Hypoadrenocorticism or Addison’s Disease is a serious health problem that can cause death if left untreated. In this disease, the adrenal glands fail to produce two very important hormones, cortisol and aldosterone. Cortisol is the stress hormone important for regulating heart rate and blood pressure. Aldosterone is the hormone that regulates electrolyte levels. Without aldosterone, levels of sodium plummet while potassium surges. Without treatment, the electrolyte derangements will slow the heart until it stops beating.
Hypoadrenocorticism is more common in females than males. Dogs may display a variety of nonspecific signs. Early in the disease, I often see intermittent bouts of bloody diarrhea, vomiting, generalized weakness, lethargy, poor appetite and increased water consumption. Blood work at this stage often shows increase in BUN and creatinine that may be confused with simple dehydration, as well as, a decrease in blood sugar. As the disease progresses, the clinical signs listed above become more consistent. In addition to an increased BUN and creatinine, blood levels of sodium fall and potassium rises. To make the diagnosis, an ACTH stimulation test is performed. ACTH causes cortisol release from the adrenal glands. Blood is drawn for cortisol analysis before and after an injection of ACTH. Humans and animals with hypoadrenocorticism do not respond to the injection. Their cortisol levels do not increase as they should.
Treatment is based on replacing the missing cortisol and aldosterone. Replacing cortisol is easy. The dog is put on oral hydrocortisone or prednisone therapy. Replacing the aldosterone is another matter. Currently, there are two medications being used for this, fludrocortisone (Florinef) and DOCP (Percorten-V). Florinef is a tablet given orally. Percorten-V is an injectable medication that is given approximately every 30 days. Please note there is a condition called atypical Addison’s disease that only requires cortisol replacement.
Most dogs respond well to treatment and live normal lives. Unfortunately, problems arise when owners cut back on the dose or frequency of administration of Flurinef or Percorten-V in order to save money. This can lead to disastrous results. Both medications must be given at the recommended dosages and frequency to control this disease.