Stress in horses refers to the physiological and behavioral responses of equines to various stressors, including environmental changes, social dynamics, and physical exertion. These responses can manifest through alterations in heart rate, cortisol levels, and behavior, among other indicators. Stress can affect a horse's overall health, performance, and welfare, making it a significant area of study in equine research. This topic encompasses research on identifying stressors, measuring stress responses, and understanding the implications of stress on equine health and behavior. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, effects, and management of stress in horses.
Herrick WC, Kingsbury HB, Lou DY.This paper describes the result of an investigation of strains and strain rates which normally occur in the tendons of the equine foreleg and presents stress-strain curves and moduli for the tendons at these rates. It has previously been demonstrated that resistance to flexion of the joints of the distal part of the equine foreleg is provided by a passive system of tendons and ligaments. It is therefore possible, using a large displacement, high-rate testing machine, to duplicate in the laboratory the strain rates and forces which are normally produced in the tendons of the foreleg of the runn...
MacKenzie G, Snow DH.An evaluation of acepromazine (0.5 mg/kg intramuscularly), azaperone (0.7 and 0.9 mg/kg intramuscularly) and xylazine (2.0 mg/kg intramuscularly) as chemical restraining agents was carried out in seven horses. (Xylazine and azaperone were used at the recommended dose rates; acepromazine at five times the recommended dose rates). Of the three drugs administered only azaperone produced sufficient sedation in all the horses to allow a percutaneous needle muscle biopsy to be taken from six muscles. With acepromazine and xylazine this procedure could be successfully carried out in five and four hor...
Johnson HD, Vanjonack WJ.Recent data on various environmental stressors and blood hormone patterns are presented for lactating cattle. Known stressor effects of such factors as environmental temperature, air pollution, and noise on the plasma thyroxine, growth hormone, cortisol, prolactin, progesterone, luteinzing hormone, epinephrine, and norepinephrine of lactating cattle are discussed. Information on stressor effects is lacking on glucagon, insulin, vasopressin, calcitonin, oxytocin, thyrotrophic hormone, follicle stimulating hormone, melatonin, parathyroid hormone, and estrogens in the lactating cow. The importanc...
Asheim A, Lindblad G.Forty-five race-horses with arthritis of non-in-fectious type in 54 joints were treated with sodium hyaluronate intra-articularly. All joints had previously been treated without lasting success by conventional methods, such as firing, blistering or intraarticular injection of cortisone. In most cases only 1 injection of 2 ml (20 mg) sodium hyaluronate was needed. To avoid subjective evaluation, the effects of the treatment were based on the joint’s capacity of withstanding extreme stress, which means that the horse should be able to train and race again. The treatment was concentrated on the...
Osborne VE.Foaling figures for Thoroughbred mares in Australia show a puzzling disparity between conception and foaling rates in the second half of the 22 years of official data collection between 1950 and 1972. In the first 9 years of the survey, the live foal percentages rose in parallel with conception rates, but then a divergence of the figures occurred with the conception rate continuing to improve by 6-25% while the foaling rate improved by only 0-01% over the same period. An hypothesis supported by data from two studs is considered that stress factors additional to those experienced by mares in th...
Mitchell D, Allen WR.Reproductive performance was studied in 137 yearling mares run with stallions in small groups for 3 months between June and August in 1968 to 1971 (four breeding seasons). Pregnancy diagnosis by repeated rectal palpation and qualitative tests for PMSG, showed that ninety-five mares conceived of which forty-four aborted spontaneously between Days 30 and 160 of gestation. Laboratory examination of twenty-one aborted fetuses failed to show any infectious agents. Serial quantitative and qualitative tests for PMSG in aborting animals gave results similar to those observed in mares with normal pregn...
Dai F, Toson M, Bertotto D, Dalla Costa A, Heinzl EUL, Lega F, Minero M, Padalino B, Stefani AL, Trestini S, Maietti F, Zonta G, Di Martino G.The present study aimed to evaluate the effects of self-loading training on the overall stress response during pre-slaughter transportation in slaughter horses. Thirty-two slaughter horses were divided into two groups: the control group (CG) and the Trained Group (TG). For six weeks, the TG horses were trained to self-load using a method based on target training and shaping. Animals from both groups were transported to the same slaughterhouse in small groups on different days using the same truck along the same route. The baseline and post-transportation values of the eye temperature and fecal...
Roig-Pons M, Bachmann I, Freymond SB.Finding feeding strategies that meet horses' needs without compromising health is essential for optimising welfare, particularly in group housing, where limited hay availability increases aggression and injury risks. Recently, two strategies have emerged: portioning daily intake into smaller, frequent meals using time-controlled hay racks, or slowing intake with "slow-feeders." However, the effects of such management practices on horse behaviour remain underexplored. We conducted a cross-over study with 18 mares divided into four groups to compare three feeding strategies: "traditional" (3 of ...
Faithfull R, Lewis K, Drury E, McBride S.Despite welfare concerns, conflict behaviours (indicative of momentary states of acute stress) are common in horses during dressage competitions. Identifying factors that affect conflict behaviours during competition therefore has the potential to improve equine welfare. The aim of this exploratory study was to assess the effect of bridle type (double versus snaffle) in relation to other potential affecting factors (e.g., average head angle, competition level and type, tack variation) on conflict behaviours during dressage competition. An ethogram was created to analyse the conflict behaviour ...
Elane GL, Blikslager AT, Mair TS.The COVID-19 pandemic represented a significant source of anxiety and stress for equine veterinarians and clients, with the potential for measurable effects on caseload and owner economics. Unassigned: To compare the number of horses presenting for emergency colic evaluation and treatment, as well as costs at two equine referral hospitals. Unassigned: Retrospective cohort. Unassigned: Medical records of horses admitted to North Carolina State University (NCSU) and Bell Equine Veterinary Clinic (BEVC) were compared. Total equine accessions, number of horses referred for colic, and patient age w...
Kroschel L, Pilger F, Aurich J, Nagel C, Aurich C.Horses in training are often stabled individually, but this is increasingly questioned. We have investigated the effects of different stabling systems in Warmblood stallions during a 12-week pretraining programme. Stallions were 24 months old and housed either in a group stable (Group 24, n = 9) or in individual boxes (Box 24, n = 10), or they were 30 months of age and housed in individual boxes (Box 30, n = 10). Cortisol, heart rate, heart rate variability (HRV), body development, injuries and selected behaviour patterns were analysed (1) at transfer from pasture to stable and (2) the...
Uldahl M, Mellor DJ.This commentary evaluates contemporary equestrian sport governance through the lens of equine welfare science. Drawing on evidence from the FEI Sport Forum 2025 debates, the IFHA Racing Integrity Handbook, media coverage of horse sport, recent scientific presentations, regulatory texts, and published research, we identify systemic shortcomings in how horse welfare is assessed, prioritised, and protected. Key issues include reliance on performance as a proxy for welfare, inadequate "fit-to-compete" protocols, neglect of horses' mental states, coercive tack and equipment practices (e.g., double ...
Reddington E, Winter S.Elite sporting careers are made up of a succession of transitions and adjustments across multiple layers. Part of the microenvironment is an athlete's romantic partner who moves through the transitions alongside them, being impacted along the way. Though researchers are yet to explore jockeys and their partners experiences within the horse racing context. Framed through the transition environment working model (Henriksen et al., 2024) and supported by the family systems theory (Broderick, 1993), this study aimed to explore the career experiences and retirement transition of a retired Champion ...
Hopkins E, Whitrod S, Marlin D, Blake R.Noseband tightness has received increasing attention within equitation science, however, there is little research into how this effects equine behaviour or performance. Objective: 1) determine the peak pressures under noseband in vivo at three different tightness; 2) assess limb and back kinematics at different noseband tightness. Methods: Noseband tightness (n = 8 horses) was set using an International Society for Equine Science (ISES) taper gauge with the three settings being; "two fingers (2F)", "one finger (1F)" and "zero fingers (0F)". Peak pressure under noseband was determined using pre...
Braun TF, Ameli K, Krämer S.Numerous studies have shown the positive effects that horses in equine-assisted interventions can have on a variety of recipients. The importance of animal welfare and implementation of animal welfare practices in equine-assisted interventions has not yet been extensively researched. Objective: The aim of this exploratory study was therefore to investigate the understanding of animal welfare from the perspective of equine-assisted professionals and how it is ensured by them. Methods: 111 equine-assisted professionals in Germany were surveyed about their knowledge of animal welfare and the indi...
Wonghanchao T, Sanigavatee K, Petchdee S, Chettaratanont K, Thongyen T, Wanichayanon B, Poochipakorn C, Chanda M.The physiological capabilities of horses begin to decline after they reach 15 years of age. However, some exceptionally talented horses can continue their sports careers beyond this age, raising concerns about their welfare. This study investigated animal welfare by observing resting heart rate (HR) and heart rate variability (HRV) metrics in geriatric horses participating in similar training or physical activities compared to younger adult horses over 30 min periods. Forty-six horses of varying ages and activity levels were divided into four groups, including horses under 15 years practising ...
Hildebrand WH, Zaleśny G.Stereotypical behaviours in animals, often linked to stress, are repetitive actions that may lack a clear purpose. This review examines the relationship between cortisol levels, a key stress hormone, and stereotypic behaviour across various animal species, including zoo mammals, horses, and dogs. A total of 99 studies were analysed to understand whether elevated cortisol levels are associated with stereotypies. While many studies report a positive correlation between cortisol and stereotypical behaviour, more detailed research suggests that these behaviours may also serve as coping mechanisms,...
Fiedler JM, Rosanowski S, Ayre ML, Slater JD.Participation in horse-related activities frequently involves relocating horses from the home stable to an activity venue, which might require local, regional, or international travel. In these circumstances, horses are exposed to unfamiliar surroundings and experience changes to their daily routines, which could have negative welfare impacts. An online survey was conducted in 2021 to ask experienced horse sector participants about the horse management practices that they perceived worked well and provided for positive horse welfare when undertaken at venues. Qualitative analysis identified fo...
Bombardi C, Salamanca G, Tagliavia C, Grandis A, Zamith Cunha R, Gramenzi A, De Silva M, Zannoni A, Chiocchetti R.The amygdala is composed of several nuclei, including the lateral nucleus which is the main receiving area for the input from cortical and subcortical brain regions. It mediates fear, anxiety, stress, and pain across species. Evidence suggests that the endocannabinoid system may be a promising target for modulating these processes. Cannabinoid and cannabinoid-related receptors have been identified in the amygdala of rodents, carnivores, and humans, but not in horses. This study aimed to investigate the gene expression of cannabinoid receptors 1 (CB1R) and 2 (CB2R), transient receptor potential...
Jastrzębska E, Dobbek D, Pawłowska A.Back pain in horses is a frequent musculoskeletal issue that affects performance and welfare. Magnetotherapy has been proposed as a complementary, non-invasive treatment to reduce pain and support soft tissue recovery, but studies in horses remain limited. This pilot study aimed to evaluate the effects of low-frequency pulsed magnetic field therapy on horses with hypersensitivity to palpation along the longissimus dorsi muscle. Four recreational horses participated in a 10-session magnetotherapy program, with changes assessed using palpation, neck flexibility tests, heart rate measurements and...
Choi Y, Jung Y, Wickens CL, Yoon M.Horses are social animals, with early life experiences playing a crucial role in their physiological and behavioral development. This study explored the influence of herd dynamics and foundational training on behavioral and hormonal changes in weaned foals. We examined 13 six-month-old Quarter Horse foals over a three-month training period, performing behavioral observations, temperament assessments, and hormone analyses at the start, midpoint, and end of the training. The results indicated that affiliative behaviors decreased significantly, while agonistic behaviors first increased and then d...
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...
Jafari H, Abebe BK, Cong L, Ahmed Z, Zhaofei W, Sun M, Muhatai G, Chuzhao L, Dang R.The domestication and selective breeding of horses have profoundly influenced the emergence of adaptive traits and stress resistance mechanisms, shaping modern equine populations. This comprehensive review examines the genomic foundations of these traits, emphasizing recent advancements in high-throughput sequencing technologies and bioinformatics. These tools have elucidated the genetic underpinnings of key characteristics such as endurance, speed, metabolic efficiency, and disease resistance. Importantly, the review identifies and connects gene variants associated with thermoregulation, immu...
In horses, heat exposure modulates the hypothalamic-pituitary-adrenal axis, autonomic nervous system, and hypothalamic-pituitary-thyroid axis to maintain body temperature and prevent excessive heat accumulation. However, during strenuous exercise under hot and humid conditions, heat production may exceed dissipation, leading to heat stress, anhidrosis, heat stroke, or brain damage. Unassigned: Incremental field standardized exercise tests (fSETs) provide a reliable approach to assess training and fitness levels. Six Arabian horses from Italia Endurance Stable and Academy were monitored during ...
Busechian S, Di Salvo A, Orvieto S, Rueca F, Villella C, Sollevanti G, Pieramati C, Nisi I, Della Rocca G.Equine Gastric Ulcer Syndrome (EGUS) is a worldwide disease described in different categories of animals. A causal relationship between exercise and EGUS has been suggested, attributed to stress as well as physiological changes in the position of abdominal organs, especially during trot and gallop. EGUS can influence athletic fitness, as has been described in various papers on racehorses. The aim of this work was to determine if gastric ulcer healing is associated with changes in selected fitness parameters (i.e., speed, heart rate during exercise and recovery, stride length and frequency) in ...
Manolăchescu D, Tripon M, Crecan C, Tătaru M, Papuc I.Emotional contagion in human-horse interactions has been widely studied; however, the role of body language in stress transfer remains insufficiently explored. Unassigned: This study examines whether human emotional states, particularly stress and anxiety, influence horses and whether the transmission occurs primarily through body language. Unassigned: A repeated-measures within-subjects design was used. The order of interaction styles was randomized across subjects during 33 HCIs. Participants were categorized as high-anxiety (HA) or low-anxiety (LA) based on State Anxiety Scale scores and he...
Copelin C, Merkies K.Equestrian sport's social license to operate has come under scrutiny due to concerns surrounding the well-being of ridden horses. Inappropriate equipment use, such as harsh bits or overtight nosebands, can negatively influence well-being by generating inescapable pressure or pain on the sensitive structures of the horse's head and limiting natural behaviours. Restrictive equipment may also be used to generate exaggerated, stressful and uncomfortable head and neck positions such as hyperflexion. Saddles must be properly fitted to both horse and rider to ensure appropriate distribution of kinema...
Fialová S, Kuřitková D, Sobotková E.This pilot study investigated stress-related behaviors in 238 dressage horse-rider combinations competing at national levels from Elementary (A) to Grand Prix (GP). Noseband tightness was assessed on-site using the FEI noseband measuring device (FNMD), and all but two horses complied with FEI regulations. Video-based analysis quantified conflict behaviors including mouth opening, tail swishing, and changes in head-neck position. Because noseband tightness showed minimal variation, no meaningful association with behavioral expression could be determined. In contrast, competition level had a cle...
Boger B, Naraian M, Hernandez E, Eaton A, Rockburn R, Tillman I, Payne S, Yob C, Panek C, Manfredi JM.Resistance bands used while horses are exercised with their handlers have shown benefits, but it is unknown if whole-body resistance bands used independently have therapeutic benefits. This study hypothesized that horses with varying gait asymmetries would experience improvements in lameness, muscular function, range of motion, posture, and cortisol following short-term use of a whole-body resistance band wrap (RBW). In this study, nine lame adult horses were evaluated with and without the RBW. The assessment included: objective gait analysis, acoustic myography, postural analysis, gait kinema...
Jung Y, Yoon M.Oxytocin (OXT) plays a crucial role in regulating the serotonin (5-HT) system and behavior. Although previous studies have reported significant relationships among OXT, 5-HT, and behavioral responses, the effects of OXT on 5-HT concentrations and behavioral traits in horses remain poorly understood. This study aimed to investigate the effects of intravenous OXT administration on plasma 5-HT concentrations and trainability in horses. A crossover design was employed using eight horses, each receiving either a 10-IU intravenous dose of OXT or normal saline. Blood samples were collected at baselin...
Gerow SL, Clegg SR, Cooke AS.In the UK, fireworks are common during several celebratory events throughout the year. Previous evidence has shown the adverse effects of fireworks on domestic companion animals. However, there has been little focus on equids. An online survey was developed to understand the impact of fireworks on horses and donkeys, how owners attempt to mitigate these impacts, and the owners' views on fireworks. A total of 1,234 horse owners and 232 donkey owners responded. The majority (77%) advocated tighter regulations surrounding the use of fireworks, including reduction in the maximum noise produced, an...
Dundjerovic I, Sneddon LU.Animal welfare concerns both the physical and mental wellbeing of animals so the assessment of animals kept in captivity, for example zoos, is important and necessary both legally and ethically. Good welfare is especially vital when breeding endangered species as stress impairs reproductive investment. As zoos often have high numbers of visitors, it is important to know if humans and the associated noise might influence the animals' welfare. The aim of this study was to investigate whether the presence of visitors and activities offered to the visitors caused a stress response in horses housed...
Çortu A, Çınar H.Rectal examination is routine in equine reproduction but may trigger acute stress affecting welfare and safety. Intraocular pressure (IOP) responds rapidly to autonomic changes and may capture short-lived stress responses. Objective: To evaluate whether rectal examination acutely affects IOP and behavioral responses in mares, and whether reactions differ by reproductive status. Methods: Twenty Rahvan mares (10 pregnant, 30-40 days' gestation; 10 non-pregnant; 4-7 years) underwent transrectal examination without sedation. IOP was measured bilaterally at six time points: 2 min pre-exam (T1), dur...
Valera M, Encina A, Sánchez-Guerrero MJ, Rodríguez-Sainz de Los Terreros A, Bartolomé E.Behavioral and emotional reactivity assessment in sport horses is essential for optimizing their management and sports performance, particularly in equestrian disciplines such as Dressage. This study investigates, in Pura Raza Española (PRE) horses, the association between facial hair whorl (FHW) patterns, behavioral traits, and physiological stress responses using ocular temperature (OT) assessed with infrared thermography as, an objective, non-invasive physiological stress indicator. Unassigned: A total of 98 male PRE horses, aged 4-6 years old and all gray coated, were evaluated during the...
Yu S, Yue X, Yang Q, Xu P, Yuan H, Tang W, Luan Y, Wang Q.Intestinal microbial homeostasis and metabolic balance play a crucial role in maintaining normal physiological function in horses. Exogenous stress involving abrupt turns and jumps during show jumping significantly impacts intestinal microbial homeostasis and metabolic balance in these animals. Results: By comparing rectal (faecal) samples from 10 Warmblood horses collected before and immediately after a show jumping competition on the same day, we observed substantial alterations in intestinal microbial homeostasis and metabolic balance post-exercise. Microbial evenness significantly increase...
Rigby C, Prutton A.Recruitment and retention of equine veterinarians presents an ongoing challenge for employers. Recent research has highlighted factors that contribute to attrition across the profession, but further understanding of the specific challenges faced in the equine sector is needed. This study builds on existing research by exploring the relative impact of different factors on veterinarians' decisions to leave equine clinical practice. Methods: Veterinarians who had left equine clinical practice in the UK within the previous 10 years were invited to participate in an anonymous online survey. The par...
