Related Experiment Video
Updated: Sep 19, 2026

Fecal Glucocorticoid Analysis: Non-invasive Adrenal Monitoring in Equids
Published on: April 25, 2016
The Influence of Season on Endocrine Testing in Equids
1Department of Internal Medicine, Liphook Equine Hospital, Liphook, GU307JG, UK.
Abstract:
Endocrine function in equids is strongly influenced by season, with photoperiod as the primary driver and additional modulation by factors such as breed, geography, age, and nutrition. These seasonal effects have important implications for the interpretation of endocrine diagnostic tests. Circannual rhythms influence pituitary activity, resulting in predictable seasonal variation in adrenocorticotropic hormone concentrations and forming the basis for seasonally adjusted diagnostic thresholds for pituitary pars intermedia dysfunction. Seasonal effects on insulin dynamics are less understood but increasingly support a winter-associated increase in serum concentrations. Recognizing seasonal patterns improves the interpretation of endocrine test results and supports accurate clinical decision-making.
Related Concept Videos
Hormonal Regulation of the Menstrual Cycle
At puberty, GnRH begins a pulsatile release pattern, which triggers the anterior pituitary gland to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The frequency and amplitude of GnRH pulses vary across the menstrual cycle, with faster pulses favoring LH release and slower pulses favoring FSH release.
Regulation of Hormone Secretion
Humoral stimuli,...
An Overview of the Endocrine System
The endocrine system collaborates...
Major Hormones and Their Functions
Oxytocin, produced in the hypothalamus and released by the pituitary gland, plays a role in social bonding, childbirth, and lactation.
Hormonal Control of the Ovarian Cycle
Before puberty, the hypothalamus releases GnRH in a low frequency, low amplitude pulsatile manner. This along with the immature hypothalamic-pituitary-gonadal axis activity, results in low estrogen levels and the absence of a fully functional ovarian cycle. At puberty, GnRH secretion increases in both frequency and...
Endocrine Signaling

