What is Cushing's disease in dogs?

Cushing's disease, or hyperadrenocorticism, is a condition where the body produces too much of the stress hormone cortisol over a long period. It mostly affects middle-aged and older dogs, develops gradually, and is easy to mistake for normal aging.

What are the signs of Cushing's in dogs?

The classic signs are greatly increased thirst and urination, a bigger appetite, a pot-bellied appearance, panting, lethargy, thinning hair or hair loss, and recurrent skin or urinary infections. They come on slowly over months, which is why they are often dismissed as the dog simply getting older.

How is Cushing's disease diagnosed?

There is no single quick test. Vets use hormone tests such as the low-dose dexamethasone suppression test and the ACTH stimulation test, often with an abdominal ultrasound to find the source. Because the tests can be ambiguous, they are run in dogs that already show signs, not as routine screening.

Can Cushing's disease in dogs be cured?

Usually it is managed rather than cured. Most dogs have the pituitary form, treated with lifelong daily medication, primarily trilostane, plus regular monitoring. Surgery to remove an adrenal tumor can be curative in some cases of the adrenal form.

How long do dogs live with Cushing's disease?

With treatment, many dogs live comfortably for a few years. Survival varies with the form and the individual dog, and the goal of treatment is to control the signs and protect quality of life rather than to cure the disease outright.

Cushing's Disease in Dogs: When “Just Getting Old” Is Really a Hormone Problem

Here is the short version: when an older dog starts drinking bowl after bowl of water, begging for food, developing a pot belly, and losing its coat, the easy explanation is "he's just getting old." Often that is wrong. These are the classic signs of Cushing's disease, a slow overproduction of the stress hormone cortisol. It creeps in over months, masquerades as aging, and is very manageable once recognized. This guide covers the forms it takes, the signs, why diagnosis is more involved than a single test, and how it is treated.

What Cushing's actually is

Cushing's disease, more formally hyperadrenocorticism, is a state of chronic excess cortisol.² Cortisol is a normal and necessary hormone, but too much of it for too long disrupts the whole body. It is a common endocrine disease of middle-aged and older dogs.¹ There are three versions worth knowing:

Pituitary-dependent (about 80 to 85% of cases): a usually-benign tumor in the pituitary gland over-signals the adrenal glands to make cortisol.¹
Adrenal-dependent (roughly 15 to 20%): a tumor on an adrenal gland itself pumps out cortisol.¹
Iatrogenic: caused by long-term steroid (glucocorticoid) medication, often given for another condition.³

The signs, and why they look like aging

The signs are distinctive once you know them, but they arrive so gradually that they blend into "getting old."¹ The most common and noticeable is a big increase in thirst and urination, present in something like 80 to 90 percent of affected dogs, often the thing that finally sends an owner to the vet.³ Alongside it:

A noticeably bigger appetite.
A pot-bellied or sagging abdomen.
Excessive panting.
Lethargy and reduced activity.
Thinning hair, symmetrical hair loss, and thin or fragile skin.
Recurrent skin and urinary infections.

Any one of these is easy to wave off. Together, in an older dog, they paint a recognizable picture that is worth investigating rather than accepting.

80–90%

of dogs with Cushing's show greatly increased thirst and urination, the sign that most often leads to diagnosis

Cornell University Riney Canine Health Center

Why diagnosis takes more than one test

Cushing's is genuinely tricky to confirm, and it helps to know that going in so the testing does not feel like runaround. There is no single, simple, perfect test. Vets rely on hormone challenge tests, principally the low-dose dexamethasone suppression test (often the first-line screen) and the ACTH stimulation test, usually paired with an abdominal ultrasound to locate the source and tell the pituitary form from the adrenal form.² The results can be ambiguous, and other illnesses can skew them, which is exactly why these tests are run in dogs that already have suggestive signs, not as a routine screen.²

How it is treated

For the common pituitary form, treatment is medical and lifelong. The mainstay is trilostane (brand name Vetoryl), the only FDA-approved drug for canine Cushing's, which reduces cortisol production and is given daily.¹ An older drug, mitotane, is also used in some cases. Either way, the dog needs regular blood tests to keep the dose in the safe, effective range, frequently at first and then periodically.² For the adrenal form, surgically removing the affected adrenal gland can be curative when the tumor is suitable and has not spread.¹ The iatrogenic type is handled by carefully tapering the steroid that caused it, never stopping it abruptly, under veterinary guidance.³

Set expectations honestly: outside of a successful adrenal surgery, Cushing's is controlled, not cured.¹ With good management, though, the thirst, appetite, and coat changes usually improve, and many dogs do well for years.³

What it costs

There are two cost phases. Diagnosis (the hormone tests and ultrasound) is a larger one-time outlay, and then trilostane plus periodic monitoring bloodwork is an ongoing expense for life. The medication cost scales with the dog's size and dose. These are market estimates that vary widely by region and dog, and they are worth budgeting for as a chronic, managed condition rather than a one-time fix.

What to do this week

If your older dog has started drinking and urinating much more than usual, note it and book a vet visit, this is the sign most worth acting on.
Mention the full cluster, appetite, pot belly, panting, coat changes, so your vet can connect the dots that look like aging in isolation.
If your dog is on long-term steroids for another problem, ask your vet about iatrogenic Cushing's and never stop the steroid suddenly.
Go into testing knowing it may take more than one test, and plan for ongoing monitoring if your dog is diagnosed.

Cushing's disease is a case study in why "old age" is not a diagnosis. The changes it causes are real, treatable, and often reversible in their impact on daily comfort, but only if someone notices that the drinking, the belly, and the thinning coat add up to something. Take the increased thirst seriously, and you give your dog the best chance at feeling like itself again.