Introduction
Cushing’s disease symptoms in cats can often mimic other diseases, and an accurate Cushing’s diagnosis involves a lot of detective work. Initial blood and urinalysis tests will help to uncover any other possible causes of the symptoms such as diabetes or hypothyroidism, and the results of these initial tests will show if Cushing’s disease is indeed a possible diagnosis.
Testing for Cushing’s
If your veterinarian suspects that Cushing’s may be the cause of your cat’s symptoms after blood and urinalysis tests are completed, there are additional tests that need to be performed to conclusively diagnose Cushing’s. These initial tests may include: a urine cortisol:creatinine ratio analysis, a low dose dexamethasone suppression blood test, a high dose dexamethasone suppression blood test, an ACTH stimulation blood test, and/or an abdominal ultrasound.
The simplest, and least expensive, of these tests is the urine cortisol:creatinine ratio test. Normally the pet owner is asked to catch the first morning’s urine at home. Then the urine is brought into the clinic and sent to a laboratory for results. A normal test result pretty much rules out the possibility of Cushing’s, and an abnormal test result indicates that Cushing’s is a definite possibility.
The dexamethasone and ACTH blood tests can provide a conclusive diagnosis of Cushing’s disease. These tests involve taking an initial draw of the cat’s blood, then giving the cat an injection of either dexamethasone or ACTH, then taking blood samples at regular intervals. All of the blood samples are sent to a laboratory for analysis.
The ACTH stimulation test is very expensive and available only in some areas. This test will only identify Cushing’s disease but not the type of Cushing’s. Only the dexamethasone suppression tests will help to diagnose the type of Cushing’s disease that is present. Your veterinarian will decide which test is best.
An abdominal ultrasound is sometimes used to aid in Cushing’s diagnosis as well. The ultrasound will show if one, or both, of the adrenal glands is affected by Cushing’s, and the ultrasound will also show if any other organs have been affected by the disease.