Cushing’s Disease in Dogs, Part 2: How We Diagnose It

Veterinarian Fargo ND | Vet Clinic Fargo ND | Dog Hormone Imbalance Fargo ND

In Part 1 of our series on Cushing’s disease (hyperadrenocorticism), we talked about what the condition is and the early symptoms—especially increased drinking and urination. But how do we confirm whether your dog actually has it?

Diagnosing Cushing’s disease can be tricky, because many of the symptoms mimic other health issues or even normal aging. That's why a combination of blood tests and imaging is often required to get a clear answer.

Step 1: A Thorough Exam and Initial Blood Work

At Two Rivers Veterinary Hospital, we begin with a physical exam and a full blood panel, including a chemistry profile and complete blood count (CBC). Dogs with Cushing’s often show elevated liver enzymes, diluted urine, and sometimes increased cholesterol. These are not specific to Cushing’s, but they do point us in the right direction.

Step 2: Specific Testing for Cushing’s

There are two main tests used to diagnose Cushing’s disease:

• Low-Dose Dexamethasone Suppression Test (LDDST):
  This is the most commonly used test. It involves taking a baseline blood sample, giving a small injection of dexamethasone (a steroid), and then taking additional samples several hours later. In healthy dogs, this steroid will suppress cortisol production. In dogs with Cushing’s, cortisol levels remain elevated.

• ACTH Stimulation Test:
  This test measures how the adrenal glands respond to a synthetic version of the hormone that normally tells them to produce cortisol. It’s also helpful but can occasionally miss mild cases.

In some cases, ultrasound imaging of the abdomen may be used to look for tumors on the adrenal glands or to help rule out other causes of similar symptoms. At our clinic, these ultrasounds are performed by specially trained technicians and interpreted by both our veterinarians and a board-certified radiologist for fast, accurate results.

Getting to the Right Answer

It’s important to note that no single test is perfect. Your veterinarian may recommend multiple tests or repeated monitoring, especially if your dog has other medical conditions that could affect the results.

Once we have a diagnosis, we can move forward with a treatment plan tailored to your dog’s needs. In Part 3 of this series, we’ll talk about what living with Cushing’s disease looks like and how we manage it to keep your dog happy and comfortable.