Cushing's disease is the excess secretion of hormones, such as cortisol, caused by slowly growing tumors in horses' pituitary glands, states petMD. The disease most often strikes horses over the age of 7.
Cushing's disease is also known as pars intermedia dysfunction, as the tumors that cause the disease are located in the pars intermedia, or middle, of the pituitary gland, notes petMD. Signs of Cushing's disease in horses include inflammation of the interior of the hoof, weight loss, mouth ulcers, excessive thirst and the development of long, thick coats with abnormal shedding. Horses with Cushing's disease are more prone to infections as a result of cuts or scrapes, and they may develop pot bellies, suffer from wasted muscles and exhibit large fat deposits along their manes.
Veterinarians diagnose Cushing's disease in horses by completing tests and blood work to rule out other conditions, and then conduct further tests to more definitively diagnose the disease, according to petMD. Veterinarians treat Cushing's disease in horses with oral medications such as pergolide, though there is no definitive treatment for the disease. Horse owners can help treat the symptoms of Cushing's disease by bringing horses with hoof inflammation on frequent farrier visits. To prevent infections, horse owners must clean and disinfect any wounds on horses suffering from Cushing's disease.