Diagnostic testing enables our team to pinpoint the underlying cause of your pet’s symptoms, diagnosing their condition(s). We want our pet parents to be involved in the decision-making process, and we thoroughly discuss the diagnostic testing we recommend for your pet and their diagnostic test results. Personalizing your pet’s diagnostic plan ensures we avoid unnecessary tests and procedures while leading us to a more personalized and effective treatment plan.

Diagnostic Overview

ACTH Stimulation Test for Cushing’s Disease

The ACTH stimulation test is a safe and non-invasive test used to diagnose and monitor Cushing’s disease in dogs and cats. It measures the ability of your pet’s adrenal glands to produce cortisol, a hormone that helps regulate various functions in the body. The test involves administering a specific dose of synthetic ACTH intravenously and measuring the cortisol response before and after one hour. Cushing’s disease produces a higher-than-average increase in cortisol response compared to normal pets.

The ACTH stimulation test helps confirm a diagnosis of Cushing’s disease if other testing is inconclusive. It is also performed to monitor and adjust treatment after your pet has started Trilostane medication for PDH. The test is safe, takes only an hour, and the results are usually received within 24-48 hours. It is the only test that can diagnose iatrogenic Cushing’s disease. In addition, it is the test of choice for initial diagnosis if a pet has concurrent but stable diseases such as diabetes or a heart condition.

However, the test is not very sensitive for initial diagnosis, and approximately 20-30% of dogs with Cushing’s disease will have normal results, and an additional 20-30% of dogs will have borderline results. The test has an 80-85% sensitivity for PDH and 60% sensitivity for adrenal tumors. Another disadvantage is that the synthetic ACTH used for the stimulation can be expensive, making the test itself expensive.

Variables that can affect accuracy include human or laboratory error, other medications a pet may be taking, and chronic stress and illness. It is important to follow the recommended guidelines for fasting, time of day, and medication administration for accurate results. Despite its limitations, the ACTH stimulation test is an essential tool for diagnosing and monitoring Cushing’s disease in pets.