Overview of Canine Hypoadrenocorticism (Addison’s Disease)
Hypoadrenocorticism, also called Addison’s disease, is an endocrine disorder that results from a deficient production of adrenal gland hormones that can occur in dogs. There are two adrenal glands in the abdomen that lie just in front of the kidneys.
The most common cause of Addison’s disease in the dog is destruction of the adrenal gland tissue by the animal’s immune system. Infrequently, certain infections, medications, cancer or diseases of the pituitary gland may also cause Addison’s disease.
Addison’s disease may also be caused by the abrupt discontinuation of steroid medication. Dogs that have been on long-term steroids should be slowly weaned off such drugs. Abruptly stopping the medication can result in an Addisonian crisis.
Addison’s disease is an uncommon disorder in dogs and is extremely rare in cats. It is thought to be familial and inherited in Leonbergers, standard poodles, and Nova Scotia duck tolling retrievers. Certain other breeds may also be predisposed, such as the Airedale, bearded collie, German shepherd dog, German shorthair pointer, Great Dane, St. Bernard, English springer spaniel, West Highland white terrier, wheaten terrier, and Portuguese water dog.
Hypoadrenocorticism most often affects young to middle-aged dogs. About 70 percent of affected dogs are female. Neutered male dogs are more likely to develop hypoadrenocorticism than intact male dogs.
In hypoadrenocorticism there is usually a deficiency of two different groups of hormones, the glucocorticoids and the mineralocorticoids. The primary glucocorticoid hormone is cortisol, and it is responsible for combating stress, helping to maintain blood sugar. The major mineralocorticoid is aldosterone. Aldosterone regulates the water, sodium, potassium, and chloride concentrations in the body. Most naturally occurring forms of Addison’s disease affects both hormones. Addison’s disease secondary to the abrupt withdrawal of steroid medications affects only the level of circulating cortisol.
What to Watch For
The clinical signs seen with Addison’s disease are somewhat variable. They may be mild and very vague initially. With an acute crisis, the signs are more pronounced and profound. Clinical signs include:
Diagnosis of Hypoadrenocorticism (Addison’s Disease) in Dogs
Because hypoadrenocorticism can mimic many other diseases, diagnostic tests are needed to confirm the presence of Addison’s disease, and to exclude other diseases that cause similar signs. These tests may include:
Treatment of Hypoadrenocorticism (Addison’s Disease) in Dogs
Treatment depends on whether the onset of illness is acute with severe symptoms, or whether more mild, chronic signs are present. For acute disease (an Addisonian crisis) treatment may include:
Treatment for chronic disease may include:
At home, administer any prescribed medication precisely as directed by your veterinarian. Observe the dog’s activity level, appetite and water intake. Also, report any occurrence of vomiting, diarrhea, weakness, and change in appetite to your veterinarian immediately. Regularly scheduled veterinary visits are needed to monitor the disease and response to treatment. Such exams often involve various tests to monitor the levels of sodium and potassium in the blood.
Some dogs have different medication needs during times of stress such as travel, surgery, or hospitalization. Be sure to discuss this with your veterinarian if you anticipate times of stress in the future.
There is no preventative measure for the naturally occurring forms of this disease. If your dog is receiving steroid medication, do not stop the medication abruptly. By doing so, an Addisonian crisis can occur. This is the only form of Addison’s disease that is preventable.
In-depth Information on Hypoadrenocorticism (Addison’s Disease) in Dogs
Hypoadrenocorticism is a relatively uncommon disease, but it is highly treatable. Nevertheless, without proper veterinary care, the condition can be fatal. Because the history, clinical signs, and presentation of dogs with hypoadrenocorticism are so variable, there are other illnesses that must initially be considered when establishing a definitive diagnosis. These illnesses may include:
Veterinary care includes diagnostic tests to identify the presence of Addison’s disease, determine any underlying causes, and help guide subsequent treatment recommendations.
Certain diagnostic tests are needed to diagnose hypoadrenocorticism and exclude other diseases that may cause similar symptoms:
Treatment of hypoadrenocorticism must be individualized for each patient. Treatment may necessitate immediate hospitalization in those cases of extreme weakness, collapse, or shock. However, in other cases, medical management can be instituted as an outpatient. Treatments may include:
Follow-up Care for Dogs with Addison’s Disease
Optimal treatment requires a combination of home and professional veterinary care. It is very important that all medication be administered exactly as prescribed by your veterinarian. It is also important that you observe your dog very closely and report any abnormalities to your veterinarian promptly. Although certain symptoms such as vomiting or diarrhea may be seen on occasion in a normal, healthy dog, it is best to report them when the dog has a history of hypoadrenocorticism.
Avoid and/or prepare for any situation that might cause physical or emotional stress to your animal. This includes strenuous exercise, marked changes in your dog’s routine or environment, and surgery. If such situations cannot be avoided, your veterinarian may recommend adjustments in your dog’s treatment regime to help him cope with any upcoming stress.
It is important to keep regularly scheduled veterinary visits for examination and blood electrolyte monitoring. Initially these visits occur every 2 to 3 weeks, with adjustments made to medications as indicated by the test results. Gradually the recheck visits are decreased to every 3 to 4 months, and eventually to every 6 months in the stable patient. If your dog is on injectable DOCP, veterinary visits are necessary every 3 to 4 weeks so that the injection can be administered.
Most dogs with hypoadrenocorticism have an excellent prognosis after proper stabilization and treatment.