Omneity® Pellets
All-In-One Vitamin & Mineral Pellet
Topic:Stress
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.
Hypothalamic-pituitary-adrenal Axis Dysfunction in Critically Ill Foals and Horses. Critical illness-related corticosteroid insufficiency is a transient dysfunction of the hypothalamic-pituitary-adrenal axis, leading to inadequate cortisol responses during severe stress from endotoxemia and sepsis in horses and foals. This condition is associated with poor outcomes, and its diagnosis is complicated by interindividual variability in cortisol response. Recent advances in dynamic testing and point-of-care hormone tests offer promise for better assessment and treatment, enabling more precise steroid replacement therapy in affected equine patients.
Human-horse interactions as complementary strategies for mental health promotion. Animal-assisted interventions (AAI) represent complementary rehabilitative approaches designed to address a range of physical and mental health conditions. Among these, Equine-assisted interventions (EAI) offer structured opportunities for engagement through diverse activities conducted within naturalistic settings, thereby integrating therapeutic processes with ecological contexts. Methods: Over the past years, our group has developed and implemented standardized AAI methodologies that are now embedded within comprehensive intervention planning. This overview summarizes the application of dif...
Training- and competition-related changes on circulating adrenocorticotropic hormone and cortisol response in Thoroughbred Racehorses. Exercise is a physiological challenge inducing intensity-dependent hypothalamic-pituitary-adrenal (HPA) axis responses. The hypothesis was that training and racing sessions induce different HPA axis activation. Objective: To assess whether different exercise sessions affect equine adrenal responsiveness according to age and sex. Methods: Ten clinically healthy Thoroughbred racehorses (6 females and 4 males) were recruited. Four were 2 years old and six were 3 years old. Horses were subjected to two exercise conditions: training and competitive racing sessions. Blood samples were collected at r...
Equine Blood and Salivary Cortisol Levels While Exercising on a Water Treadmill with an Artificial River System. A water treadmill (WT) is used in equine rehabilitation and training. This study aimed to investigate whether varying water depths and using an active artificial river (AR) system during water treadmill exercise would affect physiological stress responses in leisure horses. Thirteen leisure horses participated in five 20 min WT sessions, including those with a treadmill with dry belt, fetlock-depth WT (with/without AR), and carpal-depth WT (with/without AR) at a walking speed of 1.25 m/s. Blood and salivary cortisol levels were measured before, immediately after, and 30 min after exercise. Blo...
Disorders of Water and Tissue Perfusion (Diabetes Insipidus, Renin-Angiotensin-Aldosterone Axis, and Anhidrosis). This review highlights disorders of water and tissue perfusion in equids, specifically diabetes insipidus, the renin-angiotensin-aldosterone axis, and anhidrosis. The differences in renal versus central diabetes insipidus is discussed, as well as diagnosis and treatment of diabetes insipidus in equids. The physiology of the renin-angiotensin-aldosterone axis is reviewed, and recent research in the role of the renin-angiotensin-aldosterone axis in equids in certain states is emphasized. The proposed pathophysiology of anhidrosis in horses is discussed, as well as potential therapies.
Effects of pulsed electromagnetic therapy on the major hematological and biochemical parameters in horses. Pulsed electromagnetic field (PEMF) therapy, a commonly used supplementary treatment in the horse industry, shows promise in enhancing circulation, reducing inflammation, and supporting cellular repair; however, its effects on equine physiology remain unclear. Limited research and inconsistent protocols create uncertainty about its efficacy and safety in horses. Our study evaluates the short-term effects of PEMF on hematological and biochemical parameters in horses. Five active sport horses underwent PEMF therapy for five consecutive days using a full-body blanket at specific frequencies. Bloo...
Comparative genomic analysis of oxytocin and oxytocin receptor genes in the family Equidae. The oxytocin (OXT) - oxytocin receptor (OXTR) system regulates diverse biological processes including social behavior, stress responses, and processes related to domestication. While OXT is highly conserved, OXTR shows greater variability, which may contribute to species-specific adaptations. Methods: Comparative genomic analyses of OXT and OXTR coding sequences were performed across equid species using available genome assemblies and newly generated sequences obtained by next-generation sequencing. Phylogenetic relationships were inferred using maximum likelihood methods. Selection was assess...
Effect of equine flysheets on fly avoidance behaviours, body temperature, stress level, and heart rate. Flysheet use is common without any published scientific evidence to justify their use. Objective: To demonstrate the effectiveness of flysheets at reducing fly avoidance behaviours and measuring changes in body temperature, heart rate, and cortisol levels. Methods: Ten-week alternating crossover design. Methods: Five horses were enrolled. Flysheets were alternated (ON, OFF) between groups weekly for 10 weeks. Fly avoidance behaviours were recorded for 30 min once weekly. Cortisol samples were collected before flysheet application or removal, and again 10 min later. Star-Oddi data loggers...
Effects of Exercise on Ocular Parameters and Oxidative Stress Biomarkers in Saliva and Tear Fluid of Horses. Physical exercise is a physiological stressor in horses and may induce oxidative stress through increased production of reactive oxygen species. Saliva and tear fluid are accessible non-invasive matrices that may reflect oxidative balance, while ocular parameters including intraocular pressure (IOP), tear secretion (TS) and central corneal thickness (CCT) are key components of ocular homeostasis. Objective: To evaluate the effects of a standardised submaximal exercise session on IOP, TS and CCT, and on oxidative stress biomarkers (CAT, SOD, GSH, MDA, IMA) measured in saliva and tear fluid. Met...
Human-Animal Therapeutic Relationships: Communication, Welfare and Interpretative Asymmetry. Human-animal therapeutic relationships are commonly evaluated through their effects on human psychological, emotional and social well-being, whereas the experiences and welfare of non-human animals remain less consistently examined. This narrative interdisciplinary review analyses such relationships through interpretative asymmetry, integrating human-animal studies, ethology, animal welfare science and biological approaches to interspecies communication. Selected cultural examples are used only as illustrative boundary narratives. Interpretative asymmetry is defined not as a statistically meas...
Sleep architecture and lying behavior in horses across age groups and two housing systems: an overnight non-invasive EEG study. Sleep is a crucial factor for the well-being of horses, yet assessing equine sleep in common housing conditions remains challenging. This study investigated the effects of changes in horses' immediate environment and the influence of age on their sleep and resting behavior using a novel, non-invasive electroencephalography (EEG) mask. Ten horses from the teaching herd at the University of Veterinary Medicine Vienna were observed over four consecutive nights in two different housing systems (a large communal stable vs. two separate, adjacent individual stalls). Data collection included EEG reco...
Differences between horses (Equus caballus) displaying oral and locomotor stereotypies in their responses to a stable mirror. Recent cross-species analyses suggest that the different forms of stereotypic behaviour have heterogeneous causal mechanisms. In ungulates, there are indications that some forms of locomotor stereotypy may be linked to social factors. Using the domestic horse as a model species within this clade, we investigated whether individuals displaying the locomotor stereotypy box-walking (n=6) demonstrated greater responses to a stable mirror, intended to mimic presence of a conspecific, than horses displaying the oral stereotypy crib-biting (n=5) and non-stereotypic horses (n=5). After a 24hr baseline...
Hypothalamic-pituitary-adrenal axis response and glucose homeostasis during exercise to fatigue before and after training in old and young adult Standardbred mares. While reduced cortisol responses to exercise have been described in older horses, the effects of aging and training on the hypothalamic-pituitary-adrenal axis (HPA axis) and downstream metabolic signaling are currently unknown. Unassigned: This study tested the hypothesis that age and exercise training alter the response of the HPA axis, insulin, and glucose during an acute exercise challenge to fatigue. Methods: Six old (22.0±0.7 years) and six young adult (7.3±0.6 years) unfit Standardbred mares were tested. Mares ran a graded exercise test before (GXT1) and after (GXT2) 8 weeks of trainin...
The Transcriptomic and Proteomic Molecular Signatures of Equine Multiple-System Neuropathy (Grass Sickness). Equine grass sickness (EGS or equine dysautonomia) is a predominantly fatal multi-system neuropathy affecting grazing horses, likely caused by a neurotoxic phospholipase A2 (nPLA2) derived from a plant or microorganism. We studied neuronal tissue gene and protein expression patterns in EGS to elucidate the possible mechanisms of neurotoxicity and neurodegeneration. Tissue from the cranial cervical ganglion of eight EGS horses and six controls was examined histologically and used for transcriptomic analysis. These transcriptomic data were compared with previously published EGS-related proteomic...
Vasopressin stimulation testing in hospitalized foals. Hypothalamic-pituitary-adrenal gland axis (HPAA) dysfunction impairs survival and can be diagnosed with an arginine vasopressin (AVP) stimulation test. Objective: Adrenocorticotropic hormone (ACTH) and cortisol response to an AVP stimulation test will be attenuated in hospitalized foals compared to healthy foals and associated with severity of disease. Methods: Fifteen healthy and 45 hospitalized foals: 19 septic, 26 sick non-septic (SNS). Methods: A prospective, observational case-control design was utilized to assess HPAA function and compare corticotropin-releasing hormone, ACTH, and cortis...
Recognition of unfamiliar predators in domestic horses through only visual predator cues. Acoustic, olfactory, and visual predator cues trigger various adaptive responses among a variety of prey species even when they are under human protection since birth. Previous studies have found that domesticated animals show increased vigilance, stress, flight, and aggregation behaviors in response to predation threats. These investigations, however, did not directly test visual threatening cues alone in animals that communicate more with body language than vocalizations while considering individual temperament and social status. The current study aims to address this issue. Eighteen horses ...
Clinical and microbiota alterations in performance horses undergoing long-distance transport. Transport-associated pneumonia contributes substantially to morbidity, impaired welfare, and economic loss in high-performance horses and may be associated with alterations in the respiratory microbiota. Objective: Examine the effect of long-distance transport on the respiratory microbiota and correlate changes in microbiota diversity and composition with systemic and airway inflammation. Methods: Seventeen client-owned performance horses transported from New England to Florida under optimized trailering conditions, and 12 non-traveling horses. Methods: Physical examination, blood testing, nas...
Sixty minutes of daily solitary turnout improved physiological and behavioral indicators of stress and welfare in stall-housed horses. Housing horses in stalls restricts natural roaming behaviors, which in turn increases stress and stereotypic behaviors. Daily turnout for voluntary exercise is common for stress mitigation, but there is no consensus for optimal duration of turnout sessions. Objective: We sought to understand how minimal and moderate-duration daily turnout affects behavioral and physiological stress indicators. Methods: In a Latin-square design, adult Quarter horses (N=11) were allowed 0, 15, or 60 minutes/day of solitary turnout for 12-day periods. In-stall behaviors and 24-hour time budgets were assessed on d...
Spatiotemporal dynamics of equine group formation reveal the gradual emergence of social cohesion. Stable social relationships are essential for horse welfare, yet domestic management often involves regrouping unfamiliar individuals, potentially causing social stress. Fine-scale dynamics of social integration remain poorly quantified due to limitations of observational sampling. Using ultra-wideband real-time positioning, we tracked the development of spatial and social relationships in two newly formed equine groups (n = 19) over 2-12 months. Inter-individual distances decreased significantly, with time spent within 3 m of conspecifics increasing from 1.2 to 27.3% within two months, d...
Determining optimal practices for foal weaning – A protocol for a systematic review and network meta-analysis. Weaning is a stressful time in a foal's (Equus caballus) life. As humans artificially manage weaning in domestic horses, it provides an opportunity to safeguard horse welfare early in life, with potential long-term benefits. While numerous studies have examined the effects of different weaning and management interventions on foal stress, optimal weaning practices have yet to be identified. Overall purpose of the study: To identify which weaning interventions and management practices have the greatest potential to improve foal welfare based on physiological and behavioural outcomes. Research qu...
Untargeted Sweat Metabolomics and Targeted Plasma Amino Acid Profiling Reveal Dynamic Metabolic Remodeling During Conditioning in Yili Horses. Training induces sweat morphology changes in horses from muddy sweat (MS) to foamy sweat (FS) and clear sweat (CS), reflecting physiological adaptation. However, the metabolic mechanisms linking sweat phenotypes to systemic amino acid dynamics remain unclear. This study integrated sweat untargeted metabolomics and plasma amino acid targeted metabolomics to reveal coordinated metabolic remodeling. Six 2-year-old horse stallions underwent 10-week training. Plasma and sweat were sampled pre- and post-race at each stage. LC-MS/MS and UHPLC-MS/MS were used for sweat metabolome and plasma amino aci...
Physiological Evaluation of Quarter Horses Undergoing Five-Month Taming Focused on Hippotherapy. Preparing horses for hippotherapy programs requires management approaches that prioritize animal welfare and facilitate adaptation to novel stimuli. This study monitored physiological responses during the implementation of a progressive taming protocol for Quarter Horses intended for hippotherapy. Seven animals were monitored over a five-month period, including an acclimation phase and three taming stages. Continuous heart rate, plasma cortisol concentration, and ocular infrared thermography were assessed before and after exercise. Baseline ( = 0.0466) and minimum ( = 0.0095) heart rate values...
The progression values of heart rate and biochemical plasma parameters during training of 3-years old warmblood stallions for breeding licensing. Physiological adaptation to training in young sport horses remains incompletely characterized, particularly during standardized preparation for breeding licensing. Objective: The aim of this study was to evaluate cardiovascular and plasma biochemical responses to acute exercise and long-term training in three-year-old Czech Warmblood stallions during standardized free jumping exercise. Methods: Thirteen Czech Warmblood stallions were monitored over a 112-day training period. Heart rate parameters (minimum, maximum, and mean) were recorded during standardized free jumping tests. Plasma biochemi...
Exploration of the relationship between laboratory stress parameters and leukocyte coping capacity in ponies exposed to repetitive handling during a research project. Stress is an umbrella term indicating increased allostatic load with the potential to reach a pathological state of the organism. In this context, cortisol concentration and neutrophil granulocytes-to-lymphocyte ratio (NEU: LYM) are expected to increase. On the functional pathway, stress reduces the oxidative burst capacity of neutrophils and therefore, the leucocyte coping capacity (LCC) quantifying this oxygen radical generation of neutrophils. Therefore, we hypothesized that in ponies subjected to repetitive handling, LCC will decrease and will be negatively correlated with cortisol concent...
Observations on Anti-Predator Defense Behavior in Feral Horses in Venezuela. Apart from vigilance and flight, anti-predator defense behavior in horses has not been well documented despite its importance during natural selection. In this study, observations of a feral herd (around 140) of Venezuelan horses sympatric with puma and jaguar divided such defense into precaution and reaction. Group living and the avoidance of danger areas are precautionary measures enhanced by the stallion's vigilance and his actions to keep small foals with the band. Reactions to perceived threats comprise communication of alarm; bunching, or cohesion, as a primary response; massed flight fo...
Horsepower: equine-assisted interventions are associated with reduced PTSD symptoms, improved sleep quality, and quality of life in military veterans with treatment-resistant PTSD. Military veterans are at an elevated risk of developing posttraumatic stress disorder (PTSD), while first-line trauma-focused treatments are less effective in this population. This highlights the need for novel, evidence-based complementary interventions for military veterans with treatment-resistant PTSD. Although equine-assisted interventions (EAIs) are increasingly popular and appear promising, many studies suffer from methodological issues. Therefore, further research incorporating both psychometric and physiological parameters is warranted. Unassigned: Nine consecutive groups of eight vet...
Evidence of Physiological Comodulation During Human-Animal Interaction: A Systematic Review. This review examines the evidence in the literature for physiological co-modulation during human-animal interaction, identifying studies that assessed comodulation via simultaneous measurement of physiological signals in both species, performing quantitative comparisons. We searched (last search: August 5, 2025) PubMed, EMBASE, Scopus, Google Scholar, Animal Studies Repository, Cochrane, and the Consensus App academic search engine. Risk of bias was assessed using an adapted version of the ROBINS-I V2 tool. The results, grouped by data analysis method, interaction context, and physiological pa...
Syndrome of High Gamma-Glutamyl Transferase in Racehorses. Horses in racing and race training can develop high gamma-glutamyl transferase (GGT) syndrome (HGS), or increased GGT without overt evidence of primary liver disease. Current evidence points toward overtraining and a response to oxidative stress, but the etiology is incompletely understood. Evidence for an association of HGS with poor performance is mixed. Without a clear understanding of the etiology, the only evidence-based treatment option is rest or reduced training intensity. More research is needed to determine whether HGS is a physiologic adaptation, perhaps indicative of overtraining b...
Psycho-Spiritual Reflections on the Horse/Human Relationship. This essay offers a psycho-spiritual and psychoanalytic meditation on the horse-human relationship as a nonverbal site of attunement, regulation, and meaning-making. Drawing on autobiographical clinical narrative, it explores how horseback riding became a medium for experiencing and reflecting upon embodied connection, mutual responsiveness, and contemplative presence. Encounters with horses illuminate forms of reciprocity that preceded and exceed speech, while also opening reflection on maternal attachment, separation, loss, and the emergence of selfhood. In dialogue with Freud, Winnicott, Pi...
