Cushing's Disease is a disorder that usually occurs in older horses, although it can happen as early as age seven. It is treatable at any age, and early treatment will allow the horse to enjoy a good quality of life in its remaining years.
Cushing's Disease is triggered by a pituitary tumor, which makes cells become overactive and release too much pro-opiolipomelanocortin. It also pressures the neighboring hypothalamus, causing problems with body temperature regulation.
Symptoms include a thick, wavy coat of coarse hair that does not fall out in the spring, abnormal thirst, excessive urination, muscle loss and a hanging pot belly.
Untreated Cushing's Disease makes horses prone to other illnesses, such as the hoof disease laminitis. It can also cause rapid weight loss, abnormally distributed fat and abscesses.
Cushing's Disease is diagnosed through the symptoms or with a dexamethasone suppression test, adrenocorticotropic stimulation or a thyroid stimulating hormone release test.
Cushing's Disease can be treated with bromocriptine mesylate, but it is difficult to absorb and can have unpleasant side effects. Cyproheptadine is more popular because it is readily absorbed. Ground chastetree berry is a natural treatment that has not been scientifically proven.
Treatment relieves the symptoms, but does not cure Cushing's Disease. It can maintain a horse's quality of life for many years, but eventually euthanasia becomes necessary.