Addison's disease, also known as hypoadrenocorticism, is a relatively uncommon disorder that most frequently affects young to middle-aged female dogs. The adrenal glands, which are located next to the kidneys, are responsible for producing hormones called glucocorticoids that allow animals to respond to stressful situations and mineralocorticoids that maintain normal fluid and electrolyte levels in the body. When adrenal gland function is diminished, often by an abnormal immune response or treatment with some types of drugs, Addison's disease is the result.
Typical symptoms include vomiting, diarrhea, weakness, dehydration, loss of appetite and weight and sometimes a slow heart rate and collapse. A veterinarian may suspect Addison's disease based on an animal's clinical signs and the results of routine lab work (e.g., low sodium and high potassium levels in the blood), but definitive diagnosis requires an ACTH stimulation test. Without a comprehensive work-up, Addison's disease can be confused with gastrointestinal problems (especially whipworm infections), kidney disease, pancreatitis, a ruptured bladder and some types of poisonings.
Severely affected dogs are often hospitalized for intravenous fluid therapy, glucocorticoid injections and treatments that normalize the body's electrolyte levels. Long-term therapy includes either daily administration of an oral drug or injections roughly once a month to replace the body's missing mineralocorticoid hormones. Many dogs also must receive oral prednisone, a glucocorticoid, every few days or sometimes more frequently during times of stress.
With appropriate therapy, most dogs with Addison's disease can live full and relatively normal lives. It must be remembered, however, that Addison's disease cannot be cured, only managed, and that treatment and routine monitoring is a lifelong commitment.
Written by: Jennifer Coates, DVM
Last reviewed: October 2, 2008