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Topic:Adrenal
The adrenal glands in horses are small endocrine organs located near the kidneys, responsible for producing a variety of hormones essential for physiological regulation. These hormones include cortisol, adrenaline, and aldosterone, which are involved in stress response, metabolism, and electrolyte balance. The functioning of the adrenal glands is integral to the horse's ability to respond to stressors and maintain homeostasis. Research in equine endocrinology often focuses on understanding the regulation of adrenal hormones, their role in equine health, and the impact of disorders such as equine Cushing's disease and adrenal insufficiency. This page compiles peer-reviewed research studies and scholarly articles that explore the anatomy, function, and clinical implications of adrenal gland activity in horses.
Seasonal variation of endogenous adrenocorticotropic hormone concentrations in healthy non-geriatric donkeys in Northern California. Elevated plasma adrenocorticotropic hormone (ACTH) is often used to diagnose pituitary pars intermedia dysfunction (PPID) in horses. The hormone naturally increases in the fall in horses, and donkeys have been found to have higher ACTH concentrations than horses. However, circannual variation of ACTH has not been assessed in donkeys. The objective of the study was to establish seasonal variation of basal plasma ACTH concentrations over the course of a year in clinically healthy, non-geriatric donkeys. It was hypothesized that donkey ACTH concentrations would be higher than those reported in ho...
Perinatal Stress in Immature Foals May Lead to Subclinical Adrenocortical Dysregulation in Adult Horses: Pilot Study. The persistent endocrinological effects of perinatal stress due to gestational immaturity in horses are unknown, although effects have been reported in other livestock species. This pilot study tested the hypothesis that persistent adrenocortical dysregulation is present in horses that were gestationally immature at birth by assessing the salivary cortisol response to exogenous ACTH. Case horses (n = 10) were recruited with histories of gestation length < 315 d or dysmaturity observable through neonatal signs. Positive controls (n = 7) and negative controls (n = 5) were recruited wher...
Serum cortisol in mules intended for agricultural work. Cortisol is a hormone secreted by the adrenal glands that is stimulated by physiological and pathological factors and has been studied widely in equids, but not in mules. The objectives of this study were to obtain a reference value for serum cortisol in mules destined for agricultural activities and to identify age- and gender-related differences in the value. The concentration was obtained in blood samples using a commercial sandwich ELISA specific for cortisol. The concentration was 96.3 ± 40.6 ng/ml and similar between age groups and genders.
Corrigendum to: “The Rho kinase (ROCK) inhibitor Y-27632 reduces the β 2-adrenoceptor density but enhance cAMP formation in primary equine bronchial epithelial cells” [Eur. J. Pharmacol. 2021 Sep 15; 907:174323]. This research paper investigates the influence of the Rho kinase (ROCK) inhibitor Y-27632 on β2-adrenoceptor density and the generation of a cellular messenger called cAMP in horse bronchial cells. The [...]
Circulating Hypothalamic-Pituitary-Adrenal Axis Hormones and Insulin Concentrations in Horses and Ponies. Mechanisms resulting in breed predispositions to insulin dysregulation (ID) are poorly characterized. Cortisol antagonizes insulin, and free, biologically active cortisol can be increased in ID. Breed-related differences in serum free cortisol fraction (FCF) could contribute to ID, but FCF has not been quantified in equidae predisposed to ID, such as ponies. To compare FCF and other hypothalamic-pituitary-adrenal (HPA) axis hormones between horses and ponies during health and ID. We hypothesized: (1) FCF is higher in ponies than horses in health, and is higher still in ponies with ID and obes...
The Rho kinase (ROCK) inhibitor Y-27632 reduces the β2-adrenoceptor density but enhance cAMP formation in primary equine bronchial epithelial cells. The present study addresses the effect of the Rho-kinase (ROCK) inhibitor Y-27632 on the β-adrenoceptor density and β-agonist-stimulated intracellular second messenger cAMP formation in primary equine bronchial epithelial cells (EBEC). Y-27632 significantly decreased the β-adrenoceptor number (B) without markedly affecting the receptor affinity (dissociation constant, K) to the radioligand [I]-iodocyanopindolol (ICYP). In contrast, Y-27632 augmented the β-agonist-stimulated intracellular cAMP production. Herein, Y-27632 markedly increased the maximal cAMP responses (E) (isoproterenol >...
Adrenal Gland Ultrasonographic Measurements and Plasma Hormone Concentrations in Clinically Healthy Newborn Thoroughbred and Standardbred Foals. Adrenal hormones, ACTH plasma concentrations and the ultrasonographic evaluation of the adrenal glands are considered complementary in clinical evaluations of the hypothalamic-pituitary-adrenal (HPA) axis function in several species. In dogs, age, size and weight have a significant effect on the ultrasonographic size of the adrenal glands. In neonatal foals, ultrasonographic evaluation and measurements of the adrenal glands have been demonstrated to be reliable; however, the effect of individual variables on ultrasonographic features has not been investigated, and the clinical usefulness of ad...
Relationship between endogenous plasma adrenocorticotropic hormone concentration and reproductive performance in Thoroughbred broodmares. Pituitary pars intermedia dysfunction (PPID) is an endocrine disorder the clinical signs of which include infertility, but few reports have examined the relationship between PPID and reproductive performance in broodmares. Objective: Broodmares with infertility of unknown etiology were screened for PPID using baseline endogenous plasma ACTH concentrations, and its relationship with subsequent reproductive performance was analyzed. Methods: Sixty-seven Thoroughbred broodmares. Methods: Adrenocorticotropic hormone concentrations were measured in autumn. The broodmares were divided into 3 groups ...
Evaluation of the sensitivity and specificity of basal plasma adrenocorticotrophic hormone concentration for diagnosing pituitary pars intermedia dysfunction in horses: A systematic review. Measurement of basal adrenocorticotrophic hormone (ACTH) is currently used to diagnose pituitary pars intermedia dysfunction (PPID) in horses, yet a systematic review of the evidence for its use has not been undertaken. This study aimed to systematically review evidence regarding the sensitivity and specificity of the basal ACTH diagnostic test. Electronic databases were systematically searched in January 2019, September 2020 and January 2021, for English language publications published prior to these dates. Screening, data extraction and quality assessment of publications was undertaken by th...
The effects of an alpha-2-adrenoceptor agonist, antagonist, and their combination on the blood insulin, glucose, and glucagon concentrations in insulin sensitive and dysregulated horses. Alpha-2-adrenoceptor agonists are sedatives that can cause fluctuations in serum insulin and blood glucose (BG) concentrations in horses. The objectives of this study were to investigate the effects of detomidine and vatinoxan on BG, insulin, and glucagon concentrations in horses with and without insulin dysregulation (ID). In a blinded cross-over design, eight horses with ID and eight horses without ID were assigned to each of four treatments: detomidine (0.02 mg/kg; DET), vatinoxan (0.2 mg/kg; VAT), detomidine + vatinoxan (DET + VAT), and saline control (SAL). Blood samples were taken at 0, ...
Arterial oxygenation in anesthetized horses placed in a 5-degree reverse Trendelenburg position. Low arterial oxygen is a common complication in anesthetized horses and placing the animal in reverse Trendelenburg (RT) position may treat hypoxemia. The objective of this study was to assess the arterial partial pressure of oxygen (PaO) in horses placed in a 5-degree RT compared to horizontal (H) position. Client-owned healthy horses (n = 60) undergoing elective surgeries were enrolled in a randomized controlled clinical study. Horses were sedated with butorphanol, an α-adrenoceptor agonist, ± acepromazine and induced with ketamine combined with a benzodiazepine, propofol, or guaifenesin...
Ultrasonographic measurement of the adrenal gland in neonatal foals: reliability of the technique and assessment of variation in healthy foals during the first five days of life. Adrenal gland ultrasonographic measurements are useful in clinical evaluation of patients with adrenal dysfunction in several species. In human healthy neonates, the ultrasonographic size of the adrenal glands decreases during the first days of life. Ultrasonography of adrenal glands was demonstrated to be feasible in neonatal foals. The aims of this study were to describe a technique for ultrasonographic measurement of adrenal gland size to test its reliability in neonatal foals, and to assess any variation of ultrasonographic measurements during the first five days of life in healthy foals. ...
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...
Presence and function of β-adrenergic receptors in primary equine bronchial epithelia cells. The β-adrenergic receptor (β-AR) plays an important role in regulating a variety of cell and organ functions in different animal species and is an important target in asthma pathogenesis and therapy. The β-AR expression and function in equine bronchial epithelial cells (EBEC) were not known but innervation and significant decrease in receptor level were reported in the equine bronchial tissues from asthmatic horses. I-iodocyanopindolol (ICYP) binding studies were undertaken in primary freshly isolated and cultured EBEC to identify the presence of the β-ARs. The receptor distribution was as...
Relaxing effects of clenbuterol, ritodrine, salbutamol and fenoterol on the contractions of horse isolated bronchi induced by different stimuli. β-adrenoceptor agonists are considered the most effective drugs to counteract bronchoconstriction in horses with asthma, but only clenbuterol is commonly employed in clinical practice. We evaluated the effects of different selective β agonists: clenbuterol, ritodrine, salbutamol, and fenoterol on the contractions of isolated bronchial muscle of horses induced by electrical field stimulation (EFS), carbachol, histamine, and KCl. All β agonists reduced the amplitude of contraction induced by the different stimuli but with variable efficacy and potency. Fenoterol and salbutamol were more effec...
Plasma adrenocorticotropic hormone concentration in horses decreases after freezing for 60 days. We investigated the stability of adrenocorticotropic hormone (ACTH) in plasma after freezing for different lengths of time. The plasma ACTH concentrations of 12 horses were measured on day 0 (baseline) and over time, after stimulation with thyrotropin-releasing hormone. Samples were stored at -80°C for 3, 7, 30, 60, and 90 d, or at -20°C for 3, 7, 30, and 60 d, or between ice packs at -20°C for 3 and 7 d prior to determination of ACTH concentration. ACTH concentrations were compared to baseline (non-frozen day 0 plasma) for each storage method using a mixed model with repeated measure...
A possible solution to model nonlinearity in elimination and distributional clearances with α2 -adrenergic receptor agonists: Example of the intravenous detomidine and methadone combination in sedated horses. The alpha(α) -agonist detomidine is used for equine sedation with opioids such as methadone. We retrieved the data from two randomized, crossover studies where detomidine and methadone were given intravenously alone or combined as boli (STUDY 1) (Gozalo-Marcilla et al., 2017, Veterinary Anaesthesia and Analgesia, 2017, 44, 1116) or as 2-hr constant rate infusions (STUDY 2) (Gozalo-Marcilla et al., 2019, Equine Veterinary Journal, 51, 530). Plasma drug concentrations were measured with a validated tandem Mass Spectrometry assay. We used nonlinear mixed effect modelling and took pharmacokinetic...
Isolated airways in equine respiratory pharmacology: They never lie. Pre-clinical studies on human isolated bronchi have relevant translational value in human in vivo, conversely no investigation has been performed to assess whether data resulting from equine isolated airways can have any translational application in asthmatic horses. Thus, a meta-regression analysis via random-effect method was carried out to correlate the pharmacological characteristics of bronchodilators resulting from experiments performed in equine isolated bronchi with their impact on the lung function outcomes in asthmatic horses. Data on the potency of different bronchodilators were ext...
Cortisol and adrenocorticotropic hormone concentrations in horses with systemic inflammatory response syndrome. Plasma adrenocorticotropic hormone (ACTH) and serum cortisol concentrations increase with illness-associated stress. Dynamics of plasma ACTH and serum cortisol concentrations in adult horses with systemic illness are undocumented. Objective: To determine whether ACTH and cortisol concentrations and the ACTH/cortisol ratio vary with survival, the presence of systemic inflammatory response syndrome (SIRS), or ischemic gastrointestinal lesions at admission, or throughout hospitalization. Methods: One hundred fifty-one adult horses. Methods: Prospective study measuring serum cortisol and plasma AC...
Effect of delayed plasma centrifugation on equine adrenocorticotropic hormone concentration. Plasma adrenocorticotropic hormone (ACTH) concentration is used in the diagnosis of pituitary pars intermedia dysfunction (PPID) in horses. We enrolled 10 horses, 5 PPID-positive and 5 PPID-negative, in our study, September 20-22, 2016. On day 0, 5 mL of whole blood was collected into each of 6 EDTA tubes and immediately placed in a refrigerator at 7°C. One tube was centrifuged within 15 min of collection, followed by centrifugation of one tube from each horse at 4, 8, 12, 24, and 36 h following collection. At each time, centrifuged plasma was pipetted into 1.5-mL polypropylene tubes and stor...
Multiple adrenocortical steroid response to administration of exogenous adrenocorticotropic hormone to hospitalized foals. The hypothalamic-pituitary-adrenal axis regulates the response to sepsis-associated stress. Relative adrenal insufficiency or adrenocorticotropic hormone (ACTH):cortisol imbalance, defined as a poor cortisol response to administration of ACTH, is common and associated with death in hospitalized foals. However, information on other adrenal steroid response to ACTH stimulation in sick foals is minimal. Objective: To investigate the response of multiple adrenocortical steroids to administration of ACTH in foals. Methods: Hospitalized (n = 34) and healthy (n = 13) foals. Methods: In this prospecti...
Equine fetal adrenal, gonadal and placental steroidogenesis. The authors apologize for errors in Figure 6 of their article published in the October 2017 issue of Reproduction (vol 154 iss 4 pp 445–454). The authors explain that the addition of data (Figure 6) on steroid concentrations in the chorioallantois to their manuscript on fetal adrenal and fetal gonadal steroids during development of the equine fetus was made in response to reviewer comments. However, in compiling, summarizing and graphing the data, the wrong units were used in the final figure. The manuscript as published represents the data in Figure 6 as “ng/g”, when in fact they are ...
Adolescents’ Affective and Physiological Regulation Shape Negative Behavior During Challenging Equine Assisted Learning Activities. This study examined associations between adolescents' ( = 59; = 11.63) diurnal and momentary activity of the Hypothalamic Pituitary Adrenal (HPA) axis as marked by salivary cortisol, and affective and behavioral responses to their first, mounted equine assisted learning (EAL) activity. The introduction to riding occurred during the fifth week of an 11-week EAL program for at-risk and typically developing adolescents. Before the 11-week program began, participants collected 6 salivary cortisol samples at prescribed times (wakeup, 4 p.m., bedtime) over 2 days, from which indices of diurnal cor...
Diagnostic accuracy of post-ACTH challenge salivary cortisol concentrations for identifying horses with equine glandular gastric disease. The aims of this study were to better characterize the adrenal response to i.v. adrenocorticotropic hormone (ACTH) in horses with and without gastric disease and to validate and simplify the ACTH stimulation test by determining the diagnostic accuracy of six consecutive sampling time points after ACTH administration for equine glandular gastric disease (EGGD) and equine squamous gastric disease (ESGD). Twenty-six endurance and eventing horses without clinical disease [Sport Horse Population (SHP)] and an independent population of 62 horses [General Population (GP)] were grouped by gastroscopic...
Combining long-acting bronchodilators with different mechanisms of action: A pharmacological approach to optimize bronchodilation of equine airways. The ultra long-acting β -adrenoceptor agonist olodaterol plus the ultra long-acting muscarinic antagonist tiotropium bromide are known to relax equine airways. In human bronchi combining these drugs elicits a positive interaction, thus we aimed to characterize this information further in equine isolated airways stimulated by electrical field stimulation (EFS) and using the Concentration-Reduction Index (CRI) and Combination Index (CI) equations. The drugs were administered alone and together by reproducing ex vivo the concentration-ratio delivered by the currently available fixed-dose combina...
Plasma adrenocorticotropic hormone (ACTH) concentrations in ponies measured by two different assays suggests seasonal cross-reactivity or interference. Analysis of plasma adrenocorticotropic hormone concentration [ACTH] aids diagnosis of pituitary pars intermedia dysfunction (PPID). Comparisons of the validated chemiluminescent-immunoassay (CI) and immunofluorescent (IF) assays are limited. Objective: To compare the results of [ACTH] analysis by CI and IF methods of samples collected in autumn and spring and assess cross-reactivity. Methods: Method comparison. Methods: Plasma from nonlaminitic ponies was analysed concurrently using the IF and CI methods in autumn and the following spring. Diagnostic thresholds for the IF method were derived u...
Free and bound cortisol in plasma and saliva during ACTH challenge in dairy cows and horses. Cortisol levels reflect hypothalamic-pituitary-adrenocortical (HPA) axis activity. While most plasma cortisol is supposed to be bound to the soluble corticosteroid-binding globulin (CBG), only free cortisol (FC) actively regulates metabolic and immunological processes. We aimed to establish a multispecies suitable method to assess FC in cows and horses which in combination with total cortisol (TC) allows interpreting proportional changes of cortisol in saliva as well as in blood in response to a standardized HPA axis activation via ACTH. We further investigated if the ratios of cortisol fracti...
Profiles of pro-opiomelanocortin and encoded peptides, and their processing enzymes in equine pituitary pars intermedia dysfunction. Equine pituitary pars intermedia dysfunction (PPID) is characterized by hyperplasia of the pars intermedia (PI) melanotrophs of the pituitary gland (PG), and increased production of proopiomelanocortin (POMC). POMC is cleaved by prohormone convertase 1 (PC1) to produce adrenocorticotropic hormone (ACTH), and further processing of ACTH by PC2 to produce alpha-melanocyte stimulating hormone (α-MSH) and corticotropin-like intermediate peptide (CLIP). High plasma ACTH concentrations in horses with PPID might be related to reduced conversion of ACTH to α-MSH by PCs. The hypothesis of this study w...
Comparison of two methods for measurement of equine adrenocorticotropin. Accurate measurement of equine adrenocorticotropin (ACTH) is important for the diagnosis of equine pituitary pars intermedia dysfunction (PPID). Several radioimmunoassays (RIAs) and chemiluminescent immunoassays (CIAs) are used for measurement of ACTH concentration in horses; whether these methods yield similar results across a range of concentrations is not determined. We evaluated agreement between a commercial RIA and CIA. Archived plasma samples ( n = 633) were measured with both assays. Correlation between the 2 methods was moderate ( r = 0.49, p < 0.001). Bland-Altman analysis reveale...
