Endocrine alterations in the equine athlete: an update.

Horses spend most of their day eating, standing, and occasionally exercising. Exercise can range from running in a pasture to athletic training. Under resting conditions, horses easily maintain the internal environment. The performance of work or exercise is a major physiologic challenge, a disturbance to homeostasis that invokes an integrative response from multiple organ systems. The response to exercise involves endocrine and neuroendocrine signaling associated with the short-term and adaptive control of many systems. The coordinated control of multiple physiologic variables is essential for achieving regulation to maintain the integrity of the internal environment of the body.