Addison’s Disease In Dogs
Addison’s disease (also called hypoadrenocorticism or adrenal insufficiency) is a relatively uncommon condition that affects dogs and humans. Most of us are familiar with John F. Kennedy, but few may know he had Addison’s Disease. At Best Friends Animal Hospital, we see several cases of Addison’s disease each year. Because we have seen three cases of Addison’s disease in the last two months, we thought this information may be helpful for dog owners.
What are adrenal glands?
The adrenal glands are complex organs that reside near the kidneys in the abdomen. They are made up of two parts – the outside is the cortex and the inside is the medulla. Addison’s disease affects the adrenal cortex, which normally produces corticosteroid hormones. The two main corticosteroids produced by the cortex are cortisol (which helps us with sugar, fat, and protein metabolism) and aldosterone (which helps us regulate our electrolytes sodium and potassium and our blood pressure). Both of these corticosteroids help us deal with stress. If the adrenal gland does not function properly and produce these hormones, life threatening disease (Addison’s disease) is the result.
What are the clinical signs of Addison’s disease in dogs?
The symptoms of dogs with Addison’s disease are vague and include vomiting, diarrhea, lethargy, inappetance, weakness, and tremors or shaking. Dogs may have a history of waxing/waning symptoms but most of the dogs we diagnose often present in the shock state or “crisis” state. Dogs that present in the “crisis” state show signs of shock, low heart rate, and low body temperature. Usually patients are young (3-5 years old) and female dogs are affected twice as often as males. Any dog can develop Addison’s disease but some dog breeds are more commonly affected (Portuguese Water Dogs, Bearded Collies, Standard Poodles, Great Danes, and West Highland White Terriers).
How do you diagnose Addison’s disease?
After completing a physical examination, if we suspect Addison’s disease, one of our next steps is bloodwork to look specifically at the patient’s levels of sodium and potassium. Typically, dogs with Addison’s have an elevated potassium and low sodium. We compare these numbers with the normal range for dogs and also with each other (sodium:potassium ratio). In addition, dogs with Addison’s disease often have a mild increase in BUN (blood urea nitrogen) and creatinine. If these changes are seen on the bloodwork, we may suspect Addison’s disease but cannot diagnose the disease without a confirmation test, called the ACTH Stimulation Test. The ACTH Stimulation Test is a blood test which involves a resting cortisol blood sample, and a cortisol sample after administration of cortrosyn (a synthetic hormone which normally tells the adrenals to release cortisol). In Addison’s dogs, resting cortisol levels and levels after administration of cortrosyn are both low because the adrenal glands are not functioning properly.
How do you treat Addison’s disease?
Although dogs that present in “crisis” situations are often very sick, they often respond very well to treatment with intravenous fluids and the administration of steroids (dexamethasone or prednisone). This can also confuse the diagnosis of Addison’s disease if an ACTH Stimulation Test is not performed. Long term treatment involves supplementing the dog with corticosteroids. The two commonly used products to replace aldosterone are “Percorten-V” (desoxycorticosterone pivalate) and “Florinef” (fludrocortisone acetate). Percorten-V is an injectable product that is typically given once every 28 days. Florinef is an oral medication that is administered daily. Many experts feel that Percorten-V provides better regulation of electrolytes than oral Florinef. The cortisol is replaced with prednisone. During times of stress, dogs often need additional prednisone. During the treatment phase, we frequently perform physical examinations and check the patient’s electrolytes (sodium and potassium) to determine the correct medication levels.
What is the prognosis for dogs treated for Addison’s disease?
When treated appropriately, dogs with Addison’s disease lead remarkably normal, active lives. Treatment does require a lifetime of medication and monitoring, however. In our experience, the cost of medication and monitoring is often the limiting factor in treating dogs with Addison’s disease. All medications are dosed based on the dog’s weight so treatment is more expensive for larger dogs.
What about whipworms?
Whipworm infection has been known to potentially lead to the same signs/symptoms as a dog experiencing an Addisonian crisis. Although these patients have altered sodium/potassium ratios, they have normal results on the ACTH stimulation test. We took this information into account when choosing Sentinel as our recommended monthly dewormer for dogs.
Additional Resources: www.addisondogs.com – an excellent website dedicated to supporting owners of dogs afflicted with Addison’s Disease.