All About Iatrogenic Cushing’s Syndrome

What is iatrogenic Cushing’s syndrome?

Iatrogenic Cushing’s syndrome refers to symptoms of Cushing’s that are caused by the prolonged or excessive use of steroids, such as prednisone, dexamethasone, or steroid eye drops. These medications are frequently prescribed to manage inflammation, allergies, certain cancers, and other health issues. Because they are chemically similar to the cortisol that’s naturally produced in the body, giving a dog too high of a dose or keeping them on steroids for too long can cause urinary incontinence, excessive hunger, and other symptoms of excessive cortisol.

Clinical Signs

The clinical signs of iatrogenic Cushing’s syndrome are similar to the clinical signs of naturally occurring Cushing’s disease. These signs include frequent urination and/or accidents in the house, increased water intake, a ravenous appetite, muscle wasting, an enlarged abdomen, and hair loss.

Diagnosis

Veterinarians diagnose iatrogenic Cushing’s syndrome by evaluating symptoms and the dog’s medical history. They may also use an ACTH stimulation test to help with diagnosis. Dogs with iatrogenic Cushing’s syndrome typically have both baseline and post-ACTH values that are abnormally low, oftentimes less than 1 ug/dL.

Treatment

Treatment may consist of decreasing use of the steroid, gradually stopping its use, or finding an alternative drug. It’s important to note that steroid medications should never be stopped abruptly and that changes in treatment should always be made in consultation with a veterinarian.

In many cases of iatrogenic Cushing’s syndrome, the adrenal glands actually shut down natural cortisol production since blood cortisol levels are high due to the medication. Tapering the dose slowly over weeks or months allows the adrenal glands to wake up and resume natural hormone production safely. If steroids are stopped cold turkey, a dog may experience a life-threatening Addisonian crisis due to lack of cortisol.

References

Hyperadrenocorticism (proceedings), by Patty Lathan, DVM

Iatrogenic and Pseudo Cushing’s in Dogs, by Nancy Kerns, Whole Dog Journal

Adrenal Testing in Dogs, by Michigan State University

Cushing’s Disease in Dogs, by Natalee Holt, DVM

Diagnosing Canine Cushing’s Disease: Should the ACTH Stimulation Test Ever Be Used? by Dr. Mark E. Peterson