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.
Constable PD, Tinkler SH, Couëtil LL.To determine the degree of agreement between 2 analyzers for measurement of total CO₂ concentration (ctCO₂) in equine plasma. Methods: 6 healthy untrained horses, 6 trained Standardbreds undergoing a simulated race protocol, and 135 trained Standardbreds at a racetrack. Methods: Jugular venous blood samples were obtained from all horses. Two analyzers (commonly used analyzer A and less expensive analyzer B) were used to measure plasma ctCO₂ in each sample. Validation of both analyzers was conducted in accordance with guidelines established by the Clinical and Laboratory Standards Institu...
Ferreira TH, Brosnan RJ, Shilo-Benjamini Y, Moore SB, Hollingsworth SR.To assess the effects of ketamine hydrochloride, propofol, or compounded thiopental sodium administration on intraocular pressure (IOP) and qualities of induction of and recovery from anesthesia in horses. Methods: 6 healthy adult horses. Methods: Horses were sedated with xylazine hydrochloride (0.5 mg/kg), and anesthesia was induced with guaifenesin followed by ketamine (2 mg/kg), propofol (3 mg/kg), or thiopental (4 mg/kg) in a crossover study with ≥ 1 week between treatments. For each horse, IOP in the right eye was measured with a handheld applanation tonometer before and after xylazine ...
Nieto JE, Maher O, Stanley SD, Larson R, Snyder JR.To determine the effects of domperidone on in vivo and in vitro measures of gastrointestinal tract motility and contractility in healthy horses. Methods: 18 adult horses and tissue samples from an additional 26 adult horses. Methods: Domperidone or placebo paste was administered to healthy horses in a 2-period crossover study. Gastric emptying was evaluated after oral administration of domperidone paste (1.1 or 5.0 mg/kg) or placebo paste by means of the acetaminophen absorption test in 12 horses. Frequency of defecation, weight of feces produced, fecal moisture, and stomach-to-anus transit ti...
Serafini R, Longobardi V, Spadetta M, Neri D, Ariota B, Gasparrini B, Di Palo R.Aim of this study was to test the reliability of Trypan blue/Giemsa staining to evaluate sperm membrane integrity, acrosomal intactness and morphology in stallion to verify whether it could be applied in vitro as useful tool for sperm fertilizing ability. Fertility data on inseminated mares were collected to evaluate the relationship of sperm quality to pregnancy rates. Forty-one ejaculates were collected from 3 stallions of Salernitano Horse Breed and evaluated for gross appearance, volume, visual motility and membrane integrity with Trypan blue/Giemsa staining and thirty-five mares were inse...
Pawlak EA, Geor RJ, Watts MR, Black SJ, Johnson PJ, Belknap JK.Hypoxia-inducible factor-1α (HIF-1A) is an important protein in the regulation/induction of many genes in the cellular and tissue response to hypoxia and a central mediator in inflammatory signalling. As both hypoxia and inflammatory events are purported to occur in the lamellar epidermis in sepsis-related laminitis in the equid, HIF-1A may play a central role in this disease process. Objective: To assess the regulation of HIF-1A and HIF-1A-related genes in the equine keratinocyte in vitro and in the lamellar tissue of horses with sepsis-related laminitis. Methods: In vivo and in vitro experi...
Vendrig JC, Coffeng LE, Fink-Gremmels J.Dietary supplementation with oligosaccharides has been proven to be beneficial for health in several mammalian species. Next to prebiotic effects resulting in a modulation of gut micro biota, immunomodulatory effects of oligosaccharides have been documented in vivo. Supplementation with defined oligosaccharide fractions has been shown to attenuate allergic responses and enhance defensive immune responses. Despite the accumulating evidence for immunomodulatory effects, very limited information is available regarding the direct mechanism of action of oligosaccharides. This study aims to elucidat...
Miranda MC, Queiroz-Neto A, Silva-Júnior JR, Pereira MC, Soares OA, Borghi RT, Ferraz GC.To compare five different protocols for estimating the lactate minimum speed (LMS) with that for estimating the maximal lactate steady state (MLSS) in Arabian horses, in order to obtain a more rapid method for monitoring aerobic capacity and prescribing training schedules. Methods: Eight purebred Arabian horses were conditioned to exercise on a treadmill for 12 days then submitted to three to five exercise sessions to determine the MLSS. Blood samples were collected from a jugular catheter at specific intervals for measurement of lactate concentrations. The MLSS was the velocity maintained dur...
Stewart AJ, Wright JC, Behrend EN, Martin LG, Kemppainen RJ, Busch KA.To determine the lowest ACTH dose that would induce a significant increase in serum cortisol concentration and identify the time to peak cortisol concentration in healthy neonatal foals. Methods: Prospective randomized crossover study. Methods: 11 healthy neonatal foals. Methods: Saline (0.9% NaCl) solution or 1 of 4 doses (0.02, 0.1, 0.25, and 0.5 μg/kg [0.009, 0.045, 0.114, and 0.227 μg/lb]) of cosyntropin (synthetic ACTH) was administered IV. Serum cortisol concentrations were measured before and 10, 20, 30, 60, 90, 120, 180, and 240 minutes after administration of cosyntropin or saline s...
Sivaguru M, Eichorst JP, Durgam S, Fried GA, Stewart AA, Stewart MC.Injuries and damage to tendons plague both human and equine athletes. At the site of injuries, various cells congregate to repair and re-structure the collagen. Treatments for collagen injury range from simple procedures such as icing and pharmaceutical treatments to more complex surgeries and the implantation of stem cells. Regardless of the treatment, the level of mechanical stimulation incurred by the recovering tendon is crucial. However, for a given tendon injury, it is not known precisely how much of a load should be applied for an effective recovery. Both too much and too little loading...
Ambrósio AM, Ida KK, Souto MT, Oshiro AH, Fantoni DT.To assess if positive end-expiratory pressure (PEEP) titration improves gas exchange and respiratory mechanics, without hemodynamic impairment in horses during anesthesia. Methods: Prospective, randomized study. Methods: Thirteen isoflurane-anesthetized healthy horses. Methods: After 60 minutes of anesthesia with spontaneous breathing, mechanical ventilation was initiated with an inspiratory-expiratory ratio of 1:2, PEEP of 5 cmH2O, tidal volume of 10-20 mL kg(-1) and respiratory rate adjusted to maintain normocapnia. Constant PEEP of 5 cmH2O was continued (control group; n = 6) or titrated (P...
Canisso IF, Ball BA, Troedsson MH, Silva ES, Davolli GM.The objectives of this study were to determine pH of the mammary gland secretions and the corresponding electrolyte concentrations in prefoaling mares. Pregnant mares (seven primiparous and seven multiparous) were monitored daily from 310-320 days of gestation until parturition. Prefoaling mammary gland secretions were collected, and pH was immediately determined with a pH meter and pH strip test. An aliquot of prefoaling mammary secretions was frozen and stored until further analyses. After parturition, samples from day -4 to 0 (day of foaling) were thawed and electrolyte concentrations (ie, ...
Len JA, Beehan DP, Lyle SK, Eilts BE.It was hypothesized that optimal sperm recovery rate (RR) without damage to the sperm would be obtained after centrifugation without a cushion solution. Semen collected three times from six light breed stallions was extended to 25 × 10(6) sperm/mL and centrifuged at CON (noncentrifuged), 900NC (no-cushion), 900C (cushion), 1800NC, and 1800C × g for 10 minutes. Sperm concentration, motility (TM and PM), and intact plasma membranes (PLM) and acrosomes (ACR) pre- and postcentrifugation (D0) and after 24 hours (D1) of cooling were evaluated. The RR in the CON (100 ± 0.0), 900NC (93.7 ± 2.9), a...
Poller C, Hopster K, Rohn K, Kästner SB.Aim of the study was to compare the effect of neuroleptic sedation with acepromazine and neuroleptanalgesia with acepromazine and buprenorphine on thermal thresholds (TT) obtained at the nostrils and at the withers. The study was carried out as a randomized, blinded, controlled trial with cross-over design. Thermal thresholds were determined by incremental contact heat applied to the skin above the nostril (N) or the withers (W). Eleven horses were treated with saline (S), acepromazine (0.05 mg/kg) (ACE) or acepromazine and buprenorphine (0.0075 mg/kg) (AB) intravenously (IV). Single stimula...
Hemmann KE, Koho NM, Vainio OM, Raekallio MR.The reason why some horses begin an oral stereotypy such as crib-biting is not known. The aim of this study was to measure ghrelin and leptin concentrations in plasma concentrations to determine whether there is a link to crib-biting in horses. Plasma samples (n=3) were collected for plasma leptin and ghrelin assay before and during the morning first feeding in the usual environments of 15 horses with stereotypic crib-biting and 15 matched controls. The crib-biting intensity was scored in three 5-min phases, and a subgroup of verified crib-biters (n=8) was defined as horses that were seen to c...
Haltmayer E, Reiser S, Schramel JP, van den Hoven R.The aim of the study was to show that changes in thoracoabdominal asynchrony (TAA) between quiet breathing and CO2-induced hyperpnoea can be used to differentiate between horses with healthy airways and those suffering from inflammatory airway disease (IAD) or recurrent airway obstruction (RAO). The level of TAA was displayed by the Pearson's correlation coefficient (PCC) of thoracic and abdominal signals, generated by respiratory ultrasonic plethysmography (RUP) during quiet breathing and hyperpnoea. Changes in TAA were expressed as the quotient of the PCCs (PCCQ) during normal breathing and ...
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....
Irvine KL, Hopkins LJ, Gangloff M, Bryant CE.TLR2 recognises bacterial lipopeptides and lipoteichoic acid, and forms heterodimers with TLR1 or TLR6. TLR2 is relatively well characterised in mice and humans, with published crystal structures of human TLR2/1/Pam3CSK4 and murine TLR2/6/Pam2CSK4. Equine TLR4 is activated by a different panel of ligands to human and murine TLR4, but less is known about species differences at TLR2. We therefore cloned equine TLR2, TLR1 and TLR6, which showed over 80% sequence identity with these receptors from other mammals, and performed a structure-function analysis. TLR2/1 and TLR2/6 from both horses and hu...
Nevins M, Heinemann F, Janke UW, Lombardi T, Nisand D, Rocchietta I, Santoro G, Schupbach P, Kim DM.The objective of this proof-of-principle multicenter case series was to examine the bone regenerative potential of a newly introduced equine-derived bone mineral matrix (Equimatrix) to provide human sinus augmentation for the purpose of implant placement in the posterior maxilla. There were 10 patients requiring 12 maxillary sinus augmentations enrolled in this study. Histologic results at 6 months demonstrated abundant amounts of vital new bone in intimate contact with residual graft particles. Active bridging between residual graft particles with newly regenerated bone was routinely observed...
Dall'Aglio C, Mercati F, Pascucci L, Ceccarelli P.The aim of the present study was to demonstrate the presence and the distribution of leptin and its receptor in the pancreas of horses of both sexes by immunohistochemical techniques. The presence and the distribution of leptin receptor were also investigated in the initial portion of the duodenum, near the duodenal ampulla. The immunohistochemical investigation demonstrates the immunolocalization of both leptin and its receptor in the endocrine cells of pancreatic islets, which led us to hypothesize that leptin may possibly exert an autocrine/paracrine action on the endocrine pancreas. Examin...
The Journal of physiologyJuly 1, 2013
Volume 591, Issue 18 4499-4513 doi: 10.1113/jphysiol.2013.257956
Vengust M, Staempfli H, Viel L, Swenson ER, Heigenhauser G. During intense exercise in horses the transvascular fluid flux in the pulmonary circulation (Jv-a) represents 4% of cardiac output (Q). This fluid flux has been attributed to an increase in pulmonary transmural hydrostatic forces, increases in perfused microvascular surface area, and reversible alterations in capillary permeability under conditions of high flow and pressure. Erythrocyte fluid efflux, however, accounts for a significant fraction of Jv-a. In the lung the Jacobs-Stewart cycle occurs with diffusion of CO2 into alveolar space with possible accompanying chloride (Cl-) and water ...
Miller C, Utter ML, Beech J.To determine effects of age and pituitary pars intermedia dysfunction (PPID) on corneal sensitivity in horses. Methods: 20 adult horses allocated into 3 groups (PPID group, old [> 15 years old] horses with PPID [n = 5]; old group, old [> 15 years old] horses without PPID [9]; and young group, young [≤ 10 years old] horses without PPID [6]). All horses with PPID had hirsutism and abnormal fat deposition or laminitis; none of the old or young horses had hirsutism, abnormal fat deposition, or laminitis. Methods: A Cochet-Bonnet aesthesiometer was used to measure the corneal touch threshold (CTT...
Tadros EM, Frank N, De Witte FG, Boston RC.To test the hypothesis that glucose and insulin dynamics during endotoxemia differ between healthy horses and horses with equine metabolic syndrome (EMS). Methods: 6 healthy adult mares and 6 horses with EMS. Methods: Each horse randomly received an IV infusion of lipopolysaccharide (20 ng/kg [in 60 mL of sterile saline {0.9% NaCl} solution]) or saline solution, followed by the other treatment after a 7-day washout period. Baseline insulin-modified frequently sampled IV glucose tolerance tests were performed 27 hours before and then repeated at 0.5 and 21 hours after infusion. Results were ass...
Tadros EM, Frank N, Donnell RL.To test the hypothesis that inflammatory responses to endotoxemia differ between healthy horses and horses with equine metabolic syndrome (EMS). Animals-6 healthy horses and 6 horses with EMS. Methods: Each horse randomly received an IV infusion of lipopolysaccharide (20 ng/kg [in 60 mL of sterile saline {0.9% NaCl} solution]) or saline solution, followed by the other treatment after a 7-day washout period. Baseline data were obtained 30 minutes before each infusion. After infusion, a physical examination was performed hourly for 9 hours and at 15 and 21 hours; a whole blood sample was collect...
Barsnick RJ, Hurcombe SD, Dembek K, Frazer ML, Slovis NM, Saville WJ, Toribio RE.Resistance to the somatotropic axis and increases in ghrelin concentrations have been documented in critically ill human patients, but limited information exists in healthy or sick foals. Objective: To investigate components of the somatotropic axis (ghrelin, growth hormone and insulin-like growth factor-1 [IGF-1]) with regard to energy metabolism (glucose and triglycerides), severity of disease and survival in critically ill equine neonates. It was hypothesised that ghrelin and growth hormone would increase and IGF-1 would decrease in proportion to severity of disease, supporting somatotropic...
Hjertner B, Olofsson KM, Lindberg R, Fuxler L, Fossum C.There is accumulating evidence for the involvement of pro-inflammatory cytokines associated with a T helper 17 response in intestinal disorders such as inflammatory bowel disease (IBD) in humans. The involvement of interleukin (IL)-17 or IL-23 in equine IBD has not been studied and most gene expression studies in the equine intestine have been limited to the use of a single non-validated reference gene. In this study, expression of the reference gene candidates β2 microglobulin (β2M), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), histone H2A type 1, hypoxanthine-guanine phosphoribosyltra...
Aurich C, Weber J, Nagel C, Merkl M, Jude R, Wostmann S, Ollech D, Baron U, Olek S, Jansen T.Early pregnancy loss is a major reason for low reproductive efficiency in the horse. In humans and mice, low numbers of regulatory T cells (Treg cells) are linked to miscarriage. The percentage of Treg cells in oestrous mares at the start of the breeding season was evaluated in relation to the outcome of subsequent pregnancy. For identification and quantification of Treg cells, a highly sensitive and specific qPCR assay targeting the Treg-specific demethylated region in the equine forkhead box transcription factor (FOXP3) gene was established. In a total of 108 mares, pregnancy was followed un...
de Cocq P, Muller M, Clayton HM, van Leeuwen JL.The simplest model possible for bouncing systems consists of a point mass bouncing passively on a mass-less spring without viscous losses. This type of spring-mass model has been used to describe the stance period of symmetric running gaits. In this study, we investigated the interaction between horse and rider at trot using three models of force-driven spring (-damper)-mass systems. The first system consisted of a spring and a mass representing the horse that interact with another spring and mass representing the rider. In the second spring-damper-mass model, dampers, a free-fall and a forcin...
Pereira GR, Lorenzo PL, Carneiro GF, Ball BA, Pegoraro LM, Pimentel CA, Liu IK.In horses, successful in vitro fertilization procedures are limited by our inability to consistently mature equine oocytes by in vitro methods. Growth hormone (GH) is an important regulator of female reproduction in mammals, playing an important role in ovarian function, follicular growth and steroidogenesis. The objectives of this research were to investigate: the effects of equine growth hormone (eGH) and insulin-like growth factor-I (IGF-I) on the in vitro maturation (IVM) of equine oocytes, and the effects of eGH in addition to estradiol (E2), gonadotropins (FSH and LH) and fetal calf seru...
Nesse LL, Johansen GI, Blom AK.To measure the lymphocyte proliferation response in horses 12 to 16 hours after completion of a race. Methods: 8 Thoroughbreds that competed in 14 races and 3 control Thoroughbreds that did not race. Methods: Horses participated in races during the late afternoon or evening. Venous blood samples were collected on a morning before a race (1 or 2 days before the race or on the day of the race), on the afternoon of a race (40 to 60 minutes after the race), and on the morning of the day after a race (12 to 16 hours after the race). Lymphocyte proliferation responses and WBC count were measured in ...
Slauson DO, Skrabalak DS, Neilsen NR, Zwahlen RD.Equine neutrophils (PMN) were isolated from citrated normal blood by density gradient separation on Ficoll-Hypaque to greater than 96% purity and 98% viability and an average of 3.78 x 10(7) PMN/ml. The agonist C5a des Arg was used in serial dilutions of whole zymosan-activated equine plasma (ZAP) or was partially purified from ZAP by column chromatography. Purified equine PMN exhibited rapid aggregation following incubation with C5a des Arg which was further dependent on the availability of divalent cations, especially Mg++. The microfilament disruptive agent cytochalasin B (5 micrograms/50 m...
Rui BR, Angrimani D, Bicudo LC, Losano J, Nichi M, Pereira R.Sperm DNA fragmentation is a condition that interferes directly in the reproductive efficiency. Currently, there are several methods for assessing the sperm DNA integrity, such as Alkaline Comet, TUNEL and Sperm Chromatin Structure Assay. However, many of these techniques are laborious and require high-precision equipment. Thus, the development of new techniques can optimize the evaluation of sperm DNA damage. Therefore, the aim of this study was to standardize the toluidine blue (TB) stain technique for the analysis of DNA fragmentation of dog, cat, bull, stallion and ram spermatozoa. For thi...
Klonisch T, Steger K, Kehlen A, Allen WR, Froehlich C, Kauffold J, Bergmann M, Hombach-Klonisch S.We employed molecular and immunological techniques to investigate the expression of INSL3, a member of the insulin-like superfamily, in prepubertal testis, postpubertal testes exhibiting normal and disturbed spermatogenesis, and cryptorchid testes of male horses. In addition, the partial cDNA coding sequences of the equine homologue of the human relaxin/INSL3-receptor Lgr8 were determined. Nonradioactive in-situ hybridization with a cRNA probe for equine Insl3 and immunohistochemistry with a specific rabbit INSL3 antiserum localized Insl3 transcripts and immunoreactive INSL3 ligand to Leydig c...
Uhlir C, Licka T, Kübber P, Peham C, Scheidl M, Girtler D.In order to study the mechanism of lameness transfer from fore- and hindlimb lamenesses 2 hypotheses were investigated. Hypothesis 1: Horses with a true supporting limb lameness in one hindlimb show a false supporting limb lameness in the ipsilateral forelimb. Hypothesis 2: Horses with a true supporting limb lameness in one forelimb show a false supporting limb lameness in the contralateral hindlimb. Fourteen horses with fore- or hindlimb lameness were used for this study. Each horse was measured at the trot on a treadmill with standardised speed, before and after diagnostic blocks (9 horses),...
Wang L, Pawlak EA, Johnson PJ, Belknap JK, Eades S, Stack S, Cousin H, Black SJ.The digital laminae is a two layer tissue that attaches the distal phalanx to the inner hoof wall, thus suspending the horse's axial skeleton in the hoof capsule. This tissue fails at the epidermal:dermal junction in laminitic horses, causing crippling disease. Basal epithelial cells line the laminar epidermal:dermal junction, undergo physiological change in laminitic horses, and lose versican gene expression. Versican gene expression is purportedly under control of the canonical Wnt signaling pathway and is a trigger for mesenchymal-to-epithelial transition; thus, its repression in laminar ep...
Doreau M, Boulot S, Bauchart D, Barlet JP, Martin-Rosset W.Voluntary food intake, milk yield and composition, and blood metabolites were measured during the first 2 mo of lactation in draft broodmares fed diets containing either 95% hay and 5% concentrates (Diet F) or 50% hay and 50% concentrates (Diet C). Voluntary food intake was higher for mares fed Diet C than for those fed Diet F (22.9 vs. 21.4 kg dry matter in wk 4). Both diets, especially Diet C, were eaten in amounts exceeding the energy requirements. Daily milk yield in wk 4 was 26.4 kg and 23.4 kg for mares fed Diets C and F, respectively. Milk fat and protein concentrations were higher (P l...
Latorre R, Arencibia A, Gil F, Rivero M, Henry RW, Ramírez G, Váquez JM.To correlate anatomic features of the equine tarsus identified in plastinated sections with images obtained via magnetic resonance imaging (MRI). Methods: 4 horses. Methods: MRI (1.5-Tesla magnet) of the tarsus was performed on the pelvic limbs of 4 clinically normal horses following euthanasia. After imaging, tarsocrural joint spaces and vasculature were injected with colored latex. Sagittal and transverse sections of the tarsi were plastinated to facilitate interpretation of MR images. Results: Relevant anatomic structures were identified and labeled on the plastinated tissue slices and corr...
Floyd RV, Mason SL, Proudman CJ, German AJ, Marples D, Mobasheri A.Aquaporins (AQPs) play fundamental roles in water and osmolyte homeostasis by facilitating water and small solute movement across plasma membranes of epithelial, endothelial, and other tissues. AQP proteins are abundantly expressed in the mammalian kidney, where they have been shown to play essential roles in fluid balance and urine concentration. Thus far, the majority of studies on renal AQPs have been carried out in laboratory rodents and sheep; no data have been published on the expression of AQPs in kidneys of equines or other large mammals. The aim of this comparative study was to determ...
Bollwei H, Weber F, Kolberg B, Stolla R.Uterine and ovarian blood flow was investigated in four mares during two consecutive estrous cycles using transrectal color Doppler sonography. The uterine and ovarian arteries of both sides were scanned to obtain waves of blood flow velocity. The pulsatility index (PI) reflected blood flow. There were significant time trends in PI values of all uterine and ovarian blood vessels during the estrous cycle (P < 0.05). PI values did not differ between the uterine arteries ipsi- and contralateral to the corpus luteum or the ovulatory follicle. PI values of the uterine arteries showed a wave shap...
Gee E, Davies M, Firth E, Jeffcott L, Fennessy P, Mogg T.Copper (Cu) supplementation of dams in late gestation may be protective against articular cartilage abnormalities in foals. Articular cartilage was harvested from 22 Thoroughbred foals at 160 days of age, at sites predisposed to osteochondrosis (OC), and examined for evidence of early cartilage abnormalities and established dyschondroplastic (DCP) lesions to determine if there were any significant differences due to mare Cu supplementation by injection during late gestation, or foal liver Cu concentration. Cu supplemented mares received calcium Cu edetate injections in late gestation (250 mg a...
Thomason JJ, McClinchey HL, Faramarzi B, Jofriet JC.The horse's hoof is structurally modified for its mechanical functions, but studying the functional design of internal structures is hampered by the external keratinous capsule. Finite-element analysis offers one method for evaluating mechanical function of components within the capsule, such as the laminar junction. This is the epidermodermal connection that binds the hoof wall strongly to the distal phalanx. Primary epidermal laminae (PEL), projecting inward from the wall, vary in morphology and are remodeled despite being keratinous. The aim of this study is to investigate the suggestion th...
Kaske M, Elmahdi B, von Engelhardt W, Sallmann HP.It had been suggested that marked species differences in glucose tolerance tests were due to differences in insulin resistance. To compare insulin responsiveness, euglycemic hyperinsulinemic clamps were carried out in sheep, ponies, miniature pigs and camels. Porcine insulin was infused as primed-continuous infusions for 2 h (6 mU x kg(-1) x min(-1)). The steady state glucose infusion rates in the pigs, sheep, ponies and camels were 96.0, 18.6, 7.1 and 6.1 micromol x kg(-1) x min(-1), respectively. The maximal plasma insulin concentrations during the insulin infusions were 2,700 microU x ml(-1...
Peham C, Frey A, Licka T, Scheidl M.In this study we investigated the activity of the main back muscle (Musculus longissimus) by surface electromyography (EMG) during induced extension and lateral flexion at stance. Measurements were taken of 15 horses (age 5-20 years, 450-700 kg bwt) without signs of back pain. Reflecting markers were placed on the head, spinous processes of T5, T12, T16, L3 and on 2 of the sacral bones. The surface EMG electrodes were situated on the Musculus longissimus on both sides of the dorsal spinous processes of T12, T16 and L3. In all horses and all movements (extension, lateral flexion to the left and...
Leise BS, Faleiros RR, Watts M, Johnson PJ, Black SJ, Belknap JK.A significant proinflammatory response is known to occur in the forelimb lamina after carbohydrate administration. As the hindlimbs are often less affected by laminitis compared with the forelimbs, we assessed hindlimb inflammatory response in the early stages of carbohydrate-induced laminitis to determine whether differences in the response existed. Objective: To determine whether a similar proinflammatory response occurs in the hindlimb laminae to that previously reported for the forelimb. Methods: Archived laminar samples from 12 horses administered 17.6 g of starch (85% corn starch, 15% wo...
Lombardi F, Palumbo P, Augello FR, Giusti I, Dolo V, Guerrini L, Cifone MG, Giuliani M, Cinque B.The ability of a collagen-based matrix to support cell proliferation, migration, and infiltration has been reported; however, the direct effect of an aqueous collagen suspension on cell cultures has not been studied yet. In this work, the effects of a high-concentration aqueous suspension of a micronized type I equine collagen (EC-I) have been evaluated on a normal mouse fibroblast cell line. Immunofluorescence analysis showed the ability of EC-I to induce a significant increase of type I and III collagen levels, parallel with overexpression of crucial proteins in collagen biosynthesis, matura...
Best R, Standing R.Global positioning systems (GPS) have recently been shown to reliably quantify the spatiotemporal characteristics of Polo, with the physiological demands of Polo play at low- and high-goal levels also investigated. This study aims to describe the spatiotemporal demands of Polo across 0-24 goal levels. A player-worn GPS unit was used to quantify distance, speed and high-intensity activities performed. Data were divided into chukkas and five equine-based speed zones, grouped per cumulative player handicap and assessed using standardized mean differences. Average distance and speed per chukka inc...
Delguste C, Amory H, Guyonnet J, Thibaud D, Garnero P, Detilleux J, Lepage OM, Doucet M.Bioavailability and pharmacological effects of tiludronate were compared when administered as an intravenous (i.v.) bolus at a dosage of 0.1 mg/kg body weight (b.w.) once daily for 10 consecutive days (group 1, n = 6) and as a single constant rate infusion (CRI) at a total dose of 1 mg/kg b.w. (group 2, n = 6) in healthy adult horses. Tiludronate and carboxy-terminal cross-linking telopeptide of type I collagen (CTX-1) were measured in plasma and urine. There was no statistically significant difference in area under the curve (AUC) and clearance (Cl) between the two groups. Bioavailability of ...
Pourmohammad R, Mohri M, Seifi HA, Sardari K.Limited information existed on performance tests in Iranian Arab horses. Objective: The objective of this study is to investigate time related changes of cardiac troponin I (cTnI), atrial natriuretic peptide (ANP) and oxidative/antioxidant biomarkers in the serum of Arabian horses before and after regular training. Methods: Blood samples were collected from jugular vein of 25 Arabian horses before exercise; 5 h and 18 h after exercise and used to measure the cTnI, ANP, malondialdehyde (MDA), ferric reducing antioxidant power (FRAP), glutathione peroxidase (GPX), and superoxide dismutase (SOD) ...
Trachsel DS, Bitschnau C, Waldern N, Weishaupt MA, Schwarzwald CC.Frequent supraventricular or ventricular arrhythmias during and after exercise are considered pathological in horses. Prevalence of arrhythmias seen in apparently healthy horses is still a matter of debate and may depend on breed, athletic condition and exercise intensity. Objective: To determine intra- and interobserver agreement for detection of arrhythmias at rest, during and after exercise using a telemetric electrocardiography device. Methods: The electrocardiogram (ECG) recordings of 10 healthy Warmblood horses (5 of which had an intracardiac catheter in place) undergoing a standardised ...
Toribio RE, Kohn CW, Sams RA, Capen CC, Rosol TJ.Abnormalities in calcium (Ca(2+)) homeostasis are reported in horses with several pathological conditions; however, there is little information on Ca(2+) regulation in horses. The objectives of the present study were to determine the Ca(2+) set-point in healthy horses, to determine whether the Ca(2+)/parathyroid hormone (PTH) response curves were characterized by hysteresis, and to determine if the order of experimentally induced hypocalcemia or hypercalcemia had an effect on PTH secretion. The Ca(2+) set-point and hysteresis were determined in 12 healthy horses by infusing Na(2)EDTA and calci...
Stewart F, Gerstenberg C, Suire S, Allen WR.One of the major progesterone-dependent endometrial proteins in the mare is a novel 19 kDa lipocalin (P19). This protein is secreted by the endometrial glands and is readily detectable in uterine secretions during the luteal phase of the oestrous cycle and early pregnancy. The function of P19 is unknown, but since most lipocalins act as carriers of small hydrophobic molecules, it probably transports a maternal factor to the conceptus during pregnancy. In this study, a high titre antiserum raised against recombinant-derived P19 was used to detect by immunohistochemistry the protein in endometri...
Loux SC, Dini P, El-Sheikh Ali H, Kalbfleisch T, Ball BA.The placenta is a dynamic organ which undergoes extensive remodeling throughout pregnancy to support, protect and nourish the developing fetus. Despite the importance of the placenta, very little is known about its gene expression beyond very early pregnancy and post-partum. Therefore, we utilized RNA-sequencing to characterize the transcriptome from the fetal (chorioallantois) and maternal (endometrium) components of the placenta from mares throughout gestation (4, 6, 10, 11 m). Within the endometrium, 47% of genes changed throughout pregnancy, while in the chorioallantois, 29% of genes under...
Guschlbauer M, Feige K, Geburek F, Hoppe S, Hopster K, Pröpsting MJ, Huber K.To determine whether administration of lidocaine during ischemia and reperfusion in horses results in concentrations in smooth muscle sufficient to protect against the negative consequences of ischemia-reperfusion injury on smooth muscle motility. Methods: 12 horses. Methods: Artificial ischemia and reperfusion injury of jejunal segments was induced in vivo in conjunction with lidocaine treatment during ischemia (IRL) or without lidocaine treatment (IR). Isometric force performance was measured in vitro in IRL and IR smooth muscle preparations with and without additional in vitro application o...
Duran MC, Dumrath CAC, Bartmann CP, Medina Torres CE, Moschos A, Goehring LS.Serum amyloid A (SAA) is a sensitive acute-phase response (APR) marker in equids. Prominent APRs with elevations of SAA concentrations ([SAA]) have been reported after vaccination. The authors hypothesized that vaccination with an inactivated EHV-1/-4 vaccine would cause increase in [SAA] and antibody responses and that higher [SAA] would be positively correlated with the antibody titer in both equids. Twelve Haflinger horses and 12 mules were included in this longitudinal prospective study. All horses and mules were vaccinated with a commercially available EHV-1/-4 vaccine. Blood was sampled ...
Sheats MK, Cook VL, Jones SL, Blikslager AT, Pease AP.The post operative response of the large colon wall after a surgically corrected large colon volvulus (LCV) has not been investigated. Objective: To use transabdominal ultrasound to monitor the post operative change in large colon wall thickness following surgical correction of LCV. Objective: A prolonged period to colon wall involution is correlated with an increased rate of post operative morbidity and mortality. Methods: A prospective clinical study including horses that presented to the North Carolina State University Veterinary Teaching Hospital for colic between September 2006 and March,...
Noronha LE, Antczak DF.Pregnant mares demonstrate a reduction in cytotoxic T lymphocyte (CTL) reactivity against cells from the breeding stallion. We investigated whether this effect is limited to activity against paternal major histocompatibility complex (MHC) antigens, and whether it occurs during MHC-compatible pregnancy. Methods: Mares were mated to carry MHC-compatible or MHC-incompatible pregnancies. CTL activity of these mares when pregnant and non-pregnant was measured against cells from horses with MHC haplotypes unrelated to the mare or breeding stallion. Results: While carrying MHC-incompatible pregnancie...
Riquelme G, Sepúlveda JM, Al Ghumgham Z, Del Campo M, Montero C, Lagos N.Local anesthesia is an effective method to control pain. Neosaxitoxin is a phycotoxin whose molecular mechanism includes a reversible inhibition of voltage-gated sodium channels at the axonal level, impeding nerve impulse propagation. The present study was designed to evaluate the clinical efficacy of Neosaxitoxin as a local long-acting pain blocker in horse bucked shins, and it was found to effectively control pain. While Neosaxitoxin and Gonyautoxin, another Paralytic Shellfish Poison (PSP) toxin, have been successfully used in humans as long-lasting pain blockers, this finding marks the fir...
Hurcombe SD.Hypothalamic-pituitary (HP) dysfunction has been documented in a limited capacity in horses and foals associated with critical illness, stress, and pain. This article reviews species-specific details of anatomy, function, hormones, receptors, and testing of the HP axis in the horse. A discussion of critical care medicine relevant to HP dysfunction in the horse with some reference to current understanding in human medicine is made, focusing primarily on current and relevant literature. A brief mention of other conditions described in human and veterinary medicine is also provided for reference ...
Fenner MF, Gatta G, Sattler S, Kuiper M, Hesselkilde EM, Adler DMT, Smerup M, Schotten U, Sørensen U, Diness JG, Jespersen T, Verheule S....Small-conductance Ca2+-activated K+ (KCa2) channels have been proposed as a possible atrial-selective target to pharmacologically terminate atrial fibrillation (AF) and to maintain sinus rhythm. However, it has been hypothesized that the importance of the KCa2 current-and thereby the efficacy of small-conductance Ca2+-activated K+ current (I K,Ca) inhibition-might be negatively related to AF duration and the extent of AF-induced remodeling. Unassigned: To address the hypothesis of the efficacy of I K,Ca inhibition being dependent on AF duration, the anti-arrhythmic properties of the I K,Ca inh...
