Diagnosing and Treating Cushing's Disease in Dogs: A Complete Guide

You notice your dog is always thirsty. The water bowl empties faster than ever, and you're letting them out to pee what feels like every hour. Maybe their belly looks a bit pot-bellied, or their coat seems thin and dull. You brush it off as old age—your pup is getting up there, after all. But here's the thing I've seen too many times in the exam room: what looks like "just getting old" is often the slow, sneaky creep of Cushing's disease.

Cushing's disease, or hyperadrenocorticism, is a common endocrine disorder in middle-aged and older dogs. It happens when the body produces too much cortisol, a stress hormone. The trick is, it doesn't show up overnight. It's a master of disguise, mimicking normal aging so well that diagnosis often comes late.

Spotting the Signs: Is It Old Age or Cushing's?

The classic symptoms are a cluster. Seeing one might not ring alarm bells, but seeing three or more? That's your cue to call the vet.

Increased thirst and urination (PU/PD) are almost always the first red flags. We're talking about a dog that suddenly needs to go out in the middle of the night again, or has accidents indoors after years of being housebroken. The cortisol interferes with a hormone that helps the kidneys conserve water.

A ravenous appetite is another big one. Your dog acts like they're starving all the time, scavenging for crumbs, begging relentlessly. Cortisol stimulates appetite.

Then there are the physical changes:

• A pot-bellied appearance: This isn't just weight gain. Muscle weakness in the abdomen combined with an enlarged liver from the hormone excess gives that distinctive saggy belly.
• Hair loss and skin changes: Hair thins symmetrically, often on the flanks and belly. The skin itself can become thin, darkly pigmented, and slow to heal. You might see blackheads or calcium deposits.
• Panting excessively: For no apparent reason, like heat or exercise.
• Lethargy and reduced activity: They seem stiff, reluctant to jump on the couch or go for long walks.

How is Cushing's Disease Diagnosed in Dogs?

This is where it gets technical, and frankly, where a lot of confusion and frustration sets in for owners. There's no single perfect test. Diagnosis is a puzzle, and your vet is putting the pieces together.

It always starts with a conversation and a physical exam. Your vet will feel that pot belly, note the thin skin, and listen to your story about the water consumption.

Next comes basic bloodwork and a urinalysis. These often show suggestive changes like elevated liver enzymes (ALP), high cholesterol, and dilute urine. But these findings aren't conclusive for Cushing's.

To confirm it, we need specific endocrine tests. Here’s the breakdown that vets use:

An abdominal ultrasound is a fantastic complementary tool. It lets us visualize the adrenal glands. Are both enlarged (suggesting pituitary-dependent Cushing's, which is most common)? Or is just one enlarged with a tumor (adrenal tumor)? It also checks the liver and rules out other issues.

Navigating the Diagnostic Maze

Here's my take after seeing hundreds of these cases: Don't get hung up on one slightly abnormal test result. The LDDS test is the workhorse for a reason. If the symptoms are classic and the LDDS is positive, you very likely have your answer. Pushing for more and more tests before starting treatment often just adds cost and delay without changing the outcome.

The one exception is if an adrenal tumor is suspected on ultrasound. In that case, more precise imaging like a CT scan might be discussed, as surgery could be an option.

Understanding Your Dog's Treatment Options

Treatment isn't about curing Cushing's; it's about managing it. The goal is to reduce the excessive cortisol production to a normal level, control the symptoms, and improve your dog's quality of life. The two main medical options are oral medications.

Trilostane (Vetoryl)

This is the most commonly prescribed medication today. It works by inhibiting an enzyme in the adrenal glands needed to produce cortisol.

• How it's given: Once or twice daily with food. Consistency with meals is critical.
• Monitoring: Essential. An ACTH stimulation test is needed 10-14 days after starting, then every few months once stable, to ensure the dose is correct.
• What I see in practice: It's generally very effective. The biggest mistake owners make is not doing the follow-up ACTH tests. Without them, we're flying blind—the dose could be too low (no improvement) or, more dangerously, too high.

Mitotane (Lysodren)

An older, still effective drug that actually destroys the cortisol-producing layer of the adrenal gland.

• How it's given: Has a more intensive initial "loading" phase, followed by lower weekly maintenance doses.
• Monitoring: Also requires careful monitoring with ACTH tests.
• My perspective: It's a powerful drug that requires strict owner compliance. It's often less expensive than trilostane, which matters to some. However, the risk of over-suppression (causing the opposite problem, Addison's disease) can be higher if protocols aren't followed to the letter.

For the rare adrenal tumor, surgery (adrenalectomy) performed by a specialist can be curative. It's a major surgery with risks, but for a good candidate, it's a one-time fix.

Life After Diagnosis: Management and Care

Managing a dog with Cushing's is a partnership between you and your vet. The medication does the heavy lifting, but your daily care makes all the difference.

Diet: There's no specific "Cushing's diet," but a high-quality, moderately protein-restricted senior diet is often recommended. The main goal is to help manage the weight gain and pot-belly. Avoid free-feeding. Measured meals are your friend.

Exercise: Keep it gentle and consistent. Short, frequent walks are better than one long, exhausting one. The muscle weakness and panting mean they tire easily.

Monitoring at Home: Keep a simple log. Note water intake (refill the bowl with a measured amount), appetite, energy level, and any panting. This log is gold for your vet appointments—it's objective data.

The Financial Reality: Let's not sugarcoat it. Cushing's is a commitment. Initial diagnostics can run $500-$1000. Monthly medication (trilostane) might be $80-$200. Required monitoring ACTH tests are around $150-$250 each. Over a year, you could be looking at $1500-$3000. Pet insurance, if you have it before diagnosis, is a lifesaver. If not, talk to your vet about care plans or payment options.

The payoff? With good management, most dogs live out their normal lifespan with a greatly improved quality of life. The excessive drinking and peeing stop. The energy comes back. They're comfortable again.

Your Cushing's Disease Questions Answered