Canine Hyperadrenocorticism (Cushing's Disease): NAVLE Study Guide

Cushing’s disease is one of the highest-yield endocrine topics on the NAVLE, and it rewards students who know the details. The NAVLE loves to test the difference between pituitary-dependent hyperadrenocorticism (PDH) and adrenal-dependent hyperadrenocorticism (ADH), the interpretation of the low-dose dexamethasone suppression test, and how you manage each form. Get comfortable with those distinctions and you’ll handle whatever signalment they throw at you.

What Is Hyperadrenocorticism?

Hyperadrenocorticism means chronic excess of cortisol. In dogs, it’s almost always either PDH (overactive pituitary producing too much ACTH, which drives both adrenal glands to produce excess cortisol) or ADH (a unilateral adrenal tumor secreting cortisol autonomously). A small percentage is iatrogenic — caused by exogenous glucocorticoid administration.

PDH accounts for roughly 85% of naturally occurring Cushing’s. ADH accounts for about 15%. On the exam, if they give you a middle-aged to older dog with a pot belly, panting, PU/PD, and alopecia, your first thought should be PDH in a small-to-medium breed.