We've all heard the term, but is atypical hyperadrenocorticism real? This syndrome refers to dogs with clinical signs and laboratory abnormalities suggestive of hyperadrenocorticism but with normal cortisol concentrations after low-dose dexamethasone suppression (LDDS) and ACTH testing.

In her presentation, "Atypical canine hyperadrenocorticism: Is it real?" Dr. Ellen Behrend from Auburn University's College of Veterinary Medicine presented evidence for and against the existence of this sex-hormone-mediated disease, comparing research from the standpoint of bilaterally symmetric alopecia, sex hormone assays, and response to treatment.¹ Overall, her findings elucidate the lack of specificity of sex hormone assays since nonadrenal illness can also elevate these hormones. Additionally, some patients demonstrate clinical response to treatment with drugs such as mitotane and trilostane despite an increase in sex hormone concentrations, so other mediators such as enzymes or growth factors may also play a role. While atypical Cushing's may exist as a syndrome, much more research is still needed to understand this disease entity.

This "Presentation Recap" summary from the 2011 American College of Veterinary Internal Medicine (ACVIM) Forum, which took place in Denver, Colo., was contributed by Jennifer L. Garcia, DVM, DACVIM, a veterinary internal medicine consultant in Houston, Texas.

1. Behrend EN. Atypical canine hyperadrenocorticism: Is it real? Presented at the Annual Meeting of the American College of Veterinary Internal Medicine; June 2011.