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.
Raidal SL, Edwards S, Pippia J, Boston R, Noble GK.The pharmacokinetics, efficacy, and safety of meloxicam have been evaluated in adult horses, but not foals. Physiologic differences between neonates and adults might alter drug pharmacokinetics and therapeutic index. Objective: The pharmacokinetics of meloxicam will be different in foals compared with adult horses, and foals could be at increased risk for adverse drug effects. Methods: Twenty lightbreed foals less than 6 weeks of age at commencement of the study. Methods: Single and repeated oral dose pharmacokinetics were determined for meloxicam (0.6 mg/kg) in 10 foals. The safety of the d...
Ohta M, Kurimoto S, Tokushige H, Kuroda T, Ishikawa Y.To determine hemodynamic effects of hydroxyethyl starch (HES) infusion during anesthesia in horses, incremental doses of 6% HES were administered 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 administered 3 intravenous dose of 6% HES (5 ml/kg) over 15 min with 15-min intervals in addition to constant infusion of lactated Ringer's solution at 10 ml/kg/hr. Hemodynamic parameters were measured before and e...
Nugraheni AD, Nagao S, Yanagisawa S, Ogura T, Hirota S.We have previously shown that methionine-heme iron coordination is perturbed in domain-swapped dimeric horse cytochrome c. To gain insight into the effect of methionine dissociation in dimeric cytochrome c, we investigated its interaction with cyanide ion. We found that the Soret and Q bands of oxidized dimeric cytochrome c at 406.5 and 529 nm redshift to 413 and 536 nm, respectively, on addition of 1 mM cyanide ion. The binding constant of dimeric cytochrome c and cyanide ion was obtained as 2.5 × 10(4) M(-1). The Fe-CN and C-N stretching (ν (Fe-CN) and ν (CN)) resonance Raman ba...
Snyder LB, Wendt-Hornickle E.The purpose of this article is to update the community of veterinarians performing general anesthesia in horses on fluid therapy. The rationale behind intraoperative fluid therapy, fluid dynamics, and various fluid options (crystalloids, hypertonic saline, colloids) is discussed. Additionally, electrolytes (calcium, potassium, and sodium) are included in the discussion in relation to general anesthesia and intraoperative fluid management.
Bolat D, Bahar S, Tipirdamaz S, Selcuk ML.The aims of this study were to determine the total volume of the horse kidney and volume fractions of its functional subcomponents (cortex, medulla, renal pelvis) using stereological methods and investigate any possible difference in the functional subcomponents of the right and left kidneys that may arise from differences in shape. The study was carried out on the kidneys of 5 horses of different breed and sex. The weight of the kidneys was measured by a digital scale, and kidney volume was calculated by Archimedes' principle. Total kidney volume and volume fractions of subcomponents of the r...
Lavin TE, Nielsen BD, Zingsheim JN, O'Connor-Robison CI, Link JE, Hill GM, Shelton J.An experiment was conducted to study P digestibility in mature horses because of the growing environmental concerns regarding P runoff and previous equine research focused mostly on young and growing animals or used ponies as a model. Phytase supplementation of swine and poultry diets can result in greater phytate-P digestibility, leading to a decreased need for inorganic P supplementation and a decrease in P excreted to the environment; this, however, has not been demonstrated in the horse. Six mature Arabian geldings were fed 6 diets consisting of pelleted concentrate and alfalfa hay. The co...
Santos AS, Jerónimo E, Ferreira LM, Rodrigues MA, Bessa RJ.The potential use of odd- and branched-chain fatty acids (OBCFA) and purine bases (PB) as microbial markers in the equine hindgut was studied. For this purpose, feed particles adherent bacteria [solid associated bacteria (SAB)] and planktonic bacteria [liquid associated bacteria (PAB)] were isolated from total cecum and colon contents of 8 healthy, crossbred horses (9 ± 3 yr). Horses were fasted for 12 to 15 h before slaughter, and the cecum and colon were identified and clamped in their extremities to avoid mixing of digesta contents. The total cecum or colon contents was collected into ther...
Clauss M, Schiele K, Ortmann S, Fritz J, Codron D, Hummel J, Kienzle E.Equid digestion is often conceptualized as a high-throughput/low-efficiency system, in particular compared with ruminants. It is commonly assumed that ruminants have an advantage when resources are limited; the effect of low food intake on digestive physiology of horses has, however, not been explored to our knowledge. We used four adult ponies [initial body mass (BM) 288 ± 65 kg] in two subsequent trials with grass hay-only diets [in dry matter (DM): hay1, mid-early cut, crude protein (CP) 10.5%, neutral detergent fibre (NDF) 67.6%; hay2, late cut, CP 5.8%, NDF 69.5%], each fed subsequent...
Giraldo CE, López C, Álvarez ME, Samudio IJ, Prades M, Carmona JU.There is no information on the effects of the breed, gender and age on the cellular content and growth factor (GF) release from equine pure-platelet rich plasma (P-PRP) and pure-platelet rich gel (P-PRG). The objectives of this study were: 1) to compare the cellular composition of P-PRP with whole blood and platelet poor plasma (PPP); 2) to compare the concentration of transforming GF beta 1 (TGF-β1) and platelet derived GF isoform BB (PDGF-BB) between P-PRP treated with non-ionic detergent (P-PRP+NID), P-PRG (activated with calcium gluconate -CG-), PPP+NID, PPP gel (PPG), and plasma and; 3) ...
Deniau V, Depecker M, Bizon-Mercier C, Couroucé-Malblanc A.To compare the changes in splenic length and thickness and in packed cell volume (PCV) following detomidine or xylazine administration and subsequent epinephrine infusion. Objective: Spleen relaxation occurs following xylazine or detomidine administration and interferes with subsequent splenic contractile response to epinephrine. Methods: Randomized non-blinded crossover experimental study. Methods: 6 healthy adult mares. Methods: The mares received an intravenous (IV) epinephrine infusion (1 μg kg(-1 ) minute(-1) over 5 minutes) one hour after IV administration of detomidine (0.01 mg kg(-1) ...
Borer-Weir KE, Bailey SR, Harris PA, Menzies-Gow NJ, Elliott J.Digital vasoconstriction, ischaemia and hypoxia may predispose to acute laminitis. Laminitis incidence varies seasonally, peaking in spring and summer. Direct seasonal influences on equine digital artery (EDA) contractility have not been investigated. This study assessed seasonal variation in maintenance of phenylephrine (PHE)-induced tone in isolated EDAs under hypoxic (95% nitrogen) and hyperoxic (95% oxygen) conditions. The objective was to measure change in arterial tone over time after constriction to a plateau with PHE. Tone was measured at plateau and over time and percentage change cal...
Sabban S, Ye H, Helm B.The binding of immunoglobulin E (IgE) to its high-affinity receptor (FcɛRI) is the central protein interaction in IgE-mediated allergic reactions. The cross-linking of the IgE/FcɛRI complex, through cognate allergens, on the surface of mast cells and basophil cells results in mediator release, and thus leads to the symptoms of type I hypersensitivity responses in mammals. To develop a baseline value for subsequent equine anti-allergy drug and vaccine research, the interaction of equine IgE with its high-affinity FcɛRI receptor was investigated following the cloning and expression of equine ...
Gray SM, Bartell PA, Staniar WB.Growth hormone is a key component of the somatotropic axis and is critical for the interplay between nutrition, regulation of metabolic functions, and subsequent processes of growth. The objective of this study was to investigate potential relations between meal feeding concentrates differing in the glycemic responses they elicit and GH secretory patterns in young growing horses. Twelve Quarter Horse weanlings (5.4 ± 0.4 mo of age) were used in a crossover design, consisting of two 21-d periods and two treatments, a high-glycemic (HG) or low-glycemic (LG) concentrate meal, fed twice daily. Ho...
Greiner C, Cavalier E, Remy B, Gabriel A, Farnir F, Gajewski Z, Carstanjen B.The effect of pregnancy on bone metabolism was investigated in healthy mares. Venous blood samples were collected 7 times from 19 multiparous mares starting at 20-weeks pre-parturition, continuing 6 times in 4-week intervals, including the week of parturition and one week after parturition. Serum concentrations of osteocalcin (OC) and carboxy-terminal cross-linking telopeptide of type I collagen (CTX-I) were determined. Measurement cycles and age had a significant (p < 0.01) influence on OC and CTX-I values. Pregnancy influenced bone metabolism with peak bone formation and resorption values...
de Laat MA, Pollitt CC, Kyaw-Tanner MT, McGowan CM, Sillence MN.The reason why a sustained high concentration of insulin induces laminitis in horses remains unclear. Cell proliferation occurs in the lamellae during insulin-induced laminitis and in other species high concentrations of insulin can activate receptors for the powerful cell mitogen, insulin-like growth factor (IGF)-1. The first aim of this study was to determine if IGF-1 receptors (IGF-1R) are activated in the hoof during insulin-induced laminitis. Gene expression for IGF-1R and the insulin receptor (InsR) was measured using qRT-PCR, in lamellar tissue from control horses and from horses underg...
Hamilton NA, Tammen I, Raadsma HW.Angiotensin converting enzyme (ACE) is essential for control of blood pressure. The human ACE gene contains an intronic Alu indel (I/D) polymorphism that has been associated with variation in serum enzyme levels, although the functional mechanism has not been identified. The polymorphism has also been associated with cardiovascular disease, type II diabetes, renal disease and elite athleticism. We have characterized the ACE gene in horses of breeds selected for differing physical abilities. The equine gene has a similar structure to that of all known mammalian ACE genes. Nine common single nuc...
Zamboulis DE, Senior JM, Clegg PD, Gallagher JA, Carter SD, Milner PI.Purinergic pathways are considered important in pain transmission, and P2X receptors are a key part of this system which has received little attention in the horse. The aim of this study was to identify and characterise the distribution of P2X receptor subtypes in the equine digit and associated vasculature and nervous tissue, including peripheral nerves, dorsal root ganglia and cervical spinal cord, using PCR, Western blot analysis and immunohistochemistry. mRNA signal for most of the tested P2X receptor subunits (P2X1-5, 7) was detected in all sampled equine tissues, whereas P2X6 receptor su...
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...
Seo MS, Park SB, Kim HS, Kang JG, Chae JS, Kang KS.Recent studies have shown that mesenchymal stem cells (MSCs) are able to differentiate into multi-lineage cells such as adipocytes, chondroblasts, and osteoblasts. Amniotic membrane from whole placenta is a good source of stem cells in humans. This membrane can potentially be used for wound healing and corneal surface reconstruction. Moreover, it can be easily obtained after delivery and is usually discarded as classified waste. In the present study, we successfully isolated and characterized equine amniotic membrane-derived mesenchymal stem cells (eAM-MSCs) that were cultured and maintained i...
Cathcart MP, Love S, Sutton DG, Reardon RJ, Hughes KJ.Analyses of exhaled breath (EB) and exhaled breath condensate (EBC) are non-invasive modalities for assessing the lower airways but these methods have not been applied to Thoroughbred racehorses in training. The aims of this study were to determine whether EB and EBC could be obtained from Thoroughbred racehorses in the field and to investigate the effects of exercise per se and during different ambient temperatures and humidity on exhaled concentrations of nitric oxide (eNO), carbon monoxide (eCO) and EBC pH. EB and EBC samples were obtained from 28 Thoroughbred racehorses pre- and post-exerc...
Moens Y.The mechanical ventilation of horses during anesthesia remains a crucial option for optimal anesthetic management, if the possible negative cardiovascular side effects are managed, because this species is prone to hypercapnia and hypoxemia. The combined use of capnography and pitot-based spirometry provide complementary information on ventilation and respiratory mechanics, respectively. This facilitates management of mechanical ventilation in conditions of changing respiratory system compliance (ie, laparoscopy) and when investigating new ventilatory strategies including alveolar recruitment m...
von Lewinski M, Biau S, Erber R, Ille N, Aurich J, Faure JM, Möstl E, Aurich C.Although some information exists on the stress response of horses in equestrian sports, the horse-rider team is much less well understood. In this study, salivary cortisol concentrations, heart rate (HR) and heart rate variability (HRV), SDRR (standard deviation of beat-to-beat interval) and RMSSD (root mean square of successive beat-to-beat intervals) were analysed in horses and their riders (n=6 each) at a public performance and an identical rehearsal that was not open to the public. Cortisol concentrations increased in both horses and riders (P<0.001) but did not differ between performan...
Vernunft A, Löhrke B, Tuchscherer A, Weitzel JM, Viergutz T.Anti-Muellerian hormone (AMH) is synthesized only by granulosa cells in female mammals as an inhibiting factor for early follicular recruitment. Especially in preantral and small antral follicles, expression of AMH is very intensive. However, we hypothesize that AMH affects also the development of large follicles by an estrogenesis modification. This current investigation provides for the first time information about concentrations of AMH in equine follicular fluid and demonstrates their relationship to functional characteristics of follicle development. Therefore, fluids of follicles in diffe...
Schauvliege S, Gasthuys F.Despite the use of balanced anesthesia and fluids, drugs for cardiovascular support are often needed in anesthetized horses. Antimuscarinics can be used to treat bradycardia unrelated to hypertension. Vasopressors can be useful when hypotension is caused by vasodilation and/or when the effect of fluids and inotropes is insufficient. In most cases, however, inotropes, including sympathomimetics, calcium salts, and phosphodiesterase inhibitors, are preferred. Of the β-sympathomimetics, dobutamine remains the agent of choice. Calcium salts are mainly useful in hypocalcemic patients. Phosphodiest...
Crumley MN, McMurphy RM, Hodgson DS, Kreider SE.To compare the effects of 2 fractions of inspired oxygen, 50% and > 95%, on ventilation, ventilatory rhythm, and gas exchange in isoflurane-anesthetized horses. Methods: 8 healthy adult horses. Methods: In a crossover study design, horses were assigned to undergo each of 2 anesthetic sessions in random order, with 1 week separating the sessions. In each session, horses were sedated with xylazine hydrochloride (1.0 mg/kg, IV) and anesthesia was induced via IV administration of diazepam (0.05 mg/kg) and ketamine (2.2 mg/kg) Anesthesia was subsequently maintained with isoflurane in 50% or > 95% o...
Montgomery L, Elliott SB, Adair HS.To (1) determine the temperature change in equine tendon and muscle during therapeutic ultrasound and (2) develop guidelines for treating horses for muscular or tendinous injury using therapeutic ultrasound. Methods: Experimental, in vivo study. Methods: Adult horses (n = 10). Methods: Thermistors were inserted in the superficial and deep digital flexor tendons (SDFT and DDFT) of the thoracic limbs of 10 adult horses. On the left, 3.3 MHz therapeutic continuous ultrasound was done for 10 minutes at an intensity of 1.0 W/cm(2) and for the right thoracic limb at 1.5 W/cm(2). Thermistors were pla...
Bischofberger AS, Wereszka MM, Hadidane I, Perkins NR, Jeffcott LB, Dart AJ.To evaluate the effect of 3 laryngeal prostheses alone or in combination on rima glottidis area in horses. Methods: Experimental randomized design. Methods: Cadaveric equine larynges (n = 22). Methods: Three prostheses were preplaced in each of 14 larynges. Rima glottidis area was measured after loading each suture in 5 Newton (N) increments from 0 N to 35 N. In 8 larynges, the 3 prostheses were tied alone or in combination at a fixed load of 15 N and rima glottidis area measured. Results: Rima glottidis cross-sectional area increased as the load on each prosthesis increased with maximum area ...
Whitton RC, Mirams M, Mackie EJ, Anderson GA, Seeman E.Bone remodelling is inhibited by high repetitive loading. However, in subchondral bone of racehorses in training, eroded surface doubled in association with fatigue fracture and there was greater surrounding trabecular bone volume suggesting trabecular modelling unloads the bone focally, allowing damage repair by remodelling. Background: Remodelling replaces damaged bone with new bone but is suppressed during high magnitude repetitive loading when damage is most likely. However, in cortical bone of racehorses, at sites of fatigue fracture, focal porosity, consistent with remodelling, is observ...
Pereira GR, Lorenzo PL, Carneiro GF, Bilodeau-Goeseels S, Kastelic JP, Esteller-Vico A, Lopez-Bejar M, Liu IK.Immature oocytes synthesize a variety of proteins that include the enzyme glucose-6-phosphate dehydrogenase (G6PDH). Brilliant cresyl blue (BCB) is a vital blue dye that assesses intracellular activity of G6PDH, an indirect measure of oocyte maturation. The objective was to evaluate the BCB test as a criterion to assess developmental competence of equine oocytes and to determine if equine growth hormone (eGH) enhanced in vitro maturation (IVM) of equine oocyte. Cumulus-oocytes complexes (COCs) were recovered by aspirating follicles 0.05). Maturation was not affected significantly by BCB class...
Lancaster LS, Bowker RM, Mauer WA.Density and morphologic features of hoof wall tubules in horses' hooves are described. The sample population consisted of hooves (n=12) from both live and deceased adult horses. Full wall thicknesses of the hoof wall were prepared histologically from sites at the toe, medial quarter and lateral quarter. In defined areas, tubules were counted, and density was calculated across the three histologically defined areas of the stratum externum, stratum medium and stratum internum along with the descriptive morphologic features of the tubules. Morphologically, distinct zones were demarcated by varyin...
Muehlmann LA, Michelotto PV, Nunes EA, Grando FC, da Silva FT, Nishiyama A.Phagocytosis exerted by alveolar macrophages and neutrophils is crucial in the clearance of exogenous particles deposited in the airways. Therefore, substances that activate these phagocytes in the airways can exert important effects on the particle clearance rate. PAF, particularly, was proved to be a potent activator of several immune cells and was shown to be present in the equine lower airways in specific conditions, such as after exercise. The present study aimed to investigate if PAF is able to increase the phagocytic capacity and the production of superoxide anion in equine alveolar mac...
Dell'Aquila ME, De Felici M, Massari S, Maritato F, Minoia P.In vitro fertilization (IVF) has had poor success in the horse, a situation related to low rates of sperm penetration through the zona pellucida (ZP). Zona pellucida hardening (ZPH) is seen in mouse and rat oocytes cultured in serum-free medium. The hardened ZP is refractory to sperm penetration. Fetuin, a component of fetal calf serum, inhibits ZPH and allows normal fertilization rates in oocytes cultured in the absence of serum. We evaluated whether fetuin is present in horse serum and follicular fluid (FF) and whether fetuin could inhibit ZPH in equine oocytes matured in vitro, thus increas...
Lindsay WA, McDonell W, Bignell W.Intracompartmental muscle pressures were recorded from the right and left forelimbs (extensor carpi radialis, triceps brachii) of healthy horses maintained in left lateral recumbency while under deep halothane anesthesia for 180 to 240 minutes. Cardiac output, blood pressure, blood gases, and acid-base status were monitored throughout the anesthesia, and electrolyte levels (Ca2+, P+, K+, Cl-, Na+) and enzyme activities (aspartate aminotransferase (AST), creatine phosphokinase (CPK), and blood lactate) were monitored for 7 days. Postanesthetic forelimb lameness was produced in 5 of the 6 horses...
Yamanaka Y, Matsugano S, Yoshikawa Y, Orino K.Human immunoglobulin G (IgG) binding with zinc ions was examined using zinc ions immobilized on chelating Sepharose beads (Zn-beads). Human IgG bound to Zn-beads but not to Sepharose beads (control beads). Mouse, rat, bovine and equine IgGs also bound to Zn-beads, similar to human IgG. The human IgG F(c) fragment showed zinc ion-binding activity whereas the Fab fragment did not. Ethylenediaminetetraacetic acid (EDTA)-treated Zn-beads no longer bound human IgG; however, washing the beads, followed by the addition of zinc ions, restored the binding activity towards human IgG. Zn-beads saturated ...
Connor J, Schroit AJ.A 31-32-kDa integral membrane protein has been previously identified in erythrocytes as the protein most likely to be responsible for the transbilayer movement of phosphatidylserine (PS) [Connor & Schroit (1988) Biochemistry 27, 848-851]. Using similar techniques, we have identified analogous proteins of identical molecular weights in bovine, equine, ovine, porcine, canine, caprine, and rhesus red blood cells. Similar to human red blood cells, all of the mammalian cells were able to specifically transport an exogenously supplied fluorescent PS analogue from their outer-to-inner membrane le...
González-Fernández L, Macías-García B, Velez IC, Varner DD, Hinrichs K.The mechanisms leading to capacitation in stallion sperm are poorly understood. The objective of our study was to define factors associated with regulation of protein tyrosine phosphorylation in stallion sperm. Stallion sperm were incubated for 4 h in modified Whitten's media with or without bicarbonate, calcium, or BSA. When sperm were incubated in air at 30×10⁶/ml at initial pH 7.25, protein tyrosine phosphorylation was detected only in medium containing 25 mM bicarbonate alone; calcium and BSA inhibited phosphorylation. Surprisingly, this inhibition did not occur when sperm were incubate...
Tocci R, Sargentini C, Martini A, Andrenelli L, Pezzati A, Benvenuti D, Giorgetti A.Foot quality is essential to the horse's movement. The barefoot approach favours the animal's welfare. Environment and selection determine hoof characteristics. Methods: Hoof characteristics of eight Anglo-Arabian (AA) and nine Haflinger (HA) horses were studied. After a preliminary visual analysis of feet, nail samples were collected after trimming for physico-chemical analysis. The parameters were submitted to analysis of variance. A principal component analysis and a Pearson correlation were used to compare mineral contents. Results: The hooves of both breeds were healthy and solid. The hoo...
Malikides N, Hodgson JL, Rose RJ, Hodgson DR.To determine whether removal of 20 mL/kg of blood (approximately 25% of blood volume) resulted in adverse physiological effects in donor horses, we removed this volume of blood from five horses and selected cardiovascular, haematological and biochemical variables measured during collection and for 31 days thereafter. We found that alteration in most variables occurred, although the changes in values usually remained within published reference ranges. Also, recovery of these alterations to pre-collection values was rapid, occurring within 24--48 h in most instances. We concluded that volumes of...
Loux SC, Scoggin KE, Troedsson MH, Squires EL, Ball BA.The cervical mucus plug (CMP) is believed to play an integral role in the maintenance of pregnancy in the mare, primarily by inhibiting microbial entry. Unfortunately, very little is known about its composition or origin. To determine the proteomic composition of the CMP, we collected CMPs from mares (n = 4) at 9 months of gestation, and proteins were subsequently analyzed by nano-LC-MS/MS. Results were searched against EquCab2.0, and proteomic pathways were predicted by Ingenuity Pathway Analysis. Histologic sections of the CMP were stained with H&E and PAS. To identify the origin of ...
Dhanjal JK, Wilson DV, Robinson E, Tobin TT, Dirikolu L, Dirokulu L.To determine the optimal dose, serum concentrations and analgesic effects of intravenous (IV) tramadol in the horse. Two-phase blinded, randomized, prospective crossover trial. Seven horses (median age 22.5 years and mean weight 565 kg). Horses were treated every 20 minutes with incremental doses of tramadol HCl (0.1-1.6 mg kg(-1)) or with saline. Heart rate, respiratory rate, step frequency, head height, and sweating, trembling, borborygmus and head nodding scores were recorded before and up to 6 hours after treatment. In a second study, hoof withdrawal and skin twitch reflex latencies (HWRL ...
Sanchez LC, Robertson SA, Maxwell LK, Zientek K, Cole C.Transdermal fentanyl is used clinically in horses based on pharmacokinetic data and antinociceptive effects documented in other species. Objective: Fentanyl IV administration increases both visceral and somatic nociceptive threshold in conscious horses. Methods: Six clinically normal horses, each fitted with a permanent gastric cannula. Methods: Visceral nociception was evaluated with 2 methods of threshold detection--olorectal distention and duodenal distention. Somatic nociception was assessed by measurement of thermal threshold. Fentanyl was administered as an increasing stepwise infusion f...
Bigley RF, Gibeling JC, Stover SM, Hazelwood SJ, Fyhrie DP, Martin RB.Materials, including bone, often fail due to loading in the presence of critical flaws. The relative amount, location, and interaction of these flaws within a stressed volume of material play a role in determining the failure properties of the structure. As materials are generally imperfect, larger volumes of material have higher probabilities of containing a flaw of critical size than do smaller volumes. Thus, larger volumes tend to fail at fewer cycles compared with smaller volumes when fatigue loaded to similar stress levels. A material is said to exhibit a volume effect if its failure prop...
Cluzel C, Blond L, Fontaine P, Olive J, Laverty S.Adult articular cartilage (AC) has a well described multizonal collagen structure. Knowledge of foetal AC organisation and development may provide a prototype for cartilage repair strategies, and improve understanding of structural changes in developmental diseases such as osteochondrosis (OC). The objective of this study was to describe normal development of the spatial architecture of the collagen network of equine AC using 1.5 T magnetic resonance imaging (MRI) and polarised light microscopy (PLM), at sites employed for cartilage repair studies or susceptible to OC. T2-weighted fast-spin e...
Black A, Schoknecht PA, Ralston SL, Shapses SA.Biochemical markers of bone turnover provide sensitive, rapid, and noninvasive monitoring of bone resorption and formation. Serum concentrations of osteocalcin (OC) reflect rates of bone formation, and urinary concentrations of the pyridinium crosslinks pyridinoline (Pyd) and deoxypyridinoline (Dpd) are specific and sensitive markers of bone resorption. These markers are age-dependent and are used to detect and monitor changes in the rates of bone turnover in a variety of orthopedic diseases in humans and may prove to have similar application in horses. This study examined age differences and ...
Johnson L, Varner DD, Tatum ME, Scrutchfield WL.To evaluate the effect of age and season on Sertoli cell number per paired testes, ratio of germ cells per Sertoli cell, and daily sperm production, testes were obtained from 184 adult (4-20 yr) stallions at slaughter throughout one year. Numbers of Sertoli cells or germ cells were derived from nuclear volume density, volume of individual nuclei, and parenchymal volume. Germ cell to Sertoli cell ratios were calculated from cell numbers. Regression analysis was used to detect age-related differences in the breeding season (May-Jul) or throughout the year. A two-way analysis of variance was used...
Watson ED, Sertich PL.This study investigated the sequence of hormonal changes within the preovulatory follicles of mares. Mares were injected i.v. with 2500 IU human chorionic gonadotrophin (hCG) when a preovulatory follicle of 35 mm in diameter was detected. Fluid was aspirated from preovulatory follicles before (0 h), and 12, 24 and 36 h after administration of hCG. Concentrations of progesterone, prostaglandin (PG) E2, PGF, 6-keto-PGF1 alpha and thromboxane B2 in follicular fluid increased significantly (P less than 0.01) between 0 and 36 h. At 36 h, PGE2 was present in highest concentrations, followed by PGF a...
Schmall LM, Muir WW, Robertson JT.A comparison of the haemodynamic benefits of small volume hypertonic saline (2,400 mOsm/litre) versus isotonic saline (300 mOsm/litre) was conducted in 12 adult horses using a haemorrhagic shock model. The horses were anaesthetised and intravascular catheters placed for the measurement of haemodynamic data. Mean systemic arterial pressure was then reduced to 50 to 60 mmHg by controlled haemorrhage and maintained at that level for 40 mins. Cardiac output, stroke volume, mean systemic arterial pressure, plasma volume and urine production decreased significantly following blood loss. Hypertonic o...
Gallivan GJ, McDonell WN, Forrest JB.Pulmonary mechanics and lung volumes were measured in horses and cows to determine if differences in breathing pattern between the two species were due to differences in the mechanical properties of the lungs. Tidal volume (VT) was larger in the horses, while the respiratory rate (fR) and minute ventilation (VE) were higher in the cows. The horses often had a double peak in airflow during inspiration and, or, expiration, while the cows had a single peak during expiration. Measured lung volumes were larger in the horses and they had a higher dynamic lung compliance (Cdyn,L), although the static...
Vanderwall DK, Woods GL, Weber JA, Lichtenwalner AB.The objective of this study was to test the hypothesis that intrauterine administration of prostaglandin E(2) (PGE(2)) or estradiol-17beta (E-17beta) would prolong CL function in nonpregnant mares. Nonpregnant mares were continuously infused with 240 mug/d of PGE(2), 6 mug/d of E-17beta, or vehicle (sham-treated) on Days 10 to 16 post ovulation (ovulation = Day 0), using osmotic minipumps surgically placed into the uterine lumen on Day 10 (n = 11 per group). Nonpregnant and pregnant mares served as negative and positive controls, respectively (n = 11 per group). Mares were defined as having pr...
Bou T, Ding W, Ren X, Liu H, Gong W, Jia Z, Zhang X, Dugarjaviin M, Bai D.Traditional Mongolian endurance training is an effective way to improve the athletic ability of the horse for endurance events and is widely used. This incorporates aerobic exercise and intermittent fasting and these altered physiologic conditions are associated with switches between muscle fibre types. Objective: To better understand the adaption of horse skeletal muscle to traditional Mongolian endurance training from muscle fibre characteristics and transcriptional levels and to explore possible molecular mechanisms associated with the endurance performance of horses. Methods: Before-after ...
Hopster K, Rohn K, Ohnesorge B, Kästner SBR.To compare the effects of controlled mechanical ventilation (CMV) and constant positive end-expiratory pressure (PEEP) and interposed recruitment manoeuvres (RMs) with those of CMV without PEEP on gas exchange during general anaesthesia and the early recovery period. Methods: Prospective, randomized clinical trial. Methods: A total of 48 Warmblood horses undergoing elective surgery in lateral (Lat) (n = 24) or dorsal (Dors) (n = 24) recumbency. Methods: Premedication (romifidine), induction (diazepam and ketamine) and maintenance (isoflurane in oxygen) were identical in all horses. Groups La...
Asadi F, Mohri M, Adibmoradi M, Pourkabir M.Lipid transport systems in animals have been evaluated both as experimental models for lipid and lipoprotein metabolism in humans and to gain insight into the lipid metabolism of specific breeds. The Turkman horse is a pure-blooded horse that lives on the margins of the Caspian Basin; information about serum lipids and lipoproteins in this breed is lacking. Objective: The purpose of this study was to evaluate serum lipid and lipoprotein concentrations in clinically healthy Turkman horses. Methods: Concentrations of triglyceride (TG), total cholesterol (TC), high density lipoprotein cholesterol...
Zink MC, Yager JA, Prescott JF, Wilkie BN.Bronchoalveolar lavage was performed 5 times, sequentially, on 3 healthy foals while each foal was 6 to 63 days of age. Phagocytosis and bactericidal assays were performed on recovered alveolar macrophages. Corynebacterium equi and alveolar macrophages at a ratio of 10:1 were incubated for 1 hour in medium containing 1% heat-inactivated rabbit anti-C equi serum. After incubation, greater than 90% of the alveolar macrophages contained at least 1 ingested bacterium and each alveolar macrophage contained 9.4 +/- 1.0 bacteria (mean +/- SE). After alveolar macrophages and C equi were incubated for ...
Ortega Ferrusola C, Anel-López L, Ortiz-Rodriguez JM, Martin Muñoz P, Alvarez M, de Paz P, Masot J, Redondo E, Balao da Silva C, Morrell JM....In order to gain insight of the modifications that freezing and thawing cause to the surviving population of spermatozoa, changes in the potential of the plasma membrane (Em) and intracellular Na content of stallion spermatozoa were investigated using flow cytometry. Moreover, caspase 3 activity was also investigated and the functionality of the Na -K ATPase pump was investigated before and after freezing and thawing. Cryopreservation caused a significant (p < 0.001) increase in the subpopulation of spermatozoa with depolarized sperm membranes, concomitantly with an increase (p < 0.0...
Schmitz A, Theurillat R, Lassahn PG, Mevissen M, Thormann W.CE with multiple isomer sulfated-CD as selector was used for the simultaneous analysis of the stereoisomers of ketamine, norketamine, 5,6-dehydronorketamine and hydroxylated metabolites of norketamine in liquid/liquid extracts of (i) in vitro incubations with ketamine or norketamine and equine liver microsomes and (ii) plasma and urine of ponies receiving a target-controlled infusion of ketamine under isoflurane anesthesia. Hydroxynorketamine metabolites with the hydroxy group at the cyclohexanone ring could be shown to be formed stereoselectively both in vitro and in vivo. Due to the lack of ...
Reed KJ, Kunz IGZ, Scare JA, Nielsen MK, Turk PJ, Coleman RJ, Coleman SJ.As hindgut fermenters, horses are especially dependent on the microbiota residing in their cecum and large intestines. Interactions between these microbial populations and the horse are critical for maintaining gut homeostasis, which supports proper digestion. The current project was motivated to determine if any features of the fecal microbiota are informative of the microbial communities from the cecum, ventral colon, or dorsal colon. Digesta from the cecum, ventral colon, dorsal colon and feces were collected from 6 yearling miniature horses. Microbial DNA was isolated and the microbiota fr...
Morrell JM, Rodriguez-Martinez H, Johannisson A.This study compared the effect on semen quality of different handling methods used in the preparation of stallion semen doses for artificial insemination. The three methods were (i) extending the ejaculate to 30-50 x 10(6)/ml, (ii) single layer centrifugation (SLC) and (iii) sperm washing (centrifugation without a colloid). An additional treatment was to add seminal plasma (SP) in various proportions to some SLC preparations. The resulting samples were evaluated for sperm motility by computer assisted sperm analysis, membrane integrity using the Nucleocounter SP-100 and chromatin integrity by ...
Sessions-Bresnahan DR, Graham JK, Carnevale EM.IVF in horses is rarely successful. One reason for this could be the failure of sperm to fully capacitate or exhibit hyperactive motility. We hypothesized that the zona pellucida (ZP) of equine oocytes prevents fertilization in vitro, and bypassing the ZP would increase fertilization rates. Limited availability of equine oocytes for research has necessitated the use of heterologous oocyte binding assays using bovine oocytes. We sought to validate an assay using bovine oocytes and equine sperm and then to demonstrate that bypassing the ZP using perivitelline sperm injections (PVIs) with equine ...
Campbell-Thompson ML, Merritt AM.Gastric cannulas were placed surgically in 5 young male horses. After a 2-week recovery period, horses were studied once a week. Horses were fasted for 24 hours, and gastric fluid output was collected for 5 continuous hours. Volumes were recorded every 15 minutes, and pH and hydrogen ion concentration were determined in an aliquot from each period. In 10 basal experiments, using 5 horses, volume, pH, and hydrogen ion concentration were continuously variable. Mean acid output was 45.1 +/- 2.02 microEq/15 min/kg (mean +/- SEM). In 6 experiments, using 3 horses, 0.5 mg of ranitidine/kg of body we...
McGivney BA, Griffin ME, Gough KF, McGivney CL, Browne JA, Hill EW, Katz LM.Circulating miRNAs (ci-miRNAs) are endogenous, non-coding RNAs emerging as potential diagnostic biomarkers. Equine miRNAs have been previously identified including subsets of tissue-specific miRNAs. In order to investigate ci-miRNAs as diagnostic tools, normal patterns of expression for different scenarios including responses to exercise need to be identified. Human studies have demonstrated that many ci-miRNAs are up-regulated following exercise with changes in expression patterns in skeletal muscle. However, technical challenges such as haemolysis impact on accurate plasma ci-miRNA quantific...
