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.
Zhang R, Zhang J, Dang W, Irwin DM, Wang Z, Zhang S.The intestinal microbial composition and metabolic functions under normal physiological conditions in the donkey are crucial for health and production performance. However, compared with other animal species, limited information is currently available regarding the intestinal microbiota of donkeys. In the present study, we characterized the biogeography and potential functions of the intestinal digesta- and mucosa-associated microbiota of different segments of the intestine (jejunum, ileum, cecum, and colon) in the donkey, focusing on the differences in the microbial communities between the sm...
Benvegnen J, De Breuyn B, Gerber V, Rottenberg S, Koch C.The aim of the study was to assess the expression of the immune checkpoint inhibitor programmed death-ligand 1 (PD-L1) in equine sarcoids (ES). Programmed death-ligand 1 is expressed by various cancer cells to block T cell-mediated elimination of tumor cells. Antibodies targeting human PD-L1 were tested by immunohistochemistry for their cross-reactivity with equine PD-L1 using formalin-fixed, paraffin-embedded tissues. Our results do not support an important role of PD-L1-mediated immune evasion in ES disease and hence do not offer a rationale for anti-PD-1/PD-L1-based immunotherapy against ES...
Xing J, Liu G, Zhang X, Bai D, Yu J, Li L, Wang X, Su S, Zhao Y, Bou G, Dugarjaviin M.The community of microorganisms inhabiting the gastrointestinal tract of monogastric herbivores played critical roles in the absorption of nutrients and keeping the host healthy. However, its establishment at different age groups has not been quantitatively and functionally examined. The knowledge of microbial colonization and its function in the intestinal tract of different-age donkeys is still limited. By applying the V3-V4 region of the bacterial 16S rRNA gene and functional prediction on fecal samples from different-age donkeys, we characterized the gut microbiota during the different age...
Mercier Q, Aftalion A.The objective of this work is to provide a mathematical analysis on how a Thoroughbred horse should regulate its speed over the course of a race to optimize performance. Because Thoroughbred horses are not capable of running the whole race at top speed, determining what pace to set and when to unleash the burst of speed is essential. Our model relies on mechanics, energetics (both aerobic and anaerobic) and motor control. It is a system of coupled ordinary differential equations on the velocity, the propulsive force and the anaerobic energy, that leads to an optimal control problem that we sol...
Kang H, Zsoldos RR, Woldeyohannes SM, Gaughan JB, Sole Guitart A.Accurately measuring body temperature in horses will improve the management of horses suffering from or being at risk of developing postrace exertional heat illness. PTSM has the potential for measuring body temperature accurately, safely, rapidly, and noninvasively. This study was undertaken to investigate the relation between the core body temperature and PTSM temperatures prior to, during, and immediately after exercise. The microchips were implanted into the nuchal ligament, the right splenius, gluteal, and pectoral muscles, and these locations were then compared with the central venous te...
Alling CR, Cremer J, Liu CC, Lewin AC, Camacho-Luna P, Carter RT.To evaluate changes in intraocular pressure (IOP) with variable head position in healthy, anesthetized horses in hoisted inversion and to assess the influence of various cofactors (age, sex, body weight, body condition score, and neck length) on IOP changes during hoisting. Methods: Seventeen healthy adult horses without significant ocular abnormalities. Methods: Subjects were administered intravenous xylazine/butorphanol premedication and ketamine/midazolam induction with xylazine/ketamine boluses for anesthetic maintenance. While hoisted, IOP was measured in triplicate for each eye via rebou...
Yu L, Wei Y, Sun HX, Mahdi AK, Pinzon Arteaga CA, Sakurai M, Schmitz DA, Zheng C, Ballard ED, Li J, Tanaka N, Kohara A, Okamura D, Mutto AA, Gu Y....Dynamic pluripotent stem cell (PSC) states are in vitro adaptations of pluripotency continuum in vivo. Previous studies have generated a number of PSCs with distinct properties. To date, however, no known PSCs have demonstrated dual competency for chimera formation and direct responsiveness to primordial germ cell (PGC) specification, a unique functional feature of formative pluripotency. Here, by modulating fibroblast growth factor (FGF), transforming growth factor β (TGF-β), and WNT pathways, we derived PSCs from mice, horses, and humans (designated as XPSCs) that are permissive for dire...
Fries RC, Clark-Price SC, Kadotani S, Stack JP, Schaeffer DJ, Lascola KM.To compare measurements of left ventricular volume and function derived from 2-D transthoracic echocardiography (2DE), transesophageal echocardiography (TEE), and the ultrasound velocity dilution cardiac output method (UDCO) with those derived from cardiac MRI (cMRI) in healthy neonatal foals. Methods: 6 healthy 1-week-old Standardbred foals. Methods: Foals were anesthetized and underwent 2DE, TEE, and cMRI; UDCO was performed simultaneously with 2DE. Images acquired by 2DE included the right parasternal 4-chamber (R4CH), left apical 4- and 2-chamber (biplane), and right parasternal short-axis...
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...
Okada CTC, Kaps M, Perez Quesada J, Gautier C, Aurich J, Aurich C.Spontaneous prolongation of the luteal phase has been described in horses, but the underlying causes are still unclear. The present study investigated details of gonadotrophin and progestogen secretion in pregnant mares (n = 11) with or without experimentally reduced early postovulatory luteal function. From days 0 to 3 after ovulation, they were treated with the prostaglandin F (PGF) analogue cloprostenol or left untreated. After conceptus collection on day 34, they were assigned to the opposite treatment. Mares were affiliated to the group primary corpus luteum (n = 6) or diestrous corpus lu...
A human-animal relationship can be developed through subsequent interactions, affected by the positive or negative emotional valence of the proceeding one. Horses implement a process of categorization to classify humans with whom they interact as positive, negative, or neutral stimuli by evaluating the kind of approach and the nature of the contact. In these terms, human-animal interactions are emotionally charged events, eliciting specific emotional states in both subjects involved. Although the human-horse relationship has been mainly investigated through behavioral analysis, physiological i...
Hernández-Avilés C, Ramírez-Agámez L, Love CC, Friedrich M, Pearson M, Kelley DE, Beckham AMN, Teague SR, LaCaze KA, Brinsko SP, Varner DD.Under in vitro conditions, stallion sperm might preferentially use energy substrates that primarily undergo mitochondrial metabolism. The present study sought to determine the effects of glucose, pyruvate, lactate, or their combinations on the quality of stallion sperm subjected to cooled storage at different temperatures, when using a skim milk-based semen extender. In Experiment 1, no substrate (Control), glucose (40 mM; Glu-40), pyruvate (2 mM, 19.8 mM; Pyr-2, Pyr-19), lactate (2 mM, 19.8 mM; Lac-2, Lac-19, respectively), or their combinations (G/P/L-2 or G/P/L-19, respectively) were ...
Foote BC, Smith JD, Allbaugh RA, Sebbag L.Determine the immediate post-operative effects of MicroPulse transscleral cyclophotocoagulation (MP-TSCPC) in healthy equine eyes. Methods: Ten adult horses. Methods: MP-TSCPC was performed on sedated horses in 12 eyes (4 groups) using the following parameters (power, duration, duty cycle): (1) 2000 mW, 180 seconds, 31.3%; (2) 3000 mW, 180 seconds, 31.3%; (3) 3000 mW, 270 seconds, 31.3%; and (4) 3000 mW, 270 seconds, 50%. Three additional eyes were left untreated (control). Eyes were monitored clinically until euthanasia (mean = 3 hours post-procedure). Histologic sections were asse...
Kendall A, Nyström S, Ekman S, Hultén LM, Lindahl A, Hansson E, Skiöldebrand E.Nerve growth factor (NGF) is a neurotrophin with many functions. In humans, it is involved in inflammation, nerve growth, apoptosis and pain signalling. Increased concentrations of NGF in synovial fluid has been shown in humans and dogs with osteoarthritis. Despite osteoarthritis being a common problem in horses, no studies have previously been published on NGF in the equine joint. The aim of this study was to quantify NGF in equine synovial fluid from healthy joints, acutely inflamed septic joints and joints with structural changes associated with osteoarthritis. A secondary aim was to identi...
Cavalero TMS, Segabinazzi LGTM, Scheeren VFDC, Freitas-Dell'Aqua CP, Papa FO.The present study compared the quality of sperm collected by artificial vagina or pharmacologically induced ejaculation from a 10-year-old thoroughbred stallion with seminal vesiculitis. The pharmacological protocol involved intravenous administration of detomidine (0.01 mg/kg) and oxytocin (20 IU) and successfully induced ejaculation in all attempts of semen collection. Sperm motility, plasma membrane and acrosome integrity (PMAI), reactive oxygen species (ROS) levels, polymorphonuclear neutrophil (PMN) percentage, and bacterial profiles of fresh and cooled semen (5°C for 24 hr) were eval...
Panzani D, Quaresma M, Fanelli D, Camillo F, Moroni R, Rota A, Martins-Bessa A, Nóvoa M, Catalán J, Canisso IF, Conte G, Mirò J.Due to the long courtship needed to attain excitation and erection, donkey semen collection can take up to 90 min. ProstaglandinF2α (PGF2α) has been reported to hasten the onset of erection and ejaculation in domesticated mammals, presumably by inducing smooth muscle contractions in the internal genitalia. However, while it has been anecdotally used in donkeys, it has yet to be critically evaluated. This study aimed to compare behavioral and semen parameters in Catalan, Balearic, Amiata, and Miranda jacks treated with the PGF2α analogue cloprostenol sodium immediately prior to exposure to a...
Park IK, Lee JY, Suk MH, Yoo S, Seo YG, Oh JK, Kwon JY. Children with cerebral palsy (CP) have an impaired cardiac autonomic function. Attenuated heart rate recovery (HRR), which is a valuable prognostic parameter for autonomic nervous system, is known to be associated with an increased risk of cardiovascular events and all-cause mortality. However, only few studies have observed the effects of exercise on the cardiac autonomic function in children with CP. The purpose of this pilot study was to examine the effects of equine-assisted activity (EAA) program on cardiac autonomic function in children with CP. A single-blinded, parallel, two-arm pilo...
de Castro RVG, Pieri NCG, Fantinato Neto P, Grizendi BM, Dória RGS, Meirelles FV, Smith LC, Garcia JM, Bressan FF.The cellular reprogramming into pluripotency is influenced by external and internal cellular factors, such as culture conditions (e.g., environmental oxygen concentration), and the aging process. Herein, we aimed to generate and maintain equine iPSCs (eiPSCs) derived from fibroblasts of a horse older than 20 years and to evaluate the effect of different levels of oxygen tension (atmospheric 20% O, 5% O, or 20% to 5% O) on these cells. Fibroblasts were reprogrammed, and putative eiPSCs were positive for positive alkaline phosphatase detection; they were positive for pluripotency-related genes ...
Vieira LA, Matás C, Torrecillas A, Saez F, Gadea J.Seminal plasma (SP) plays a crucial role in sperm protection and functionality. However, the effect of SP on the sperm cryopreservation is dependent on the stallion and SP composition. The use of epididymal spermatozoa incubated in the presence of SP could help the identification of the components of SP that are able to confer protection upon the spermatozoa during freezing. The aims of this study were (i) to identify SP components involved in the potential protection of epididymal spermatozoa during the freeze-thawing process and (ii) to identify and evaluate the proteins likely related to sp...
Cerullo M, Driessen B, Douglas H, Hopster K. In anesthetized adult horses, changes in recumbency can influence the cardiovascular system but how arterial blood pressures and oxygen tension change in isoflurane anesthetized animals as a direct result of hoisting has not been investigated. To evaluate effects of hoisting on hemodynamic function and pulmonary gas exchange in isoflurane-anesthetized horses. Prospective, experimental study. Six adult horses were anesthetized three times using isoflurane in pure oxygen (inspired fraction 0.9-1.0), and allowed breathing spontaneously in lateral recumbency. After 45 min horses were hoisted u...
Ertelt A, Stumpff F, Merle R, Kuban S, Bollinger L, Liertz S, Gehlen H.Asymmetric dimethylarginine (ADMA) is a cardiac biomarker in humans, symmetric dimethylarginine (SDMA) a renal biomarker in humans, cats, and dogs. The purpose of this prospective study was to investigate if measuring serum ADMA and SDMA concentrations via ELISA allows detection of cardiac disease in horses in a routine laboratory setting. In this context, reference values in horses were established. Methods: Seventy-eight horses with no known medical history were compared to 23 horses with confirmed structural cardiac disease with/or without arrhythmias. Horses underwent physical examination,...
Domino M, Romaszewski M, Jasiński T, Maśko M.Infrared thermography (IRT) is a valuable diagnostic tool in equine veterinary medicine; however, little is known about its application to donkeys. This study aims to find patterns in thermal images of donkeys and horses and determine if these patterns share similarities. The study is carried out on 18 donkeys and 16 horses. All equids undergo thermal imaging with an infrared camera and measurement of the skin thickness and hair coat length. On the class maps of each thermal image, fifteen regions of interest (ROIs) are annotated and then combined into 10 groups of ROIs (GORs). The existence o...
Pfau T, Reilly P.Low-cost sensor devices are often limited in terms of sample rate. Based on signal periodicity, the Nyquist theorem allows determining the minimum theoretical sample rate required to adequately capture cyclical events, such as pelvic movement in trotting horses. Objective: To quantify the magnitude of errors arising with reduced sample rates when capturing biological signals using the example of pelvic time-displacement series and derived minima and maxima used to quantify movement asymmetry in lame horses. Methods: Data comparison. Methods: Root mean square (RMS) errors between the 'reference...
Rigoleto Júnior WL, Dias de Camargo Neto W, de Paula Nogueira G, Ferrari TA, Bertan Membrive CM, Giometti IC, Castilho C.The objective of this study was to quantify serum progesterone levels, uterine features, and pregnancy rates in acyclic, embryo recipient mares using a bovine progesterone-releasing intravaginal device in a commercial embryo transfer (ET) program. The study included 73 recipient mares of unknown breed, aged 3-10 years, weighing 350-500 kg, and kept under an intensive management system on Tifton 85 (Cynodon spp.) pastures with water and mineral salt ad libitum. The horses were divided into two groups: a group with a progesterone-releasing intravaginal device (1 g progesterone, G-IVP4, n = 24...
Ask K, Rhodin M, Tamminen LM, Hernlund E, Haubro Andersen P.Equine orthopedic pain scales are targeted towards horses with moderate to severe orthopedic pain. Improved assessment of pain behavior and pain-related facial expressions at rest may refine orthopedic pain detection for mild lameness grades. Therefore, this study explored pain-related behaviors and facial expressions and sought to identify frequently occurring combinations. Orthopedic pain was induced by intra-articular LPS in eight horses, and objective movement asymmetry analyses were performed before and after induction together with pain assessments at rest. Three observers independently ...
Egenvall A, Engström H, Byström A.Biomechanical studies of walk, especially walk on the circle, are scarce, while circles or curved tracks are frequently used during equestrian activities. To study horse-rider-circle interactions on the circle, the first steps would be to investigate how the unridden, freely walking horse is influenced by circular movement, and then add a rider. The aim was to study horse vertical trunk movements, and sagittal cannon angles (protraction-retraction) during walk in straight-line and on the circle without rider, and on the circle with a rider using minimal influence. Methods: Ten horses were ridd...
Lotz J, Içli S, Liu D, Caliskan S, Sieme H, Wolkers WF, Oldenhof H.Rational design of cryopreservation strategies for oocytes and ovarian cortex tissue requires insights in the rate at which cryoprotective agents (CPA) permeate and concomitant water transport takes place. The aim of the current study was to investigate possible differences in permeation kinetics of different CPAs (i.e., glycerol/GLY, ethylene glycol/EG, dimethyl sulfoxide/DMSO, and propylene glycol/PG), in equine oocytes as well as ovarian tissue. Membrane permeability of oocytes to water (Lp) and to CPAs (Ps) was inferred from video microscopic imaging of oocyte volume responses during perfu...
Jaramillo C, Arias MP, Mosqueda D, Darby S, Renaud D, Gómez DE.This study aimed at describing selected hematological, biochemical, and acid-base variables of adult horses living at sea level and comparing them to those living at 5 different altitudes. One hundred and thirty-eight healthy Paso Fino horses > 2 years old were enrolled. Altitudes included the following: altitude A (0 to 50 m above sea level, masl; n = 23), B (1000 to 1050 masl; n = 25), C (1450 masl; n = 30), D (1950 to 2050 masl; n = 30), and E (2950 to 3100 masl; n = 30). A portable blood gas analyzer was used to determine selected biochemical and acid-base variab...
Lee HY, Kim JY, Kim KH, Jeong S, Cho Y, Kim N.Horses have been studied for exercise function rather than food production, unlike most livestock. Therefore, the role and characteristics of tissue landscapes are critically understudied, except for certain muscles used in exercise-related studies. In the present study, we compared RNA-Seq data from 18 Jeju horse skeletal muscles to identify differentially expressed genes (DEGs) between tissues that have similar functions and to characterize these differences. We identified DEGs between different muscles using pairwise differential expression (DE) analyses of tissue transcriptome expression d...
Raspa F, Dinardo FR, Vervuert I, Bergero D, Bottero MT, Pattono D, Dalmasso A, Vinassa M, Valvassori E, Bruno E, De Palo P, Valle E.Horses reared for meat production are fed high amounts of cereal grains in comparison with horses raised for other purposes. Such feeding practice may lead to risk of poor welfare consequences. The aim of this study was to investigate the effects of two feeding practices on selected metabolic parameters and production aspects. Nineteen Bardigiano horses, 14.3 ± 0.7 months of age, were randomly assigned to two groups-one fed with high amounts of cereal grains (HCG; n = 9; 43% hay plus 57% cereal grain-based pelleted feed) vs. one fed with high amounts of fibre (HFG; n = 10; 70% hay plus...
Kim H, Lee T, Park W, Lee JW, Kim J, Lee BY, Ahn H, Moon S, Cho S, Do KT, Kim HS, Lee HK, Lee CK, Kong HS, Yang YM, Park J, Kim HM, Kim BC, Hwang S....The modern horse (Equus caballus) is the product of over 50 million yrs of evolution. The athletic abilities of the horse have been enhanced during the past 6000 yrs under domestication. Therefore, the horse serves as a valuable model to understand the physiology and molecular mechanisms of adaptive responses to exercise. The structure and function of skeletal muscle show remarkable plasticity to the physical and metabolic challenges following exercise. Here, we reveal an evolutionary layer of responsiveness to exercise-stress in the skeletal muscle of the racing horse. We analysed differentia...
Lindner AE.The objective of the study was to examine the validity of v(4) [velocity run under the defined conditions inducing 4 mmol/L of blood lactate concentration ([LA])] and v(200) (velocity run under the defined conditions inducing a heart rate of 200 beats/min) to differentiate performance level among Standardbred racehorses. For this purpose, 19 Standardbred trotting racehorses with differing racing time records in 2 training yards were submitted to a standardized exercise test to determine their v(4) and v(200) (6 horses of one yard only). The test consisted of 4 or more consecutive intervals dep...
Sweeney CR, Rossier Y, Ziemer EL, Lindborg S.Bronchoalveolar lavage (BAL) fluid was analyzed in healthy horses, using different lavage fluid volumes and lung sites. The only significant difference in the cellular composition of BAL fluid between the right and left lungs was the mast cell numbers, which were significantly higher in the left lung. Total cell count ranged from 34 to 330 cells/microliter for the right lung and 43 to 330 cells/microliter for the left lung. Percentage of neutrophils ranged from 1 to 7% in the right lung and 1 to 5% in the left lung. The small-volume (50 ml) lavage had a greater percentage of neutrophils and a ...
Bischofberger AS, Dart CM, Perkins NR, Kelly A, Jeffcott L, Dart AJ.To compare the effects of manuka honey and manuka honey gel on second intention healing of noncontaminated distal limb wounds and those contaminated with feces. Methods: Experimental study. Methods: Standardbred horses (n = 10). Methods: Five full-thickness wounds (2 × 2 cm) were created on both metacarpi. Wounds on 1 forelimb were covered with horse feces for 24 hours. Wounds on the contralateral limb were left uncontaminated. Wounds were assigned to the following 5 different treatments: manuka honey, manuka honey gel or gel applied for 12 days, manuka honey gel applied throughout healing an...
Ambrisko TD, Schramel JP, Adler A, Kutasi O, Makra Z, Moens YP.The aim was to evaluate the feasibility of using electrical impedance tomography (EIT) in horses. Thoracic EIT was used in nine horses. Thoracic and abdominal circumference changes were also measured with respiratory ultrasound plethysmography (RUP). Data were recorded during baseline, rebreathing of CO2 and sedation. Three breaths were selected for analysis from each recording. During baseline breathing, horses regularly took single large breaths (sighs), which were also analysed. Functional EIT images were created using standard deviations (SD) of pixel signals and correlation coefficients (...
De Schauwer C, Meyer E, Cornillie P, De Vliegher S, van de Walle GR, Hoogewijs M, Declercq H, Govaere J, Demeyere K, Cornelissen M, Van Soom A.Mesenchymal stromal cells (MSC) represent a promising population for supporting new clinical concepts in cellular therapy. A wide diversity of isolation procedures for MSC from umbilical cord blood (UCB) has been described for humans. In contrast, a few data are available in horses. In the current study, a sedimentation method using hydroxyethyl starch and a method based on the lysis of red blood cells using ammonium chloride (NH(4)Cl) were compared with two density gradient separation methods (Ficoll-Paque and Percoll). Adherent cell colonies could be established using all four isolation meth...
Parbhakar OP, Duke T, Townsend HG, Singh B.Horses are unique in their extreme sensitivity to endotoxin-induced cardio-pulmonary shock and mortality. The mechanisms behind increased sensitivity of the horse to endotoxin remain unknown. Pulmonary intravascular macrophages (PIMs) are pro-inflammatory cells occurring in horses. Because the functions of equine PIMs in endotoxemia remain unknown, we studied the role played by equine PIMs in endotoxin-induced pulmonary pathophysiology. We achieved this by using a recently developed protocol to deplete PIMs in order to compare lipopolysaccharide (LPS)-induced pulmonary responses in horses with...
Haugaard MM, Pehrson S, Carstensen H, Flethøj M, Hesselkilde EZ, Praestegaard KF, Diness JG, Grunnet M, Jespersen T, Buhl R.Only few pharmacologic compounds have been validated for treatment of atrial fibrillation (AF) in horses. Studies investigating the utility and safety of flecainide to treat AF in horses have produced conflicting results, and the antiarrhythmic mechanisms of flecainide are not fully understood. Objective: To study the potential of flecainide to terminate acutely induced AF of short duration (≥ 15 minutes), to examine flecainide-induced changes in AF duration and AF vulnerability, and to investigate the in vivo effects of flecainide on right atrial effective refractory period, AF cycle length...
Tiley HA, Geor RJ, McCutcheon LJ.To determine effects of dexamethasone on glucose dynamics and insulin sensitivity in healthy horses. Methods: 6 adult Standardbreds. Methods: In a balanced crossover study, horses received dexamethasone (0.08 mg/ kg, IV, q 48 h) or an equivalent volume of saline (0.9% NaCl) solution (control treatment) during a 21-day period. Horses underwent a 3-hour frequently sampled IV glucose tolerance test (FSIGT) 2 days after treatment. Minimal model analysis of glucose and insulin data from FSIGTs were used to estimate insulin sensitivity (Si), glucose effectiveness (Sg), acute insulin response to gluc...
Aurich C, Budik S.Early equine pregnancy shares many features with that of more intensively assessed domestic animals species, but there are also characteristic differences. Some of those are poorly understood. Descent of the equine conceptus into the uterine lumen occurs at day 5 to 6 after ovulation but is only possible when the embryo secretes prostaglandin E2. Although maintenance of equine pregnancy probably involves secretion of a conceptus derived anti-luteolytic factor, this agent has not been identified. Rapid growth, conceptus mobility and presence of an acellular capsule at the time of maternal recog...
Thorpe CT, Stark RJ, Goodship AE, Birch HL.Damage to the flexor tendons, particularly the superficial digital flexor tendon (SDFT), is one of the most common musculoskeletal injuries sustained by horses competing in all disciplines. Our previous work has shown that SDFTs from different individuals show a wide variation in mechanical strengths; this is important clinically as it may relate to predisposition to injury. The high mechanical strength of tendon relies on the correct orientation of collagen molecules within fibrils and stabilisation by the formation of chemical cross-links between collagen molecules. It is not known whether t...
Natali AN, Carniel EL, Frigo A, Pavan PG, Todros S, Pachera P, Fontanella CG, Rubini A, Cavicchioli L, Avital Y, De Benedictis GM.What is the central question of this study? Prostheses for treatment of urinary incontinence elicit complications associated with an inadequate mechanical action. This investigation aimed to define a procedure addressed to urethral mechanical characterization. Experimental tests are the basis for constitutive formulation, with a view to numerical modelling for investigation of the interaction between the tissues and a prosthesis. What is the main finding and its importance? Horse urethra, selected for its histomorphometric similarity to human urethra, was characterized by integrated histologic...
McGuire TC, Crawford TB, Hallowell AL, Macomber LE.Failure in colostral immunoglobulin G (IgG) transfer was found in 9 of 87 Thoroughbred foals. Seven (78%) of these 9 foals acquired infections requiring therapy. Twelve of the foals had partial failure in colostral IgG transfer, and 3 of these had infections requiring therapy. The remaining 66 foals had normal transfer of colostral IgG, and only 2 had detectable infections. The failure of colostral IgG transfer was attributable to nursing problems in only one case. When presuckle postpartum colostrum was collected, 2 of 4 failures of colostral IgG transfer and 4 of 6 partial failures of colost...
Perry E, Cross TL, Francis JM, Holscher HD, Clark SD, Swanson KS.The effects of travel stress on the equine cecal microbiota are poorly understood. We hypothesized that travel would affect the equine cecal microbiota. Cecally-cannulated horses (n = 6) were randomly assigned to one of two groups, travel (n = 3) and control (n = 3). Horses received a basal diet (Strategy, Purina Animal Nutrition) with 1.2% body weight mixed grass/alfalfa. Travel horses were transported to an unfamiliar location, stalled to simulate weekend horse show conditions, and then returned to the Southern Illinois University Equine Center. Control horses remained at the equine cente...
Brown NA, Pandy MG, Buford WL, Kawcak CE, McIlwraith CW.To determine whether muscle moment arms at the carpal and metacarpophalangeal joints can be modeled as fixed-radius pulleys for the range of motion associated with the stance phase of the gait in equine forelimbs. Methods: 4 cadaveric forelimbs from 2 healthy Thoroughbreds. Methods: Thin wire cables were sutured at the musculotendinous junction of 9 forelimb muscles. The cables passed through eyelets at each muscle's origin, wrapped around single-turn potentiometers, and were loaded. Tendon excursions, measured as the changes in lengths of the cables, were recorded during manual rotation of th...
Serra Bragança FM, Hernlund E, Thomsen MH, Waldern NM, Rhodin M, Byström A, van Weeren PR, Weishaupt MA.There is a paucity of research describing the gait pattern of lame horses at the walk. Objective: To describe the changes in motion pattern and vertical ground reaction forces (GRFz) in horses with induced forelimb lameness at the walk and compare those changes with the changes observed at the trot. Methods: Experimental study. Methods: In 10 clinically sound Warmblood horses, moderate forelimb lameness was induced using a sole pressure model followed by trot and walk on a treadmill. Kinematic data were collected using 3D optical motion capture (OMC), and GRFz by an instrumented treadmill. Mix...
Salamon Z, Tollin G.Cyclic voltammetry has been used to study the effects of interactions between horse cytochrome c and solid-supported planar lipid membranes, comprised of either egg phosphatidylcholine (PC) or PC plus 20 mol.% cardiolipin (CL), on the redox potential and the electrochemical electron transfer rate between the protein and a semiconductor electrode. Experiments were performed over a wide range of cytochrome c concentrations (0-440 microM) at low (20 mM) and medium (160 mM) ionic strengths. Three types of electrochemical behavior were observed, which varied as a function of the experimental condit...
Ascenzi P, Ciaccio C, Sinibaldi F, Santucci R, Coletta M.Upon interaction with bovine heart cardiolipin (CL), horse heart cytochrome c (cytc) changes its tertiary structure disrupting the heme-Fe-Met80 distal bond, reduces drastically the midpoint potential out of the range required for its physiological role, binds CO and NO with high affinity, and displays peroxidase activity. Here, the effect of CL on peroxynitrite isomerization by ferric cytc (cytc-Fe(III)) is reported. In the absence of CL, hexa-coordinated cytc does not catalyze peroxynitrite isomerization. In contrast, CL facilitates cytc-Fe(III)-mediated isomerization of peroxynitrite in a d...
Glazar AI, Mullen SF, Liu J, Benson JD, Critser JK, Squires EL, Graham JK.Stallion spermatozoa exhibit osmotic damage during the cryopreservation process. Recent studies have shown that the addition of cholesterol to spermatozoal membranes increases the cryosurvival of bull, ram and stallion spermatozoa, but the exact mechanism by which added cholesterol improves cryosurvival is not understood. The objectives of this study were to determine if adding cholesterol to stallion sperm membranes alters the osmotic tolerance limits and membrane permeability characteristics of the spermatozoa. In experiment one, stallion spermatozoa were treated with cholesterol-loaded cycl...
Scott EM, Arnold C, Dowell S, Suchodolski JS.Next generation sequencing (NGS) studies have demonstrated a rich and diverse ocular surface-associated microbiota in people that was previously undetected by traditional culture-based methods. The ocular surface microbiome of horses has yet to be investigated using NGS techniques. This study aimed to determine the bacterial composition of the ocular surface microbiome in healthy horses, and to identify whether there are microbial community changes over time and following topical antibiotic use. One eye of 12 horses was treated 3 times daily for 1 week with neomycin-polymyxin-bacitracin ophtha...
Pedersen PJ, Kanters JK, Buhl R, Klaerke DA.Cardiac repolarization, measured as QT and Tpeak to Tend (TpTe) intervals on the ECG, is important, as irregularities caused by diseases, ventricular hypertrophy, drugs and genetic defects can trigger arrhythmias which predispose human patients to syncope and sudden cardiac death. In horses, repolarization is not well described and therefore QT analysis cannot yet be used diagnostically. Therefore, we sought to describe reference values for the normal QT and TpTe intervals in Standardbreds and to determine the best method for heart rate (HR) correction. Methods: 30 Standardbreds. Methods: QT a...
Lindner A, Mosen H, Kissenbeck S, Fuhrmann H, Sallmann HP.The velocity at which blood lactate concentration ([LA]) of 4 mmol/L is reached (v(4)) is widely used to determine fitness, but there are few published data on using [LA] as a guide for the exercise speed for training in horses. In this study, the effect of 3 conditioning programs with [LA] guided exercise speeds on v(4), v(200) (speed at a heart rate of 200 beats/min), blood [LA], plasma FFA ([FFA]), and alanine concentrations ([alanine]), before and after exercise, as well as heart rate during exercise, of horses was examined. Six 2-yr-old Haflinger stallions underwent an initial treadmill-b...
Neild D, Chaves G, Flores M, Mora N, Beconi M, Agüero A.The aim of the study was to evaluate equine sperm membrane integrity using the hypoosmotic swelling (HOS) test and to correlate this test with different sperm parameters in raw and frozen thawed semen. The HOS solutions were made with fructose, sucrose, lactose and sodium citrate each at 300, 150, 100, 50 and 25 mosm. Maximum numbers of swollen spermatozoa were observed in solutions of fructose, sucrose and lactose each at 100, 50 and 25 mosm. Correlations between progressive motility, morphologically normal spermatozoa and the HOS test were r = 0.75 and r = 0.51 in raw semen and r = 0.26 and ...
Forster HV, Bisgard GE, Rasmussen B, Orr JA, Buss DD, Manohar M.The present study was designed to provide further insight into the role of the carotid and aortic chemoreceptors in ventilatory (VE) acclimatization during sojourn at altitude. Measurements were made: 1) on 10 ponies near sea level (SL, 740 Torr) under normal conditions, 2) on 6 of these at SL following chemoreceptor denervation (CD), and 3) subsequently on all 10 during 4 days of hypobaric hypoxia (PaO2 = 40-47 Torr). CD resulteo in hypoventilation at SL (deltaPaCO2 = d8 Torr, P less than 0.05), and it prevented hyperventilation normally observed with injection of NaCN and acute exposure to h...
Kitamura N, Yamada J, Calingasan NY, Yamashita T.Endocrine cells immunoreactive for somatostatin, gastrin, glicentin, glucagon, secretin, cholecystokinin, motilin and neurotensin were identified immunocytochemically in the gastrointestinal mucosa of the horse. Somatostatin-, glicentin- and glucagon-immunoreactive cells were very numerous in the cardiac and fundic regions of the stomach, whereas most gastrin-immunoreactive cells were confined to the pyloric region. Somatostatin-immunoreactive cells also were detected in all portions of the small intestine while gastrin-immunoreactive cells were confined exclusively to the upper portion and gl...
Bouwman FG, van Ginneken MM, Noben JP, Royackers E, de Graaf-Roelfsema E, Wijnberg ID, van der Kolk JH, Mariman EC, van Breda E.The major aim of the present study was to investigate the proteome of standardbred horses at different stages of training and intensified training. We searched for biomarkers using small skeletal muscle biopsies of live animals. 2D gel electrophoresis and mass spectrometry were successfully applied to investigate training-induced differential expression of equine muscle biopsy proteins. Despite the poor resolution of the equine genome and proteome, we were able to identify the proteins of 20 differential spots representing 16 different proteins. Evaluation of those proteins complies with adapt...
Hada T, Onaka T, Takahashi T, Hiraga A, Yagi K.This study investigated the effects of novelty stress on neuroendocrine activities and running performance in Thoroughbred horses. First, to examine the neuroendocrine responses to novelty stress, we exposed horses to two types of novel environmental stimuli (audiovisual or novel field stimuli). After the stimuli, plasma concentrations of vasopressin, catecholamines and adrenocorticotropin (ACTH), as well as heart rates, were significantly increased in each experiment. Second, we investigated neuroendocrine activities during incremental exercise. Plasma concentrations of vasopressin, catechola...
McCutcheon LJ, Geor RJ, Hinchcliff KW.The effect of warm-up exercise on energy metabolism and muscle glycogenolysis during sprint exercise (Spr) was examined in six fit Standardbred horses exercised at 115% of maximal O(2) consumption (VO(2 max)) until fatigued, 5 min after each of three protocols: 1) no warm-up (NWU); 2) 10 min at 50% of VO(2 max) [low-intensity warm-up (LWU)]; and 3) 7 min at 50% VO(2 max) followed by 45-s intervals at 80, 90, and 100% VO(2 max) [high-intensity warm-up (HWU)]. Warm-up increased (P < 0.0001) muscle temperature (T(m)) at the onset of Spr in LWU (38.3 +/- 0.2 degrees C) and HWU (40.0 +/- 0. 3 de...
Zsoldos RR, Kotschwar AB, Kotschwar A, Groesel M, Licka T, Peham C.Skeletal muscle activity can be concentric or eccentric, anisometric or isometric and correlation of the equine splenius muscle activity with the movement of its effector joints at walk and trot has not yet been fully characterised. Objective: Investigating activity of the splenius muscle together with kinematics of head and cranial neck at walk and trot. Methods: Kinematics and surface electromyography were measured in 6 horses (8-20-years-old, 450-700 kg) without signs of neck pain. Markers were placed on left and right crista facialis, and on left and right cervical vertebrae 1 and 3. Head ...
