Frost • Faith • Love • Awareness

Diagnosis

Recognizing the pattern

There is no single symptom that identifies Addison's disease. A veterinarian begins with the dog's history, physical examination, medications, and laboratory results. Repeated gastrointestinal problems, weakness, weight loss, poor appetite, or episodes that seem to improve and then return may prompt an adrenal evaluation.

Initial blood and urine testing

A complete blood count, chemistry profile, electrolyte measurements, and urinalysis can provide important clues. Low sodium and high potassium are classic findings in many dogs with primary Addison's, but they are not present in every case. Other abnormalities can include changes related to dehydration, kidney values, blood sugar, blood proteins, or the expected stress response.

These screening results can raise or lower suspicion, but they do not by themselves establish the diagnosis. Other illnesses can produce similar findings, so the results have to be interpreted in context.

Confirming Addison's disease

The ACTH stimulation test is the standard confirmatory test for canine hypoadrenocorticism. Blood cortisol is measured before and after administration of a synthetic form of adrenocorticotropic hormone (ACTH). Affected dogs have little or no increase in cortisol after stimulation.

A resting cortisol measurement can be useful for screening: a sufficiently high result in an appropriately evaluated dog makes Addison's very unlikely. A low resting cortisol, however, does not by itself prove Addison's disease and generally needs follow-up testing.

When it is an emergency

If a dog is severely weak, collapsed, dehydrated, repeatedly vomiting, or otherwise critically ill, a veterinarian may need to stabilize the patient while the diagnostic workup is underway. An adrenal crisis is a medical emergency.