Cushing’s disease, or hyperadrenocorticism, is a common endocrine (glandular) disease in dogs. It is caused by the excess production, by the adrenal glands, of a hormone called cortisol. It can develop naturally or be caused by the administration of corticosteroids such as prednisone (iatrogenic Cushing's disease). More than 80 to 90 percent of dogs with the naturally acquired form of this disease --"pituitary dependent" Cushing's disease -- has a tumor in the pituitary gland, which is located at the base of the brain. This tumor stimulates the adrenal gland to produce cortisol. The remaining cases of naturally occurring Cushing’s disease -- adrenal tumor hyperadrenocorticism -- result from a tumor of the adrenal gland that causes the production of too much cortisol. Cushing’s disease usually has a negative effect on quality of life in affected dogs, but it is very rarely life threatening.
Cushing’s disease is a syndrome comprised of a group of clinical symptoms. The most common symptoms of Cushing’s disease include excessive drinking and urination, increased appetite, hair loss, muscle weakness, a "potbellied" appearance, panting, thin skin, and lethargy. Other symptoms include susceptibility to infections and slow wound healing. Virtually all dogs with Cushing's disease have at least one of these symptoms, but it would be uncommon to have all of them. Most owners reach a point where the water consumption and urination become noticeable and a matter of concern.
Whenever your pet is showing signs of a health issue your first step is to contact your primary care veterinarian. If it is indicated that your pet may suffer from Cushing's disease or another serious condition, a veterinary specialist is available at an ExpertVet certified hospital.
The most important initial screening tests for Cushing's disease are a review of the pet’s history and a physical examination. Cushing’s disease is comprised of a constellation of clinical signs referable to the disease. Testing patients with isolated blood work abnormalities (such as an elevation in serum alkaline phosphatase) without compatible clinical signs may lead to a false diagnosis of hyperadrenocorticism. Cushing's disease is not an acute disease (having a short and relatively severe course), but one with signs symptoms that progress slowly over time. Rarely are these patients critically or seriously ill.
Both laboratory testing and imaging studies (such as ultrasound) are helpful in making the diagnosis of Cushing’s disease and differentiate between pituitary dependent Cushing’s disease and adrenal tumor Cushing’s disease. A biochemical profile can provide additional information that Cushing's disease may be present. Urine tests may be performed to determine how concentrated the urine is or to screen for infection.