Urine Test for Cushing's Disease in Dogs

Dogs around the age of 6 or 7 years commonly contract Cushing’s disease, a condition whereby the body produces too much of the hormone cortisol. All dogs of any breed are at risk of contracting Cushing’s, but most terrier breeds, as well as boxers, dachshunds, golden retrievers and Labrador retrievers, are at greater risk. A vet uses a urine test to screen for Cushing's disease, the urine cortisol:creatinine ratio test, and urinalysis to help diagnose it.

The urine cortisol:creatinine ratio test determines whether further testing is needed. The adrenal glands produce cortisol, an essential hormone responsible for regulating blood glucose levels and red blood cell production, among other bodily functions. The body's cortisol level varies based on need or on stress. The owner must collect the urine sample at home to avoid stress-raising cortisol levels. The cortisol level is compared with the level of creatinine, a protein metabolite. If the cortisol level is high compared with that of the creatinine, it is assumed the blood cortisol level is also high, indicating the need for further testing.

Once screening tests determine Cushing’s is a possibility, other tests can be run to determine if it’s present. An abdominal ultrasound can be run to determine the size and shape of the organs that may be affected by Cushing’s disease. Urinalysis can also be used to determine if the specific gravity and the level of protein in the urine fall within the parameters for Cushing’s disease.