Addison's Disease in Dogs - Causes, Diagnosis and Treatments

Addison's disease in dogs occurs due to the reduced secretion of corticosteroid by the adrenal gland and is also called as hypoadrenocorticism. This disease is hard to detect in its early stages but once diagnosed it can be treated successfully.

Causes

The adrenal gland secretes a number of substances that are needed to regulate the normal functions of the body of which glucocorticoids and mineralocorticoids are very important. The glucocorticoids like cortisol influence the balance of fat, sugar and protein metabolism and the mineralocorticoids like aldosterone regulate the electrolytes in the body like sodium and potassium, especially during stressful situations. Symptoms of Addison's disease appear when these hormones are not secreted in adequate amounts by the adrenal glands.

The failure of adrenal glands can be caused due to the destruction of the glands itself by the body or due to some infection in the glands. Other causes for Addison's disease include inadequate secretion of ACTH by the pituitary glands which stimulates the adrenal glands and the failure of hypothalamus to secrete CRH that controls the adrenal glands.

Symptoms

Though Addison's is predominantly a disease found in female dogs it can develop in dogs of either sex at any age. It is also not partial to any particular breed. Symptoms of this disease are quite vague and most often dogs exhibit these symptoms for a prolonged time before being diagnosed. Common symptoms include decreased heart rate, hypothermia, muscle weakness, lethargy, vomiting and anorexia. The symptoms might come and go which further complicates and delays the diagnosis. In some extreme cases the dog might collapse in shock due to electrolyte and metabolism imbalance when under stress. This condition called 'Addisonian Crisis' can be fatal without immediate treatment.

Diagnosis

Confirmation of Addison's disease in dogs is done through a blood test called ACTH stimulation test. However, since this disease is not that common and because of its many and vague symptoms the ACTH test is most often done only after other tests for more common diseases are performed to rule them out.

In case a pet is taken to a hospital in a state of shock due to electrolyte imbalance then it first receives treatment for a presumptive diagnosis and only after it recovers the ACTH stimulation test to confirm Addison's disease is done.

In case the animal exhibits one or all of the symptoms, blood count and a chemistry profile will be probably recommended first. If the tests reveal the presence of chronic anemia, elevated blood urea nitrogen or creatinine then the ACTH test is performed to confirm Addison's disease.

For a normal dog the ACTH test results will show increased levels of blood cortisol. But, if the dog has the Addison's disease then the results will not show any increase in the blood cortisol levels which confirms the presence of the disease.

Treatment

Prognosis for Addison's disease in dogs is excellent and once diagnosed treatment for Addison's disease is quite simple. Typically, treatment involves drugs like Florinef (fludrocortisones) to replace the glucocorticoids and mineralocorticoids in the body. Advanced treatments involve drugs like DOCP which needs to be injected only once every 25 days. Intense tests have shown that DOCP regulates the electrolytes better than Florinef which usually has to be given two times a day.