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.
The contraceptive efficacy of a self-assembling intra-uterine device in domestic mares. The primary aim of this study was to investigate the contraceptive efficacy of a self-assembling uterine device (iUPOD™) in the mare. In addition, the effects of iUPODs on oestrous cyclicity, uterine health and circulating concentrations of cortisol were evaluated. Methods: Domestic mares underwent oestrous monitoring and artificial insemination. After subsequent ovulation, mares underwent either placement (n = 7) or sham placement (n = 7; controls) of an iUPOD device. Devices were left in place for at least 3 months. Pregnancy diagnoses were carried out 14 days post-ovulation, with any pr...
Stress response after race and endurance training sessions and competitions in Arabian horses. Assuring a high level of animal welfare is a critical aspect of contemporary animal husbandry. Equine athletes begin their careers at a very young age when they are still developing and they are both physically and mentally immature. Lack of scientific knowledge of the stress related to horse racing impedes the development of optimal training programs to attain equilibrium between the best sport results and optimal welfare. This study aimed to determine the influence of the intensity and type of physical activity on peripheral blood cortisol concentration. Thirty untrained Arabians, 9 enduranc...
Hormone Concentrations and Semen Parameters in Criollo Breed Stallions Under Training. The stress associated with training may reduce reproductive efficiency in Criollo stallions. The objective of this study was to compare semen quality and hormone concentrations in Criollo stallions under training or under regular field conditions. Criollo breed stallions (n = 18) were evaluated during the spring. The exercise group (n = 9) performed 1 hour of exercise per day and participated in competitions during the experimental period. The control group (n = 9) neither performed exercise nor participated in competitions. Serum and semen samples were obtained every 15 days (two separat...
Glucagon, insulin, adrenocorticotropic hormone, and cortisol in response to carbohydrates and fasting in healthy neonatal foals. The endocrine pancreas and hypothalamic-pituitary-adrenal axis (HPAA) are central to energy homeostasis, but information on their dynamics in response to energy challenges in healthy newborn foals is lacking. Objective: To evaluate glucagon, insulin, ACTH, and cortisol response to fasting and carbohydrate administration in healthy foals. Methods: Twenty-two healthy Standardbred foals ≤4 days of age. Methods: Foals were assigned to fasted (n = 6), IV glucose (IVGT; n = 5), PO glucose (OGT; n = 5), and PO lactose (OLT; n = 6) test groups. Blood samples were collected frequently for 210 min...
Effect of Pen Size on Stress Responses of Stall-Housed Horses Receiving One Hour of Daily Turnout. Group turnout provides important socializing opportunities for horses, particularly those that are primarily stalled. A high percentage of equine injuries occur during group turnout, which could partly be due to the physical constraints of fencing. To investigate appropriate paddock sizes for group turnouts, horses (n = 12) from a single herd were divided into groups of 4, stalled for 24 hours, and then turned out for 1 hour into one of three differently sized pens: 342, 263, and 184 m per horse. Groups rotated through pens across 3 days, receiving one treatment per day. Blood was sampled ...
Clinical implications of using adrenocorticotropic hormone diagnostic cutoffs or reference intervals to diagnose pituitary pars intermedia dysfunction in mature horses. Diagnosis of pituitary pars intermedia dysfunction (PPID) is problematic because of large variations in ACTH concentrations. Objective: Compare the test characteristics of baseline and post-thyrotropin-releasing hormone (TRH) stimulation plasma ACTH concentrations in horses using diagnostic cutoff values (DCOVs) and reference intervals (RIs) and determine the clinical consequences of using each method. Methods: One hundred six mature horses: 72 control cases and 34 PPID cases. Methods: Prospective case-controlled study. Horses underwent monthly TRH stimulation tests. Diagnostic cutoff values w...
The intensity of physiological and behavioral responses of horses to predator vocalizations. Predatory attacks on horses can become a problem in some parts of the world, particularly when considering the recovering gray wolf populations. The issue studied was whether horses transformed by humans and placed in stable-pasture environments had retained their natural abilities to respond to predation risk. The objective of the study was to determine the changes in cardiac activity, cortisol concentrations, and behavior of horses in response to the vocalizations of two predators: the gray wolf (Canis lupus), which the horses of the breed studied had coevolved with but not been exposed to r...
Evaluating Stress in Riding Horses: Part One-Behavior Assessment and Serum Cortisol. Stress can impact the health and well-being of animals negatively. Behavioral and physiological changes, particularly serum cortisol, offer objective and easy-to-use methods of evaluating stress in horses. However, limited studies support a positive relationship between changes in stress-related serum cortisol concentrations and stress-related behaviors in horses. This study assessed differences in stress-related behaviors and serum cortisol concentrations in horses used in a therapeutic riding program (TRH) or university riding program (UNI). Riders were grouped by disability type (TRH) or by...
Effects of administration of ascorbic acid and low-dose hydrocortisone after infusion of sublethal doses of lipopolysaccharide to horses. Sepsis is associated with ascorbic acid (AA) depletion and critical illness-related corticosteroid insufficiency (CIRCI) in humans. Objective: Intravenous infusion of lipopolysaccharide (LPS) would (a) decrease endogneous AA concentrations, (b) induce CIRCI and (c) administration of a combination of AA and hydrocortisone (HC) would have decreased indices of inflammation compared to either drug alone. Methods: Thirty-two healthy horses. Methods: Randomized placebo-controlled experimental trial. Horses were assigned to 1 of 4 groups (saline, AA and HC, AA only, or HC only). Treatments were admin...
Circannual variation in plasma adrenocorticotropic hormone concentrations and dexamethasone suppression test results in Standardbred horses, Andalusian horses and mixed-breed ponies. To compare circannual plasma concentrations of adrenocorticotropic hormone (ACTH) and seasonal dexamethasone suppression test (DST) results between three different equine breed groups. Methods: Six Standardbred horses, six Andalusian horses and six mixed-breed ponies were followed over a 1-year period, during which time groups were managed identically. Blood samples were collected monthly (around the autumn equinox) or in every second month (other times of the year) for the determination of plasma ACTH concentrations using a chemiluminescent immunoassay. Overnight DSTs were performed quarterly...
Differences in Endocrine and Cardiac Changes in Mares and Her Fetus before, during, and after Parturition in Horses of Different Size. Equine fetomaternal monitoring is based on endocrine and cardiac parameters which may differ among small, medium-size, and full-size horses. Therefore, Shetland ( = 6), Haflinger ( = 8), and Warmblood pregnancies ( = 9) were studied during late gestation and at foaling. Weight of mares, foals and placenta, plasma progestin and cortisol concentration, heart rate and heart rate variability (HRV) were determined. Foal weight always approximated 10% of mare weight but relative placenta weight was highest in full-size mares ( < 0.05). Progestin ( < 0.001) and cortisol ( < 0.05) concentrati...
Association Between Disease Severity, Heart Rate Variability (HRV) and Serum Cortisol Concentrations in Horses with Acute Abdominal Pain. Heart rate variability (HRV) is a noninvasive technique to detect changes in the autonomous nervous system. It has rarely been investigated in horses with colic. Therefore, the objective was to assess the evolution of HRV parameters and cortisol concentrations in horses with colic. The 43 horses included in this study were categorized into three groups according to the treatment (1, surgical; 2, conservative; 3, euthanized). The HRV and laboratory variables were measured at admission (T1), the day after admission (T2), and at discharge (T3) and compared between groups and over time with an ANO...
Can Endocrine Dysfunction Be Reliably Tested in Aged Horses That Are Experiencing Pain? The aim of the present study was to evaluate (i) the effects of different intensities and types of treated pain on the basal concentrations of adrenocorticotropic hormone (ACTH) and cortisol, and (ii) the thyrotropin-releasing hormone (TRH) stimulation test, to determine whether treated pain caused a marked increase of ACTH, which would lead to a false positive result in the diagnosis of pituitary pars intermedia dysfunction (PPID). Methods: Fifteen horses with treated low to moderate pain intensities were part of the study. They served as their own controls as soon as they were pain-free agai...
Effects of pituitary pars intermedia dysfunction and Prascend (pergolide tablets) treatment on endocrine and immune function in horses. It remains unclear how pituitary pars intermedia dysfunction (PPID) and pergolide treatment (Prascend [pergolide tablets]) affect endocrine and immune function in horses. To evaluate these effects, blood was collected regularly from 28 university-owned horses (10 Non-PPID, 9 PPID control [PC], and 9 PPID treatment [PT]) over approximately 15 mo. Pergolide treatment was initiated after Day 0 collections. Analyses included ACTH, insulin, total cortisol, free cortisol, complete blood counts, plasma myeloperoxidase, and cytokine/receptor gene expression in basal whole blood and in vitro stimulat...
The effect of diet-induced obesity and pasture on blood pressure and serum cortisol in Standardbred mares. Obesity is associated with insulin resistance, vascular dysfunction and altered cortisol metabolism both in humans and in horses. Objective: Evaluate the effect of weight gain induced by a haylage diet low in nonstructural carbohydrates (NSC) on insulin sensitivity, blood pressure and serum cortisol concentrations. Methods: In vivo experiment. Methods: Nine adult Standardbred mares fed a fat supplemented haylage diet at 250% of the horses' daily metabolisable energy requirements for 22 weeks. Horses were then turned out on pasture for 4 weeks. Insulin sensitivity (SI ) was measured before an...
Serum concentrations, pharmacokinetic/pharmacodynamic modeling, and effects of dexamethasone on inflammatory mediators following intravenous and oral administration to exercised horses. Corticosteroids are potent anti-inflammatory drugs and as such are commonly administered to performance and racehorses. The objectives of the current study were to describe blood and urine concentrations and the pharmacokinetics and effects on cortisol and inflammatory mediator concentrations, following intravenous and oral administration to 12 exercised horses. Horses received an intravenous administration of 40 mg of dexamethasone sodium phosphate and 20 mg of dexamethasone tablets with a 4 week washout in between administrations. Blood and urine samples were collected prior to and for up to...
Neonatal glucocorticoid overexposure alters cardiovascular function in young adult horses in a sex-linked manner. Prenatal glucocorticoid overexposure has been shown to programme adult cardiovascular function in a range of species, but much less is known about the long-term effects of neonatal glucocorticoid overexposure. In horses, prenatal maturation of the hypothalamus-pituitary-adrenal axis and the normal prepartum surge in fetal cortisol occur late in gestation compared to other precocious species. Cortisol levels continue to rise in the hours after birth of full-term foals and increase further in the subsequent days in premature, dysmature and maladapted foals. Thus, this study examined the adult ca...
Pulmonary response of severely asthmatic horses after intra-articular administration of methylprednisolone. Intra-articular (IA) administration of corticosteroids is performed routinely in equine practice. The lung function of severe asthmatic horses has recently been shown to be improved by IA triamcinolone acetonide (TA). We therefore hypothesised that IA methylprednisolone acetate (MPA), another commonly used corticosteroids, would also decrease the airway obstruction in severe asthmatic horses. Objective: To compare the effects of intra-articular (IA) and intramuscular (IM) methylprednisolone acetate (MPA) administration on lung function and serum cortisol levels in horses with severe asthma. Me...
Modulation of the renin-angiotensin-aldosterone system by steroid hormones during the oestrous cycle in mares. In women and females of different species of laboratory animals, oestrogens stimulate the renin-angiotensin-aldosterone system (RAAS) by increasing tissue and circulating levels of angiotensinogen and renin during the preovulatory period. Progesterone and cortisol compete with aldosterone for mineralocorticoid receptors, which results in increased Na+ reabsorption during the postovulatory period. The purpose of the current research was to analyse the relationship of oestradiol-17β, progesterone and cortisol with RAAS in 23 mares during an oestrous cycle. During the preovulatory period, signif...
The different hormonal system during exercise stress coping in horses. The review discusses the hormonal changes during exercise stress. The exercise generally produces a rise of adrenaline (A), noradrenaline (NA), adrenocorticotropic hormone (ACTH), cortisol, glucagon, growth hormone, arginine vasopressine, etc., and a drop of insulin. The hormonal events during reestablishment of homeostasis due to exercise stress can be divided into a catabolic phase, with decreased tolerance of effort, and reversible biochemical, hormonal and immunological changes, and an anabolic phase, with a higher adaptive capacity, and enhanced performance. The two main hormonal axes act...
Serum cortisol and thyroid hormone concentrations and survival in foals born from mares with experimentally induced ascending placentitis. There are few publications on occurrence of nonthyroidal illness syndrome in foals and on the prognostic value of cortisol and thyroid hormone (TH) concentrations in newborn foals. Objective: To determine serum cortisol and TH concentrations (total and free thyroxine: T and T ; total and free triiodothyronine: T and T ) in foals born from mares with placentitis, to determine their association with survival, and their use as prognostic markers. Methods: A cohort of 29 newborn foals comprising 5 Control, 14 Low-risk, and 10 Sick foals were evaluated over the first week of life. Methods: In thi...
Temporary Relocation during Rest Periods: Relocation Stress and Other Factors Influence Hair Cortisol Concentrations in Horses. Horse transportation for temporary relocation during rest periods is a common and widespread practice among horse owners, either from sport competition or working tasks. This study aimed to determine the effect of a relocation period and the multiple factors associated with a rest period on hair cortisol concentrations (HCCs) in horses. Additionally, this study reports the seasonal effect on HCCs and hair growth over a year. Thirteen police horses, Pure Spanish stallions of various ages (5-13 y), were selected to participate in this study. Hair sample collection was carried out approximately e...
Validation of exercise-response genes in skeletal muscle cells of Thoroughbred racing horses. To understand the athletic characteristics of Thoroughbreds, high-throughput analysis has been conducted using horse muscle tissue. However, an in vitro system has been lacking for studying and validating genes from in silico data. The aim of this study is to validate genes from differentially expressed genes (DEGs) of our previous RNA-sequencing data in vitro. Also, we investigated the effects of exercise-induced stress including heat, oxidative, hypoxic and cortisol stress on horse skeletal muscle derived cells with the top six upregulated genes of DEGs. Enriched pathway analysis was conduct...
Salivary cortisol measurement in horses: immunoassay or LC-MS/MS? The aim of the present study was to measure salivary cortisol concentrations of horses before and after hypothalamic-pituitary-adrenal (HPA) axis stimulation by means of liquid chromatography-tandem-mass spectrometry (LC-MS/MS) and an immunoassay (cELISA) for method comparison. Nine clinically healthy horses participated in the study. An ACTH stimulation test was performed. Saliva samples were collected before (T0) and 60 (T60) min after intravenous injection of 1 μg/kg BW synthetic ACTH1-24. LC-MS/MS was assessed for the determination of equine salivary cortisol. The results of these measur...
Effects of Transport Conditions on Behavioural and Physiological Responses of Horses. The regulations for minimal space and direction of travel for land transport in horses vary worldwide and there is currently no definitive guidance to promote equine health and welfare. This study evaluated the effects of bay size and direction of travel (forwards/backwards) in horses by comparing the behavioural, physiological, laboratory and gastroscopy parameters between transported and confined horses. A total of twenty-six mares took part in the study; 12 horses were confined for 12 h, and all mares underwent 12 hours' transportation, travelling in single (n = 18) or wide bays (n = 8), an...
Effect of food contamination and collection material in the measurement of biomarkers in saliva of horses. This study aims to evaluate the effect of the presence of food and the material used in a panel of biomarkers in saliva of horses. For the food effect study, clean saliva was incubated with a known amount of food consisting of oats, hay or grass. Significant changes were observed when saliva was incubated with oats for total protein (P = .050) and phosphorus (P = .008), with grass for total protein (P = .037), salivary alpha-amylase (sAA, P = .018), total esterase (TEA, P = .018), butyrilcholinesterase (BChE, P = .037), adenosine deaminase (ADA, P = .037), and total bilirubin (P...
Weight estimation and hormone concentrations related to body condition in Icelandic and Warmblood horses: a field study. The main objectives of this study were to evaluate the accuracy of different body weight formulas for estimating body weight of Icelandic and Warmblood horses, as well as to assess the associations between the variables cresty neck score, body condition score, and plasma concentrations of leptin, insulin and cortisol. A total of 81 adult (≥ 4 years of age) horses (43 Icelandic and 38 Warmblood horses) was included in this study. The following morphological measurements were collected by two examiners simultaneously; body weight; height at withers; neck length; 0.5 neck length; neck circum...
Road Transport of Late-Pregnant Mares Advances the Onset of Foaling. Cortisol is involved in the initiation of parturition and we hypothesized that increased maternal cortisol release advances the onset of foaling. Transport is a stressor for horses and induces an increase in cortisol release. To determine stress effects on the time of foaling, late-pregnant mares were transported by road for 3 hours (n = 12) or remained in their stable as controls (n = 4). Starting on day 325 of gestation, saliva and blood samples were taken for cortisol and progestin analysis, respectively. Fetomaternal electrocardiograms were recorded repeatedly. Mares were checked for im...
Effects of breed, management and personality on cortisol reactivity in sport horses. Sport horses need to fulfill high physical and psychological requirements during training and competition. These as well as certain conditions of modern husbandry may affect their wellbeing. Here we aimed to (1) evaluate effects of demographic and management factors as well as personality traits on stress reactivity of sport horses, (2) investigate if elite sport horses have elevated stress levels compared to amateur sport horses, and (3) assess whether different equestrian disciplines differentially influence equine adrenal cortex responsiveness. For this purpose, we visited 149 healthy elite...
Plasma steroid profiles before and after ACTH stimulation test in healthy horses. This study describes steroid profiles in equine plasma before and after ACTH stimulation. In human medicine, other steroids have been shown to have a more pronounced reaction to an ACTH stimulation test than cortisol. This study aimed to determine if the same was true for the horse. A total of 11 clinically healthy horses were selected for this study. Ethylenediaminetetraacetic acid plasma samples were taken before and 60 min after stimulation with 1 μg/kg BW of synthetic ACTH administered intravenously. The samples were analyzed for cortisol, 11-deoxycortisol, 21-deoxycortisol, cortisone, ...