Chapter 50 Diseases of the Endocrine System
The endocrine system of the horse controls almost all of the body’s functions. Because of this, it is readily apparent when a horse has an endocrine problem. Fortunately, few problems are seen in this system.
Equine Cushing’s syndrome is one of the more common endocrine diseases that affect horses. This disease is more commonly found in older horses, that is, those in their late teens to early twenties. The disease is a result of hypertrophy and hyperplasia of pituitary gland (it gets bigger). The body experiences a decrease in dopamine production and an increase in adrenocorticotropic hormone (ACTH) secretion. ACTH causes increased cortisol concentrations. Cortisol causes a number of changes in the body, including decreased immune responsiveness, loss of the muscle mass due to catabolism, and increase in blood glucose concentrations. The first signs of this disease in the older horse may be the presence of a long, shaggy coat that is not shed normally in the spring.