Addison’s Disease
By Dr. Karen Burgess

What is Addison’s disease?
Addison’s disease, or hypoadrenocoticism, occurs when the adrenal gland fails to produce adequate amounts of hormone.  Dogs and cats have two adrenal glands that are found next to the kidneys.  These small glands have different layers that are responsible for releasing several hormones and substances that profoundly impact the whole body and are essential for life.  Addison’s disease is a deficiency of cortisol and aldosterone.  Cortisol is necessary to deal with stress and aldosterone is essential for water and electrolyte balance.

How do pets get Addison’s disease?
While infection or trauma to the adrenal gland can cause Addison’s disease, the most common cause is immune related.  The immune system is very powerful, designed to “fight off” anything identified as foreign.  In cases of auto-immune disease, the immune system for unknown reasons attacks itself, or in the case of Addison’s disease the adrenal gland.  Addison’s disease also occurs secondary to drug therapy for another condition called Cushing’s or with long-term use of steroids.  When pets receive steroids orally or topically it can cause the adrenal glands to stop producing steroid or go dormant.  If therapy is stopped suddenly the adrenal glands do not automatically turn on and start producing hormone again, thus creating a crisis situation.  Pituitary disease rarely causes Addison’s disease.

What does a pet with Addison’s disease look like?
Unfortunately Addison’s disease does not have one “look”.  It is more commonly recognized as a disease that mimics or masquerades with vague and non-specific symptoms.  Owners may notice gastrointestinal signs (vomiting, diarrhea, weight loss) that come and go, changes in thirst or urination, or even shaking at odd times.  Mild signs often self-resolve.  When a pet is experiencing an Addisonian Crisis it is a medical emergency.  This is when the disease has affected hydration or electrolytes to the point of potential collapse and sudden death.  Hospitalization and emergency supportive care are necessary to treat the Crisis situation.

How is Addison’s diagnosed?
While testing of electrolyte values may hint at the presence of Addison’s, an ACTH test specifically diagnoses the disease by measuring cortisol levels.

How is Addison’s treated?
Fortunately the prognosis with Addison’s is good and there is essentially a cure in the form of medication that replaces lacking hormone.  Depending on the type of Addison’s disease present, there are oral and injectable treatment options.  Monitoring of electrolytes will be necessary on a regular basis.  Special attention should be paid during stressful times as these are common times of decompensation and may require extra supplementation.