1998 Volume 9 Issue 3 Pages 77-81
The hormones of the adrenal axis help athletes adapt to the stress of training and racing. When performance is poor, dysfunction of this axis is often suspected, but confirming this has been difficult. We have found three hallmarks of chronic stress in horses that are easily monitored: 1) loss of the circadian cortisol rhythm, 2) decrease in corticosteroid-binding globulin and an increase in free cortisol, and 3) reduced ACTH (& hence cortisol) response to a small dose (2 μg) of equine/human corticotropin-releasing hormone (CRH). The presence of some or all of these abnormalities is a good indication that the horse is not coping with the stresses imposed upon him.
