Introduction
Hypoadrenocorticism, commonly called “Addison’s disease,” is a potentially life-threatening endocrine condition that is extremely rare in cats and cannot be cured but, if caught early, may be controlled. Addison’s can be primary (due to damage to the adrenal glands) or secondary (from destructive lesions or congenital defects of the hypothalamus or pituitary gland). The clinical signs of Addison’s are caused by an inability or insufficiency of the cat’s adrenal glands to produce the necessary amounts of steroid hormones. The disease can wax and wane and normally causes progressively severe signs in cats ranging from mild gastrointestinal upset to acute collapse. Treatment protocols for cats with Addison’s disease depend upon the underlying cause of the condition.
Treating Addison's Disease in Cats
The goals of treating acute Addison’s episodes are to replace bodily fluid volume, correct electrolyte imbalances and provide an immediate source of rapid-acting systemic corticosteroids. These goals focus on stabilizing cortisol levels and minimizing the harmful consequences of low circulating corticosteroids, which include shock, vomiting and diarrhea, and initially requires hospitalization. Owners normally can manage their cats at home once the acute crisis has resolved.
The aggressiveness of initial treatment will depend in large part on the cat’s clinical status. Acute Addisonian episodes are medical emergencies and require immediate veterinary intervention, even before diagnosis of the disease is confirmed. Waiting for the results of diagnostic tests may result in death. Emergency treatment includes placing the cat on intravenous fluids (usually normal saline) and giving injections of appropriate glucocorticoids. While dogs often show marked improvement within 24 hours of treatment, cats tend to have a slower initial response to therapy and may remain weak and listless for 3 or 5 days despite appropriate treatment. ACTH stimulation testing should be done once the cat is stabilized.
Once fluid levels are restored and hormone levels are stabilized, and after the cat has recovered from any other adverse effects of the disease, the owner can take the pet home. Chronic treatment typically will involve lifelong oral supplementation with corticosteroids, the choice of which will be made by a veterinarian based upon whether the cat’s disease is primary or secondary. Addison’s patients should have regular urine and blood tests to monitor their systemic cortisol and electrolyte levels. If elevated blood potassium levels persist, the cat may need additional drug therapy.
The prognosis for cats with Addison’s disease is excellent as long as their owners are conscientious about daily treatments and periodic veterinary monitoring. Excellent communication between owners and their veterinarians is critical to the successful treatment of this uncommon disease in cats.