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.
Piccione G, Assenza A, Fazio F, Giannetto C, Caola G.Circadian rhythmicity of physiological processes in animals has been described for some variables. In order to investigate the daily rhythmicity of blood pressure, seven foals (Equus caballus) were used for 40 days after birth. Measurements of blood pressure were done by means of an oscillometric apparatus (Argus TM-7, Schiller, Barr Switzerland) with the foals in a standing position and the cuff placed around the tail. Blood pressure was recorded twice a day, 1 hour before dawn and 1 hour before dusk for the first 10 days of life, every 2 days from the 11th to the 32nd day, on the 36th and on...
Clulow JR, Evans G, Morris LH, Maxwell WM.Intrinsic differences between stallions exist for semen traits such as motility, morphology fertility and the ability of spermatozoa to survive cryopreservation processes. Ejaculates from 11 stallions were used to test the differences between stallions when selecting X- and Y-chromosome bearing spermatozoa using a modified flow cytometer. Data on orientation and viability of spermatozoa were collected during sex-sorting, and motility characteristics of sex-sorted and non-sorted (control) spermatozoa were assessed before and after cryopreservation. An index was created to rank each stallion in ...
Fowden AL, Forhead AJ, Ousey JC.Delivery of viable young requires co-ordination of fetal maturation with the onset of labour at term. In turn, this depends on a cascade of fetal and maternal endocrine events. The sequence of these events is broadly similar in most mammals but there are differences in placental hormone synthesis and in the timing and magnitude of key prepartum endocrine changes between species. In most farm animals, maternal progesterone (P4) levels decline and oestrogen levels increase in the last 5 - 10 days before delivery in response to activation of the fetal hypothalamicpituitary-adrenal (HPA) axis and ...
Dall'aglio C, Pascucci L, Mercati F, Giontella A, Pedini V, Ceccarelli P.The aim of the present study was to investigate the presence and the distribution of cells containing orexin A and orexin type 2 receptor in the horse stomach and gut, by means of immunohistochemical techniques. Orexin A was identified in the stomach fundic and pyloric regions and in the duodenum. In the same stomach regions, a large subset of orexin A-positive cells also showed orexin type 2 receptor-like immunoreactivity. Moreover, in the duodenum, many of them, seemed to store serotonin. Characteristically, enteric neurons or ganglia also displayed orexin A and, sometimes, orexin type 2 rec...
Holopainen JT, Brama PA, Halmesmäki E, Harjula T, Tuukkanen J, van Weeren PR, Helminen HJ, Hyttinen MM.The effects of growth and maturation on the mineral deposition and the collagen framework of equine subchondral bone (SCB) were studied. Methods: Osteochondral specimens (diameter 6 mm) from the left metacarpophalangeal joint of 5-(n=8), 11-(n=8) and 18-month-old (n=6) horses were investigated at two differently loaded sites (Site 1 (S1): intermittent peak loading; Site 2 (S2): habitual loading). The SCB mineral density (BMD) was measured with peripheral quantitative computer tomography (pQCT), and the data were adjusted against the volume fraction (Vv) of the bone extracellular matrix (ECM). ...
de Camargo MM, Kuribayashi JS, Bombardieri CR, Hoge A.Studies focusing on the equine humoral response are scarce, with a bias towards the pre- and post-parturition mare and its foal. The present study attempted to expand current knowledge by establishing normal ranges for adult horse serum isotypes. Immunoglobulin (Ig) concentrations were obtained by screening 47 horses of various breeds and in different training regimes. Radial immunodiffusion values (mg/dL) were 196+/-73 for IgA, 2704+/-1424 for IgG, 419+/-220 for IgG(T) and 70+/-30 for IgM. All values passed the Kolmogorov-Smirnov normality test. The results will be of use to the field veterin...
MacKay RJ.The aim of the current study was to quantify sweating responses to intradermal terbutaline in normal horses. Seven Thoroughbred horses were used. Terbutaline (10-fold dilutions from 1000-0.001 mg/l) and a saline control were injected intradermally (0.1 ml/site) and sweat collected for 30 min into absorbent pads taped over each injection site. Tests were performed monthly for 11 successive months and temperature, relative humidity and dewpoint were measured at the time of testing. There was no significant effect (P<or=0.05) of environmental variables or time of year on sweat responses at any...
Doyle LK, Hogg CO, Watson ED, Donadeu FX.The response of follicles to IGF1 was compared between the transition into the ovulatory season (transitional period) and the ovulatory season (ovulatory period) in eight mares using a cross-over experimental design within periods. Granulosa cells were collected from follicles 15-24 or 25-34 mm and expression of IGF1R, IGF2R, FSHR, LHCGR and PAPPA was determined by qPCR. In addition, 10 mg IGF1 or vehicle were injected into the largest follicle (transitional period) or the second largest follicle (ovulatory period) of a follicular wave before the beginning of diameter deviation between the two...
Decourt C, Tillet Y, Caraty A, Franceschini I, Briant C.To determine if kisspeptin could be implicated in the control of reproduction in equine species, we studied the distribution of kisspeptin neurons and their anatomical interactions with GnRH neurons in the hypothalamus of pony mares. Brains were collected in three pony mares between 2 and 4h after ovulation. One major population of kisspeptin immunoreactive cell bodies was found in the arcuate nucleus (ARC), where they extended from the middle of the nucleus to the premammillary recess. Kisspeptin immunoreactive varicose fibers extended from the preoptic area to the mammillary nuclei, with imp...
Janowski T, Skolimowska A, Zdunczyk S, Baranski W.Total of 30 pregnant mares were used in this study: 17 Thoroughbred and 13 Primitive Polish Horse. The concentration of total unconjugated oestrogens was determined by radioimmunoassay in faecal samples obtained every second week after mating until delivery or interruption of pregnancy. Concentration of oestrogens in pregnant healthy mares ranged from 40 to 200 ng/g and showed typical profiles for pregnancy. In 5 of 30 mares (16.6%) of either breed abortions and cases of embryonic death occurred. Abortions were preceded by sharp or gradual decrease in oestrogen concentration, whereas prior to ...
Pikul J, Wójtowski J, Danków R, Kuczyńska B, Lojek J.The effect of the stage of lactation, the number of foals and age of the mare on changes in the fat content and fatty acid composition of colostrum and milk of primitive Konik horses was investigated. Colostrum and milk samples from 12 lactating mares were collected at the beginning of lactation, on the days 1 and 2 after foaling and then, starting from the first month of lactation, at 4-week intervals up to the sixth month of lactation. Significant differences were observed in fat content as well as the composition of some analysed fatty acids between colostrum and milk of mares of the Konik ...
Hollis AR, Furr MO, Magdesian KG, Axon JE, Ludlow V, Boston RC, Corley KT.Critical illness is associated with hyperglycemia in humans, and a greater degree and duration of hyperglycemia is associated with nonsurvival. Hypoglycemia is also seen in critically ill humans, and is associated with nonsurvival. This might also be true in the critically ill foal. Objective: To investigate the association of blood glucose concentrations with survival, sepsis, and the systemic inflammatory response syndrome (SIRS). Methods: Blood glucose concentrations at admission (515 foals) and 24 hours (159 foals), 36 hours (95), 48 hours (82), and 60 hours (45) after admission were analy...
Wong DM, Vo DT, Alcott CJ, Peterson AD, Brockus CW, Hsu WH.Arginine vasopressin (AVP) has received increased attention in equine critical care but there is minimal information of AVP concentration in foals. The clinical usefulness of measuring AVP in ill foals depends on knowledge of age-related changes in AVP concentrations in healthy foals. Objective: Plasma AVP concentrations will be significantly different when measured from birth to 3 months of age in healthy foals. Methods: Thirteen healthy university-owned foals. Methods: Prospective, observational study. Blood was collected from healthy foals at birth and 3, 5, 7, 10, 14, 21, 28, 42, 56, and 8...
Durando MM, Corley KT, Boston RC, Birks EK.To compare cardiac output (CO) obtained by the lithium dilution method (LiDCO) with CO calculated from the Fick principle (FickCO), in horses maximally exercising on a high-speed treadmill. Methods: 13 Thoroughbreds. Methods: In part 1 of the study, 5 horses performed a warm-up (walk, trot, and canter) and exercise test (walk, trot, canter, and gallop [90% to 100% maximum oxygen consumption [{VO(2)max}]) with measurements of LiDCO and FickCO obtained simultaneously after 60 seconds at each exercise level, for a total of 7 measurements. In part 2 of the study, 8 horses performed a warm-up (walk...
Ginther OJ, Rodrigues BL, Ferreira JC, Araujo RR, Beg MA.Blood collections for characterising 13,14-dihydro-15-keto-PGF2alpha (PGFM) pulses in mares and colour-Doppler examinations for estimating percentage of corpus luteum with blood-flow signals were done hourly for a 24-h session on Day 15 (ovulation = Day 0; n = 13 mares) or during 12-h sessions from Days 12 to 16 (n= 10 mares). Luteolysis was defined as extending from the beginning of a precipitous decrease in progesterone until progesterone was <2 ng mL(-1). Comparisons were made among preluteolysis, luteolysis, and postluteolysis. Greater prostaglandin F2alpha activity (mean PGFM concentra...
Roberto da Costa RP, Costa AS, Korzekwa AJ, Platek R, Siemieniuch M, Galvão A, Redmer DA, Silva JR, Skarzynski DJ, Ferreira-Dias G.Nitric oxide (NO) plays an important role in prostaglandin secretion and angiogenesis in the reproductive system. In the present study, the roles of the NO donor spermine NONOate and tumour necrosis factor-alpha (TNF; as a positive control) in prostaglandin production and angiogenic activity of equine endometria during the oestrous cycle were evaluated. In addition, the correlation between NO production and the expression of key prostaglandin synthase proteins was determined. The protein expression of prostaglandin F synthase (PGFS) increased in early and mid-luteal stages, whereas that of pro...
Muhonen S, Connysson M, Lindberg JE, Julliand V, Bertilsson J, Jansson A.The objective of this study was to investigate the effect of CP intake from 2 grass silage-only diets, differing in CP concentration, fed at similar DMI on the equine colon ecosystem after an abrupt feed change between the diets. Four adult right ventral colon-fistulated geldings were fed one silage-only diet high in CP (HP, 873 g of CP/d) and one diet providing recommended intakes (RP, 615 g of CP/d). An adaptation period of 15 d on either the HP or the RP diet was followed by 2 experimental periods when the diets were fed for 22 d each in a crossover design. Colon samples were taken before a...
Araujo GH, Rocha Filho AN, Lopes EP, Moya CF, Alvarenga MA.The effects of a low dose of equine purified FSH (eFSH) on incidence of multiple ovulations and embryo recovery rate in mares were studied. During the physiological breeding season in Brazil (19 degrees 45'45'S), 14 Mangalarga Marchador donor mares were used in a crossover study and another 25 mares of the same breed, between 3 years and 12 years of age were used as recipients for the embryo transfers. Donors were monitored during two consecutive oestrus cycles, an untreated control cycle followed by a treated cycle, when eFSH was administered. In both cycles, after an embryo collection attemp...
Bollwein H, Schulze JJ, Miyamoto A, Sieme H.The goal of this study was to investigate for the first time a possible association between plasma concentrations of testosterone and total estrogen and testicular blood flow in the stallion. Correlations between these variables were calculated before and after administration of human chorionic gonadotropin (hCG). Eight mature warmblood stallions received 5,000 IU hCG intravenously, and four stallions received solvent only. Testicular blood flow in the left and right testicular arteries was assessed using colour Doppler sonography by measuring blood flow volume (BFV) and pulsatility index (PI)...
Starke SD, Robilliard JJ, Weller R, Wilson AM, Pfau T.Walking and running are two mechanisms for minimizing energy expenditure during terrestrial locomotion. Duty factor, dimensionless speed, existence of an aerial phase, percentage recovery (PR) or phase shift of mechanical energy and shape of the vertical ground reaction force profile have been used to discriminate between walking and running. Although these criteria work well for the classification of most quadrupedal gaits, they result in conflicting evidence for some gaits, such as the tölt (a symmetrical, four-beat gait used by Icelandic horses). We use established pattern recognition meth...
Bellone RR, Brooks SA, Sandmeyer L, Murphy BA, Forsyth G, Archer S, Bailey E, Grahn B.The appaloosa coat spotting pattern in horses is caused by a single incomplete dominant gene (LP). Homozygosity for LP (LP/LP) is directly associated with congenital stationary night blindness (CSNB) in Appaloosa horses. LP maps to a 6-cM region on ECA1. We investigated the relative expression of two functional candidate genes located in this LP candidate region (TRPM1 and OCA2), as well as three other linked loci (TJP1, MTMR10, and OTUD7A) by quantitative real-time RT-PCR. No large differences were found for expression levels of TJP1, MTMR10, OTUD7A, and OCA2. However, TRPM1 (Transient Recept...
Carrick JB, Begg AP.Assessment of peripheral blood leukocytes is the most common clinical pathology test in equine practice. It is always a part of complete body function assessment and frequently is used alone, or in conjunction with, fibrinogen to monitor response to treatment.
Brooks MB.The most common cause of hemorrhage is vascular injury; however, the possibility of hemostatic failure should be considered in the initial differential diagnosis. This article provides an overview of preliminary screening and definitive tests to identify hemostatic defects in horses.
Crisman MV, Scarratt WK, Zimmerman KL.Activation of the host response to infection, the "acute-phase response," is a highly organized physiologic reaction that includes changes in concentrations of plasma acute-phase proteins (APPs). The APPs are increasingly being used as markers for prognosis and monitoring response to therapy along with general determinants of equine health. Use of APPs in veterinary medicine is becoming more widespread as more commercial diagnostic kits are being validated. This article reviews the salient features of APPs and examines their current application and potential utility in equine inflammatory diso...
Lording PM.In this article, the normal kinetics, morphology and other unique characteristics of equine erythrocytes are reviewed, the influence of the spleen on erythrocyte values is discussed, and selected normal reference intervals are presented. In addition, the classification and causes of anemia and polycythemia are reviewed and the appropriate laboratory tests for accurate diagnosis are presented.
Uquillas E, Dart CM, Perkins NR, Dart AJ.To compare the effects of two concentrations of oxygen delivered to the anaesthetic breathing circuit on oxygenation in mechanically ventilated horses anaesthetised with isoflurane and positioned in dorsal or lateral recumbency. Methods: Selected respiratory parameters and blood lactate were measured and oxygenation indices calculated, before and during general anaesthesia, in 24 laterally or dorsally recumbent horses. Horses were randomly assigned to receive 100% or 60% oxygen during anaesthesia. All horses were anaesthetised using the same protocol and intermittent positive pressure ventilat...
Esteller-Vico A, Liu IK, Vaughan B, Steffey EP, Brosnan RJ.In the uterus of the mare, data obtained using transrectal Doppler ultrasonography indicate that uterine blood flow (UBF) is dynamic and changes throughout the estrous cycle. Degenerative lesions in the uterus are associated with subfertility and infertility. Among these lesions, vascular elastosis has been reported in aged, multiparous, and infertile mares. Angiosis of the uterine vasculature could potentially compromise UBF. The objectives of this experiment are to determine levels of UBF and perfusion of reproductively healthy mares and compare them to levels of subfertile/infertile mares a...
Khan SH, Islam A, Hassan MI, Sharma S, Singh TP, Ahmad F.A sequence alignment of horse cytochrome c (cyt c) with all known cyts c shows that Leu at position 94 is conserved, except in 14 species which have either Val or Ile at this position. It is also known that Leu94 of the mammalian cyt c plays an important role in folding and stability. The important question here is as to what will happen in terms of folding and stability if Leu94 of the mammalian cyt c is substituted by Val or Ile. To answer this question, we introduced natural substitutes of Leu94 by Val and Ile in horse cyt c. The purified L94V and L94I mutants under native condition (pH 6.0...
Corrêa MJ, da Mota MD.The aim of this study was to estimate genetic parameters for racing performance traits in Quarter Horses in Brazil. The data (provided by the Sorocaba Jockey Club) came from 3 Brazilian hippodromes in 1994-2003, with 11 875 observations of race time and 7775 of the speed index (SI), distributed in 2403 and 2169 races, respectively. The variance components were estimated by the MTGSAM program, under animal models including the random additive genetic effect, random permanent environmental effect, and the fixed effects of sex, age and race. Heritabilities for race time and the SI, for the 3 dist...
Ebling AJ, McKnight AL, Seiler G, Kircher PR.The complexity of the equine skull makes the temporomandibular joint a difficult area to evaluate radiographically. The goal of this study was to determine the optimal angle for a complementary radiographic projection of the equine temporomandibular joint based on a computed tomography (CT) cadaver study. CT was performed on six equine cadaver heads of horses that were euthanized for other reasons than temporomandibular joint disease. After the CT examination, 3D reconstruction of the equine skull was performed to subjectively determine the angle for a complementary radiographic projection of ...
Pollina GF, Pepe M, Dean A, Di Marco V, Marton D.Gallium (Ga) is under study for the treatment of osteolytic disorders in equines. Previous studies indicate that oral gallium maltolate (GaM) would provide a higher bioavailability than oral Ga salts. However, oral administration to adult horses of 2 mg/kg of GaM, in the form of a solution mixed with food, did not lead to detectable Ga levels in plasma. Therefore, a study was performed to model the chemical behaviour of GaM in the digestive tract. The equilibrium formation constants for Ga(III) and maltol were calculated by means of UV–visible measurements and validated by 1H-NMR measurement...
Mouney MC, Townsend WM, Moore GE.To determine whether differences exist in the calculated intraocular lens (IOL) strengths of a population of adult horses and to assess the association between calculated IOL strength and horse height, body weight, and age, and between calculated IOL strength and corneal diameter. Methods: 28 clinically normal adult horses (56 eyes). Methods: Axial globe lengths and anterior chamber depths were measured ultrasonographically. Corneal curvatures were determined with a modified photokeratometer and brightness-mode ultrasonographic images. Data were used in the Binkhorst equation to calculate the ...
Kowalik S, Wiśniewska A, Kędzierski W, Janczarek I.Skeletal muscle is considered to be the largest endocrine organ determining the maintenance of energy homeostasis. Adaptive changes in skeletal muscles in response to physical exercise influence the production as well as secretion of myokines, which are bioactive factors that play a crucial role in energy expenditure processes. The aim of the study was to investigate the impact of two different types of exercise on the circulating level of two of these, myostatin and irisin, in trained horses. Twenty purebred Arabian horses were involved in the study: 10 three-year-old horses trained on the ra...
Bailey SR, Elliott J.5-hydroxytryptamine (5-HT) is a potent vasoconstrictor of equine digital arteries and veins which may play a role in the ischaemic disease, laminitis. The present investigation compared the properties of 5-HT1B/1D receptors in arteries with those in veins using isolated rings of equine digital blood vessels. The 5-HT1B/1D receptor-selective agonists, anpirtoline and sumatriptan were 17.9 and 10 times more potent and produced 4.1 and 5.6 times greater maximum contractions, respectively, in veins when compared to arteries. Other agonists tested were of equal potency and produced the same maximum...
Slowikowska M, Bajzert J, Miller J, Stefaniak T, Niedzwiedz A.Non-invasive diagnostic biomarkers of equine asthma syndrome (EAS) from blood or urine are sought. The aim of this study was to assess the absorbance of circulating immune complexes (CICs) during the exacerbation, remission, and treatment of an asthma episode and assess the potential usefulness of CIC levels in the diagnosis and monitoring of the disease. The control group, asthma group, and treated asthma group each contained six horses. Following an initial examination and group classification, the horses were kept in a dusty environment for seven days and then moved to an asthma-friendly en...
Davankar SP, Deane NJ, Davies AS, Firth EC, Hodge H, Parry DA.Since horses bred for the racing industry are subject to rigorous training procedures there is a real need to understand how the stresses experienced by their tendons and ligaments in vivo relate to the major load-bearing elements-the collagen fibrils. Consequently, an age-related study has been made of the collagen fibril diameter distributions of nine ligaments in and around the equine carpus. This is the first stage of a larger study aimed at understanding the ultrastructural changes that occur as a result of exercise. Most of the ligaments showed a bimodal diameter distribution at maturity...
Livesey JH, Donald RA, Irvine CH, Redekopp C, Alexander SL.Plasma ACTH, arginine vasopressin (AVP), and alpha MSH were measured in pituitary venous effluent at 5-min intervals from five unanesthetized horses during cortisol infusion and after an iv bolus of AVP or ovine (o) CRF. In control experiments (no hormone) there was a significant overall correlation between the timing of concentration changes in ACTH and alpha MSH. Cortisol infusion increased jugular cortisol levels by 70% and was associated with a reduction in mean ACTH, AVP, and alpha MSH secretion rates and ACTH peak secretion rate, but did not alter the observed pulse frequencies of these ...
Young SS, Tesarowski D.Respiratory mechanics were compared using conventional and forced oscillation techniques in six conscious horses and a mechanical model of the equine respiratory system. The parameters calculated from conventional airflow and esophageal pressure measurements were pulmonary resistance and dynamic compliance. The impedance of the respiratory system was measured at 1, 2, and 3 Hz with the forced oscillation technique, and respiratory system resistance, compliance, inertance, and resonant frequency were calculated. Pulmonary resistance was 1.0 +/- 0.3 cmH2O.l-1.s, and pulmonary dynamic compliance ...
Green SA, Jenkins SJ, Clark PA.The biuret total protein method and a bromcresol green (BCG) albumin method were used on the Abbott ABA-100 chemistry analyzer to assay serum proteins in clinically normal cattle, sheep, ponies, pigs, and ducks. Total proteins were also read on a refractometer and mylar supported cellulose acetate electrophoresis was performed. Globulins and A/G ratios were calculated from the chemical method and the results compared with the electrophoretic method. Total protein, albumin and A/G ratios in the ponies, sheep and older cattle were in agreement between the two methods. The younger cattle and all ...
Miró J, Catalán J, Marín H, Yánez-Ortiz I, Yeste M.While artificial insemination (AI) with frozen-thawed sperm results in low fertility rates in donkeys, the addition of seminal plasma, removed during cryopreservation, partially counteracts that reduction. Related to this, an apparent inflammatory reaction in jennies is induced following AI with frozen-thawed sperm, as a high amount of polymorphonuclear neutrophils (PMN) are observed within the donkey uterus six hours after AI. While PMN appear to select the sperm that ultimately reach the oviduct, two mechanisms, phagocytosis and NETosis, have been purported to be involved in that clearance. ...
Veen I, de Grauw JC.Endotracheal intubation is a routine procedure in veterinary anaesthesia, yet no consensus guidelines exist for endotracheal tube (ETT) cuff inflation and pressure measurement. The aim of this study was to assess current practice of ETT cuff inflation and seal verification in veterinary medicine. An online questionnaire was distributed among veterinary professionals who administer anaesthesia, comprising six demographic and twelve ETT cuff-related questions per species. N = 348 questionnaires were completed. Cuff pressure was measured by 30% of respondents in cats, 32% in dogs and 9% in both f...
Rubin CT, Seeherman H, Qin YX, Gross TS.Distributions of normal strain, shear strain, and strain energy density (SED) were determined across the midshaft of the third metacarpal (MCIII, or cannon bone) of 3 adult thoroughbred horses as a function of speed and gait. A complete characterization of the mechanical demands of the bone made through the stride and from mild through the extremes of locomotion was possible by using three 3-element rosette strain gauges bonded at the diaphyseal midshaft of the MCIII and evaluating the strain output with beam theory and finite element analysis. Mean ± sd values of normal strain, shear strain,...
Lucas RG, Rodríguez-Hurtado I, Álvarez CT, Ortiz G.Equine back pain can potentially initiate an unstable intervertebral situation that results in atrophy and dysfunction of the epaxial muscles even after back pain has resolved. Several physiotherapy approaches are advocated to promote the strengthening of the multifidus muscle. This study aimed to asses and compare the effect of dynamic mobilization exercises (DME) and neuromuscular electrical stimulation (NMES) in 8 adult horses (4 individuals by group) to increase the cross-sectional area (CSA) of this muscle after a 7-weeks period treatment. The epaxial muscles of NMES group were electrical...
Asplin KE, Patterson-Kane JC, Sillence MN, Pollitt CC, Mc Gowan CM.Ponies with laminitis associated with insulin resistance and hyperinsulinaemia lack systemic and/or intestinal inflammatory signs, suggesting a different pathogenesis potentially reflected in differing histopathology. Objective: To describe the histological appearance and quantify morphological changes in primary and secondary epidermal lamellae (PEL and SEL) of laminitis lesions from ponies with insulin-induced laminitis. Methods: Equine hoof lamellar tissue was obtained from 4 control ponies and 5 ponies with laminitis induced following infusion of insulin (1036 ± 55 µU/ml) while maintai...
Oltner R, Edqvist LE.Progesterone concentrations in heparinized plasma harvested immediately after blood collection were compared with levels obtained after storage of the corresponding whole blood for 2 h, 4 h, 6 h, 1 day, 2 days and 5 days at room temperature and in a refrigerator. The blood was taken during the luteal phase from 4 dogs, 4 horses, 4 pigs and 8 cows. For 4 cows the storage time was extended to 9 and 20 days. No significant effect of whole blood storage time on plasma progesterone concentrations could be shown for dogs or pigs. For the horse a slight but significant decrease was demonstrated when ...
Creighton CM, Lemke KA, Lamont LA, Horney BS, Doyle AJ.To compare the effect of xylazine bolus versus medetomidine constant rate infusion (MCRI) on serum cortisol and glucose concentrations, urine production, and anesthetic recovery characteristics in dorsally recumbent, spontaneously breathing, isoflurane-anesthetized horses. Methods: Prospective, randomized crossover study. Methods: 10 healthy Standardbreds. Methods: Horses were premedicated with xylazine or medetomidine IV. Anesthesia was induced with diazepam and ketamine and maintained with isoflurane for 150 minutes. For the xylazine treatment, end-tidal isoflurane concentration was maintain...
Wilkens MR, Marholt L, Eigendorf N, Muscher-Banse AS, Feige K, Schröder B, Breves G, Cehak A.Intestinal calcium absorption plays a key role in the maintenance of calcium homeostasis and may either occur by paracellular or transcellular mechanisms. The horse has some unique peculiarities in calcium homeostasis compared to other species including a high absorptive capacity for calcium in the intestine, high plasma calcium concentrations, high renal excretion, and low plasma concentrations of vitamin D metabolites. So far, knowledge about the underlying mechanisms and the regulation of intestinal calcium absorption is still limited concerning this species. Several studies have documented...
Ronéus N, Essén-Gustavsson B, Lindholm A, Persson S.Blood samples from the jugular vein and muscle biopsies (gluteus medius) in 25 Standardbred trotters were obtained 5-10 min after racing. The biopsies were analysed for fibre type composition and enzymatic profile and blood samples for plasma lactate and ammonia concentrations. Muscle characteristics, plasma lactate and ammonia concentrations after racing were compared with each horse's individual performance index (IPI). The IPI is calculated annually from the individual horse's racing performance (% placing 1, 2 or 3, total annual earnings, average earning per start, and best racing record),...
Hanzawa K, Kai M, Hiraga A, Watanabe S.We examined the relationship in horses between osmotic fragility of erythrocytes (OFE) measured as the red cell haemolysis rates (HLR) in 0.56% NaCl and certain physiological characters. Animals were exercised on a treadmill: warmed up at 30% VO2max for 5 min or at 105% VO2max for 1 min, given an exercise test at 80 or 105% VO2max until fatigued, and then cooled down. The pH and temperature of the blood had a significant correlation for the HLR: r = 0.93 and 0.92 (P < 0.01) on arterial and mixed venous blood, respectively. In multiple regression analysis, heart rate and packed cell volume s...
Moens Y, Schramel JP, Tusman G, Ambrisko TD, Solà J, Brunner JX, Kowalczyk L, Böhm SH.The use of alveolar recruitment maneuvers during general anaesthesia of horses is a potentially useful therapeutic option for the ventilatory management. While the routine application of recruitments would benefit from the availability of dedicated large animal ventilators their impact on ventilation and perfusion in the horse is not yet well documented nor completely understood. Methods: A healthy 533 kg experimental horse underwent general anaesthesia in lateral recumbency. During intermittent positive pressure ventilation a stepwise alveolar recruitment maneuver was performed. Results: Anae...
Hintze S, Schanz L.Identifying and validating behavioral indicators of mood are important for the assessment of animal welfare. Here, we investigated whether horses' eye wrinkle expression in a presumably neutral situation is a measure of mood as assessed in a cognitive judgment bias task (JBT). To this end, we scored pictures of the left and right eyes of 16 stallions for different aspects of eye wrinkle expression and tested the same individuals on a spatial JBT with active trial initiation. Eye wrinkle expressions were assessed by a qualitative assessment, i.e., the overall assessment of how "worried" horses ...
Coleman MC, Whitfield-Cargile C, Cohen ND, Goldsby JL, Davidson L, Chamoun-Emanuelli AM, Ivanov I, Eades S, Ing N, Chapkin RS.Evaluating the health and function of the gastrointestinal tract can be challenging in all species, but is especially difficult in horses due to their size and length of the gastrointestinal (GI) tract. Isolation of mRNA of cells exfoliated from the GI mucosa into feces (i.e., the exfoliome) offers a novel means of non-invasively examining the gene expression profile of the GI mucosa. This approach has been utilized in people with colorectal cancer. Moreover, we have utilized this approach in a murine model of GI inflammation and demonstrated that the exfoliome reflects the tissue transcriptom...
McGilloway M, Manley S, Aho A, Heeringa KN, Lou Y, Squires EJ, Pearson W.Leaky gut syndrome (LGS) is an idiopathic disorder characterised by alterations in intestinal permeability and low-grade systemic inflammation. Factors contributing to development of LGS are not well-understood but physiological stressors such as exercise and transport may play a role which may be of pathophysiological relevance in horses. Objective: To characterise the combined effect of transport stress and exercise on gastrointestinal permeability, and to determine whether these effects are associated with increased inflammatory biomarkers in plasma. Methods: Controlled, randomised and cros...
Rose MT.The objective of this study was to determine the effect of platelet derived growth factor BB (PDGF), epidermal growth factor (EGF), transforming growth factor β1 (TGFβ1), insulin like growth factor-1 (IGF-1) and fibroblast growth factor-2 (FGF-2) on the proliferation and migration of equine oral mucosa and leg skin fibroblast cell lines, using an in vitro scratch assay. Fibroblasts from the two sites were firstly grown to confluence and then an area of cells removed (cell void area). Cell migration alone (with the addition of the mitosis inhibitor mitomycin-C to the culture media) and prolif...
The Journal of physiologySeptember 15, 1996
Volume 495 ( Pt 3), Issue Pt 3 863-874 doi: 10.1113/jphysiol.1996.sp021638
Mills PC, Marlin DJ, Demoncheaux E, Scott C, Casas I, Smith NC, Higenbottam T.1. The effects of exercise on the production rate of nitric oxide (NO) in exhaled air (VNO) and the effects of inhaled NO (80 p.p.m.) on cardiovascular and respiratory parameters were investigated in five Throughbred horses. 2. The concentration of NO ([NO]) in exhaled air collected from within the nasal opening was lower when collected at a high flow rate of 80 l min-1 than at a low flow rate of 20 l min-1: when trotting at 3.7 m s-1 the values were 0.78 +/- 0.15 and 1.23 +/- 9.14 p.p.b., respectively, and when cantering at 9 m s-1 the values were 1.69 +/- 0.31 and 2.25 +/- 0.32 p.p.b., respe...
