation of subtle lameness and often with the specific demands of the different equine sports. Imaging is usually vital to diagnosis development and understanding of lesion influences on locomotion. Therapy is lesion dependent. Return to competitive exercise and performance is dictated by an understanding of skeletal tissue response to injury, rational progressive treatment,...
Flaminio MJ, Gaughan EM, Gillespie JR.Endurance competition requires synchronism and development of metabolic and musculoskeletal systems. An understanding of the existence of performance-limiting factors may permit the detection of exercise intolerance that could lead to performance failure, fatigue, and exhaustion. New concepts for assessment of fitness have increased the understanding of individual capacities and deficiencies and the interaction of the different systems involved in exercise.
Ito S, Ishimaru M, Hobo S, Fujinaga T.Rapid infusion is believed to be harmful to the lung, however, the pathological status of pulmonary edema resulting from excessive fluid therapy in horses has not been clarified because the quantitative diagnosis of pulmonary edema is impossible. To evaluate the precision of the double indicator dilution method using heat and sodium in horses, which allows the quantitative diagnosis of pulmonary edema, we compared extravascular lung water volume measured using a lung water computer based on the theory of the double indicator dilution method with that determined by the direct method. The value ...
Wehrman RF, Genschel U, Charli A, Kanthasamy AG, Allbaugh RA, Ben-Shlomo G.To establish a physiologically relevant ex vivo model of equine corneal epithelial wound healing. Methods: Fourteen equine corneas were randomly assigned to one of two groups: wounded (n = 8) or unwounded (n = 6) controls. In the wounded group, the axial corneal epithelium was removed by applying a 6 mm filter paper disk soaked in 1N-NaOH for 60 s. Corneas were subsequently cultured using an air-liquid interface model. Evaluation of corneal healing was performed daily, and culture medium was collected. Corneas were randomly assigned to undergo processing via histopathology and RNAscope i...
Boudreaux MK, Koehler J, Habecker PL, Del Piero F.Exercise-induced pulmonary hemorrhage (EIPH) is a common disorder of equine athletes. The role of polymorphisms in genes encoding hemostasis-regulatory proteins in horses with abnormal hemorrhage is unknown. Objective: The goal of this study was to evaluate the genes encoding 2 ectonucleotidases, CD39/NTPDase-1 and CD39L1/NTPDase-2, and one ecto-5' nucleotidase, CD73, in horses with abnormal hemorrhage or pathologic changes consistent with EIPH. Methods: Twenty-three horses with histories of abnormal hemorrhage, 8 horses with gastrointestinal signs, and 45 healthy horses were evaluated using p...
Jensen-Waern M, Lindberg A, Johannisson A, Gröndahl G, Lindgren JA, Essén-Gustavsson B.The effects of an endurance ride on neutrophil functions in endurance-trained horses were evaluated and related to metabolic changes and changes in cortisol concentrations. Blood samples were taken from 7 horses (aged 9-15 years) one day before, and then 30-60 min, 1 day and 8 days after the ride. The race resulted in elevated serum cortisol levels (< 465 nmol/l) and an increased neutrophil:lymphocyte ratio. Immediately post race, the neutrophil ability to engulf yeast was increased. One day after the race, a decrease in leukotriene B4 production (approximately 40%) and in the respiratory b...
Valentini S, Castagnetti C, Musella V, Spinella G.Objective of this study was to describe intraocular measurements in newly born foals (1-7 days of age) and assess the association between globe measurements and gender, laterality, and body weight. B-scan ultrasonographic biometry was performed on both eyes of 22 healthy foals (44 eyes) ages 1-7 days using a 10-MHz transducer. Intraocular measurements (anterior chamber depth, central lens thickness, vitreous chamber depth, axial globe length, longitudinal globe length, lens poles distance) were carried out using the ultrasound internal calipers. The influence of gender (male or female), latera...
El-Sheikh Ali H, Scoggin K, Murase H, Norris J, Menarim B, Dini P, Ball B.The equine chorioallantois (CA) undergoes complex physical and biochemical changes during labor. However, the molecular mechanisms controlling these changes are still unclear. Therefore, the current study aimed to characterize the transcriptome of equine CA during spontaneous labor and compare it with that of normal preterm CA. Placental samples were collected postpartum from mares with normal term labor (TL group, n = 4) and from preterm not in labor mares (330 days GA; PTNL group, n = 4). Our study identified 4137 differentially expressed genes (1820 upregulated and 2317 downregulat...
Batellier F, Gérard N, Courtens JL, Palmer E, Magistrini M.Milk-based diluents are generally considered efficient for survival of stallion spermatozoa in vitro. However, milk is a complex and variable medium and native phosphocaseinate is a milk component that is more efficient for preservation of sperm motility and fertility, although the mechanisms involved in this protection have not yet been elucidated. The aim of the present study was to characterize the interactions between native phosphocaseinate and equine spermatozoa. No binding between sperm membranes and native phosphocaseinate was observed using indirect immunofluorescent staining or elect...
Holcomb KE.Shade or shelter as protection from extremes of weather is required for horses at agricultural research and teaching facilities and is recommended or required by many states, professional organizations, and industry groups. The focus of this paper is the recent research on the responses of horses to hot, sunny weather, which has begun to provide scientific evidence that characterizes how and when shade is used and any benefits shade confers on horses. These behavioral and physiological findings support provision of shade as a resource for thermal comfort and the expression of normal behavior t...
Ek N.A method for the rapid electrophoresis on a cellulose acetate membrane of serum proteins from horses, sheep and pigs is discussed. The various main globulin fractions in the serum of these animals were experimentally identified. Normal values for the percentage composition of serum from normal horses, sheep and pigs were calculated. In the horse there was great individual variation in the shape of the β-fraction, assumed to be due to different transferrin types. The mean value for β-globulin of 19.5 % in the horse was higher than for the other two species. The albumin percentage was highest ...
Keen JA, Hillier C, McGorum BC, Bunton D, Nally JE.Pharmacological evaluation of the unique equine laminar microvasculature is crucial to understanding its role in health and in diseases such as laminitis. However, separating the distinctive characteristics of arterial versus venous components of this complex vascular network has previously proved to be extremely difficult. Encased in a hard hoof capsule, isolation of individual blood vessels presents a considerable challenge. Exacerbating this difficulty, the laminar venous network is adapted to sustain high intravascular pressures and consequently has thickened walls, making the normally str...
Hansen PJ, Hoggard MP, Rathwell AC.The ability of stallion seminal plasma to modify phagocytosis of spermatozoa and Streptococcus zooepidemicus was examined. Phagocytosis was monitored indirectly as the H2O2 produced by peripheral blood leukocytes after addition of spermatozoa or bacteria. Hydrogen peroxide production after addition of ejaculated spermatozoa was greater (P less than 0.01) than after addition of epididymal sperm. Furthermore, pre-incubation of epididymal sperm with 6.25-50% seminal plasma caused a dose-dependent increase in subsequent H2O2 production by leukocytes (P less than 0.05). In addition, equine serum wa...
Peters GJ, Oosterhof A, Veerkamp JH.1. Activities of ADA, PNP and AK were measured in splenocytes and thymocytes of newborn children, young horses, pigs, sheep, rats and mice and compared with the activities previously found in peripheral lymphocytes. 2. With all species, except horse, the activity of ADA (per 10(6) cells) was higher in thymocytes than in lymphocytes. Activity of ADA was highest in splenocytes of pig and sheep. Activity of ADA was lowest in all lymphoid cells of the horse and only about 10% of the activity in human splenocytes and lymphocytes. 3. With all species, except horse, the activity of PNP was lower in t...
Ruggeri E, DeLuca KF, Galli C, Lazzari G, DeLuca JG, Carnevale EM.Intracytoplasmic sperm injection (ICSI) is an established method to fertilise equine oocytes, but not all oocytes cleave after ICSI. The aims of the present study were to examine cytoskeleton patterns in oocytes after aging in vitro for 0, 24 or 48h (Experiment 1) and in potential zygotes that failed to cleave after ICSI of oocytes from donors of different ages (Experiment 2). Cytoplasmic multiasters were observed after oocyte aging for 48h (P<0.01). A similar increase in multiasters was observed with an increased interval after ICSI for young mares (9-13 years) but not old (20-25 years) mares...
Dagleish MP, Brazil TJ, Scudamore CL.Lipopolysaccharide (LPS) and N-formyl-methionyl-leucyl-phenylalanine (fMLP)-like peptides are Gram-negative bacterial cell wall components which, when released into the peripheral circulation in endotoxaemia, have the potential to activate leucocytes. In vitro, equine neutrophils require priming with LPS in order to generate reactive oxygen intermediates (ROI) in response to fMLP. Objective: The aim of this study was to examine whether the release of other neutrophil products is similarly dependent on prior priming with LPS. In particular, neutrophil elastase (NE), a potent proteolytic enzyme,...
Watts TJ, Handy RD.The haemolytic effect of verapamil on red blood cells (RBCs) exposed to varying osmolarity was investigated. The experimental approach used a modified red cell haemolysis assay with concentrations of verapamil ranging from 50-1500 microM compared to drug free controls. The time-course of haemolytic effects was also investigated. We also briefly determined the haemolytic effects of verapamil in Ca2+-free conditions (with added EGTA). In conditions representing decreasing osmolarity (dilution from 140-0 mM NaCl) there was a significant increase in erythrocyte haemolysis that was also dependent o...
Wilkołek P, Sitkowski W, Szczepanik M, Adamek Ł, Pluta M, Taszkun I, Gołyński M, Malinowska A.Allergic responses in humans, horses and other species are mediated by immunoglobulin E (IgE) antibodies. Serum testing to detect allergen-specific IgE antibodies has been developed for dogs, cats and horses; this allows for the identification of allergens and determination of appropriate allergen- specific immunotherapies. This study compared serum allergen-specific IgE concentrations in atopic and healthy horses. The study was performed on Malopolski breed atopic (n=21) and nonatopic (n=21) clinically healthy horses. Allergen-specific IgE serum concentrations were measured in summer seasons ...
Nostell KE, Lindåse SS, Bröjer JT.Insulin resistance (IR) in humans is related to hypertension and impaired vasodilation. Insulin administration has been shown to lower blood pressure both in insulin resistant as well as in insulin sensitive individuals. The aim of the study was to investigate the association between insulin sensitivity and alterations in blood pressure in healthy horses before and after a euglycemic-hyperinsulinemic clamp (EHC). A 3-h EHC was performed in 13 healthy horses (11 mares, 2 geldings). Blood samples for measurement of plasma glucose and insulin were collected before the start of the EHC, every 10 ...
Gastal MO, Gastal EL, Kot K, Ginther OJ.The temporal relationships among day of conceptus fixation (cessation of mobility), conceptus diameter, uterine tone, uterine contractility, and myometrial and endometrial thickness of the middle and caudal segments of the uterine horns were assessed in 13 pony mares with fixation in the caudal segment of a uterine horn. The mean day of fixation (14.9 +/- 0.3) was established by 2-h mobility trials. Uterine tone increased (P < 0.0001) gradually over Days 11 to 21, whereas uterine contractility decreased (P < 0.0001) between Days 14 and 18. The diameter of the spherical embryonic vesicle ...
Hatazoe T, Endo Y, Iwamoto Y, Korosue K, Kuroda T, Inoue S, Murata D, Hobo S, Misumi K.Aim of this study was to evaluate the relationships of exercise and tendon injury with Doppler flows appearing in the superficial digital flexor tendon (SDFT) of young Thoroughbreds during training periods. The forelimb SDFTs of 24 one- to two-year-old Thoroughbreds clinically free of any orthopaedic disorders were evaluated using grey-scale (GS) and color Doppler (CD) images during two training periods between December 2013 to April 2015. Twelve horses per year were examined in December, February, and April in training periods that began in September and ended in April. The SDFT was evaluated...
Venugopal CS, Holmes EP, Koch CE, Curtis LA, Holm AS, Moore RM.To evaluate the effectiveness of 2 potential endothelin (ET)-1 antagonists in blocking the contractile responses of equine colonic vessels to increasing concentrations of ET-1. Methods: Mesenteric vessels from 6 clinically healthy horses. Methods: Colonic vessels (arterial and venous rings) were placed in organ baths with oxygenated Tyrode solution at 37 C. Each was attached to a force transducer interfaced with a polygraph, and 2 g of tension was applied and equilibrated for 45 minutes. Then, B-1 (PD 142893) and B-2 (PD 145065) ET-1 antagonists were tested. One ring from each vessel type was ...
Benamou AE, Art T, Marlin DJ, Roberts CA, Lekeux P.Chronic obstructive pulmonary disease (COPD) represents a major cause of loss of performance in the horse. The role of endothelin (ET), a potent bronchoconstrictive and vasoactive peptide, is currently being investigated in asthma and other obstructive respiratory diseases in man. We have previously found elevated systemic and pulmonary endothelin levels in horses during exacerbation of COPD. In the present study, our aim was to examine possible variations in ET concentrations occurring during exercise in COPD horses. We compared the effects of intense treadmill exercise on the recovery of end...
Utt MD, Acosta TJ, Wiltbank MC, Ginther OJ.The acute effects of prostaglandin F(2alpha) (PGF) on circulating oxytocin and progesterone concentrations were characterized in mares during the mid- or late-luteal phase. Pony mares were randomly assigned to the following experimental groups based on treatment with PGF (2.5mg) or saline on Day 8 or Day 13 (Day 0=ovulation): PGF-8, PGF-13, saline-8, or saline-13 (n=7/group). Mares were fitted with indwelling, jugular vein catheters and two blood samples (-5 and 0 min) were collected prior to treatment. Treatments were administered into the jugular vein (0 min) and blood collection continued t...
Santos MM, Benvenuto GV, Ramos GV, Titotto AC, Adão MDS, de Lacerda LCC, Lisbôa JAN, Lacerda-Neto JC.During exercise, equines can suffer severe water and electrolyte imbalances depending on the intensity and duration. In this sense, conditioning aims to promote adaptations to the organism in order to maintain cardiovascular and thermoregulatory stability during exertion. This study aimed to evaluate the effect of conditioning guided by lactate minimum speed (LMS) test on the blood osmolality of horses. We hypothesized that after conditioning the blood osmolality would vary less during exercise and that LMS could be used in equine conditioning program. Ten Arabian horses were evaluated before ...
Stammers JP, Hull D, Silver M, Fowden AL.The effects of different nutritional states on plasma lipid concentrations have been examined in pregnant mares and their fetuses. Maternal and fetal arterial catheters were inserted into 12 pony mares between 244-303 days' gestation (term 320-360 days) and observations made from 5 days following the insertion of catheters. After recovery from surgery maternal and fetal arterial samples were withdrawn from 7 mares with normal feeding patterns (Group IA), from four of these mares at the end of a 30 h fast and 3 h later following refeeding (Group IB) and six mares who failed to re-establish norm...
Martins FC, Keating SC, Clark-Price SC, Schaeffer DJ, Lascola KM, DiMaio Knych H.To determine the physiologic and behavioral effects and pharmacokinetic profile of hydromorphone administered intravenously (IV) to horses. Methods: Prospective, randomized, crossover study. Methods: A group of six adult healthy horses weighing 585.2 ± 58.7 kg. Methods: Each horse was administered IV hydromorphone (0.025 mg kg; treatment H0.025), hydromorphone (0.05 mg kg; treatment H0.05) or 0.9% saline in random order with a 7 day washout period. For each treatment, physiologic, hematologic, abdominal borborygmi scores and behavioral data were recorded over 5 hours and fecal output was tota...
Ahern BJ, Lukas E, Lam K, Wilke E, Bertin FR, Van Eps A, Franklin S.To evaluate a prototype dynamic laryngoplasty system (DLPS) in a static airflow model. Methods: Experimental. Methods: Ten equine larynges. Methods: The right arytenoid was fixed in abduction in all specimens. A left-sided laryngoplasty was performed with No. 2 Fiberwire and a FASTakII anchor. Each larynx was tested in a static airflow model. The system was adjusted to a flow rate of 55 L/s and prelaryngeal pressure of 12 mm Hg prior to testing in maximal arytenoid abduction. In phase 1, the left suture was loosened, shortened, and tested in 3-mm steps from 0 to 30 mm. In phase 2, the su...
Taylor PM.Some metabolic and endocrine effects of hypercapnia were studied in six ponies during halothane anaesthesia with neuromuscular blockade and controlled ventilation. Each was anaesthetised twice, once with a 40-minute-period of hypercapnia (10 kPa) and once when normocapnia (5.3 kPa) was maintained throughout two hour's anaesthesia. Routine cardiovascular monitoring was performed and blood samples were taken for assay of cortisol, insulin, glucose, lactate, muscle and liver enzymes and total protein. Anaesthesia induced hypotension and lacticacidaemia which were slightly ameliorated during hyper...
Grev AM, Hathaway MR, Sheaffer CC, Wells MS, Reiter AS, Martinson KL.Reduced lignin alfalfa (Medicago sativa L.) has the potential to provide a higher-quality forage source for livestock by improving forage digestibility. This study was conducted to evaluate apparent digestibility when feeding reduced lignin and nonreduced lignin alfalfa hay to adult horses, and to examine mean fecal particle size (MFPS) and mean retention time (MRT) between alfalfa forage types. In 2017, reduced lignin ("54HVX41") and nonreduced lignin ("WL355.RR") alfalfa hay was harvested in Minnesota at the late-bud stage. Alfalfa hays were similar in crude protein (CP; 199 g/kg), neutral d...
Bennett RC, Taylor PM, Brearley JC, Johnson CB, Luna SP.This prospective clinical study compared the physiological effects of two commonly used anaesthetic induction techniques in horses maintained with halothane. One hundred horses admitted for elective surgery were randomly allocated to receive either guaiphenesin (to effect) and thiopentone (5 mg/kg), or detomidine (20 microg/kg) and ketamine (2 mg/kg) for the induction of anaesthesia after acepromazine premedication. Anaesthesia was maintained with halothane in oxygen. There were no significant differences in breed, age, sex, weight, type of surgery and duration of anaesthesia between the group...
Sodré TDRP, Sousa LN, Silva CA, Santos JM, Sampaio MQ, Coni ROS, Dantas RTS, Ferreira APG, Manso Filho HC, Fazio F, Coelho CS.Vaquejada is an important Brazilian equine discipline. Understanding physiological adaptations of these athletes is crucial to improve properly performance, guaranteeing welfare. The objective of this study was to evaluate the influence of three vaquejada simulation tests (VST) on physiological parameters of horses and standardize a possible rest interval between races. Ten clinically healthy Quarter horses, 8.9 ± 4.3 year-old and 441.3 ± 25.0 kg, executed three VST, 5 days apart from each other. Vaquejada simulation tests consisted of two horses, a puller, and a helper, running with a bul...
Kaps M, Okada CTC, Gautier C, Aurich J, Scarlet D, Kuhl J, Aurich C.Behavior during the estrous cycle of mares can affect their performance and therefore inhibition of cyclical ovarian activity is indicated. We hypothesized that implants containing the GnRH analog deslorelin downregulate GnRH receptors and inhibit ovulation in mares. The estrous cycles of Shetland mares were synchronized with 2 injections of a PGF analog. One day after the second injection (day 0), mares received 9.4 (group D1, n = 6) and 4.7 mg deslorelin (D2, n = 5) as slow-release implants or 1.25 mg short-acting deslorelin as a control (C, n = 5). Ultrasonography of the reproductive trac...
