The treatment of dogs with Addison's disease depends on the severity of the presenting signs. Many dogs diagnosed with Addison's disease are severely ill at the time of presentation, often with potentially life-threatening fluid deficits and abnormal serum electrolyte concentrations. These animals must receive immediate medical attention, since rapid treatment is extremely important to stabilize dogs experiencing an Addisonian crisis. The main goals of treatment are to correct fluid volume deficits, to improve blood vessel integrity, to provide a source of glucocorticoids, to correct electrolyte and acid base abnormalities, and to confirm the diagnosis. Fluid volume deficits are addressed most appropriately with intravenous fluid administration; usually, saline is used. If low blood sugar concentrations are known or suspected, then the fluids should be supplemented with dextrose. Glucocorticoids usually are given via injection. Glucocorticoids that will not affect ACTH stimulation test results are better used than those that might make it difficult to confirm a diagnosis of Addison's disease if they are given prior to the ACTH stimulation test.
Electrolyte imbalances are corrected with the intravenous fluids and with administration of mineralocorticoid replacement drugs. These drugs generally are not used until the diagnosis is confirmed, since the other measures used to treat a dog in crisis are usually successful in stabilizing a dog in an Addisonian crisis. Sometimes it will be necessary to take specific measures to lower dangerously high serum potassium concentrations, such as the administration of glucose and insulin, calcium, and sodium bicarbonate. Bicarbonate also can be used to treat animals with extreme acid-base system disturbances. Most dogs in crisis will improve within one to two hours with appropriate treatment. Intravenous fluids often are maintained for 24 to 48 hours, until the dog is eating and drinking on its own without vomiting. Injectable medications can then be switched to oral medications
Once the crisis period has passed, dogs are given either oral or injectable mineralocorticoids. The oral medications need to be given on a daily basis, usually twice a day, and sometimes very high doses are needed to control the disease. The injectable mineralocorticoid used most commonly is called DOCP. It is given via injection approximately every 25 days, and is almost always effective. For many dogs, especially large breed dogs, the injectable drug is much less expensive than the oral form. Most dogs with Addison's disease do well clinically with mineralocorticoid replacement alone, but others will require glucocorticoid supplementation with prednisone as well. As many as 50 percent of dogs on injectable DOCP also will require prednisone administration. For any dog with Addison's disease that may be undergoing stress, surgery, or that develops a non-adrenal gland dependent disease, prednisone should be considered on a short-term basis. Dogs that are used as working dogs also should take prednisone on a short-term basis.
