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Topic:Physiology

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.
Correction: Wang et al. Multi-Omics Analysis Reveals Biaxial Regulatory Mechanisms of Cardiac Adaptation by Specialized Racing Training in Yili Horses. Biology 2025, 14, 1609.
Biology    January 23, 2026   Volume 15, Issue 3 209 doi: 10.3390/biology15030209
Wang T, Li M, Ren W, Meng J, Yao X, Chu H, Yao R, Zhai M, Zeng Y. [...].
Evaluation of oxidative stress in the newborn foal: a multibiomarker approach.
Journal of equine veterinary science    January 20, 2026   Volume 158 105786 doi: 10.1016/j.jevs.2026.105786
Bindi F, Cingottini D, Sorvillo B, Sala G, De Marchi L, Monni G, Celardo S, Bonelli F, Sgorbini M.During the perinatal period, neonates experience a sudden increase in oxygen exposure, predisposing them to oxidative stress. Objective: This prospective, in vivo study aimed to evaluate biomarkers of oxidative stress and antioxidant defence in healthy neonatal foals during the first 48 hours of life. Methods: Ten Standardbred foals were enrolled. Blood samples were collected at birth, 24 hours, and 48 hours after birth and analyzed for biomarkers using spectrophotometry assays. Statistical analysis was performed using non-parametric tests and linear regression. Results: The results revealed s...
Doppler assessment of testicular arterial blood flow in stallions: influence of age and 180° spermatic cord torsion.
Theriogenology    January 17, 2026   Volume 255 117837 doi: 10.1016/j.theriogenology.2026.117837
Freitas Silva D, Passagli Barbosa D, de Paula Rodrigues J, Robaina Sancler-Silva YF, Saules Ignácio F, Lucena Fredou M, Segabinazzi L, Monteiro GA.Doppler ultrasonography is a valuable tool for monitoring testicular hemodynamics, offering improved diagnostic insight and supporting treatment monitoring. However, its use in equine andrology remains limited due to a scarcity of published data and reference values. Therefore, this study aimed to characterize the testicular arterial blood flow patterns in clinically normal stallions and stallions with 180° spermatic cord torsion. Spectral Doppler ultrasonography was performed on both testes of 48 Mangalarga Marchador stallions. Thirty stallions with normal testes were divided into three age ...
Functional and molecular characterization of equine intestinal organoids across media conditions and intestinal segments.
BMC veterinary research    January 16, 2026   Volume 22, Issue 1 142 doi: 10.1186/s12917-025-05222-9
Richardson LM, Gordon J, Davila C, Chamoun-Emanuelli AM, Zdyrski C, Whitfield-Cargile CM.Gastrointestinal (GI) disease is a major cause of morbidity and mortality in horses, with disruption of the intestinal epithelial barrier playing a central role in disease pathogenesis. A deeper understanding of the molecular and functional properties of the equine intestinal barrier is essential to improve diagnostics and therapeutics. While intestinal organoids have emerged as a promising tool for modeling GI physiology and disease, equine-specific data remain limited. Existing studies vary in methodology and often lack functional characterization, particularly across different intestinal re...
Unraveling ovarian histology: The key morphological aspects that spur the development of the Fossa ovarii in equine.
Anatomical record (Hoboken, N.J. : 2007)    January 16, 2026   doi: 10.1002/ar.70131
Ver Goltz L, Gomes SP, Schimming BC, Abdala FCM, Miglino MA, de Castro Sasahara TH.The equine ovary exhibits unique structural and developmental features that distinguish it from those of other domestic species, including the presence of an ovulation fossa and an inversion of cortical and medullary layers. This study aimed to investigate the morphostructural development of the equine fetal ovary, with particular emphasis on the formation of the ovulation fossa. Fourteen female equine fetuses, ranging from 70 to 200 days of gestation, were collected from a commercial abattoir. Results revealed a progressive increase in ovarian volume and marked histological changes througho...
The Effect of Seasonal Changes in Non-Structural Carbohydrates in Pasture on the Metabolic Profile of Horses with Laminitis.
Animals : an open access journal from MDPI    January 15, 2026   Volume 16, Issue 2 267 doi: 10.3390/ani16020267
Mlyneková E, Zaťko S, Halo M, Imrich I, Halo M.This study aimed to examine the seasonal dynamics of non-structural carbohydrates in pasture and their relationship to metabolic indicators in horses with a history of laminitis. Thirty Hucul mares were divided into a laminitis group (LG, = 15) and a control group (CG, = 15). Insulin, glucose, fructosamines concentrations and body weight were monitored during four sampling periods (S0-S3), while pasture variables were analyzed during three periods (S1-S3). The concentration of water-soluble carbohydrates was highest in May (126.8 g/kg DM) and measured lower in October (57.9 g/kg DM), while s...
Affiliative behaviours regulate allostasis development and shape biobehavioural trajectories in horses.
Nature communications    January 13, 2026   Volume 17, Issue 1 47 doi: 10.1038/s41467-025-66729-1
Valenchon M, Reigner F, Lefort G, Adriaensen H, Gesbert A, Barrière P, Gaude Y, Elleboudt F, Lévy I, Ducluzeau C, Dupont J, Lainé AL, Uszynski I....Social interactions shape both the physiological and behavioural development of offspring, and poor care/early caregiver loss is known to promote adverse outcomes during infancy in both animals and humans. How affiliative behaviours impact the future development of offspring remains an open question. Here, we used Equus caballus (domestic horse) as a model to investigate this question. By coupling magnetic resonance imaging, longitudinal biobehavioural assessments and advanced multivariate statistical modelling, we found that prolonged maternal presence during infancy promotes the maturation o...
Parasympathetic tone, cardiovascular variables, and behavioral alterations in conscious horses before and after castration and during anesthesia: A pilot study.
Journal of equine veterinary science    January 9, 2026   Volume 158 105781 doi: 10.1016/j.jevs.2026.105781
Mendoza Flores JE, Terrazas A, Lara Sagahon AV, Aleman M.Parasympathetic tone activity (PTA) and its association with behavior in conscious versus anesthesia in horses are unknown. Objective: To study PTA, heart rate (HR), minimum alveolar concentration (MAC), and mean arterial pressure (MAP) during castration under anesthesia. To study PTA, HR, Horse Grimace Scale (HGS), locomotor activity (LA), and behavior in conscious horses before and after castration. Methods: Pilot study including seven healthy adult horses. After habituation (days 1, 2, and 3), PTAm, HR, HGS, LA, and behavior were investigated during pre-surgery (days 4-, 5-, and one-hour pr...
The Effect of Training on the Expression of Protein and Metabolites in the Plasma Exosomes of the Yili Horse.
Animals : an open access journal from MDPI    January 6, 2026   Volume 16, Issue 2 158 doi: 10.3390/ani16020158
Yuan X, Yao X, Zeng Y, Wang J, Ren W, Wang T, Li X, Yang L, Yang X, Meng J.The effects of physical exercise on protein expression and metabolites in the plasma exosomes of horses are not yet clear. This study aims to elucidate the effects of exercise training on the expression of plasma extracellular vesicle proteins and metabolites in horses through multi-omics analysis, providing reference indicators for the training and performance evaluation of horses. Methods: Eight healthy 3-year-old horses were selected for the study, with four untrained horses as the control group and four trained horses as the training group. After conducting proteomic and metabolomic an...
Mono-dimensional, two-dimensional and Doppler echocardiographic measurements in healthy Standardbred neonatal foals in the first 5 days of life.
Equine veterinary journal    January 6, 2026   doi: 10.1002/evj.70140
D'el Rey Dantas FT, Forni G, Hallowell G, Castagnetti C, Menchetti L, Romito G, Lanci A, Mariella J, Freccero F.Bodyweight, age and breed influence the echocardiographic assessment of foals. There are no echocardiographic studies in Standardbred neonatal foals. Objective: To describe echocardiographic values for selected variables, evaluate intra- and inter-observer variability and assess cardiac changes in the first 5 days of life in healthy Standardbred neonatal foals. Methods: Prospective observational study. Methods: Fifty-six healthy Standardbred neonatal foals were examined by transthoracic echocardiography using standard right parasternal and subcostal views at three time points: in the first 4...
Effect of horse sleep behavior on performance in a field-side spatial reversal learning test.
Scientific reports    January 6, 2026   Volume 16, Issue 1 4265 doi: 10.1038/s41598-025-34463-9
Hämäläinen MJ, Brotherus IL, Wigren HM, Kaimio TE, Suomala H, Olbricht AM, Hänninen LT, Mykkänen AK.Reduced rapid-eye-movement (REM) sleep is associated with impaired learning in many species. We developed a reversal learning test (RLT) suitable for field conditions to explore this association in 16 healthy horses. Nocturnal REM-like sleep behavior was recorded five times for 48 h over a six-week period. The horses performed a target training task followed by an RLT using two objects. When the horses reached a predefined frequency of touching the object, the spatial location was reversed. Mean test parameters were statistically analysed using GENLIN models, longitudinal continuous variables...
A pilot study to investigate the effect of insemination on secretory cell activity post-ovulation in the isthmus of the equine oviduct.
Journal of equine veterinary science    January 3, 2026   Volume 157 105765 doi: 10.1016/j.jevs.2026.105765
Jones CJP, Aplin JD, Wilsher S.There is little information on non-ciliated secretory cell numbers in the equine oviduct isthmus over the course of the estrous cycle and the effect, if any, of insemination. Lectin histochemistry was used on a series of 13 oviducts taken at different stages of the estrous cycle, with and without insemination, to monitor glycosylation changes and the distribution of secretory cells characterised by a prominent cytoplasmic accumulation of glycoconjugates. There appeared to be an increase in secretory cells expressing a wide range of glycans in all specimens at estrus. One day after ovulation, o...
Effect of transdermal melatonin on circulating cortisol and blood chemistry in horses exposed to transport stress.
Journal of equine veterinary science    December 26, 2025   Volume 157 105756 doi: 10.1016/j.jevs.2025.105756
Crossland WL, Aviles-Rosa EO, Perry EB, Crowell C, Webberson E, Brown J, Fassbender J.Our objective was to evaluate the effect of transdermal melatonin on physiological stress biomarkers in horses, with some subjected to transport stress. Sixteen horses were assigned to a 2 × 2 factorial design assessing treatment (melatonin vs. no melatonin) and transport status (transported vs. non-transported), creating four groups: Control (CON), Transport only (TRS), Melatonin only (MEL), and Melatonin plus Transport (MELTRS). Horses in melatonin groups received 24 mg/day transdermally for 21 days and transported groups underwent a 3-hour trailer ride on day 21. Day 21 blood samples were ...
Comparison of body temperatures and pulse rate between athletic and non-athletic horses during the hot-humid condition.
International journal of biometeorology    December 24, 2025   Volume 70, Issue 1 1 doi: 10.1007/s00484-025-03106-z
Ake AS, Akinniyi OO.Clinical assessment of parameters that give indications of the health status and fitness of horses are very important in equine practice. The study aimed to compare the resting body temperatures at different anatomical sites and resting pulse rates of athletic and non-athletic horses. Eighteen horses were used for the study, comprising ten athletic and eight non-athletic horses. Measurements of environmental parameters, rectal temperature (RT), body surface temperature (BST) and pulse rate were recorded between 9 and 11 am twice with one week interval at the Ibadan Polo Club, Eleyele, Ibadan, ...
Advances in Equine Genomics: Decoding the Genetic Architecture of Morphology, Performance, Behavior, and Adaptation.
Molecular biotechnology    December 19, 2025   doi: 10.1007/s12033-025-01544-z
Sharma M, Singh A, Kumar V, Olla N, Arora R, Sharma R, Mohan NH, Ahlawat S.The genus Equus, encompassing horses, donkeys, and extinct relatives, has evolved over approximately 55 million years from small, multi-toed ancestors to the modern horse. Selective breeding has produced over 600 distinct horse breeds optimized for diverse traits such as size, conformation, performance, and adaptability. In the past two decades, rapid advances in equine genomics have significantly deepened our understanding of the molecular basis of these traits. The integration of high-throughput sequencing, genome-wide association studies (GWAS), and single-nucleotide polymorphism (SNP) geno...
Measuring emotional contagion in Horse-Human interactions: A systematic scoping review of methods and outcomes.
Journal of equine veterinary science    December 16, 2025   Volume 156 105754 doi: 10.1016/j.jevs.2025.105754
Tripon MA, Manolăchescu D, Papuc I, Daradics Z, Crecan CM.Emotional contagion between horses and humans is a key aspect of their interaction, influencing welfare, training, and therapy, yet current methods for measuring this phenomenon lack standardization and consistency. Objective: The aim of this study was to verify what methods are used to assess emotional contagion in horse-human interactions, and what outcomes have been reported. Methods: A systematic search of Google Scholar, Web of Science, Scopus, PubMed, and Science Direct was conducted up to March 2024. Peer-reviewed studies assessing emotional transfer through behavioral and/or physiologi...
I feel your pain: Individual differences in welfare indicators after castration in horses.
Veterinary journal (London, England : 1997)    December 16, 2025   Volume 315 106538 doi: 10.1016/j.tvjl.2025.106538
Briefer-Freymond S, Dalla Costa E, Jolivald A, Bruckmaier RM, Atallah E, Giorgia Riva M, Ijichi C.Personality affects both experience and expression of pain and the welfare impact of castration on horses is poorly understood. Therefore, the current study observed 19 horses to determine: the welfare impact of standard castration on horses; whether individuals consistently vary in their behavioural and emotional responses to pain; the influence of personality on behavioural and physiological responses to pain; whether Horse Grimace Scale (HGS) indicates how individuals feel about painful experiences. Eye temperature (IRT), salivary cortisol, HGS and a pain ethogram were measured at intervals...
Gut microbial signatures and cardiac-microbiota axis in Yili horses with divergent exercise-induced cardiac remodeling.
Frontiers in microbiology    December 3, 2025   Volume 16 1689293 doi: 10.3389/fmicb.2025.1689293
Bao Y, Wang T, Adina W, Yao R, Chu H, Yao X, Meng J, Wang J, Ren W, Zeng Y.This study aimed to investigate how different training outcomes affect the gut microbiota composition in racehorses. Twenty-six Yili horses underwent a 9-month conditioning training regimen under uniform husbandry and management conditions. Post-training, the horses were divided into an excellence group (D. Y group) and a general group (D. P group) based on their athletic performance, with the top 10 performers constituting the D. Y group and the bottom 10 the D. P group. Cardiac morphology and function were quantitatively assessed via echocardiography, and metagenomic sequencing was performed...
Metabolic Profiles of Finishing and Nonfinishing Horses in Uruguayan Raid Competitions.
Veterinary medicine international    November 29, 2025   Volume 2025 4217400 doi: 10.1155/vmi/4217400
Brito G, Damián JP, Trigo P, Ruprechter G.The Raid Hípico Uruguayo (RHU) is the oldest equestrian endurance sport in Uruguay. A high percentage of horses fail to complete RHU rides. Therefore, the aim of this study was to investigate whether weather conditions (comfort index [CI]), horse experience, and ride distance affect horse performance (finishing ride [FR] or nonfinishing ride [NFR]) in the RHU. An additional objective was to determine whether finishing the ride affects the hematological and biochemical parameters of the horses. This study involved 17 RHU rides over distances of 60-90 km and 284 horses. Blood samples were tak...
Physiological and behavioural effects of continuous remifentanil-xylazine administration in donkeys.
Equine veterinary journal    November 27, 2025   doi: 10.1111/evj.70131
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...
Child horse harmony in motion: a preliminary study to explore heart rate synchronization in equine assisted therapy for neurotypical and ADHD children.
Scientific reports    November 25, 2025   Volume 15, Issue 1 45312 doi: 10.1038/s41598-025-29330-6
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...
Salivary cortisol concentration in western performance horses and riders: Associations with performance.
Journal of equine veterinary science    November 20, 2025   Volume 156 105737 doi: 10.1016/j.jevs.2025.105737
Pennington MV, Zoller JL, White-Springer SH, Harlin JF, Huseman CJ, Leatherwood JL, O'Reilly CL.Competition stress is a common factor influencing the success of performing athletes. However, few studies have quantified the physiological stress responses in horses and riders surrounding an equestrian event. Objective: The objectives of the current study were to determine salivary cortisol concentrations (SCC) as an indicator of stress in fifteen horse and rider pairs competing in western stock horse events and to investigate the relationship between SCC and performance. Methods: Subjects included male and female Quarter horses aged 3-15 years and equestrians aged 18-22 years. Salivary sam...
Cardiac-Metabolic Coupling Revealed by Lipid and Energy Metabolomics Determines 80 km Endurance Performance in Yili Horses.
Biology    November 12, 2025   Volume 14, Issue 11 1581 doi: 10.3390/biology14111581
Wang T, Huang J, Ren W, Meng J, Yao X, Chu H, Yao R, Zhai M, Zeng Y.This study aimed to investigate the regulatory mechanisms underlying the relationship between cardiac structure and function and plasma metabolic characteristics in Yili horses participating in an 80-km endurance, by integrating echocardiography, lipidomics, and energy metabolomics analyses. Twenty four competing Yili horses were selected and divided based on competition outcomes: Pre-Completion Group: PCG ( = 6); Post-Completion Group: PoCG ( = 6); Overtime Completion Group: OCG ( = 6); and Non-Completion Group: NCG ( = 6). Cardiac structural and functional parameters were assessed via echoca...
Proof of concept of a wearable IoT-based system for monitoring respiratory rate and surface temperature in horses.
Journal of equine veterinary science    November 8, 2025   Volume 155 105729 doi: 10.1016/j.jevs.2025.105729
Farias BJP, Furtado DA, Barbosa do Nascimento JW, Neto JPL, de Morais FTL, Santos TLS, Vasconcelos AS, Silva RC, Alves JIP, Mcmanus C, Silveira RMF....This study presents the development and proof of concept of a wearable monitoring system designed to measure respiratory rate (RR) and coat surface temperature (CST) in horses. The device integrates an embedded system based on an ESP-32 microcontroller equipped with sensors for RR (strain gauge) and CST (DS18B20) Data are transmitted in real time via Wi-Fi and stored locally on SD cards. The system was validated against conventional manual methods under field conditions. Agreement between methods was evaluated using Intraclass Correlation Coefficients (ICC) and Bland-Altman plots. Results show...
Exploring the association between stress-related hormonal changes, behaviours and facial movements after an interval training exercise in French Standardbred.
PloS one    November 5, 2025   Volume 20, Issue 11 e0328430 doi: 10.1371/journal.pone.0328430
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...
Chronic State and Relationship to Humans Influence How Horses Decode Emotions in Human Voices: A Brain and Behavior Study.
Animals : an open access journal from MDPI    November 5, 2025   Volume 15, Issue 21 3217 doi: 10.3390/ani15213217
d'Ingeo S, Siniscalchi M, Quaranta A, Cousillas H, Hausberger M.Current research on acoustic encoding of emotional content suggests that there are universal cues, allowing for decoding within and across taxa. This is particularly important for human-animal relationships, wherein domestic animals are supposed to be particularly efficient in decoding human emotions. Here we investigated whether the decoding of the emotional content in human voices shared universal acoustic properties, or whether it could be influenced by experience. Emotional human voices were presented to two populations of horses, in which behavioral, cardiac, and brain responses were meas...
Heart rate and heart rate variability responses during three exercise tests and recovery in horses participating in the Fédération Équestre Internationale Eventing World Challenge.
BMC veterinary research    October 24, 2025   Volume 21, Issue 1 631 doi: 10.1186/s12917-025-05090-3
Wonghanchao T, Sanigavatee K, Pongnarudech P, Suchairat T, Jitsopin S, Wanichayanon B, Rattanakarn D, Jantakanangkoon P, Jaraswutiwong T, Kalanuson N....Horses competing in eventing competitions encounter significant challenges that increase their risk of severe injuries and metabolic disorders. Numerous studies have focused on the risk of such injuries and disorders during the cross-country segment. While one study has examined autonomic responses during this segment, research on these responses across all three phases of competition, particularly during one-day events, is still limited. The objective of this study was to analyse the autonomic responses of horses by measuring heart rate (HR) and heart rate variability (HRV) during three exerc...
Locomotory Profile, Heart Rate Variability, and Blood Parameters Reveal Adaptive Responses in Endurance Horses Trained on Deep Sand.
Veterinary sciences    October 23, 2025   Volume 12, Issue 11 1028 doi: 10.3390/vetsci12111028
Training on deep sand is commonly employed in endurance horses, but its physiological adaptation remains poorly characterized. This study aimed to characterize locomotor adaptations during a 7 km controlled-speed canter on deep sand in eighteen endurance horses, to identify heart rate variability (HRV) components, and to investigate changes in hematological variables before and after exercise. Stride frequency (SF) and stride length (SL), HRV, and hematological profiles were recorded during exercise and recovery with a fitness tracker. Associations between maximum speed and locomotor parameter...
Editorial: Advances in the application of technology for monitoring horse welfare and health.
Frontiers in veterinary science    October 16, 2025   Volume 12 1715133 doi: 10.3389/fvets.2025.1715133
Dalla Costa E, Bovo M.Flowchart illustrating interdisciplinary collaboration in animal research. A horse symbolizes the focus, with pathways connecting physiology, behavior, and environment to decision-making and regulatory indications. Data analysis, system understanding, and data interpretation lead to feedback and warning. Visual elements include sun, clouds, a light bulb, gears, and a graph.
Assessment of olfactory sensitivity in horses using positively conditioned scent.
Animal : an international journal of animal bioscience    October 15, 2025   Volume 19, Issue 12 101680 doi: 10.1016/j.animal.2025.101680
Wnuk E, Janicka W, Stachurska A, Owerczuk R, Łuszczyński J.Differences in the ranges and capacities of sensory modalities cause horses to perceive their surroundings differently than humans. To date, the horses' sense of smell has been studied mainly regarding social and reproductive behaviour. The role of olfaction in horse management and use also seems to be of utmost importance. The aim of this study was to determine the response to a scent of different intensities by horses of different sexes and types (warmblood horses vs ponies). The study involved 21 adult mares and geldings, of which 15 subjects learned how to complete the required task and we...