What is atypical Cushing’s disease?
Atypical Cushing’s disease is a condition in which a dog’s cortisol levels are normal, but two or more sex steroid hormones are elevated. These steroid hormones are 17-hydroxyprogesterone (also called 17-OH progesterone or 17-OHP), progesterone, androstenedione, estradiol, and aldosterone. Atypical Cushing's can be caused by a tumor on either the pituitary gland or one of the adrenal glands. Some experts consider it to be an early stage of typical Cushing's disease, with elevated cortisol.
Clinical Signs
The clinical signs of atypical Cushing’s disease are similar to the clinical signs of other types of Cushing’s. These include frequent urination and/or accidents in the house, increased water intake, a ravenous appetite, muscle wasting, an enlarged abdomen, and hair loss. And bloodwork will most likely show an elevated alkaline phosphatase (ALP).
Diagnosis
If your dog has atypical Cushing’s, standard screening tests (such as the Low Dose Dexamethasone Test) will most likely come back negative, even if he or she has symptoms of the disease. This is because the standard tests only measure cortisol levels and not the other steroid hormones. At the moment, the most specific and sensitive test for atypical Cushing’s is the adrenal steroid panel offered by the University of Tennessee’s College of Veterinary Medicine (UTCVM). A blood sample can be submitted to UTCVM through your veterinarian. You can find more information about UTCVM’s testing program on their website, available at this link.
Treatment
UTCVM recommends treating atypical Cushing's with melatonin and lignans supplements (for more details, see Treatment Option Considerations for Hyperadrenocorticism in Dogs). Please note that pet owners who have used these supplements for their dogs report varying degrees of success. Many people say that it can take four months or longer for melatonin and lignans to improve symptoms. Some veterinarians will treat atypical Cushing's with a low dose of medication, especially if symptoms are severe.