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.
Reis KJ.A hemolytic assay was developed for the measurement of functional equine complement activity. The assay utilizes antibody sensitized chicken erythrocytes as the target cell and was specific for classical pathway (antibody dependent) complement activity. The assay was found to be reproducible and more sensitive than previous reports using other species of target cells. Total serum complement (CH50) values were determined for five mares and their foals and followed over a period of 3 months.
Jones RS, Lawrence TL, Veevers A, Cleave N, Hall J.Fifty-three horses, all but two of them over two years of age and varying in type, sex and liveweight (230 to 707 kg) were weighed and seven different body measurements were recorded in duplicate by a single operator. The best overall prediction of liveweight using an equation with two variables was found to be: liveweight (kg) = (umbilical girth [cm])1.78 X (length of body from tuber ischii to elbow [cm]0.97/3011). This equation had an adjusted R2 value of 94.9 per cent and was derived from the pooled data, because differences of sex, type and weight did not significantly affect the relations...
Tanaka T, Aramaki S, Momose A.A thin-layer chromatographic screening procedure for some basic, neutral and acidic drugs was developed using 3 ml of horse plasma. Chloroform-2-propanol (95:5, v/v) was used as the extraction solvent. The drugs were identified by a high-performance thin-layer chromatographic plate and spraying successively with some detection reagents. In this study, the extraction recovery rates and the detection limits were determined at the same time.
Winder NC, Pellegrini A, von Fellenberg R.A peroxidase antiperoxidase technique was used to identify alpha 2-macroglobulin in formalin-fixed sections of normal equine lung and liver and in tissue sections and bronchoalveolar lavage fluid from horses with various lung diseases. Equine peripheral blood leucocytes and bronchoalveolar lavage samples from clinically normal horses were negative for alpha 2-macroglobulin. It was concluded that liver and pulmonary macrophages may be potential sources of alpha 2-macroglobulin. Although alpha 2-macroglobulin may play a role in various chronic bronchointerstitial pneumonias of the horse, it is d...
Singh AK, McArdle C, Gordon B, Ashraf M, Granley K.A high performance liquid chromatographic method is described for the simultaneous determination of furosemide and bumetanide in horse plasma. The C8 (3 microns) reversed phase column (4.8 x 150 mm) provided clear separation of furosemide and bumetanide with other components present in the horse plasma. The detection limit for both the drugs was 10 ng/mL. Both drugs were stable in plasma (at natural or acidic pH) for up to 24 h. The method is sufficiently sensitive to detect furosemide levels in plasma obtained from horses receiving a therapeutic dose of furosemide.
Sosnicki AA, Lutz GJ, Rome LC, Goble DO.Until now, there has been no reliable method for histochemical determination of fiber types of single skinned muscle fibers. The major problem arises from the fact that most histochemical techniques use cross-sections of a large group of fibers and compare a given fiber with those surrounding it. This is not possible with a single skinned fiber which has been separated from a bundle to be used for mechanical analysis. A further problem is that the skinning procedure itself may alter the staining pattern. We have developed a procedure by which multiple cross-sections of single skinned fibers ca...
Wheeler SJ.Sensory nerve conduction velocity was measured in the lateral palmar nerve of 8 horses. The limb temperature was manipulated by external means and monitored. Alterations in the nerve conduction velocity related to limb temperature variation were identified at both increased and decreased temperatures. These were quantified and a mean value of 2.15 +/- 0.2 m/s/degree Celsius was determined. The effect of altered limb temperature should be considered in nerve conduction velocity determinations.
Sangiah S, MacAllister CC, Amouzadeh HR.The basal gastric pH and free acid contents from five young adult healthy horses were determined at one hour intervals for eight hours. The basal gastric pH and free acid contents varied from 1.63 +/- 0.06 to 1.97 +/- 0.11 and 26.42 +/- 4.14 to 17.92 +/- 5.28 mmol litre-1, respectively. Misoprostol, a methylester analogue of prostaglandin (5 micrograms kg-1, orally) produced a time-dependent increase in the basal gastric pH to above 3.5 (P less than 0.05) at three, four and five hours after administration with a concomitant reduction of 80 to 90 per cent in the basal gastric free acid contents...
Smith JE, Erickson HH, Debowes RM, Clark M.Five horses were exercised at 10m/sec at a 3 degree incline for 2 mins. Packed cell volume, erythrocyte count, haemoglobin concentration, mean corpuscular volume, plasma protein, total white cell count and lymphocytes increased significantly in blood samples taken after exercise, compared with those taken before exercise; but mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration decreased. Erythrocytes were more resistant to osmotic stress after exercise, but their shape and degree of deformity were unaffected by exercise.
Hinchcliff KW, McGuirk SM, MacWilliams PS, Cooley AJ.Changes in renal function, determined by pharmacokinetics of phenolsulfonphthalein (PSP), and renal morphologic features were examined in adult pony mares given 20 mg of gentamicin sulfate/kg of body weight, IV, q 8 h (group A) n = 7 or isotonic saline solution, IV, q 8 h, n = 5 (group B) for 14 days. Susceptibility of ponies to gentamicin-induced nephrotoxicosis was varied. Two group-A ponies developed acute renal failure and were euthanatized before treatment day 14, whereas 5 group-A A ponies did not develop physical or behavioral abnormalities after 14 days of gentamicin administration. Al...
Byrd SK, McCutcheon LJ, Hodgson DR, Gollnick PD.This study examined the effects of acute high-intensity exercise on the rate and capacity of Ca2+ uptake and Ca2+-stimulated adenosinetriphosphatase (ATPase) activity of the sarcoplasmic reticulum and the reversibility of these effects. Thoroughbred horses were run at maximal O2 uptake on a high-speed treadmill until fatigued. Muscle temperatures and biopsy samples were collected at rest, immediately after exercise, and 30 and 60 min after exercise. Blood samples were collected at rest and 5 min after exercise. Muscle and blood (lactate concentration) were three- and fivefold greater than pre-...
Clark ES, Moore JN.Lateral cecal arterial blood flow, carotid arterial pressure, heart rate, and mechanical activity in the duodenum, right ventral colon, cecal body, and cecal apex were measured in 6 conscious healthy horses for 60 minutes during and for 120 minutes after IV infusion of 0.9% NaCl solution (control) or fenoldopam. There were no significant changes in these measurements during or after infusion of 0.9% NaCl (saline) solution. Fenoldopam, a selective dopamine-1 receptor agonist, was administered in saline solution at dosages of 0.01, 0.05, and 0.1 micrograms/kg/min. Intravenous infusion of fenoldo...
Löfman CO, Brännström M, Holmes PV, Janson PO.Surface cell changes at the apices of preovulatory follicles and ovulations were documented in isolated perfused ovaries from immature rats treated with pregnant mare serum gonadotropin (20 IU) and 48 h later with human chorionic gonadotropin (hCG) (10 IU). A video camera coupled to an inverted microscope and a video recorder captured the preovulatory and ovulatory events at a cellular level. At around 8 h post-hCG, the follicular apex changed from a smooth and optically homogeneous appearance into a rough surface with bleb formation and extrusions of single cells through minute perforations (...
Bayly WM, Hodgson DR, Schulz DA, Dempsey JA, Gollnick PD.The effects of exercise intensity and duration on blood gases in thoroughbred horses were studied to characterize the apparent exercise-induced failure in pulmonary gas exchange that occurs in these animals. In response to 2 min of exercise, arterial CO2 tension (PaCO2) decreased in mild and moderate exercise, returned to normocapnic levels in moderate to heavy exercise, and rose 5-10 Torr above resting values during very heavy exercise when CO2 production (VCO2) exceeded 20 times the resting value, and mixed venous CO2 tension approximated 140 Torr. Exercise-induced hypoxemia occurred at the ...
Dintinger T, Gaillard JL, Moslemi S, Zwain I, Silberzahn P.The ability of equine and human placental microsomes to aromatize testosterone and 19-nortestosterone was studied. When 3 microM [1 beta,2 beta-3H]testosterone was used as substrate, the specific activity of equine placental microsomal aromatase was 2.5 times higher than that of the human microsomal enzyme. Although 19-nortestosterone was aromatized 67 times more rapidly by equine than by human aromatase, we found that equine aromatase exhibited a markedly weaker affinity for this substrate than did the human enzyme. Competitive inhibition of testosterone aromatization by 19-nortestosterone oc...
Desmet J, Van Dael H, Van Cauwelaert F, Nitta K, Sugai S.The enthalpy change of the binding of Ca2+ and Mn2+ to equine lysozyme was measured at 25 degrees C and pH 7.5 by batch microcalorimetry: delta H degrees Ca2+ = -76 +/- 5 kJ mol-1, delta H degrees Mn2+ = -21 +/- 10 kJ mol-1. Binding constants, log KCa2+ = 6.5 +/- 0.2 and log KMn2+ = 4.1 +/- 0.5, were calculated from the calorimetric data. Therefore, delta S degrees Ca2+ = -131 +/- 20 JK-1 mol-1 and delta S degrees Mn2+ = 8 +/- 44 JK-1 mol-1. Removal of Ca2+ induces small but significant changes in the circular dichroism spectrum, indicating the existence of a partially unfolded apo-conformatio...
Rijkenhuizen AB, Nemeth F, Dik KJ, Goedegebuure SA.An arteriographic and histological study of the arterial blood supply of 35 navicular bones, from 19 adult horses with no clinical or radiographical signs of navicular disease, is described. The arteries enter the navicular bone from four directions: distal, proximal, medial, and lateral. The navicular bone can be divided into areas which receive arteries from one, two, or three directions, whereas the distal supply covers the largest part of the navicular bone. The distal arteries enter the navicular bone through the nutrient foramen which contains loose connective tissue, nutrient vessels an...
Field JR, Jeffcott LB.Laminitis is an important condition in horses and ponies, not just because of the seriousness of the clinical signs and systemic changes involved, but because of the potentially poor prognosis and likelihood of recurrence. Laminitis is particularly prevalent in ponies and involves a multiplicity of aetiological factors. Fat ponies and those having previously suffered laminitis were found to be far more intolerant to oral glucose loading (1 g/kg bwt) than normal ponies or Standardbred horses. These ponies also exhibited a far greater response in plasma insulin levels after glucose loading. Insu...
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...
Mück WM, Henion JD.The performance of microbore high-performance liquid chromatography and capillary zone electrophoresis, both equipped with on-line tandem mass spectrometric detection capability, was evaluated critically for the determination of endogenous amounts of leucine enkephalin and methionine enkephalin in equine cerebrospinal fluid. Using an identical sample clean-up and enrichment procedure, capillary zone electrophoresis-mass spectrometry is limited in its concentration detection capacity owing to its much smaller injection volume. Leucine enkephalin was identified in post-mortem equine cerebrospina...
Yamanaka H, Shimatani S, Tanaka M, Katsu T, Ono B, Shinoda S.The hemolytic activity of Vibrio vulnificus hemolysin (VVH) against erythrocytes from several animal species (sheep, horse, cow, rabbit, chicken) was investigated. VVH was active against erythrocytes from all species, but the amount of VVH causing 50% hemolysis under identical conditions (hemolytic susceptibility to VVH) differed. The degree of 125I-labeled VVH (125I-VVH) binding to each erythrocyte species correlated with the susceptibility of the cells to hemolysis. However, marked differences in the binding ability of 125I-VVH were not observed against liposomes constructed with lipids from...
Copland VS, Hildebrand SV, Hill T, Wong P, Brock N.Blood pressure during anesthesia and surgery was compared for 2 groups of horses. Group A, consisting of 23 horses, had a tourniquet placed on the distal portion of a limb. The other group of 20 horses (group B) had surgery of comparable nature and duration as did group-A horses, but a tourniquet was not used. There was a statistical difference (P less than 0.05) in the peak systolic arterial blood pressure between the groups; group-A horses had a mean (+/- SEM) peak of 151 +/- 6 mm of Hg and group-B horses had a peak of 118 +/- 4 mm of Hg. In addition, group-A horses had immediate decrease in...
Singh AK, Gordon B, Hewetson D, Granley K, Ashraf M, Mishra U, Dombrovskis D.Gas chromatography with chemical ionization mass spectrometry and selected-ion monitoring provided a sensitive method for the screening and confirmation of steroids in horse urine and plasma. Chemical ionization mass spectrometry was more sensitive than the electron impact ionization mass spectrometry for most of the steroids except for testosterone, prednisone-metabolite-2 and prednisolone-metabolite-2. The chromatographic conditions used in this study provided clean separation of different natural and synthetic steroids. Approximately 75-85% of the steroids added to plasma and approximately ...
Raub RH, Jackson SG, Baker JP.Nineteen weanling horses (average age = 147 d) were divided into exercised (EX; n = 10) and nonexercised (NEX; n = 9) groups, with age, sex and breed represented as equally as possible. The EX group was exercised on an automatic walker at a medium trot for up to 20 min, 5 d each week. Both groups were fed to meet 100% of their protein and 110% of their energy requirements (NRC, 1978). The EX group's diet was supplemented, on exercise days, with corn starch to meet the additional energy requirements for exercise. The experiment was conducted over a 111-d period. Body weight was measured at 10-d...
Watanabe K, Sohara T, Takeda M, Ueno K, Suzumura N, Rokurouda Y, Rokurouda I, Yamamoto S.Each of five genetic variants of horse serum transferrin (Tf), D, F, H, O, and R, was separated into two bands by polyacrylamide gel isoelectric focusing (PAGIEF). The more acidic band, termed component a, was more abundant than the other one, termed component b, in all variants. Components a and b of TFO variant were immunologically indistinguishable from each other by double immunodiffusion test. Determination of the content ratio of component a to component b in each variant revealed that the variants were classified into two groups: one group (D, F, and H) had a relatively high ratio withi...
Wallace KD, Selcer BA, Becht JL.Transrectal ultrasonography was successfully used to image the cranial mesenteric artery and its branches in 23 adult horses. The artery could be imaged from its origin at the aorta distally to identify several bifurcations. The method for transrectal imaging of the cranial mesenteric artery and its major branches required 3 distinct transducer positions. One position was used to locate the cranial mesenteric artery by imaging the caudal portion of the aorta from the aortic bifurcation cranially to the level of the cranial mesenteric artery. The second position was used to image the origin of ...
Roser JF, Lofstedt RM.Blood and urine samples collected from 12 mares at frequent intervals from 25 to 210 d of pregnancy were analyzed for equine chorionic gonadotropin (eCG). Blood and urine samples were collected daily through two consecutive ovulatory periods from five cyclic mares for comparative purposes. Separate radioimmunoassays (RIA) were developed to detect eCG in the urine and plasma. A simple and quick commercial dipstick enzyme-linked immunospecific assay (ELISA), developed for eCG in the blood, was also utilized in this study to detect eCG in the urine. In the 12 pregnant mares, eCG concentrations in...
Bochsler PN, Slauson DO, Chandler SK, Suyemoto MM.The use of cultured tissue has not yet become widespread in research involving equine disease, and this may be attributable in part to the scarcity of published reports concerning tissue culture methods for this species. We report here the isolation of equine microvascular endothelium (EMVE) from fresh omental tissue of horses and ponies. Fresh donor tissue was minced, subjected to collagenase digestion, and filtered. Cells were layered on 5% bovine serum albumin for gravity sedimentation, the bottom layer was collected, and the cells were plated onto fibronectin-coated flasks. Medium consiste...
Wilde MH, Dinger JE, Hoagland TA, Graves-Hoagland RL, Woody CO.Transcervical diagnostic techniques may alter the length of the equine estrous cycle and affect subsequent luteal function. Therefore, nine mares were used to determine the effect of cervical dilation on plasma 13, 14-dihydro, 15-keto-prostaglandin F(2) (PGFM), progesterone (P(4)) and posttreatment duration of luteal function. Mares were given a daily score of 0 to 4 based on sexual receptivity. Five days following the end of receptivity, mares were randomly assigned to one of three, 3 x 3 latin squares. Control mares received no cervical dilation. Cervically stimulated mares recieved cervical...
Bröjer J, Jonasson R, Schuback K, Essén-Gustavsson B.The purpose was to investigate the degradation of proglycogen and macroglycogen in skeletal muscle during intense exercise. Ten Standardbred trotters performed a maximal treadmill exercise test comprising a warm-up period, an exercise period, starting at 7 m/s with increments of 1 m/s every 60 s until the onset of fatigue (mean +/- s.d. 246 +/- 32 s) and a walking recovery period. Muscle biopsies were taken at rest, immediately after exercise and 15 min postexercise. The exercise caused a marked anaerobic metabolism as shown by the decrease in both muscle ATP and creatine phosphate and increas...
Willette C, Aarnes TK, Lerche P, Ricco-Pereira C, Ballash GA, Bednarski RM.To assess anesthetic induction, recovery quality and cardiopulmonary variables after intramuscular (IM) injection of three drug combinations for immobilization of horses. Methods: Randomized, blinded, three-way crossover prospective design. Methods: A total of eight healthy adult horses weighing 470-575 kg. Methods: Horses were administered three treatments IM separated by ≥1 week. Combinations were tiletamine-zolazepam (1.2 mg kg), ketamine (1 mg kg) and detomidine (0.04 mg kg) (treatment TKD); ketamine (3 mg kg) and detomidine (0.04 mg kg) (treatment KD); and tiletamine-zolazepam (2.4 mg ...
Strickland K, Smith F, Woods M, Mason J.Four horses were stabled and fed a diet of hay ad libitum, and 2 kg oats per animal per day, for a month. The basic diet was then supplemented with molybdenum, at a rate of 20 mg/kg dry matter for 4.5 months. For one month of this period the diet was supplemented also with sulphur at a rate of 1.2 g/kg dry matter. Analyses of jugular blood samples, obtained at intervals varying between two and 20 days, showed no evidence of a decline in total plasma copper or of an increased proportion of trichloroacetic acid (TCA) insoluble copper in plasma over this period. In separate studies, two other hor...
McKeever KH, Scali R, Geiser S, Kearns CF.The purpose of the present study was to determine whether the training-induced hypervolaemic response seen in the horse is associated with aldosterone-mediated renal mechanisms affecting sodium conservation during the first days of training. Five healthy, Standardbred mares (weight 450-500 kg, age 4-8 years) that were unfit, but accustomed to running on the treadmill, were used to test the hypothesis that repeated submaximal exercise would alter plasma aldosterone (ALDO) concentration and renal excretion of electrolytes in horses within the first 3 days of training. The experiment consisted of...
Owens SD, Johns JL, Walker NJ, Librach FA, Carrade DD, Tablin F, Borjesson DL.To evaluate N-hydroxysuccinimide (NHS)-biotin labeling of equine RBCs and determine posttransfusion survival of autologous equine RBCs stored in citrate phosphate dextrose adenine-1 (CPDA-1) for 0, 1, 14, and 28 days. Methods: 13 healthy adult Thoroughbreds. Methods: Serial dilutions of biotin and streptavidin-phycoerythrin (PE) were evaluated in vitro in blood collected from 3 horses. One horse was used to determine RBC distribution and recovery. Twelve horses were allocated to 4 groups for in vivo experiments in which blood was collected into CPDA-1. Blood was labeled with biotin and reinfus...
De Mello Costa MF, Anderson GA, Davies HM, Slocombe RF.Angiotensin I-converting enzyme (ACE) level measurement in blood samples is an important tool in human medicine for the detection, treatment and control of diseases such as sarcoidosis and hypertension. Recently ACE has been advocated as being correlated to athletic aptitude in human athletes and a genetic polymorphism has been shown to be responsible for the enzymatic levels in the circulation. The objective of this research was to evaluate the effects of acute exercise in horses in order to increase the understanding of a possible correlation between ACE levels in plasma and performance in e...
Kortz GD, Madigan JE, Goetzman BW, Durando M.Intracranial pressure (ICP) and cerebral perfusion pressure (CPP) were determined in 8 clinically normal neonatal foals. After the foals oriented themselves and nursed the mares, they were sedated as necessary, and local anesthesia was provided for making the skin incisions. Using a technique similar to that used in human beings, an indwelling subdural catheter was placed to measure ICP. Carotid artery catheterization was used to measure arterial blood pressure. Cerebral perfusion pressure was calculated as the difference between mean arterial blood pressure and ICP. Intracranial pressure and ...
Chalmers HJ, Yeager AE, Ducharme N.Dorsal displacement of the soft palate is an important cause of poor performance in racehorses, yet its etiology is not fully understood. Diagnosis requires treadmill videoendoscopy, which is not widely available. The relationship of the larynx, the hyoid apparatus, and the remainder of the skull may be important in predisposing horses to dorsal displacement of the soft palate. We hypothesized that this relationship could be accurately assessed in unsedated horses through ultrasonographic examination. Fifty-six racehorses presented for evaluation of poor performance were subjected to treadmill...
Shibany KA, Tötemeyer S, Pratt SL, Paine SW.1. Scaling factor values for the in vitro-in vivo extrapolation of hepatic metabolic clearance for xenobiotics have not yet been determined in horses. Scaling factors were determined by comparing the total protein and or cytochrome (CYP) P450 content in microsomes and cryopreserved hepatocytes against the content in the liver. 2. Microsomal protein per gram of liver (MPPGL) and hepatocellularity number per gram of liver (HPGL) using CYP P450 content method ranged 41-73 mg/gram of liver (mean= 57 mg/gram of liver, n = 39) and 146-320 × 10 cells/g of liver (mean = 227× 10 c...
Rathi R, Nielen M, Cheng FP, van Buiten A, Colenbrander B.Subfertility in stallions is attributed to the inability of spermatozoa to undergo the acrosome reaction in response to progesterone. In the present study, it was assessed whether there is a correlation between stallion fertility, defined on the basis of first cycle foaling rate and first cycle 'non-return rate', and the proportion of spermatozoa with exposed progesterone receptors on their plasma membranes. Semen from Dutch Warmblood (n=10) and Friesian (n=4) stallions was analysed. Progesterone 3-(o-carboxymethyl) oxime-BSA coupled with fluorescein isothiocyanate was used as a progesterone r...
Merritt AM, Burrow JA, Horbal MJ, Madison JB, Tran T.To better characterize the source of the large nonparietal secretory response to pentagastrin (PG) expressed in gastric contents of cannulated horses. Methods: Adult cross-bred horses: 4 geldings and 1 mare. Methods: Horses were prepared by surgical insertion of a silastic gastric cannula from which gastric contents after feed was withheld could be continuously collected by gravity drainage. During experiments, the horses were lightly restrained in stocks, the gastric cannula was opened, and a catheter was inserted into a jugular vein. Over the next 5 hours, gastric contents were collected in ...
Bessonnat A, Vanore M.Evaluate the effect of repeated doses of topical 1% cyclopentolate hydrochloride alone and in combination with topical 2.5% phenylephrine on pupil diameter (PD), tear production (STT-1), intraocular pressure (IOP), digestive function (gut motility and feces production), and heart rate (HR). Methods: Six healthy mares. Methods: In a prospective, randomized, controlled, and crossover design study, the left eye of six healthy mares was administered 0.2 mL of cyclopentolate alone and in combination with 0.2 mL of phenylephrine. The drugs were administered 3 times a day for 1 day, twice a day fo...
Haezebrouck P, Noppe W, Van Dael H, Hanssens I.From fluorescence measurements on mixtures of bis-ANS and equine lysozyme and from Ca(2+)-dependent hydrophobic interaction chromatography of equine lysozyme, it is demonstrated that Ca2+ binding induces a conformational change upon which hydrophobic regions in the protein become less accessible. Bis-ANS fluorescence titrations in the absence of Ca2+ and in 2 mM Ca2+ are also performed with equine alpha-lactalbumin variants B and C. These variants differ by an amino-acid exchange Asp----Ile at residue 95. The fluorescence titration curves indicate that the accessibility of the probe to the Ca2...
Bröjer JT, Essén-Gustavsson B, Annandale EJ, Valberg SJ.To determine concentrations of proglycogen (PG), macroglycogen (MG), glucose, and glucose-6-phosphate (G-6-P) in skeletal muscle of horses with polysaccharide storage myopathy (PSSM) before and after performing light submaximal exercise. Methods: 6 horses with PSSM and 4 control horses. Methods: Horses with PSSM completed repeated intervals of 2 minutes of walking followed by 2 minutes of trotting on a treadmill until muscle cramping developed. Four untrained control horses performed a similar exercise test for up to 20 minutes. Serum creatine kinase (CK) activity was measured before and 4 hou...
Levanti B, Hannestad J, Esteban I, Ciriaco E, Germanà G, Vega JA.The neurotrophins are a family of growth factors that act on responsive cells through specific high-affinity signal-transducing receptors called Trk (A, B, and C) proteins. The neurotrophin receptor proteins are widely distributed in both nervous and nonnervous tissues, including the lymphoid organs. The expression of these receptor proteins by a cell population is an indication of responsiveness to the respective binding neurotrophin. The present study investigated the presence and cellular localization of high-affinity neurotrophin receptor proteins in equine and bovine Peyer's patches. Peye...
Hoffman AM, Couetil LL, Miller CJ.To describe the spectrum of nonspecific airway reactivity in a group of clinically normal foals. Methods: 12 clinically normal mixed-breed foals, 48 to 92 days old, without history of clinical lung disease. Methods: Nonspecific airway reactivity was determined by measuring the extent of changes in dynamic compliance during nebulization of incrementally increasing concentrations of histamine aerosol. Degree of airway reactivity was expressed as the dose of histamine that evoked a decrease in dynamic compliance (Cdyn) to 65% of the after saline nebulization value (PC65Cdyn) or increase in pulmon...
Caffey SR, Lund CM, Farnsworth KD, Fransson BA, Ragle CA.The effects of head position on internal carotid artery (ICA) and external carotid artery (ECA) pressures in standing sedated horses were evaluated in this study. The common carotid artery (CCA) was catheterized in 6 horses using an ultrasound-guided technique to facilitate placement of a pressure transducer within the ICA and ECA at the level of the guttural pouch. Transducer position was confirmed by endoscopic visualization. Mean arterial pressure (MAP) was measured with horses in both a head-up and head-down position. The dorsal metatarsal artery was catheterized as a control. Maintaining ...
Bayly WM, Slocombe RF, Weidner JP, Schott HC, Hodgson DR.The influences of facial airflow, exercise and wearing a facemask on gas exchange and upper airway (Pu), transpulmonary (PTP) and transdiaphragmatic (PTD) pressures were investigated in 6 horses performing an incremental exercise test on an inclined (10%) treadmill. The test consisted of a 2 min walk followed by two 2 min exercise bouts at intensities which produced 40% and 80% of maximal oxygen consumption. Horses performed the test 4 times, once for each of 4 protocols, which involved not wearing a facemask (A), wearing a mask with either no biased flow through it (B), with an expiratory bia...
Boone L, Schumacher J, DeGraves F, Cole R.The objective of this study was to determine if buffering mepivacaine HCL (mepHCl) with sodium bicarbonate (NaHCO3) would significantly decrease the time to onset of analgesia when performing median and ulnar nerve blocks in naturally lame horses. Median and ulnar nerve blocks were performed on the naturally lame limb of nine horses during two separate study periods, with a minimum washout period of three days between study periods. Nerve blocks were performed by administering mepHCl alone or mepHCl mixed with NaHCO3 (nine parts 2 per cent mepHCl to one part 8.4 per cent NaHCO3). Lameness was ...
Kyvsgaard NC, Høier R, Brück I, Nansen P.Ionizing irradiation and binary ethylenimine treatment have previously been shown to be effective for in-vitro inactivation of virus in biological material. In the present study the 2 methods were tested for possible effects on measurable concentrations of reproductive hormones in equine plasma (luteinizing hormone (LH), folliclestimulating hormone (FSH), progesterone (P4), and oestradiol-17 beta (E2)). The inactivation methods were electron beam irradiation with a dose from 11 to 44 kGy or treatment with binary ethylenimine (BEI) in concentrations of 1 and 5 mmol/L. Generally, there was a clo...
Rodriguez H, Bustos Obregon E.The fertilizing ability of stallion semen was analyzed using fresh and frozen samples, obtained before (June-July) or during (October-November) the breeding season. Thirty ejaculates obtained from 4 stallions were used. The analysis comprises routine seminogram; ATP concentration (Comhaire et al., 1983); subjective and objective motility and sperm velocity (Makler, 1980). Freezing was done following the technique of Martin et al. (1979). Sperm velocity, ATP content and objective motility in ejaculates of subjective motility >50% show values of 14.0 + or - 0.84 mu m s(-1); 4.8 + or - 2.7x10(...
Dart A, Tee E, Brennan M, Dart C, Perkins N, Chapman S, Debney S.To assess the effect of 1 or 2 laryngeal prosthetic sutures on rima glottidis areas in equine laryngeal specimens. Methods: Experimental, randomized design. Methods: Cadaveric equine larynges (n=16). Methods: Larynges were collected from 10 horses; 2 sutures each were preplaced in the right and left sides of each larynx. A dorsal suture (DS) was placed through the caudal rim of the dorsal midline of the cricoid cartilage, under the cricopharyngeus muscle and through the proximal and rostral aspect of the muscular process. A lateral suture (LS) was placed 1.5 cm lateral to the DS and through th...
Orsolini MF, Verstraete MH, van Heule M, Orellana D, Ortega A, Meyers S, Dini P.Intracytoplasmic sperm injection (ICSI) is the only method for in vitro embryo production (IVP) in horses. Besides oocyte developmental competence, the outcome of IVP is also highly dependent on sperm quality. Therefore, it is not only essential to employ superior methods of selecting high quality sperm, but also to be able to characterize which quantifiable properties of sperm quality are most indicative of its fertility. In men, a net negative surface charge, estimated by zeta potential (ZP) is highly correlated with sperm quality and in vitro embryo developmental outcomes. However, there ...
Nogueira GP.Twelve female ponies were examined daily for 30 days and classified as ovulating (OV; N = 6; 197 +/- 6 kg) or prepubertal (PP; N = 6; 196 +/- 9 kg). Follicles were detected by ultrasound and gonadotropins quantified by radioimmunoassay. The mean diameter of the largest follicles was significantly larger in OV (38 +/- 1 mm) than in PP (26 +/- 2 mm) but there was no difference between groups in the size of the second largest follicle. There were more small follicles (29 mm than the OV fillies. Follicle-stimulating hormone (FSH) levels did not differ between groups but PP fillies had lower lutein...
Xu J, Lasry JB, Svaren J, Wagner B, Darien BJ.P-selectin glycoprotein ligand-1 (PSGL-1, CD162) is a dimeric, mucin-like, transmembrane glycoprotein constitutively expressed on leukocytes. A high baseline level of P-selectin expression in circulating equine platelets suggests a primed state toward inflammation and thrombosis via P-selectin/PSGL-1 adhesion. To investigate the potential role of equine P-selectin in these events, we first identified the cDNA sequence of equine PSGL-1 (ePSGL-1) using degenerate PCR and RACE-PCR and then compared the predicted sequence with that of human PSGL-1 (hPSGL-1). ePSGL-1 protein subunit is predicted to...
Wetmore LA, Derksen FJ, Blaze CA, Eyster GE.The relationship between mixed venous O2 tension and cardiac output was studied in six anesthetized horses breathing 100% O2. Cardiac output, O2 consumption, mean arterial pressure, heart rate, and arterial and venous blood gases were measured after administration of xylazine or dobutamine to horses in lateral, sternal, and dorsal recumbencies. After approximately 3 hours, Escherichia coli endotoxin was administered while horses were in dorsal recumbency, and all measurements were repeated. Relationships between cardiac index (CI) and PVO2, heart rate, mean arterial pressure, jugular PVO2, and...
Singh B, Minhas KJ, Atwal OS.The pulmonary intravascular macrophages (PIMs) of the ponies possess all the characteristics of a fully differentiated resident macrophage, which forms adhesive plaques with the capillary-endothelial cells. In addition, it has a unique surface coat which does not conform to the concept of a carbohydrate rich membrane bound glycocalyx generally associated with macrophages. We studied the responses of these cells especially in the context of its globular surface coat to multiple doses of MB intravenously: 0.2 ml/kg body copper tracer substance. The ponies were treated with three doses of MB intr...
Poradowski D, Chrószcz A.Histological and morphometrical analysis of the stomach wall was performed during the foetal period divided into three age groups (4th-11th month of gestation). The material was taken from non-glandular (the blind ventricular sac) and glandular parts (the plicated edge margin/cardiac part, the body of stomach and the pyloric part) of the stomach. It was preserved and prepared according to the standard protocol. The histological slides were stained (H-E, Masson-Goldner and PAS). The analyses were performed using the light microscope. All measurements were statistically elaborated. The crown-rum...
Jamieson CA, Hanzlicek AS, Payton ME, Holbrook TC.To determine reference intervals and the effect of sample agitation and rest time on Sonoclot analysis in healthy adult horses. Methods: Original prospective study. Methods: University veterinary medical teaching hospital. Methods: Sixty healthy adult horses. Methods: Blood was collected for assessment of complete blood count, serum biochemical analysis, and Sonoclot analysis. Results: Horses were determined to be healthy based upon physical examination, CBC, and serum biochemistry analysis. Blood was analyzed in a glass bead-containing cuvette using the Sienco Sonoclot analyzer following 2 re...
Irvine CH, Alexander SL, McKinnon AO.The aim was to define precisely the FSH secretion pattern in mares during the two ovulatory cycles before, and for 24 days after, the last ovulation of the season and to compare this with the profiles of other reproductive hormones and follicular growth to identify changes which may lead to the termination of follicular cycles. Jugular blood was collected every 6 h from ten light horse mares for 6 weeks in autumn. Samples were assayed for FSH, LH, prolactin, inhibin, oestrone conjugates and progesterone. Luteolysis occurred earlier and periovulatory oestrone, but not inhibin, concentrations we...
