Hormones in horses are chemical messengers produced by various glands and tissues, regulating numerous physiological processes essential for maintaining homeostasis. These hormones influence a wide range of functions, including growth, metabolism, reproduction, and stress responses. Key hormones in equine physiology include cortisol, estrogen, testosterone, and insulin, among others. The levels and effects of these hormones can vary based on factors such as age, sex, and environmental conditions, impacting overall health and performance. This page compiles peer-reviewed research studies and scholarly articles that explore the production, regulation, and physiological roles of hormones in equine biology.
Pinto-Bravo P, Rebordão MR, Amaral AS, Szóstek-Mioduchowska A, Fernandes C, Galvão AM, Silva E, Alpoim-Moreira J, da Costa RPR, Skarzynski DJ....Oviduct glycoprotein 1 (OVGP1) is a key protein involved in oviductal functions. β-estradiol (E) and progesterone (P), oxytocin (OXT) and tumor necrosis factor-α (TNFα) modulate the equine oviduct function, through prostaglandin regulation. The objective was to evaluate OVGP1 expression within each equine oviduct segment (infundibulum, ampulla isthmus), throughout the estrous cycle. The in vitro effect of (i) E, P, OXT, TNFα; and (ii) spermatozoa, on oviduct OVGP1 transcription and secretion was studied. Gene transcription was assessed by real-time PCR; protein expression by western blot; ...
Massardi E, Gaudenzi G, Carra S, Oldani M, Rybinska I, Persani L, Vitale G.Cushing's disease (CD) is a rare neuroendocrine disorder caused by ACTH-secreting pituitary adenomas, presenting significant diagnostic and therapeutic challenges. Given the evolutionary conservation of the hypothalamic-pituitary-adrenal axis, this review explores the translational value of spontaneous CD forms in dogs, horses, cats, small mammals, and rats, as well as of experimental models in mice, rats, and zebrafish. Dogs are the most studied, showing strong molecular and clinical similarities with human CD, making them valuable for preclinical drug and diagnostic research. While equine an...
Omyla K, Conley A, Varner D, Dini P.Persistent stallion-like behavior is a common sign of cryptorchidism in supposed geldings. The presence of testicular tissue can be evaluated by analyzing hormones such as testosterone and anti-Müllerian hormone (AMH). Here, we used hormonal analysis to investigate relationships between the likely presence of testicular tissue and stallion-like behavior in samples submitted from presumptive geldings (n = 1,202), retrospectively. Most geldings with stallion-like behaviors had serum concentrations of testosterone (851/1,056; 80.6 %) and AMH (682/877; 77.8 %) below the laboratory reference range...
Muñoz-Jurado A, Requena F, Agüera EI, Escribano BM.Anti-Müllerian hormone (AMH) is a dimeric glycoprotein belonging to the superfamily of the transforming growth factor-β. Due to the discovery of AMH functions, relative to the ovarian function, it is being postulated as being a highly important marker in studies on mammalian reproduction. Therefore, the objective of this review was to describe the role of this hormone in different reproductive aspects of female mammals, taking women, cows, and mares as reference species. The relationship between ovarian reserve and AMH was analysed, and it has been verified that there is a relationship betwe...
Shakeel M, Yoon M.Brain-derived neurotrophic factor (BDNF) and its receptor neurotrophic tyrosine receptor kinase-2 (NTRK2) have known important roles in the central nervous system for neurite growth, survival, and differentiation. Nevertheless, the significance of BDNF in spermatogenesis remains unclear in stallions. Therefore, the present study was designed 1) to investigate the expression of BDNF and its receptor NTRK2 and 2) the seasonal variation in the expression patterns of BDNF and NTRK2 in stallions' testes. We used testes from eight postpubertal Thoroughbred stallions collected after a field castratio...
Raeside JI, Christie HL, Chenier T, Brewer D, Charchoglyan A.Mass spectrometry (MS) has become pivotal for accurately delineating intricate molecular structures for steroids present in minute quantities within biological samples. This study utilized liquid chromatography-high resolution tandem mass spectrometry (LC-HRMS/MS) to identify and characterize a 'new' estrogen metabolite, 5α,6α-epoxy-estrone sulfate, in stallion serum from three animals. The estrogen structure was predicted previously using radiolabeled steroids. HRMS/MS, in combination with a seamless sample preparation involving liquid-liquid extraction and chromatographic separation, enabl...
Steel R, Timms M, Bamford N, Spence R, Sillence M.Previous liquid chromatography/mass spectrometry (LC/MS) methods for the detection of insulin and other similar peptide hormones in equine plasma relied on the use of antibody affinity extraction. As a result, these methods were not suitable for routine high-throughput analysis. A solid-phase extraction (SPE) method incorporating size exclusion as well as reversed-phase interactions allows the selective extraction of peptide hormones such as adrenocorticotropic hormone (ACTH), insulin and their synthetic analogues from equine plasma with approximately 80% extraction efficiencies. This extracti...
Li M, Lin J, Ma C, Wei G, Hu Q, Li X.L-selenomethionine (L-SeMet), a highly bioavailable organic form of selenium, plays a critical role in maintaining antioxidant homeostasis, regulating reproductive hormone secretion, and improving intestinal microbial ecology. Previous studies have demonstrated that appropriate supplementation with L-SeMet can significantly enhance the production performance and health status of ruminants. However, the nutritional regulatory mechanisms and physiological effects of L-SeMet in monogastric herbivores, particularly horses during mid- to late gestation, remain inadequately understood. Therefore, th...
Yang X, Wen L, Wen M, Yao X, Meng J, Zeng Y, Ren W.Equus caballus is a species of considerable economic and cultural significance. However, the regulatory networks involved in equine sexual maturation remain unclear and eventually limit its reproduction and utilization. In this study, testicular tissues from eight Kazakh horses at two developmental stages (2 years, representing pre-maturation, and 3 years, representing post-maturation) were analyzed using whole transcriptome sequencing, data-independent acquisition (DIA) proteomics, and untargeted metabolomics. An integrated regulatory network was constructed encompassing ceRNA, mRNA, prot...
Rivers S, Robertson G, O'Sullivan L, Powell T, Porr S.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...
Auvinen JRE, Stapley ED, Bertin FR.To evaluate the diagnostic performance of a post-/pre-thyrotropin-releasing hormone (TRH) plasma ACTH ratio for the diagnosis of pituitary pars intermedia dysfunction (PPID) in horses. Unassigned: This was a prospective, case-controlled study conducted monthly from January through December 2018 on 21 horses with PPID and 63 control horses. The ratios were calculated by dividing the plasma ACTH concentration obtained 30 minutes after IV injection of TRH by the pre-TRH plasma ACTH concentration. The effect of PPID and month were assessed using a linear mixed-effect model, and the diagnostic perf...
Hennes N, Tutin L, Foury A, Vancassel S, Bourguignon H, Duluard A, Ruet A, Lansade L.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...
Siwińska N, Żak-Bochenek A, Jawor P, Pietrzak A, Kutermak O, Słowikowska-Łoś M, Kaczmarek B.Due to growing interest in endocrine diseases, more studies aim to interpret the baseline concentrations and reference intervals of hormone values like adrenocorticotropic hormone (ACTH) and thyroxine (T4) in horses. Most studies available in the literature focus on evaluating ACTH and thyroid hormone values in adult and geriatric horses, with only a few considering younger donkeys and ponies. This study aimed to measure ACTH and T4 in autumn and spring in younger equids. The study included 42 young equids, which were divided into three groups: horses, ponies, and donkeys. The concentration of...
