Related Experiment Video
Updated: Jun 25, 2026

Fecal Glucocorticoid Analysis: Non-invasive Adrenal Monitoring in Equids
Published on: April 25, 2016
Hypothalamic-pituitary-adrenal axis assessment in healthy term neonatal foals utilizing a paired low dose/high dose
K A Hart1, G L Heusner, N A Norton
1Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA. khart4@uga.edu
Background:
Hypothalamic-pituitary-adrenal (HPA) axis function is dynamic in the neonatal foal. The paired low dose/high dose cosyntropin (ACTH) stimulation test allows comprehensive HPA axis assessment, but has not been evaluated in neonatal foals.
Hypothesis:
Foal age will significantly affect cortisol responses to a paired 10 and 100 microg dose cosyntropin stimulation test in healthy neonatal foals.
Animals:
Twenty healthy neonatal foals.
Methods:
HPA axis function was assessed in 12 foals at birth and at 12-24, 36-48 hours, and 5-7 days of age. At each age, basal cortisol and ACTH concentrations were measured and cortisol responses to 10 and 100 microg cosyntropin were assessed with a paired ACTH stimulation test protocol. Eight additional 36-48-hour-old foals received saline instead of 10 microg cosyntropin in the same-paired ACTH stimulation test design.
Results:
At birth, foals had significantly higher basal cortisol and ACTH concentrations and higher basal ACTH : cortisol ratios compared with foals in all other age groups. A significant cortisol response to both the 10 and 100 microg doses of cosyntropin was observed in all foals. The magnitude of the cortisol response to both doses of cosyntropin was significantly different across age groups, with the most marked responses in younger foals. There was no effect of the paired ACTH stimulation test design itself on cortisol responses.
Conclusions And Clinical Importance:
A paired 10 and 100 microg cosyntropin stimulation test can be used to evaluate HPA axis function in neonatal foals. Consideration of foal age is important in interpretation of HPA axis assessment.
More Related Videos
Related Concept Videos
Hypothalamic-Pituitary Axis
Cushing Syndrome II: Pathophysiology
Cushing Syndrome I: Introduction
Adrenal Gland Disorders
Adrenal insufficiency, characterized by insufficient cortisol and aldosterone production, leads to conditions like Addison's disease. This disorder, affecting the adrenal cortex, exhibits symptoms such as skin bronzing, dehydration, low blood pressure, fatigue, and weight loss. Congenital adrenal hyperplasia, a genetic ailment causing...
Hormones of the Adrenal Glands
The adrenal cortex, a powerhouse of hormone synthesis, generates over two dozen corticosteroid hormones. The zona glomerulosa produces mineralocorticoids, exemplified by aldosterone, influencing the electrolyte composition of body fluids. The synthesis of glucocorticoids such as cortisol and corticosterone...
Physiological Foundation of Stress
Role of the Sympathetic Nervous System
Adrenaline triggers the...

