Adrenal Gland Disease in Cats

Types

• There are two primary types of adrenal gland disease in cats: hypoadrenocorticism, or Addison's disease, and hyperadrenocorticism, also called Cushing's disease. When the adrenal glands produce too little hormone, a diagnosis of Addison's disease is given. Cushing's disease results when the cat's adrenal glands produce excess levels of glucocorticoid hormones. A third type of adrenal disease, Conn's syndrome, is extremely rare.

Causes

• Addison's disease generally results from an autoimmune disorder, when the cat's immune system destroys adrenal tissue. Pituitary gland tumors are the most common cause of Cushing's disease in cats, accounting for more than 50 percent of cases. These tumors cause the adrenal glands to develop extra hormone-producing tissue. Sometimes, the tumors develop inside the adrenal glands themselves. Conn's syndrome results from abnormal cell growth in the adrenal gland.

Symptoms

• Symptoms of Addison's disease include vomiting, excessive urination and drinking, weakness, dehydration, lethargy, loss of appetite and urethreal obstruction. Cushing's disease usually presents with signs of diabetes mellitus, since most cats that develop this adrenal gland disease also develop diabetes mellitus. Symptoms include excessive drinking, thirst, urination and eating. In addition to symptoms of diabetes, cats may develop thin, fragile skin, hair loss, depression, a potbelly, frequent infections and muscle weakness and wasting. Conn's syndrome presents with lower than normal levels of potassium, muscle weakness and high blood pressure.

Diagnosis and Treatment

• Before treatment for Cushing's disease can begin, the diagnosis must be confirmed using ultrasound to look for tumors or adrenal gland enlargement. Surgery to remove the adrenal glands is the primary treatment for Cushing's disease. Sometimes, veterinarians will try treatment with a medication called mitotane before surgery to reduce hormone production. Diagnosis of Addison's disease depends on the results of urine and blood tests. Treatment is with supplemental fluids and hormone-replacement therapy. Conn's syndrome is treated with potassium supplements and blood pressure medications, or with surgery to remove any adrenal tumors responsible for the disorder.

Warning

• Abrupt discontinuation of steroid medications used to treat allergies or other conditions can sometimes trigger the development of Addison's disease in cats. For this reason, cats should only take steroids short-term, and the medications should be gradually discontinued when they are no longer necessary. Adrenal disease in cats is fatal without prompt treatment. A veterinarian must evaluate any cat showing symptoms of adrenal disorders as soon as possible.