Cushing's Disease in Dogs: Symptoms, Causes, Diagnosis and Treatment

Most owners arrive at Cushing’s slowly. The water bowl empties faster, there are accidents from a dog who has not had one in years, and the coat starts to look wrong. It rarely feels like one thing, which is why so many people assume it is simply old age. Cushing’s disease, also known as hyperadrenocorticism, is a hormonal disorder seen most often in middle-aged and older dogs of the smaller breeds, in which the body produces too much cortisol, the main stress hormone. Left unchecked it can affect the skin, the muscles, the immune system and the bladder, but it is usually a manageable condition, and many dogs feel considerably better once treatment starts.

Key takeaways

• Cushing’s disease occurs when the body produces too much cortisol over an extended period, which puts it under strain and causes a range of knock-on effects.
• Common signs of Cushing’s include excessive thirst, increased hunger, panting and a pot-bellied appearance.
• Diagnosing Cushing’s rests on the history, a physical examination, and blood and urine tests, including a specific hormone test.
• Most cases are managed with long-term medication, though surgery may be an option for some dogs.

What Is Cushing's Disease in Dogs?

Cortisol production is normally kept in careful balance: the pituitary gland in the brain releases a hormone called ACTH, which tells the adrenal glands how much cortisol to make. In Cushing’s disease, that feedback loop breaks down and the adrenal glands produce far more cortisol than the body needs.

Cortisol and the Adrenal Glands

The adrenal glands sit just in front of the kidneys and are made up of two main parts. The outer cortex produces a number of hormones including cortisol, while the inner medulla makes adrenaline.

Cushing's vs Addison's Disease

Addison’s is, in many ways, the mirror image of Cushing’s. An Addisonian dog does not make enough cortisol or aldosterone, and needs lifelong replacement of those missing hormones. The two conditions are linked in practice, because treating Cushing’s too aggressively can tip a dog into an Addisonian crisis.

Symptoms of Cushing's Disease in Dogs

The symptoms build slowly over months, which is why so many owners put the early changes down to age, and why nobody should feel they missed something obvious. None of them is unique to Cushing’s, and the same picture can be caused by conditions such as diabetes, pyometra or kidney disease.

Drinking and Urinating More

This is usually the first change owners spot. Your dog empties the water bowl far more often and passes larger, more frequent puddles of urine. Reliably toilet-trained dogs may start having accidents indoors or asking to go out overnight.

Increased Appetite

Affected dogs develop a voracious appetite. They beg, scavenge, raid bins and clear their bowl the moment it goes down, often in a way that is out of character.

Pot Belly

Their belly may appear swollen and to hang down. This comes from a combination of weakened abdominal muscles, fat redistributing towards the belly, and an enlarged liver.

Hair Loss and Skin Changes

Thinning fur and symmetrical bald patches over the flanks are common, and a classic sign is a ‘rat tail’, a tail with little to no fur left on it. The skin itself often becomes thin and slow to heal.

Many patients also pick up repeated skin infections and become itchy. Persistently high cortisol suppresses the immune system, which leaves them open to infections they would otherwise shrug off.

Panting

Dogs with Cushing’s pant a great deal, which is linked to weakened chest muscles, fat around the chest and a faster metabolism. All dogs pant when they are hot, stressed or recovering from exercise, so what stands out here is panting at rest, in a cool room, or through the night.

Cushing's Symptoms Checklist

The symptoms that can occur in Cushing’s include:

• Excessive thirst and urination, and greater risk of dehydration
• Panting
• Lethargy
• A pot belly
• Increased hunger
• More regular infections, such as UTIs
• Fur and skin changes, which can include hardened plaques (calcinosis cutis)
• Increased risk of inflammatory conditions, like pancreatitis

What Causes Cushing's Disease?

The cause of Cushing’s is not the same for every dog.

Pituitary-Dependent Cushing's

In around 85 per cent of patients, a small tumour in the pituitary gland is to blame. In the great majority of cases this tumour is benign, but it produces too much ACTH, which drives both adrenal glands to overproduce cortisol. Breeds including Yorkshire Terriers and Poodles are predisposed.

Adrenal Tumours

In around 15 per cent of cases, a tumour develops on one of the adrenal glands itself. These are split roughly evenly between benign adenomas and malignant carcinomas, which is why imaging matters before deciding on treatment.

Steroid-Induced (Iatrogenic) Cushing's

Some cases are caused by the medication itself. Steroids prescribed over long periods, particularly at higher doses, can produce exactly the same picture. This is most often seen in dogs on long-term treatment for conditions such as allergic skin disease or immune-mediated illness, and it is never a reason to stop steroids suddenly at home.

Breeds and Ages Most Affected

Most dogs are middle-aged or older at diagnosis, with a median age of around ten. Smaller breeds including Jack Russells, Bichon Frises, Miniature Poodles and Dachshunds are most at risk, though any breed can be affected.

How Cushing's Disease Is Diagnosed

Diagnosing Cushing’s takes more than one test, and it can feel slow when you just want an answer. Your vet is building a picture from the history you give them, the examination findings and a series of blood and urine results, and the detail you provide about what has changed at home is genuinely one of the most useful parts of it.

Blood and Urine Screening

The first step is usually general bloods (haematology and biochemistry) and a urine sample. These assess your dog’s overall health, flag the raised liver enzymes that are common in Cushing’s, and help rule out other causes of excessive drinking such as kidney disease and diabetes.

ACTH Stimulation and Dexamethasone Suppression Tests

The Low Dose Dexamethasone Suppression Test is the usual screening test, and involves taking blood samples over several hours, so your dog will spend most of the day at the practice. The ACTH stimulation test is less sensitive for diagnosis but is the test of choice for checking how well treatment is working once it has started.

Ultrasound and Imaging

Your vet may recommend an ultrasound scan of the adrenal glands, or advanced imaging of the brain. This shows whether the problem sits in the pituitary gland or the adrenal gland, which determines what treatment is possible.

Treatment for Cushing's Disease in Dogs

Most dogs are managed with long-term medication.

Medication and Monitoring

Daily tablets reduce how much cortisol the adrenal glands can produce. The dose is adjusted to the individual dog, so patients need regular vet checks and repeat blood tests, both to confirm the condition is controlled and to make sure cortisol has not been pushed down too far.

Surgery for Adrenal Tumours

Where a single adrenal tumour is responsible, surgical removal can be curative. This is specialist surgery with a real risk attached, and it is expensive, so it is not right for every patient.

Managing Steroid-Induced Cushing's

If your dog’s Cushing’s is caused by their medication, your vet will usually wean them off the steroids slowly, which can reverse the condition. This has to be done under veterinary guidance, as stopping abruptly can cause a dangerous drop in cortisol.

Living With a Dog That Has Cushing's

This is the part worth holding on to. Untreated Cushing’s has a real impact on quality of life, but many owners notice their dog settling within a few weeks of starting treatment, with the thirst and the constant hunger usually easing first. Skin and coat changes take longer, often several months, so do not lose heart if the fur is slow to come back. These patients need lifelong medication, regular check-ups and monitoring blood tests, and that routine quickly becomes just another part of looking after them.

Cushing's Emergencies: When to Call a Vet Immediately

Cushing’s itself rarely causes an emergency. The situation to know about is the opposite problem: treatment pushing cortisol too low, which produces an Addisonian crisis. Warning signs include vomiting, marked lethargy, collapse, a slow heart rate and cold extremities, and these dogs need immediate vet care.

Depending on how unwell your dog is, it may be possible to ave your dog seen at your home. The nurse or vet on call will talk through whether a home visit is suitable, or whether your dog needs the equipment and monitoring of a clinic.

Get Emergency Veterinary Advice for Your Dog

If something about your dog is worrying you, whether or not they have already been diagnosed with Cushing’s, you are welcome to ring us at any hour for 24/7 vet care. If you are in the capital, you can reach an emergency vet in London at any hour.

Cushing's Disease in Dogs: FAQs

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

The earliest changes are usually increased thirst and hunger, accidents indoors, panting at rest and a coat that looks thin or dull.

How long can a dog live with Cushing's disease?

With treatment, many dogs live a further two to three years, and some go considerably longer, often with a good quality of life once the condition is well controlled. Age at diagnosis, the type of Cushing’s and any other conditions all affect this, so the range between individuals is wide.

Is Cushing's disease painful for dogs?

Cushing’s should not be painful in itself, but an untreated dog is often uncomfortable, weak, restless and unsettled. If your dog is limping or has discomfort in their back or belly, there is likely more going on.