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Topic:Cortisol
Cortisol is a steroid hormone produced by the adrenal glands in horses, playing a significant role in the regulation of metabolism, immune response, and stress management. As a glucocorticoid, cortisol influences various physiological processes, including glucose metabolism, inflammation modulation, and the maintenance of homeostasis during stress. Its levels in horses can vary due to factors such as exercise, environmental changes, and psychological stressors. Cortisol is often measured to assess stress responses and overall well-being in equine health management. This page compiles peer-reviewed research studies and scholarly articles that explore the production, regulation, and implications of cortisol in equine physiology and health.
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...
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...
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...
Exploring the postpartum period in mares: hormonal dynamics and ovarian activity under physiological and pathological conditions. The aims of the study were to evaluate factors influencing the resumption of postpartum ovarian activity and to compare hormone concentrations among mares with physiological/pathological postpartum period and cyclic non-lactating mares. Follicular dynamics were monitored ultrasonographically in 38 postpartum mares from foaling or admission (Tpp/Ta) every other day until the emergence of a dominant follicle (Td), then daily until ovulation (To). Blood samples were collected at Tpp/Ta, Td, and To in postpartum mares and at Td and To in cyclic mares to determine serum estradiol, progesterone, lep...
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...
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...
Hair steroid hormones concentrations in jennies and their donkey foals from parturition to 6 months postpartum. The period after parturition/birth represents a delicate time for the dam and the offspring, during which several physiologic changes occur under finely tuned hormonal control, with the hypothalamic-pituitary- adrenal (HPA) axis playing a key role. This period, well studied in horses, received little attention in donkeys, despite the importance of species-specific knowledge for population preservation programs in many endangered donkey breeds. The present study aimed to investigate cortisol (C), DHEA(S), 17-β-estradiol (E2), progesterone (P4), testosterone (T), and allopregnanolone (AlloP) ha...
Meta-Analysis and Physiologically-Based Modeling of the Pharmacokinetics and Pharmacodynamics of Dexamethasone in Horses. Dexamethasone (DEX) is widely used in equine practice for its potent anti-inflammatory effects and diverse studies have examined its pharmacology in horses. We integrated all available pharmacokinetic (PK) and pharmacodynamic (PD) data from 12 studies to quantify DEX disposition and endocrine effects in horses. Methods: DEX concentrations in blood, urine and synovial fluid, plus cortisol (CTS) and glucose (GLU) in plasma, following various administration routes (intravenous (IV), intramuscular (IM), intra-articular, oral) were available from original studies or digitized from literature. A mi...
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...
Annual Variation in Stallion Testicular Measurements and Its Association With Hormonal Profiles and Semen Quality. In a stallion breeding-soundness examination, testicular volume may be estimated either from total scrotal width or by measuring the height, width and length of both testes. This study aimed to determine whether testicular morphometric parameters obtained by ultrasonography fluctuate throughout the year, and whether these variations affect semen quality and hormone production in stallions located at low latitudes in the Southern Hemisphere. Eight healthy light-breed stallions were evaluated every 15 days for 1 year, encompassing the breeding (October-April) and non-breeding(May-September) ...
Evaluating hormonal levels in plasma and saliva as temperament indicators in horses. Assessing the temperament of horses is important to ensure their welfare, management, and safety. This study evaluated the plasma-saliva relationships for cortisol, oxytocin, and serotonin, and explored their associations with temperament traits in 40 horses using enzyme-linked immunosorbent assays. Significant correlations were observed between cortisol (r = 0.441) and oxytocin (r = 0.587) concentrations, whereas serotonin showed a weak correlation (r = 0.133). Bland-Altman analysis revealed acceptable agreement for cortisol but substantial individual variability for oxytocin, despite its str...
Welfare Assessment in Equine-Assisted Service (EAS) Horses. Equine-Assisted Service (EAS) horses can be exposed to stressors that affect their behavior and welfare. Previous studies investigated behavioral and physiological indicators (PI) only during therapy sessions. This study evaluated the frequency of stress and pain behaviors (FSPB) in horses with different riders, while assessing welfare through housing, management, and PI. Ten horses were observed during EAS sessions with three rider groups: able-bodied, clients with significant physical impairment, and clients with no significant physical impairment, totaling twenty-six riders. Behavioral data...
The Effects of Boron Mineral on Performance, Bone and Mineral Metabolism in Purebred Arabian Foals. Boron plays significant roles in various biological systems, including mineral, lipid, and energy metabolism, immune and endocrine systems, and brain function. It has been suggested to enhance performance and may prevent conditions such as osteoporosis, osteoarthritis, and arthritis. Despite these known benefits, its effects on growth performance and mineral metabolism in horses remain understudied, particularly in young animals like Purebred Arabian foals. The primary objective of this study was to investigate the effects of different doses of boron supplementation (0, 5, 10, and 15 mg/day ...
Beyond cortisol: evaluating serotonin, brain-derived neurotrophic factor, and oxytocin as indicators of equine welfare across three training regimens. BACKGROUND: Quantifying the balance between workload, stress, and recovery across equine disciplines remains challenging, and no single circulating biomarker provides a definitive index of welfare-related stress load. Cortisol, oxytocin, serotonin (5-hydroxytryptamine, 5-HT), and brain-derived neurotrophic factor (BDNF) may provide complementary information on endocrine and neuromodulatory responses. METHODS: Paired serum samples were collected from show jumping horses (n = 17) before and after competition, racehorses (n = 43 enrolled, n = 41 analyzed) before and after sessions at ...
A scoping review of neuroendocrinological biomarkers with potential for use in equine behavioral medicine practice. BACKGROUND: Equine emotion and welfare are of increasing concern to the general public, equestrians and researchers. There is growing demand for more objective indicators of specific emotional states, as well as the well-being of horses in a variety of contexts. Such markers may also assist in both the diagnosis and selection of biological therapies within equine behavioral medicine. RESULTS: This scoping review summarizes and appraises the published findings relating to relevant biological measurements from the last two decades. Particular attention is given to methodological, subject-related...
Effect of season of collection and storage method on equine hair cortisol concentration. Serum cortisol concentration is one of the common physiological reference standards for evaluating stress in animals. However, it only evaluates acute stress at the moment of blood collection. Hair cortisol concentrations (HCC) could provide a method for assessing cortisol concentrations over extended periods of time, giving an estimate of chronic stress levels. In this case, high HCC results could help equine managers alter management practices to improve welfare. Objective: To evaluate the effect of the month of collection and the storage method on equine HCC. Methods: Tail hair was collecte...
Associations among beta-endorphin, ACTH, cortisol concentration, age, and clinical signs indicative of pituitary pars intermedia dysfunction in geriatric horses. Limited published data are available regarding the relationships among clinical signs associated with pituitary pars intermedia dysfunction (PPID), age, and concentrations of proopiomelanocortin-derived peptides and cortisol. Objective: Identify clinical signs associated with age, beta-endorphin (β-END), adrenocorticotropic hormone (ACTH), and cortisol concentrations and compare β-END and cortisol concentrations between horses with PPID and geriatric controls. Methods: A total of 113 horses aged 18-32 years. Methods: Cross-sectional study. Clinical signs were scored, plasma β-END, ACTH, an...
Pharmacokinetics and Anti-Inflammatory Effects of Intramuscular Betamethasone in Exercised Thoroughbred Horses. The pharmacokinetics and pharmacodynamics of betamethasone following intra-articular administration to horses have been described; however, studies characterizing intramuscular administration are lacking. Twenty-four horses received an intramuscular dose of 12 mg betamethasone sodium phosphate/betamethasone acetate. Blood and urine were collected at post administration for up to 408 h. Concentrations of betamethasone were determined using LC-MS/MS and pharmacokinetic parameters determined using a Population PK three-compartment model. The duration of pharmacodynamic effects was assessed by...
Effects of a rehabilitative whole-body resistance band wrap on equine gait, posture, cortisol, and muscular function. 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...
Effects of total parenteral nutrition and electrolyte solutions with or without glutamine on the hormonal profiles of horses subjected to exploratory laparotomy. Starvation and nutritional support clinically influence horses, particularly during the treatment of gastrointestinal diseases and post-surgical recovery. In this study, we aimed to evaluate the effects of different nutritional strategies on the endocrine response of horses subjected to exploratory laparotomy followed by food deprivation. Sixteen healthy adult horses were randomly allocated into four groups (n=4) based on treatments: enteral fluid therapy without (ENTFL) or with glutamine (ENTGL), and parenteral fluid therapy with glucose (PARFL) or total parenteral nutrition with glutamine (P...
Effects of Social Interactions and Foundational Training on Behavior, Temperament, and Hormone Levels in Weanling Horses. 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...
Serum cortisol concentrations in newborn foals are increased by transfusion with anti-rhodococcal hyperimmune plasma and inversely associated with immunoglobulin activity. Transfusion of Rhodococcus equi hyperimmune plasma (REHIP) to neonatal foals is done to reduce the incidence of rhodococcal pneumonia. Objective: To determine effects in newborn foals of REHIP transfusion on serum cortisol concentrations; the association of serum cortisol concentrations with serum globulin concentration and anti-rhodococcal immunoglobulin activity; and cumulative incidence of rhodococcal pneumonia. Methods: Serum samples were collected from 356 newborn foals from 13 New York farms immediately before and after transfusion of 1 L or 2 L of REHIP. Serum samples were assayed for c...
Effect of transdermal melatonin on circulating cortisol and blood chemistry in horses exposed to transport stress. 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 ...
Measuring emotional contagion in Horse-Human interactions: A systematic scoping review of methods and outcomes. 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. 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...
Monitoring Weaning Stress in Fillies and Colts on a Thoroughbred Breeding Farm by Cortisol and Blood Inflammatory Markers: The Benefits of Gradual Separation and Social Support. Weaning represents a major developmental milestone for foals, especially when 4- to 7-month-old foals are abruptly separated from their dams. Studies have shown that the post-weaning period is associated with physiological and psychological stress, which may affect immune function. The present study aimed to describe and analyze the pattern of blood inflammatory biomarkers related to the innate immune system. A gradual foal-dam separation procedure was chosen, which included post-weaning social buffering by a familiar adult horse. Twelve Thoroughbred foals (six fillies, six colts) aged 4-6 mon...
Introducing an Innovative Pain Scale for Assessing Postpartum Pain in Mares: Preliminary Clinical Evaluation. Pain after giving birth is commonly observed in horses, yet there has not been a specific tool developed for assessing this pain in postpartum mares. The goal was to adapt existing equine pain scales and to preliminarily validate a practical pain scale for use by veterinarians and caregivers after foaling. Methods: The pain scale was developed by adapting items from other pain scales, including established orthopedic and colic equine pain scales, and incorporating caregiver feedback. The final scale includes eight areas for assessing pain: behavior, facial expressions, vital signs, udder exami...
Characterization of intramuscular Isoflupredone acetate in horses: pharmacokinetics and effects on anti-inflammatory mediators and plasma electrolytes. Corticosteroids, such as isoflupredone, are effective anti-inflammatory medications and as such are commonly used to treat inflammation associated with training and injuries in performance horses. While the pharmacokinetics and pharmacodynamics of isoflupredone acetate (IPA) following intra-articular administration to horses has been well described, studies characterizing intramuscular (IM) administration are lacking. The objective of the current study was to describe the pharmacokinetics and anti-inflammatory effects of IPA following IM administration to horses. Twelve horses received a singl...
Exploring the association between stress-related hormonal changes, behaviours and facial movements after an interval training exercise in French Standardbred. 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...
