Cushing's Syndrome

Cushing's syndrome (Hyperadrenocorticism) is a very complicated and serious disease. It results when too much steroid hormone (cortisol) is produced by the body or when steroids (such as prednisone) are given for a prolonged period of time to treat other diseases.

Cortisol is produced and secreted from the adrenal glands that are located in the abdomen near the kidneys. How much steroid they produce and when it is released is controlled by the pituitary gland in the brain. This complex relationship can be altered in several ways to produce Cushing's disease.

There are 3 forms of Cushing's Disease:

1. Pituitary-Dependent Cushing's Disease - This is the most common form of Cushing's Disease. It accounts for approximately 85% of cases. It occurs when a very small tumor develops in the pituitary. This tumor sends excessive messages to the adrenal glands to produce and release steroids beyond what the body needs.

2. Adrenocortical Tumors - Tumors of the adrenal glands account for the other 15% of the cases. These are functional masses which are malignant about 50% of the time. The majority of dogs with adrenal tumors are female.

3. Iatrogenic Cushing's Syndrome - This form of the disease is caused by excessive and/or prolonged steroid administration.

Cortisol affects all organ systems. Some of these changes can be readily apparent while others are hidden inside and only detectable with diagnostic tests. The symptoms a dog with Cushing's may demonstrate include:

¨ Pot-bellied appearance

¨ Symmetrical hair loss

¨ Dull, dry haircoat

¨ Thin skin

¨ Pigmented skin

¨ Muscle atrophy

¨ Excessive urination

¨ Excessive thirst

¨ Recurrent infections

¨ Panting

¨ Lethargy

¨ Weakness

Dogs affected with Cushing's are typically middle-aged to older pets. Poodles, dachshunds, Boston terriers and boxers are more commonly affected.

The diagnosis of Cushing's is based on the results of blood tests. When Cushing's is suspected, a CBC, chemistry panel and urinalysis should be performed to establish a baseline and to detect underlying diseases. If the baseline lab results are supportive of Cushing's Disease, specific tests of adrenal gland function should be run. This requires 1 to 3 more blood tests to determine which form of the disease the pet has.

The treatment for Cushing's depends on which form of the disease the pet has. If the disease is being caused by an adrenal tumor, surgery may be indicated. If it is being caused by the administration of steroids, judicious removal of the medication should be considered. The treatment for pituitary-dependent Cushing's Disease is more complicated. It involves the use of oral medication such as, Lysodren^â or Vetoryl^â. Whatever the form of the disease, treatment is not risk free.

The life expectancy of a dog with Cushing's is shorter than for normal dogs. The average survival time after diagnosis is 2-3 years with the appropriate treatment. Complications that may arise include blood clots, infections, hypertension, heart failure diabetes, pancreatitis, and other illnesses.

Owning a pet with Cushing's Disease can be problematic. The decision to test and treat is based on many things. Please feel free to discuss all the options with us before making your decisions.