Hello Lynn, and welcome to you and your boy. I apologize that I can’t write as lengthy a reply as I’d like right now, but I can start with a couple of quick thoughts. First, it is very unlikely that an ACTH would give a result where the first (resting) cortisol reading is significantly higher than the second (stimulated) reading. My best guess is that the two test tubes were accidentally reversed and/or mislabeled in conjunction with the lab submission and analysis. The other possibility is that the stimulating agent was ineffective. However, given the two numbers that were listed, I’d guess that the samples were simply reversed. If this were the case, then the result would still be negative for Cushing’s because I feel certain that 11 would fall within the normal range for a diagnostic post-ACTH test.

Iatrogenic Cushing’s refers to development of the syndrome secondary to a dog being given supplemental steroids such as prednisone. Dogs who are given steroids for sufficiently long periods of time can see disruption in their normal adrenal activity, and the development of the same symptoms that result from naturally occurring Cushing’s. The cure is simply to wean the dog off the steroids.

Hypoadrenalcorticism refers to Addison’s Disease, or the situation where the adrenal glands are not producing enough hormones (as opposed to producing too much).

So, turning back to your test results, we’re not exactly sure what happened that led to this odd result. If the samples were simply reversed, it is a negative result for Cushing’s. If the stimulating agent was ineffective, however, then the test was not accurate. Even when conducted correctly, one drawback to the ACTH is that it produces a fair number of “false negatives,” especially in the presence of an adrenal tumor (as opposed to a pituitary tumor). There is another blood test, the LDDS, that is less likely to miss making the diagnosis in a dog who does have the disease. So depending upon the outcome of the bile acid test, one alternative might be to retest with a LDDS. Another, different option might be to conduct an abdominal ultrasound in order to actually view the status of the adrenal glands, as well as the liver and other internal organs. The imaging might help provide additional clues as to what is at the root of your boy’s problems.

Marianne