Daily Serum Cortisol Concentrations in Horses with Colic Requiring Exploratory Celiotomy

1. Introduction
Horses with colic may show signs of abdominal pain, cardiovascular abnormalities, and endotoxaemia, all of which cause physiological stress. This physiological stress induces stimulation of the hypothalamic-pituitary-adrenal (HPA) axis that ultimately stimulates cortisol release from the adrenal gland.¹

There are limited studies that have evaluated serum cortisol levels in horses with colic.^2–7  Interestingly, horses with colic that do not survive to discharge from hospital have significantly higher plasma cortisol concentrations at admission compared with horses that do survive to discharge.^3,7  Additionally, horses with higher heart rates, packed cell volumes, more severe colic signs, and strangulating lesions have higher serum cortisol concentrations at admission than those with low heart rates, normal packed cell volumes, mild colic signs, and non-strangulating lesions.⁷  Additionally, in humans with septic shock, high basal cortisol levels are described,⁸ and these are associated with an increased risk of death.^{9 –11} [...]