Cushing's Disease in Dogs: Symptoms, Causes & Treatment

Cushing's disease — known medically as hyperadrenocorticism — is a hormonal disorder that affects many middle-aged and older dogs. Because its symptoms creep in slowly and look a lot like normal ageing, it's often overlooked for months. Understanding what to watch for can help you catch it early, and with the right treatment most dogs go on to live comfortable lives. Here's what you need to know.

Symptoms of Cushing's disease in dogs

Cushing's disease is caused by the body producing too much cortisol, the stress hormone. Because cortisol affects so many systems, the signs are wide-ranging. The most common include:

• Increased thirst and urination — often the first thing owners notice
• A bigger appetite and constant hunger
• A pot-bellied, sagging appearance
• Excessive panting, even at rest
• Hair loss or thinning, usually symmetrical, and a dull coat
• Thin skin, slow wound healing, and recurring skin or urinary infections
• Muscle weakness and lethargy

These changes develop gradually over months, which is exactly why they're so easy to dismiss.

What causes Cushing's disease?

There are three main forms:

• Pituitary-dependent — by far the most common, caused by a small, usually benign tumour on the pituitary gland that overstimulates cortisol production. This accounts for the large majority of cases.
• Adrenal-dependent — caused by a tumour on one of the adrenal glands themselves.
• Iatrogenic — caused by long-term use of steroid medications such as prednisone, which is why steroids are tapered rather than stopped abruptly.

It's most often seen in dogs over the age of six, and some breeds appear more prone to it than others.

How Cushing's disease is diagnosed

Diagnosing Cushing's takes more than one test. Your vet will start with a physical exam, routine bloodwork and a urine sample, which often show telltale changes. To confirm it, they'll run specific hormone tests — such as an ACTH stimulation test or a low-dose dexamethasone suppression test — that measure how the adrenal glands respond. An ultrasound of the abdomen may be used to check the adrenal glands and distinguish the pituitary form from an adrenal tumour, which guides treatment.

Treatment and management

Treatment depends on the form of the disease, but the goal is always to bring cortisol back under control and ease symptoms:

• Daily medication — the pituitary form is usually managed with a lifelong daily drug (such as trilostane) that reduces cortisol production. This is the most common approach.
• Regular monitoring — periodic blood tests are essential to fine-tune the dose and avoid pushing cortisol too low.
• Surgery — an adrenal tumour may sometimes be removed surgically.
• Tapering steroids — if the cause is long-term steroid use, your vet will gradually reduce them.
• Supportive care — treating secondary infections, supporting skin and coat, and monitoring related conditions like weight and blood pressure.

With treatment, most dogs see their thirst, appetite and coat improve over the following weeks and months.

Can Cushing's disease be prevented?

The naturally occurring forms of Cushing's — pituitary and adrenal — can't be prevented, since they're driven by tumours. What you can influence is the iatrogenic form: only use steroid medications under veterinary guidance, at the lowest effective dose and for the shortest necessary time, and never stop them abruptly. Beyond that, the best strategy is early detection through regular senior wellness checks, which catch subtle changes before they progress.

When to see a vet

Book a vet visit if your older dog is drinking and urinating noticeably more, developing a pot belly, panting excessively, or losing hair — especially if several of these appear together. While Cushing's usually progresses slowly, seek prompt care if your dog suddenly becomes very unwell, collapses, or shows signs of a serious infection, as dogs with the condition are more prone to complications. Early diagnosis makes management far smoother.

Frequently asked questions

What are the first signs of Cushing's disease in dogs?

The earliest and most common signs are increased thirst and urination, a bigger appetite, and a gradually developing pot-bellied appearance. Owners often also notice more panting, hair loss or thinning coat, and skin changes. These signs come on slowly over months, so they are easy to mistake for normal ageing, which is why they are worth mentioning to your vet.

Is Cushing's disease in dogs fatal?

Cushing's disease itself is usually a slowly progressive condition rather than an immediately life-threatening one, and many dogs live comfortably for years with treatment. Left untreated, though, the excess cortisol raises the risk of complications such as infections, high blood pressure, diabetes and blood clots. With proper diagnosis, medication and monitoring, most dogs have a good quality of life.

How is Cushing's disease in dogs treated?

The most common treatment for the typical pituitary form is a daily medication that reduces cortisol production, given for life alongside regular blood tests to fine-tune the dose. Adrenal tumours may be treated with surgery in some cases. If the disease is caused by long-term steroid medication, the vet will taper those drugs carefully. Treatment aims to control symptoms and keep your dog comfortable.

This guide is educational and not a substitute for professional veterinary care. If you're worried about your dog, contact your vet.