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Cushing's Disease in Dogs: Signs, Tests and Treatment

Cushing's disease is a common hormone disorder in older dogs. The signs to look for, how it's tested for, treatment with trilostane, and what monitoring involves.

Updated October 2026 · 7 min read · By the Hushku editorial team · 2 sources

Short answer

Cushing's disease (hyperadrenocorticism) is caused by too much cortisol. It's common in middle-aged and older dogs and causes drinking and peeing more, a big appetite, a pot belly, panting and thin skin and coat. About 85–90% of cases are caused by a small pituitary tumour. It's diagnosed with blood tests and usually managed with daily medication (trilostane) and regular check-ups.

Key facts

About 85–90% of cases are caused by a pituitary tumour, 10–15% by an adrenal tumour.
Signs: drinking and peeing more, big appetite, pot belly, panting, thin coat.
Diagnosed with ACTH stimulation or low-dose dexamethasone tests.
Usually managed with daily trilostane and regular blood tests.

Definition

Cushing's disease, or hyperadrenocorticism, is a hormonal disorder in which the adrenal glands produce too much cortisol, a stress hormone that affects metabolism, the skin, muscles and the immune system.

There are three main types:

Pituitary-dependent Cushing's (about 85–90% of cases, according to the Merck Veterinary Manual): a usually benign tumour in the pituitary gland at the base of the brain overstimulates the adrenal glands.
Adrenal-dependent Cushing's (about 10–15%): a tumour in one adrenal gland produces too much cortisol itself. Some of these tumours are malignant.
Iatrogenic Cushing's: caused by long-term steroid medication, which goes away when steroids are carefully tapered off.

Cushing's develops slowly, so the signs are often put down to ageing. Poodles, Dachshunds, terriers and Boxers are among the breeds most often affected. It's rare in cats.

Signs and symptoms

Drinking and peeing much more, sometimes with accidents
A ravenous appetite
A pot-bellied appearance
Panting more, even at rest
Thin coat and hair loss on the body, without itching
Thin skin, blackheads and slow-healing wounds
Muscle weakness and less energy
Recurring skin or urinary infections

Causes and risk factors

A benign pituitary tumour (most cases)
An adrenal gland tumour
Long-term steroid medication

Treatment

Trilostane, a daily oral medicine that reduces cortisol production, is the most common treatment
Regular blood tests to adjust the dose, especially in the first months
Surgery to remove an adrenal tumour in suitable cases
Gradually reducing steroids for iatrogenic Cushing's (never stop them suddenly)

How it's diagnosed

Signs and routine blood and urine tests raise suspicion: raised liver enzymes (especially ALP), dilute urine and high cholesterol are common. Specific tests include the ACTH stimulation test and the low-dose dexamethasone suppression test (LDDS). A urine cortisol:creatinine ratio can help rule Cushing's out. Ultrasound of the adrenal glands helps tell pituitary from adrenal causes.

Monitoring treatment

Treatment controls Cushing's rather than curing it. Your vet will recheck cortisol levels and blood tests after starting or changing the dose and then every few months. Too much medication can cause the opposite problem, low cortisol (an Addisonian crisis): vomiting, diarrhea, weakness and collapse. Stop the medication and call your vet if you see these.

Why treat it?

Untreated Cushing's can lead to diabetes, high blood pressure, blood clots, urinary infections and stones, and pancreatitis. Most dogs feel much better within weeks to months of treatment, with less thirst and panting and a better coat.

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Sources

We check guides against veterinary sources and update them when guidance changes. How we write and review.

Questions.

How long do dogs live with Cushing's?

Many treated dogs live for years with a good quality of life. The outlook depends on the type, the dog's age and other health problems.

Is Cushing's painful?

It isn't usually painful in itself, but it can cause muscle weakness, skin infections and other complications that affect comfort.

Can I treat Cushing's with diet alone?

No. Diet can help with weight and complications, but medication or surgery is needed to control cortisol.