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.
Moore RM, Charalambous AC, Masty J.To measure colonic arterial (CA) and colonic venous (CV) plasma neuropeptide concentrations during low-flow ischemia and reperfusion of the large colon in horses. Methods: 10 adult horses. Methods: CA and CV plasma samples collected from anesthetized horses during experimentally induced low-flow colonic ischemia and reperfusion were assayed for vasoactive intestinal polypeptide (VIP), calcitonin gene-related peptide (CGRP), and substance P (SP), using radioimmunoassays. In 6 anesthetized horses, colonic ischemia (20% of baseline (BL]) was maintained for 3 hours, then blood flow was restored an...
Wagner PD, Erickson BK, Seaman J, Kubo K, Hiraga A, Kai M, Yamaya Y.Although the horse is considered an elite athlete with a specific VO2max some 2-4 times higher than man, maximal O2 transport is compromised both by moderately severe arterial desaturation and by failure to extract all O2 from blood perfusing exercising muscle. This prompted the present study to ascertain whether correction of arterial desaturation would proportionally augment VO2max and, if so, would O2 extraction behave in a manner predicted by diffusional transport limitation. Six two year old thoroughbreds were exercised to VO2max on a treadmill each on three separate occasions breathing g...
Martin RB, Gibson VA, Stover SM, Gibeling JC, Griffin LV.In studying the flexural fatigue properties of the equine third metacarpal (cannon) bone, we previously found that the dorsal region was weaker monotonically, but more fatigue resistant, than the lateral region. Fatigue resistance was associated with fracture surfaces which demonstrated that secondary osteons had "pulled out" of the surrounding matrix; this never happened in lateral specimens. We therefore became interested in the osteonal structure of this bone, and began to study its birefringence patterns in circularly polarized light. We found that the predominant type of secondary osteon ...
Riley CB, Archer FJ, Bailey JV.To compare the effects of different commercial nutrient media and sera on protein synthesis and maintenance of cellular density in cultures of the equine superficial digital flexor tendon (SDFT). Methods: 8 healthy 2- to 4-year-old horses. Methods: First Dulbecco's modified Eagle's medium, Ham's F12 nutrient mixture, RPMI 1640 medium, minimum essential medium with Earle's salts, minimum essential medium with Hanks' salts, and a Dulbecco's modified Eagle's medium/Ham's F12 nutrient mixture with 10% fetal bovine serum (FBS) were compared. Then FBS, fetal equine serum, and donor horse serum, each...
Rakestraw PC, Snyder JR, Woliner MJ, Sanders KM, Shuttleworth CW.To evaluate the role of nitric oxide (NO), vasoactive intestinal peptide (VIP), and a transmitter acting through an apamin-sensitive mechanism in mediating inhibitory transmission in the equine jejunal circular muscle, and to determine the distribution of VIP-and NO-producing nerve fibers in the myenteric plexus and circular muscle. Methods: Circular muscle strips were suspended in tissue baths containing an oxygenated modified Krebs solution and attached to isometric force transducers. Responses to electrical field stimulation (EFS), tetrodotoxin, the NO antagonists L-N-nitro-arginine-methyl-...
Krzywanek H, Mohr E, Mill J, Scharpenack M.Until the age of about 2 years, trotters normally grow up on pasture without any kind of training. In the stud farm Lindenhof (Templin, Germany), however, these first 2 years are used for a special fitness training for the young animals: 2-3 times a week, a group of the yearlings is forced to run a distance of about 1700 m on a track at an average speed of up to 10 m/s. Until now, little was known about changes of blood parameters which may occur during such special exercise. This study therefore investigated the activity of selected serum enzymes (aspartate-amino-transferase (AST), alanine-am...
Douglas JE, Mittal C, Thomason JJ, Jofriet JC.During normal weight-bearing and locomotion, the equine hoof wall deforms in a consistent pattern; the proximal dorsal wall rotates caudo-ventrally about the distal dorsal border and there is latero-medial flaring posteriorly. The aim of this study is to examine whether there are regional differences in the modulus of elasticity of hoof wall material and whether such differences correlate with the pattern of deformation which occurs in vivo. The modulus of elasticity of equine hoof wall was determined in tension and compression for samples from six forefeet. Samples were tested at the mid-poin...
Wilson DA, Adelstein EH, Keegan KG, Barrett BA, Kutz RR.To determine whether monokines produced by activated rabbit peritoneal macrophages can inhibit development of exuberant granulation tissue formation in distal limb wounds in ponies. Methods: Randomized block. Methods: 5 castrated male ponies, 2 to 6 years old and weighing 140 to 190 kg. Methods: In vitro activity of cell-free rabbit peritoneal macrophage supernatant was determined after incubation of fibroblasts from the flank and the distal portion of limbs of horses and ponies. Tritiated thymidine was then added, and after reincubation, radioactivity was measured. After creation of a 4-cm2, ...
Gustchina A, Kervinen J, Powell DJ, Zdanov A, Kay J, Wlodawer A.Equine infectious anemia virus (EIAV), the causative agent of infectious anemia in horses, is a member of the lentiviral family. The virus-encoded proteinase (PR) processes viral polyproteins into functional molecules during replication and it also cleaves viral nucleocapsid protein during infection. The X-ray structure of a complex of the 154G mutant of EIAV PR with the inhibitor HBY-793 was solved at 1.8 A resolution and refined to a crystallographic R-factor of 0.136. The molecule is a dimer in which the monomers are related by a crystallographic twofold axis. Although both the enzyme and t...
Roy TK, Popel AS.Characterizing the resistances to O2 transport from the erythrocyte to the mitochondrion is important in understanding potential transport limitations. A steady-state model of this process was developed to predict the minimum (critical) end-capillary PO2 required to prevent hypoxia at maximal O2 consumption (VO2max) in a circular region of tissue surrounding the venular end of a capillary. Capillary density was used as a measure of O2 delivery, and mitochondrial density was used as a measure of O2 consumption. The effects of oxyhemoglobin dissociation kinetics and diffusion facilitation by hem...
Waran NK, Robertson V, Cí·¯ord D, Kokoszko A, Marlin DJ.The effects of transporting horses facing either forwards or backwards were compared by transporting six thoroughbred horses in pairs in a lorry on one journey facing in the direction of travel, and on another journey facing away from the direction of travel, over a standard one-hour route. Heart rate monitors were used to record their heart rate before, during and after the journey and the horses' behaviour was recorded by scan sampling each horse every other minute. The average heart rate was significantly lower (P < 0.05) when the horses were transported facing backwards, and they also t...
Mostert HJ, Lund RJ, Guthrie AJ, Cilliers PJ.A theoretical integrative model was developed to determine the heat balance of horses working in a given environment. This model included the following parameters: metabolic heat gain, solar heat gain, evaporative heat loss due to sweating, respiratory tract heat loss, radiation from the body and heat gain or loss due to convection and conduction. The model developed in this study includes an unique approach for estimating heat loss via evaporation of sweat from the animal's skin surface. Previous studies modelling evaporative heat dissipation were based on the volume of sweat loss. While it i...
Scott CM, Marlin DJ, Schroter RC.Modification of a ventilated capsule technique for the measurement of sweating rate (SR) is described for application in an exercising horse. The plastic capsule was sealed against the coat of the horse. Dry air was blown through the capsule over the skin and the change in absolute humidity (g/m3) between air entering and leaving the capsule was used to calculate SR. The effect of flow rate on the response characteristics of the system was investigated and measured over a range of sweating rates in a group of horses completing a short exercise test. Repeatability of SR measurements made at 2 s...
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) ...
Alm H, Hinrichs K.The period of protein synthesis necessary for meiotic maturation in horse oocytes initially having compact or expanded cumulus cells was studied. Oocytes incubated in the presence of cycloheximide after 0, 4, 8, 12 or 16 h maturation in vitro (total incubation time 24 h) were matured for 24 h, or were incubated with cycloheximide for 24 h and then matured for 24 h. Incubation with cycloheximide from 0 h was effective in suppressing maturation (no significant increase in maturing oocytes compared with controls fixed directly after removal from the follicle) in both expanded and compact groups a...
Rivero JL, Henckel P.Biopsies were taken from three different depths of the gluteus medius muscle of 36 endurance horses aged between four and 17 years. Twenty of the horses were considered excellent performers according to their three fastest records in endurance events over the previous two or three years. The other 16 horses were moderate performers, with a mean racing speed < 3.5 ms-1 (in 120 to 180 km endurance rides), < 4.0 ms-1 (in 80 to 120 km endurance rides) or < 3.75 ms-1 (in 40 to 60 km endurance rides). The biopsy specimens were analysed for fibre type distribution (type I, IIA and IIB), fibr...
Todhunter RJ, Fubini SL, Wootton JA, Lust G.The effect of different doses of methylprednisolone acetate (MPA) on proteoglycan and collagen metabolism of articular cartilage from normal equine joints was tested in vitro. Methods: Cultured explants were treated with 0, 0.0004, 0.004, 0.04, 0.4 and 4.0 mg/ml (approximately 10(-6)-10(-2) M) MPA for 72 h. Proteoglycan synthesis was measured by incorporation of sodium [35S]sulfate into proteoglycans and proteoglycan degradation was measured by release of total and radiolabeled proteoglycan into the culture media. The size of the proteoglycans was assessed with size exclusion chromatography un...
Mitten LA, Hinchcliff KW, Pate JL.The effect of inhibition of cyclooxygenase activity on the hemodynamic response to exertion was examined in 6 horses. Rates of O2 consumption and CO2 production and carotid, pulmonary arterial, and right atrial pressures were measured while the horses performed a standardized exercise test on a treadmill after treatment with phenylbutazone or a placebo. Phenylbutazone (8.8 mg/kg p.o. for 2 days and 4.4 mg/kg i.v. 60 min before exertion) abolished the exertion-induced increases in plasma 6-ketoprostaglandin F1 alpha and thromboxane B2 concentrations, confirming inhibition of cyclooxygenase acti...
Ensink JM, Vulto AG, van Miert AS, Tukker JJ, Winkel MB, Fluitman MA.To determine the oral bioavailabilities of 3 ampicillin esters (pivampicillin, bacampicillin, and talampicillin) and ampicillin sodium, and to determine in vitro stability of the ampicillin esters in ileal contents (pH 8.3 to 8.5). Methods: A crossover design to administer the 4 drugs orally, and ampicillin i.v. to all horses in the study. Methods: 4 healthy adult horses. Methods: The drugs were administered intragastrically to the horses at a dosage equimolar to 15 mg of ampicillin/kg of body weight. Also, ampicillin sodium was administered i.v. at the same dosage. Blood samples were taken up...
McDowell KJ, Little TV, Timoney PJ, Adams MH.The major proteins in stallion seminal plasma were characterised by two-dimensional polyacrylamide gel electrophoresis, and compared with the patterns of proteins in normal geldings (castrated males) and geldings supplemented with testosterone. The major proteins or groups of proteins identified according to their approximate relative molecular weight in kilodaltons (kDa) and apparent isoelectric point (pl) were: 1) 60 kDa. pl 7; 2) 23 kDa, pl 4-5; 3) 25-30 kDa, pl 5.5-6; 4) 23 kDa, pl 7-8; and 5) 15-20 kDa, pl 6-7.5. Protein groups 1 and 2 were more prominent in the seminal plasma from the st...
Owens JG, Kamerling SG, Stanton SR, Keowen ML.Detomidine (10, 20 and 40 micrograms/kg i.v.) and saline were administered to eight adult horses with hoof pain and lameness associated with chronic laminitis. Mechanical noxious stimulation was applied to 16 loci over the solar surface of each forefoot by means of an electronic hoof tester to determine chronic pain thresholds. Horses were evaluated before and at 25, 55 and 120 min after treatment for lameness and to determine hoof compression thresholds (HCTs), the percentage of responsive loci and the subjective grade of hoof withdrawal response at each responsive locus. Detomidine produced ...
Guhl A, Lindner A, von Wittke P.To examine the reproducibility of blood lactate-running speed curve parameters derived by a curve-fit equation and by linear interpolation from the results of 4-speed tests of sport horses under field conditions. Methods: Thoroughbreds completed 10 test pairs with 3 to 11 days between tests and retest. Methods: 7 Thoroughbreds. Methods: The 4-speed test consisted of 4 runs over a distance of 2,110 m. Exercise intensity was increased by 1 m/s for each run. Blood lactate concentration measured after each run was plotted against running speed to determine the blood lactate-running speed relation....
Gottlieb-Vedi M, Dahlborn K, Jansson A, Wroblewski R.In this study, 4 Standardbred geldings were exercised at 20 and 35 degrees C. The exercise test (ET) consisted of 2 exercise bouts separated by 2 h of rest in their boxes. Blood samples were taken before, during and after the second exercise bout and muscle (m. gluteus medius) biopsies were taken before the first exercise bout and after an intensive trot over 2600 m in the second exercise bout. The blood samples were analysed for plasma potassium and total plasma protein concentration (TPP) and the muscle fibres were analysed for elemental composition by x-ray microanalysis. The intracellular ...
Weng X, Cloutier G, Pibarot P, Durand LG.Erythrocyte aggregation levels in pig, horse, sheep, and calf blood samples were investigated and compared to that of normal human blood. The aggregation kinetics and adhesive forces between red cells, and an index of structure of the aggregates were determined with an erythroaggregameter (Regulest, France) at constant hematocrit (0.40 l/l) and temperature (37 degrees C). The adhesive forces and the index of structure in pig blood were close to those of normal human blood. The results for horse blood showed a very high level of aggregation kinetics and adhesive forces between red cells. For sh...
Harkins JD, Mundy GD, Stanley S, Woods WE, Sams RA, Richardson DR, Tobin T.Isoxsuprine is a therapeutic medication used to treat navicular disease and other lower limb problems in horses and is one of the more frequently detected therapeutic agents in racing horses. In a crossover study, horses were administered isoxsuprine i.v. to determine the character and duration of its pharmacological effects. Isoxsuprine significantly increased heart rate 5-150 min following injection. Unrestrained activity following isoxsuprine treatment was significantly greater than control activity for 105 min after treatment. There was an apparent, although statistically nonsignificant, i...
McClure SR, Watkins JP, Hogan HA.To compare the axial stability provided by 4 methods of attaching transfixation pins into a fiberglass cast. Methods: Axial stability of 4 methods of transfixation pin attachment to a fiberglass cast cylinder was determined in vitro. Methods of attachment included simple incorporation of the pins into the cast, placement of a washer and nut on the pin and incorporation into the cast, extension of pins beyond the cast and attachment to a steel halo, and washers within the cast and attachment to a steel halo. Methods: A model was designed to simulate a transfixation cast applied to the equine me...
Nyman S, Jansson A, Dahlborn K, Lindholm A.To avoid dehydration and a decrease in performance capacity in horses, fluid and electrolyte losses need to be compensated for during long distance rides as well as on other occasions when sweat losses are high during exercise. Thirteen endurance-trained horses, age 5-14 years, were used to compare 3 strategies of voluntary rehydration during prolonged exercise, offering 1) water, 2) water after administering salt paste (3 x 30 g of NaCl) per os and 3) 0.9% saline. The ride covered 62 km and consisted of 3 rounds, of 20, 22 and 20 km, respectively. During the first 20 km, no fluid was offered ...
Maldonado PA, Montoya TI, Acevedo JF, Keller PW, Word RA.Although the positive effects of vaginal estrogens and the selective estrogen receptor modulator, ospemifene (OS), on the vaginal epithelium are well recognized, less is known regarding the effects of these therapies on the lower urinary tract or vaginal muscularis. Clinical evidence suggests that vaginally administered estrogen may improve overactive bladder-related symptoms. The objective of this study was to compare the effects of OS, vaginal conjugated equine estrogens (CEE), or both on the vaginal wall and lower urinary tract in a rat model of menopause. Contractile force of the bladder n...
Prickett TCR , Inder WJ, Evans MJ, Donald RA.The acute-phase cytokine interleukin-1 (IL-1) is known to activate the hypothalamic pituitary adrenal axis, primarily via corticotropin releasing hormone (CRH). The aim of this study was to determine whether IL-1beta could directly stimulate ACTH secretion from perifused equine anterior pituitary cells, and whether CRH pre-incubation affected corticotroph responsiveness. Isolated equine anterior pituitary cells were pre-incubated with media containing 10 nM CRH or vehicle for 20 hours before being loaded onto columns and perifused with 0.02 nM CRH and 100 nM cortisol. Columns were given a 5-mi...
Lindner A, Dag Erginsoy S, Kissenbeck S, Mosen H, Hetzel U, Drommer W, Chamizo VE, Rivero JL.The effects of three different blood-guided conditioning programmes on ultrastructural and histochemical features of the gluteus medius muscle of 2-year-old sport horses were examined. Six non-trained Haflinger horses performed three consecutive conditioning programmes of varying lactate-guided intensities [velocities eliciting blood lactate concentrations of 1.5 (v1.5 ), 2.5 (v2.5 ) and 4 (v4 ) mm respectively] and durations (25 and 45 min). Each conditioning programme lasted 6 weeks and was followed by a 5-week resting period. Pre-, post- and deconditioning muscle biopsies were analyse...
De Gasperi D, Dzierzak SL, Muir P, Vanderby R, Brounts SH.OBJECTIVE To assess the effects of sedation on results of acoustoelastography of the superficial digital flexor tendons (SDFTs) in clinically normal horses. ANIMALS 27 clinically normal horses. PROCEDURES For each horse, the pathology index (PI) for the SDFT of each thoracic limb was determined by use of acoustoelastography at 4 locations (5, 10, 15, and 20 cm distal to the accessory carpal bone). Horses were evaluated before and after they were sedated with a combination of detomidine hydrochloride (0.01 mg/kg, IV) and butorphanol tartrate (0.01 mg/kg, IV). A repeated-measures ANOVA was used ...
Jernigan AD, Wilson RC, Booth NH, Hatch RC, Akbari A.In steers, horses and dogs, the comparative pharmacokinetics of yohimbine were determined using model-independent analysis. The intravenous dose of yohimbine was 0.25 mg/kg of body weight in steers, 0.075 or 0.15 mg/kg in horses, and 0.4 mg/kg in dogs. The mean residence time (+/- SD) of yohimbine was 86.7 +/- 46.2 min in steers, 106.2 +/- 72.1 to 118.7 +/- 35.0 min in horses, and 163.6 +/- 49.7 min in dogs. The mean apparent volume of distribution of yohimbine at steady state was 4.9 +/- 1.4 L/kg for steers, 2.7 +/- 1.0 to 4.6 +/- 1.9 L/kg for horses, and 4.5 +/- 1.8 L/kg for dogs. The total ...
Hochi S, Fujimoto T, Choi YH, Braun J, Oguri N.Immature equine oocytes were frozen-thawed with ethylene glycol (EG), 1,2-propanediol (PD) or glycerol (GL) in PBS and cultured to assess the rate of in vitro maturation (Experiment 1). Compact-cumulus oocyte complexes were collected from slaughterhouse ovaries and equilibrated for 10 min in the freezing medium containing 10% (V/V) cryoprotectant and 0.1 M sucrose. The 0.25-ml straws, loaded with 10 to 30 oocytes, were seeded at -6 degrees C and cooled to -35 degrees C at 0.3 degrees C/min before being plunged into liquid nitrogen. The straws were thawed rapidly in a 37 degrees C waterbath for...
Bolann BJ, Ulvik RJ.The redox interaction between O2.- and ferritin cannot solely be regarded as as a Fe(II) release reaction. We demonstrate that native copper bound to horse spleen ferritin and apoferritin, stimulated the decay of O2.- in a catalytic reaction. Copper was determined by atomic absorption spectrophotometry. Decay of O2.- was monitored spectrophotometrically as the decrease in (A250-A360) at pH 9.5. The catalytic effect was linearly related to the copper content of the protein. Ferritin copper was less efficient than equimolar CuCl2, and iron-poor ferritin was more efficient than iron-rich ferritin...
Noble P, Collin B, Lecomte-Beckers J, Magnée A, Denoix JM, Serteyn D.This study describes an equine joint friction test using a cartilage-on-cartilage arrangement and investigates the influence of age and load on the frictional response. Osteochondral plugs were extracted from equine shoulder joints (2-5 years, n=12; 10-14 years, n=15), and mounted in a pin-on-disc tribometer. The frictional response was then measured under constant conditions (2N; 20 degrees C; 5 mm/s), and with increasing load (2N, 5N, 10N). In all experiments, the friction coefficient of young cartilage was significantly (P<0.001) smaller than obtained from old cartilage, while the applicati...
Lu Z, Kasaragod DK, Matcher SJ.We present a phase fluctuation calibration method for polarization-sensitive swept-source optical coherence tomography (PS-SS-OCT) using continuous polarization modulation. The method uses a low-voltage broadband polarization modulator driven by a synchronized sinusoidal burst waveform rather than an asynchronous waveform, together with the removal of the global phases of the measured Jones matrices by the use of matrix normalization. This makes it possible to average the measured Jones matrices to remove the artifact due to the speckle noise of the signal in the sample without introducing aux...
Evans MJ, Marshall AG, Kitson NE, Summers K, Donald RA.The multifactorial control of ACTH is well established. We wished to establish and characterize an in-vitro perifusion system, using equine anterior pituitary cells and physiological concentrations of secretagogues, to investigate factors which affect the dynamics of ACTH secretion. Anterior pituitary tissue was divided for dispersion into cells with collagenase, trypsin or dispase, or by mechanical dispersion. After dispersal followed by 18-h incubation, cells were perifused and the ACTH response to 10-min pulses of arginine vasopressin (AVP; 100 nmol/l), corticotrophin-releasing hormone (CRH...
Ohta M, Kurimoto S, Ishikawa Y, Tokushige H, Mae N, Nagata S, Mamada M.To determine dose-dependent cardiovascular effects of dobutamine and phenylephrine during anesthesia in horses, increasing doses of dobutamine and phenylephrine were infused to 6 healthy Thoroughbred horses. Anesthesia was induced with xylazine, guaifenesin and thiopental and maintained with sevoflurane at 2.8% of end-tidal concentration in all horses. The horses were positioned in right lateral recumbency and infused 3 increasing doses of dobutamine (0.5, 1.0 and 2.0 µg/kg/min) for 15 min each dose. Following to 30 min of reversal period, 3 increasing doses of phenylephrine (0.25, 0.5 and 1....
Jacobson CC, Sertich PL, Mc Donnell SM.To investigate effects of a 5-day oral misoprostol regimen recommended for use in horses as a gastrointestinal mucosal cytoprotectant during colic on mid-gestation pregnancies. Objective: To monitor cervical tone, ultrasonographic characteristics of the uterus, cervix and conceptus, as well as serum progesterone and oestrone sulphate concentrations, and observations of general health, behaviour and comfort of mid-gestation mares given a 5-day course of misoprostol or control treatment. Methods: Eleven light horse and pony mares with known breeding dates were administered 5 µg/kg bwt misoprost...
Murray A, Cottrell DF, Woodman MP.Equine grass sickness (EGS) is a pan-dysautonomia of horses that involves central and peripheral neuronal degeneration and ultimately depletion. This is the first reported functional study on the motility of equine intestine taken immediately post mortem from horses with EGS. Strips of smooth muscle from the small intestine of healthy and EGS-affected horses were suspended in an organ bath and their motility was measured isometrically. The activity of the cholinergic system was studied. Physostigmine enhanced the motility of all muscle strips. Tissues taken from horses suffering from acute gra...
Bramucci M, Miano A, Quassinti L, Maccari E, Murri O, Amici D.This study was conducted to determine the presence of the angiotensin converting enzyme in commercial sera used in cell culture medium. The aim of the research was to bring the presence of proteinases (angiotensin converting enzyme) to cell culture users' knowledge and to give some data for solving problems about the development of peptides as useful drugs. The enzymes, purified from foetal bovine, adult bovine, foetal equine, adult equine, and human sera, showed molecular weights of about 170 kDa. Captopril and lisinopril inhibited enzyme activities at nanomolar concentrations. The enzymes we...
Bailey SR, Cunningham FM.Accumulation of equine eosinophils at sites of parasite infestation or allergic inflammation depends upon their adherence to vascular endothelial cells and subsequent migration through the endothelium and extracellular matrix. This study has examined whether cytokines, which cause endothelial cell-dependent eosinophil adherence in other species, and histamine and substance P, which increase adherence of equine eosinophils to protein coated plastic, induce equine eosinophil adherence to cultured equine digital vein endothelial cell (EDVEC) monolayers. The EDVEC monolayers were stimulated with r...
Hansen TL, Rankins EM, Bobel JM, McKinney M, Hackmann TJ, Warren LK.In humans, the consumption of soluble fibers reduces glycemic response after a meal. We hypothesized high soluble fiber diets would reduce and delay postprandial glucose and insulin responses in horses. In a 4 × 4 Latin square design experiment, four Quarter Horse geldings were adapted to diets containing orchardgrass hay (ORCH) or ORCH with 1 of 3 treatment ingredients: molassed sugar beet pulp (BEET), almond hulls (HULL), or steam-crimped oats (OATS). Blood was serially sampled for 6 hours after feeding 0.15% body weight (BW) of the treatment ingredient (meal test) or 1.1 g starch/kg BW ...
Brink P, DeGraves F, Ravis WR, Johansen D, Campbell JD, Duran SH.To determine intravascular and intrasynovial pharmacokinetics of the R and S enantiomers of ketoprofen after i.v. and i.m. administration to horses. Methods: 6 healthy adult mares. Methods: Horses were weighed and ketoprofen (2.2 mg/kg of body weight) was administered i.v. Blood and synovial fluid samples were obtained and analyzed for concentrations of the R and S enantiomers by means of a modified reverse-phase stereospecific high-pressure liquid chromatographic method. Three weeks later, the procedure was repeated, except that ketoprofen was given IM. Protein binding of ketoprofen enantiome...
Gonda KC, Wilcke JR, Crisman MV, Ward DL, Robertson JL, Finco DR, Braselton WE.To determine whether pharmacokinetic analysis of data derived from a single i.v. dose of iohexol could be used to predict creatinine clearance and evaluate simplified methods for predicting serum clearance of iohexol with data derived from 2 or 3 blood samples in clinically normal foals. Methods: 10 healthy foals. Methods: Serum disposition of iohexol and exogenous creatinine clearance was determined simultaneously in each foal (5 males and 5 females). A 3-compartment model of iohexol serum disposition was selected via standard methods. Iohexol clearance calculated from the model was compared ...
Gable TL, Woods GL.The objective was to test the hypothesis that increasing equine oocyte culture time from 48 to 96 or 144 h increases nucleus maturation of equine oocytes. The hypothesis was not supported because condensed chromatin-stage oocytes decreased (P<0.01) from 33/126 (26.2%) at 48 h or 34/95 (35.8%) at 96 h to 11/117 (9.4%) at 144 h, and polar body-stage oocytes decreased (P<0.01) from 65/126 (51.6%) at 48 h to 25/95 (26.3%) at 96 h and (P<0.01) to 1/117 (0.9%) at 144 h. Negative (non-staining) oocytes increased (P<0.01) from 16/126 (12.7%) at 48 h or 15/95 (15.8%) at 96 h to 39/117 (33.3%) at 144 h....
Löfgren M, Ekman S, Svala E, Lindahl A, Ley C, Skiöldebrand E.Formation of synovial joints includes phenotypic changes of the chondrocytes and the organisation of their extracellular matrix is regulated by different factors and signalling pathways. Increased knowledge of the normal processes involved in joint development may be used to identify similar regulatory mechanisms during pathological conditions in the joint. Samples of the distal radius were collected from prenatal and postnatal equine growth plates, zones of Ranvier and articular cartilage with the aim of identifying Notch signalling components and cells with stem cell-like characteristics and...
Schott HC, Hinchcliff KW.In an attempt to enhance performance, primarily by delaying the onset of fatigue, a variety of formulations of fluids, electrolytes, and sodium bicarbonate are administered to performance horses. Some current practices of fluid and electrolyte supplementation are well justified; others have no basis to support their use. In addition, occasional combined administration of certain agents (i.e., furosemide and sodium bicarbonate) can have detrimental effects on performance.
Matsumoto T, Okumura S, Hirata S.This study aimed to apply radar technology to a large quadruped animal. We first developed a non-contact respiration measurement system using millimeter-wave array radar for a horse in standing position. Specifically, we measured the respiration of a stationary domestic horse in stables. Simultaneously, we measured the respiration rate using infrared thermography and developed a method for analyzing the radar information while verifying the rate of agreement. Our results suggested that the radar technology detected breathing and accurately measured the respiration of a horse, despite variation...
Gérard N, Monget P.The profiles of insulin-like growth factor-binding proteins (IGFBPs) in follicular fluid have been characterized in a number of mammals (rats, pigs, sheep, cattle, humans) and are good indicators of follicular status. We studied the IGFBP profiles of equine serum and ovarian follicular fluid recovered at various stages of the follicular phase. The levels of IGFBPs were related to the morphology and the steroidogenic activity of the follicles. Follicular fluids were recovered by ultrasound-guided follicular aspiration. In the first experiment, the dominant follicles of 10 mares were partly punc...
Parillo F, Verini Supplizi A.The present work was undertaken to determine the glycoconjugates secreted by the epithelium of the equine ampulla ductus deferentis, using conventional (PAS, AB pH 2.5, AB pH 1.0) and lectin histochemical procedures in conjunction with enzymatic digestion and chemical treatment. The presence of abundant apical cytoplasmic blebs suggests that the equine ampulla secretes its products mainly in an apocrine manner. Glandular cells secrete neutral and acidic sialylated glycoconjugates as revealed by conventional histochemical procedures. Lectin histochemistry helped us to discover the following his...
Ellis MJ, Mulligan RS, Evans MJ, Donald RA.Antagonists are useful for probing hormone action and receptor characteristics. In this study we have investigated the inhibitory effects of analogues of arginine vasopressin (AVP) and corticotrophin-releasing hormone (CRH) on stimulated release of immunoreactive ACTH from perifused equine anterior pituitary cells in vitro. Our aims were to gain some insight into the characteristics of the CRH and AVP receptors of the horse pituitary and to establish whether the response induced by AVP and CRH together could be blocked by combining antagonists. Experimental design included 5-min pulses of AVP ...
Kent JE, Blackmore DJ.This paper describes the quantitative measurement of IgG concentrations in equine blood/serum by turbidimetric analysis and the qualitative assessment using latex agglutination. The concentration of IgG in foal serum measured by turbidimetry correlated well with the results obtained by radial immunodiffusion (r = 0.91) and the gamma-globulins estimated from the electrophoresis of serum on cellulose acetate (r = 0.92). The method, using antibody-coated latex beads, to detect foals with serum IgG concentrations of less than 4 g/litre (whole blood less than 2 g/litre) proved to be accurate in 96 ...
Di Filippo PA, Vieira V, Rondon DA, Quirino CR.The aim of the study was to determine if dental correction changes fecal fiber length (FFL) in horses that had never been subjected to dental treatments. Thirty adult horses with mild to moderate dental abnormalities were selected. Dental disorders noted included sharp enamel points, focal overgrowths, shear mouth, step mouth, wave mouth, accentuated transverse ridges, and diastema. The horses were confined to individual stalls and fed Tifton hay (Cynodon spp.) 1.5% bwt/d, divided equally between two feedings. Fecal samples were taken for FFL analysis before (Day 0) and after (Day 15) dental c...
Art T, Votion D, McEntee K, Amory H, Linden A, Close R, Lekeux P.Two randomly distributed groups of thoroughbred horses were compared during a 12-week period for their cardio-respiratory and metabolic adjustment to strenuous exercise, training and detraining. The horses were trained following the same standardized schedule and were regularly investigated using standardized treadmill exercise tests (SET) of increasing speed. After the first SET and during the whole experimental period, a group of 6 horses received a probiotic (Bioracing) once a day while a group of 5 horses received a placebo. All other conditions were similar for both groups. During each SE...
Ramsook AH, Dominelli PB, Angus SA, Senefeld JW, Wiggins CC, Joyner MJ.Studies of animal physiology not only provide valuable knowledge for the species in question, but also offer insights into human physiology. This thought is best highlighted by the 'Krogh Principle', which states "for many problems there is an animal on which it can be most conveniently studied". This graphical review focuses on three distinct stages of the oxygen transport cascade in which human exercise physiology knowledge has been enhanced by studies carried out in animal models. We begin by exploring ventilation, and the detrimental effects of cold, dry air on the airways in two sets of e...
This work proposes an application of a minimal complexity physiologically based pharmacokinetic model to predict tramadol concentration vs time profiles in horses. Tramadol is an opioid analgesic also used for veterinary treatments. Researchers and medical doctors can profit from the application of mathematical models as supporting tools to optimize the pharmacological treatment of animal species. The proposed model is based on physiology but adopts the minimal compartmental architecture necessary to describe the experimental data. The model features a system of ordinary differential equations...
