Cushing's Disease/Hyperadrenocorticism in Cats

Feline Cushing's disease (syndrome), also known as hyperadrenocorticism, results from chronic excess of the cortisol hormone in the bloodstream. Cushing's develops from long-term administration of corticosteroid drugs or because of adrenal gland or pituitary gland tumors. Pituitary tumor is the cause in about 80 percent of cats, according to Petplace.com. Feline Cushing's occurs mostly in middle-aged or older cats, with about 70 percent being female and over 90 percent having concurrent diabetes.

  1. Symptoms

    • The most common signs of feline Cushing's are excessive drinking and urination and increased appetite. Cats may also exhibit one or several other symptoms including enlarged abdomen, lethargy and muscle weakness, muscle wasting, poor coat and/or symmetrical hair loss, curled ear tips, very thin fragile skin that is easily bruised and torn, weight gain or loss, excessive panting and recurrent infections. Because cortisol interferes with the effects of insulin, the development of diabetes that is difficult to control may also indicate Cushing's.

    Diagnosis

    • "Cushing's syndrome is not a diagnosis that should be made solely on the basis of laboratory testing," according to Petplace.com. Historical information and physical examination are equally important. Diagnostic tests can include complete blood count, biochemical profile, urinalysis with culture and sensitivity, blood pressure evaluation, chest and abdomen X-rays, abdominal ultrasound, CT or MRI of the abdomen, an ACTH (a pituitary hormone) level test as well as reactions to hormone administration and drug administration tests, delivered separately and in combination with each other.

    Treatment

    • Medical therapy is of limited value in the control of feline Cushing's, although the drug metyrapone has shown occasional success. Surgical treatment is the treatment of choice. "Since pituitary dependent Cushing's disease causes bilateral adrenal enlargement, the most effective treatment option is the surgical removal of both adrenal glands," says Petplace.com. Adrenal tumor-caused Cushing's is treated by unilateral adrenalectomy, removal of the affected adrenal gland. Both types of surgeries are difficult and require extensive post-operative care. They're usually done at a referral institution or specialty hospital.

    Home Care

    • Following surgery, the cat's owner must watch for weakness, disorientation, lethargy, vomiting, diarrhea or any change in the cat's attitude. Frequent blood tests are required to monitor the cat's blood glucose and electrolytes. It's important for owners to closely follow the veterinarian's instructions for adjustments to insulin and oral medications. They'll need to take the cat in for evaluations at least several times a year. Cats with concurrent diabetes need to be watched closely for changes in water consumption and urine production.

    Expert Insight

    • According to the Feline Advisory Bureau (FAB) website, "Cushing's syndrome is a serious disease and carries with it a guarded to poor prognosis. Treatment options are very limited, treatment can be expensive, stressful for the cat and owner and, unfortunately, there is no guarantee of treatment being a success. Even with 'successful' treatment, less than 50 percent of cats afflicted with the disease will survive beyond a year. Hopefully, in the future newer treatment modalities will become available improving the outlook of cats with Cushing's syndrome."