The disease typically begins with extremely heavy sweating all over, followed by the development of patchy sweating under the mane and between the legs over a period of 1-3 months. As the ability to sweat is progressively lost, the horse will begin puffing and blowing forcibly after exercise in efforts to compensate heat loss. A dry coat, thinning hair on the head and upper neck, and poor stamina are also symptoms of the disease. In more severe cases, the horse may develop “heat overload” and collapse during strenuous exercise.

Equine anhidrosis, also known as dry coat, is a disease in which a horse is unable to sweat in response to temperature extremes. The disease occurs in areas where hot and humid conditions predominate. In North America, the disease is most common in the Gulf Coast states. It has been estimated that 20 percent of horses in Miami, Florida are affected. Horses involved in training are more susceptible to the disease. There is no coat-color, age, sex, or breed predilection.

Anhidrosis - a look into the causes and some ways to control anhidrosis, or non-sweating, in horses. It can affect horses of all breeds and all ages. It is thought to be triggered by stress - exercise, heat etc. It can come on suddenly, or develop over a period of time. It can vary in severity - from a horse which sweats a little, especially under the saddle and between the hind legs, to one whose coat remains completely dry. In a horse with anhidrosis, the horse's body temperature and respiration will stay dangerously high, risking heat stroke unless steps are taken to help him cool down.