Addison's disease (hypoadrenocorticism) in dogs is a disorder that can cause a wide range of symptoms. The most common signs are lethargy, loss of appetite, vomiting, and diarrhea. In severe cases, Addison's disease can lead to shock and even death. Fortunately, the condition can be treated with medication, and most dogs who receive treatment make a full recovery.
What is Addison's disease in dogs?
Addison's disease is an endocrine disorder that affects the adrenal glands. The adrenal glands are located near the kidneys (one on each side of the body) and produce several different hormones, including cortisol. Cortisol has many functions in the dog, but one of its responsibilities relates to handling stress and emergencies.
The most common cause of Addison's disease is an autoimmune reaction that targets the adrenal glands. This means the immune system is malfunctioning and mistakenly attacking healthy tissue, in this case, the adrenal glands.
Addison's disease can also be caused by a tumor in the dog's adrenal gland and other processes that destroy the adrenal glands such as infections.
What Causes Addison's Disease in Dogs?
Immune-mediated destruction of the adrenal gland is the most likely and common cause of Addison's disease. Addison's disease occurs when the adrenal glands are not able to produce adequate quantities of hormones, including cortisol (glucocorticoid) and aldosterone (mineralocorticoid). These are important regulators of water retention, blood pressure, and potassium levels in the blood. Without proper levels of these hormones, many bodily functions are negatively affected.
What are the most common breeds affected by Addison's Disease?
There are many breed predilections but the most common breeds affected are:
- Standard poodle
- Labrador retriever
- Portuguese water dog
- Cocker spaniel
- Cairn terrier
- West Highland white terrier
80% of all cases are less than 7 years of age and the majority are females.
What are the symptoms of Addison's disease in dogs?
Addison's is often referred to as the great pretender by veterinarians because the symptoms often overlap with other, more common conditions. Typical symptoms of Addison's disease in dogs include:
In severe cases, there may be a sudden onset of vomiting and diarrhea which progresses to lethargy, collapse, and shock.
How is Addison's disease in dogs diagnosed?
Addison's disease can be quite difficult to identify because the symptoms are broad and non-specific. In addition, other conditions can cause similar signs including liver disease, pancreatitis, renal failure, Cushing's disease, and diabetes mellitus.
Several tests are usually needed to help confirm the diagnosis including:
Sodium and potassium levels in the blood - low sodium and high potassium are the hallmark signs of Addison's disease but may not be present early on when the dog is still producing some mineralocorticoid hormone. Atypical Addison's disease cannot be diagnosed by measuring sodium and potassium levels.
Urinary cortisol to creatinine ratio - this test measures the amount of cortisol (glucocorticoid hormone) excreted by the kidney and compared to creatine which is a product of muscle breakdown. If the dog has Addison's disease, urine cortisol will be low or absent while serum cortisol will be within normal limits.
ACTH stimulation test - Results of this test confirm the diagnosis. This test directly stimulates the adrenal glands. After stimulating the adrenal glands with ACTH (a pituitary hormone that stimulates the adrenal glands to produce cortisol), blood cortisol levels are checked. If the values are low, Addison's disease is confirmed. This test will confirm typical and atypical forms of Addison's disease in dogs.
What is atypical Addison's disease in dogs?
This is also referred to as secondary Addison's disease. In the atypical Addison's disease, dogs are only deficient in cortisol (glucocorticoid) and NOT aldosterone (mineralocorticoid). Therefore the symptoms are much different whereas atypical Addison's disease, chronic symptoms such as vomiting, diarrhea, hair loss, and weight loss are more common.
Maintenance therapy for dogs with Addison's disease
Mineralocorticoid supplementation is needed for cases of primary Addison's disease to help regulate the sodium and potassium levels in the blood. Typical options include:
Fludrocortisone acetate (Florinef®) - oral medication with mineralocorticoid and some glucocorticoid effects. It can be dosed once or twice daily.
DOCP (Percorten®, Zycortal®) - are injectable mineralocorticoid supplements. The injection will be performed by your veterinarian every 28 days. At our animal hospital, most of our Addisonian patients receive this injection as we feel it provides better control compared to that of Florinef®.
Glucocorticoids (prednisone, dexamethasone) - Patients with Addison's disease, as well as those being treated with DOCP injections, require glucocorticoid supplementation. It is sometimes also needed in patients being treated with fludrocortisone but because fludrocortisone has some glucocorticoid activity, prednisone may not be needed.
What is the prognosis for dogs with Addison's disease?
Although lifetime therapy is required, the prognosis is usually very good with the appropriate therapy.
Common questions about Addison's disease in dogs
What is the life expectancy of a dog with Addison's disease?
If left untreated or treated improperly, Addison's disease can be fatal. Dogs that are well managed however can live normal lives and expect normal life expectancy.
What triggers Addison's disease in dogs?
There are no definitive triggers for the development of Addison's disease in dogs. Dogs that have Addison's disease can have a difficult time with stressful events, however. Often dogs that have undiagnosed Addison's disease will have an Addisonian crisis after a stressful event.
Is Addison's disease painful for dogs?
Yes, Addison's disease can cause abdominal pain in dogs.
Addison's disease is a disorder that can cause a wide range of symptoms in dogs. The most common signs are lethargy, loss of appetite, vomiting, and diarrhea. In severe cases, Addison's disease can lead to shock and even death. Fortunately, the condition can be treated with medication, and most dogs who receive treatment make a full recovery.