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.
This article provides an overview of initial assessment and management of common emergency presentations in donkeys and mules. The principles are similar to those in horses (and ponies), but clinicians must be aware of differences in recognition of signs of pain/disease, approach to handling, pharmacology of some drugs, and subtle differences in the physiology and local anatomy in donkeys and mules. The epidemiology of common disease presentations will vary between pet/companion or working/farmed donkeys and mules. Regular dental checks, deworming, vaccination, and monitoring of behavior and q...
Mares were inseminated with motile spermatozoa suspended in 30-150 microliters Tyrode's medium directly onto the uterotubal papilla at the anterior tip of the uterine horn, ipsilateral to the ovary containing a dominant preovulatory follicle of > or = 35 mm in diameter, by means of a fine gamete intrafallopian transfer (GIFT) catheter passed through the working channel of a strobed light videoendoscope. Insemination of 10, 8, 25, 14, 11 and 10 mares with, respectively, 10.0, 5.0, 1.0, 0.5, 0.1 or 0.001 x 10(6) motile spermatozoa resulted in conception rates of, respectively, 60, 75, 64, 29,...
The objective of this study was to enhance the in vitro sperm quality and in vivo fertility of frozen-thawed equine semen by the addition of l-carnitine (LC) to post-thawed semen. Different concentrations of LC were added to thawed samples to obtain four treatments control and 0.5, 1 and 2 mM LC. In the in vitro experiments, sperm motility and kinematics, membrane integrity and intracellular calcium ion concentration ([Ca ] ) were investigated, and the antioxidant bioactivity of LC was assessed by measuring hydrogen peroxide and nitrite concentrations (NO ). The fertility rate was assessed v...
Respiratory diseases are a major cause of morbidity and mortality in the horses of all ages including foals. There is limited understanding of the expression of immune molecules such as tetraspanins and surfactant proteins (SP) and the regulation of the immune responses in the lungs of the foals. Therefore, the expression of CD9, SP-A and SP-D in foal lungs was examined. Results: Lungs from one day old (n = 6) and 30 days old (n = 5) foals were examined for the expression of CD9, SP-A, and SP-D with immunohistology and Western blots. Western blot data showed significant increase in the...
To evaluate the effect of four recumbent body positions on intraocular pressure (IOP) in anesthetized normal horses. Methods: Ten nonglaucomatous adult horses. Methods: Intraocular pressure was measured with a rebound tonometer in both eyes of standing sedated horses (baseline), then under general anesthesia during four randomized recumbent body positions, including Trendelenburg (Tr; 15-degree head down), reverse Trendelenburg (RTr; 15-degree head up), dorsal, and lateral; only the superior eye was measured in lateral positions. The mean of 3 IOP readings was taken at each position, allowing ...
This Opinion piece is offered as a cursory overview of sperm development, function, and transport through the eyes of an equine veterinarian. My professional background is predominantly clinical in nature, but my fascination with sperm function and preservation has led to a fairly sizeable review of the scientific literature over the years in hopes of extracting laboratory findings that have application to my daily activities in the clinical arena. Spermatozoa are quite unique among cellular types with regard to both form and function, and represent the only endogenously derived cell type that...
The objective of this study was to graft autologous mesenchymal stem cells (MSCs) at the site of surgical repair of a soft palate defect in an adult horse in an attempt to improve wound healing and to investigate whether the transplanted MSCs would integrate into the soft palate structure and participate in regeneration. Bone marrow was collected from an adult horse with a full-thickness soft palate defect. The MSCs were isolated, cultured in monolayers, and labeled with 5-bromo-2-desoxymidine (BrdU) and chloromethylbenzamido-DiI-derived (cm-DiI) before transplantation. The soft palate defect ...
Verstraete MH, Dini P, Orellana D, Uribe-Salazar JM, Veras MM, Carneiro F, Daels P, Fernandes CB.The proper function of the placenta is essential for the health and growth of the fetus and the mother. The placenta relies on dynamic gene expression for its correct and timely development and function. Although numerous studies have identified genes vital for placental functions, equine placental molecular research has primarily focused on single placental locations, in sharp contrast with the broader approach in human studies. Here, we hypothesized that the molecular differences across different regions of the equine placenta are negligible because of its diffuse placental type with a macro...
Lefèvre RA, Barluet de Beauchesne L, Sabarros F, Briefer Freymond S, Ramseyer A, Keller M, Reby D, Fitch WT, Briefer ÉF.Understanding why the frequencies of some species' vocalizations are far above or below those predicted by body size is key for explaining the remarkable diversity of mammalian vocal behavior. Horses, among the largest terrestrial mammals, provide a clear example of such deviation: their whinnies contain a very high fundamental frequency (>1,000 Hz) in addition to a second, lower one (∼200 Hz). While the lower fundamental frequency of whinnies is readily attributed to vocal fold (laryngeal) vibrations, the biomechanical processes underlying the production of the higher one remain unknown. Us...
Helmer A, Hacohen A, Bart O.Equine-Assisted Services (EAS) encompass a range of therapeutic interventions utilizing equine interactions to achieve therapeutic goals. This study explores heart rate synchronization between horses and riders during mounted and unmounted interactions, focusing on its potential implications for emotional regulation. A total of 25 participants aged 6-12 took part in the study, which included two groups: novice riders diagnosed with Attention Deficit Hyperactivity Disorder (ADHD) (n = 15) and experienced neurotypical riders (n = 10). Heart rate measurements were obtained using Polar Equ...
Shakeel M, Yoon M.Brain-derived neurotrophic factor (BDNF) and its receptor neurotrophic tyrosine receptor kinase-2 (NTRK2) have known important roles in the central nervous system for neurite growth, survival, and differentiation. Nevertheless, the significance of BDNF in spermatogenesis remains unclear in stallions. Therefore, the present study was designed 1) to investigate the expression of BDNF and its receptor NTRK2 and 2) the seasonal variation in the expression patterns of BDNF and NTRK2 in stallions' testes. We used testes from eight postpubertal Thoroughbred stallions collected after a field castratio...
Harbowy RM, Nielsen BD, Colbath AC, Robison CI, Buskirk DD, Logan AA.Though circular exercise is commonly used in equestrian disciplines, it may be at the detriment of horses' musculoskeletal system. To investigate the effects of circular exercise on bone and joint health, 42 lambs were randomly assigned to a non-exercised control, straight-line, small circle, or large circle exercise regime at a slow (1.3 m/s) or fast (2.0 m/s) speed for 12 wk. Blood samples were taken biweekly. Animals were humanely euthanized upon study completion, and the fused third and fourth metacarpals were collected for biomechanical testing and bone density analysis. Fast groups were ...
Canetti EFD, Gersbach-Seib A, Moore R, Schram B, Orr R.Within individual policing organisations, there are a wide variety of units and job roles. Unassigned: To profile the occupational tasks performed by Australian mounted police officers, aiming to offer conditioning insight into this unique job role. Unassigned: Thirteen fully qualified and operational mounted police officers (n = 11 females), who served in the mounted police unit for ∼3.3 (±2.3) years, participated in this observational cohort study. Participants completed a survey outlining common occupational tasks and were monitored throughout four consecutive shifts. Participants' h...
Friend MM, Nicodemus MC, Lemley CO, Cavinder CA, Prince P, Holtcamp K.Substance withdrawal presents a barrier to substance use disorder (SUD) recovery in part due to symptoms implicating neurotransmitters and their metabolites. Despite this relationship, research investigating alternative treatments such as psychotherapy incorporating equines (PIE) have primarily targeted vital signs and cortisol concentrations. Previous research has also proposed benefits of human-horse physiological coupling, but the role of neurotransmitters in the relationship between humans and horses during PIE has not yet been investigated. The purpose of this study was to characterize ne...
Damasceno KFA, Mouta AN, Alves LSA, Arcoverde KN, Aragão HR, Cavalcante JM, Veras de Paula V.Remifentanil and xylazine are used as continuous infusions to facilitate standing surgery in horses. Their use for this purpose has not been reported in donkeys. Objective: To evaluate the behavioural, sedative, and cardiorespiratory effects of continuous intravenous infusion of remifentanil and xylazine in donkeys. Methods: Non-blinded in vivo experiments. Methods: Ten donkeys were sedated with an intravenous bolus of xylazine (0.8 mg/kg). After 3 min, continuous infusions of xylazine (0.65 mg/kg/h) and remifentanil (6 μg/kg/h) were administered for 60 min. Cardiorespiratory physio...
Stanisławczyk R, Żurek J, Rudy M, Gil M, Krajewska A, Dziki D.The aim of this study was to demonstrate the effect of horse age, high-pressure cooking, and various heat-treatment methods on the quality of horse meat. The research material consisted of samples of the longissimus thoracis muscle obtained from 14 horse carcasses from two age groups. Samples of the muscle were subjected to traditional cooking (TC), sous-vide cooking (S-V), high-pressure cooking (HHP), HHP + TC, and HHP + S-V. The chemical composition, physicochemical properties, color parameters, pigment levels, texture parameters, and sensory properties of the meat were determined. Exposing...
Lizarraga I, Castillo-Alcala F.Donkeys have contributed to the development and livelihoods of humans for almost 7,000 years. They have been used for traction and transportation, kept as pets, utilized in animal-assisted therapies, or farmed as food-producing animals. Over the past two decades, significant progress has been made in bridging the knowledge gap in veterinary medicine between donkeys and horses. Veterinary practitioners are now more aware that donkeys have important behavioral, anatomical, and physiological characteristics that distinguish them from horses. These peculiarities should be considered when treating ...
Dufourni A, Demeyere M, Vera L, van Loon G, Decloedt A.This study aimed to compare two-dimensional, M-mode, color, pulsed-wave Doppler (PWD) and continuous-wave Doppler (CWD) echocardiography, and PWD ultrasonography of the caudal common carotid artery (CCA) in horses with aortic regurgitation (AR). Methods: Warmblood horses without (n = 20) and with mild, moderate, and severe AR (n = 60) were included in the study. Methods: A retrospective descriptive study focused on cardiac dimensions, aortic and CCA Doppler flow. Non-invasive blood pressure and presence of ventricular arrhythmia were recorded. Groups were compared using analysis of varianc...
Naber A, Kreuzer L, Zink R, Millesi E, Palme R, Hediger K, Glenk LM.This exploratory study aimed to analyse physiological interaction processes in equine-assisted-therapy (EAT) between client, therapy horse and therapist. Methods: We measured heart rate (HR), heart rate variability (HRV) and cortisol levels before, during and after a standardized therapy session and a control condition in one therapist, four therapy horses and ten female clients in emerging adulthood (Mn = 21.8 years, SD = 3.39). The clients were diagnosed with mild (N = 5) to moderate (N = 5) intellectual disability (ID). Results: There was no significant change in the client's HR, HR...
Ebisuda Y, Kitaoka Y, Takahashi Y, Sugiyama F, Yoshida T, Mukai K.Heat acclimation enhances thermoregulation and cardiovascular function. While daily training protocols are typically recommended for humans, optimal training protocols for Thoroughbred horses remain unclear. Here, we compared the effects of two heat acclimation protocols, consecutive and intermittent, in Thoroughbred horses. In a randomized crossover study, eight trained Thoroughbred horses completed either a consecutive (CONS: 9 consecutive days) or an intermittent (INT: 3 days/week for 3 weeks) heat acclimation protocol, comprising 30 min of exercise in hot conditions (WBGT 30°C). Increment...
Abraham AJ, Duvall ES, Doughty CE, Riond B, Ortmann S, Terranova M, le Roux E, Clauss M.The assimilation, retention, and release of nutrients by animals fundamentally shapes their physiology and contributions to ecological processes (e.g., zoogeochemistry). Yet, information on the transit of nutrients through the bodies of large mammals remains scarce. Here, we examined how sodium (Na), a key element for animal health and ecosystem functioning, travels differently through fecal and urinary systems of cows (Bos taurus) and horses (Equus ferus caballus). We provided a large dose of Na and compared its timing of release in feces and urine to that of nonabsorbable markers. Na excreti...
Pfannkuche H, Maus J, Engel KM, Schiller J, Schneider MR.Skin sebaceous glands (SGs) synthesize and secrete sebum, a mixture of lipids and cellular debris that defends the external body surface against physicochemical challenges. Recent data define the SG as a dynamic entity with potential functions beyond skin protection, including immunomodulatory actions and the regulation of energy metabolism. We postulate that the SG also has important, unrecognized roles in physiological and pathological processes in domestic animals. Conversely, data derived from domestic animals may have translational relevance for humans. This review article summarizes SG s...
Al Aiyan A, Alnahdi AF, Abu Hayah S, Alshamsi A, Alshebli H, Aleissaee S, Balan R.The cerebral blood supply in horses is maintained by carotid and vertebrobasilar systems, which join the cerebral arterial circle to ensure continuous brain perfusion. This study aimed to comprehensively describe the origins, courses, and interconnections of the vertebrobasilar and carotid systems in the horse brain. Unassigned: Ten adult equine specimens were obtained from horses euthanized for non-neurological reasons. Following perfusion with 10% formaldehyde, colored latex was injected into the arterial system, and detailed dissections were performed to study major intracranial vessels. Un...
Priester VC, Knickelbein KE.To investigate the effects of atropine on the iridocorneal angle (ICA) and ciliary cleft (CC) of normal equine eyes using ultrasound biomicroscopy (UBM). Unassigned: 12 normal adult horses underwent measurement of intraocular pressure (IOP), vertical and horizontal pupil diameter, and UBM of the superior, temporal, inferior, and nasal ICA/CC in both eyes. Measurements were repeated 2 hours following ophthalmic atropine 1% solution application. Measurements of the ICA and CC, including pectinate ligament distance (PLD), CC length (CCL), height of opening distance (HOD), CC area (CCA), and pecti...
Nehme-Haily J, Yin L, Diaz V, Lin D, Hu DL.Seventy percent of mammals copulate using repeated pelvic thrusting, while the transfer of sperm requires just a single intromission. Why did thrusting evolve to be the dominant form of sexual intercourse? In this study, we investigate how the rate of sexual pelvic thrusting changes with body size. By analyzing films of copulating mammals, from mice Mus musculus to elephants Elephantidae, we find that bigger animals thrust slower. The rate of pelvic thrusting decreases from 6 Hz for the pocket mouse Pergonathus to 1.3-1.8 Hz for humans to an absence of thrusting for the rhino Rhinocerotidae an...
Coletta M, Zingale GA, De Simone G, De Sanctis G, Quadrotta V, Polticelli F, Ascenzi P.Mini-myoglobin (mini-HH-Mb) is a proteolytic fragment of horse heart myoglobin (HH-Mb) comprising residues 32-139, grossly corresponding to the central exon of the HH-Mb gene, which encodes residues 31-105. Unlike HH-Mb, which displays a single exponential for both CO association and CO dissociation kinetics, mini-HH-Mb shows a biphasic kinetic behavior for both processes, indicating the presence of at least two distinct conformations which are in a very slow (or no) equilibrium with each other. Between pH 2 and 12, CO association to both species of mini-HH-Mb shows two proton-linked transiti...
Maas LT, Morgan JM, Case J, Chell DD, McLean AK.Mules and donkeys are the 5th largest equine population in the U.S., yet basic information such as heart rate and arrhythmia prevalence in mules has not been described. Analysis of heart rate variability (HRV) provides valuable insight into physiologic and autonomic differences between mules, horses, and donkeys. We aimed to pilot the evaluation of heart rate and variability in a healthy population of mules using a 24 h electrocardiogram. Twenty-four-hour ambulatory electrocardiogram (aECG) recordings were collected from an athletic population of seven privately owned healthy mules in Northern...
Ida T, Tominaga H, Iwamoto E, Kurogi A, Okura A, Shimada K, Kato J, Kuwano A, Ode H, Nagata S, Kitamura K, Yazawa T, Sato-Hashimoto M, Yasuda M....Ghrelin is a peptide hormone with various important physiological functions. The unique feature of ghrelin is its serine 3 acyl-modification, which is essential for ghrelin activity. The major form of ghrelin is modified with n-octanoic acid (C8:0) by ghrelin O-acyltransferase. Various acyl modifications have been reported in different species. However, the underlying mechanism by which ghrelin is modified with various fatty acids remains to be elucidated. Herein, we report the purification of bovine, porcine, and equine ghrelins. The major active form of bovine ghrelin was a 27-amino acid pep...
Hennes N, Tutin L, Foury A, Vancassel S, Bourguignon H, Duluard A, Ruet A, Lansade L.Physical exercise can act as a physiological and a mental stressor. Monitoring exercise-induced stress is therefore essential to understand racehorses 'responses to effort and to ensure their welfare. Stress perceived by the horse during physical activity can be measured using various indicators, including stress-related hormones such as cortisol and adrenaline, and other neuromodulators such as serotonin, all involved in the stress response and its regulation. Another approach to assess physiological and emotional responses to stimuli such as exercise is through behaviours and facial movement...
