Cushing’s Disease in Dogs

Cushing’s disease is the more commonly used name for a condition called hyperadrenocorticism. It’s caused by the chronic overproduction of the hormone cortisol, and is fairly common in middle-aged and older dogs. There are a wide range of symptoms associated with Cushing’s disease, but it’s a condition that progresses slowly, making signs sometimes difficult to spot. This article will explain what Cushing’s disease is and how it can affect dogs, as well as describe the main symptoms so you know what to look out for.

What is Cushing’s Disease in Dogs?

Cushing’s disease is caused by the body producing too much cortisol.

Cortisol is a naturally occurring steroid hormone produced by the adrenal glands, which are located near the kidneys. The pituitary gland, located at the base of the brain and commonly referred to as the ‘master gland’, sends signals to the adrenal glands to ensure cortisol is produced in a regulated amount. Like all hormones, cortisol is an essential chemical that helps to control many functions within the body. Normal levels of cortisol help to regulate blood pressure, maintain metabolism, control blood sugar and even help with the body’s sleep-wake cycle.

Cortisol levels will also increase in times of perceived threat, ensuring the body can stay on high alert and act quickly, slowing nonessential or harmful body functions and triggering the release of glucose for fast energy. Once a threat or danger has passed, cortisol levels should reduce back to normal levels, allowing the body to return to its normal functionality. This natural response is perfectly healthy and is an important way for the body to protect itself.

However, in a dog with Cushing’s disease, too much cortisol is produced which has a negative impact on the body.

Causes of Cushing’s Disease in Dogs

The reason a dog’s body starts producing too much cortisol is usually because of small growths forming on either the pituitary or adrenal glands.

Pituitary gland tumour: A tumour of the pituitary gland, at the base of the brain, is the most common cause of Cushing’s disease in dogs. It causes the gland to send too many signals to the adrenal glands, stimulating them to produce more cortisol than the body needs.

These tumours can be benign (otherwise harmless) or malignant (cancerous). The tumours can vary drastically in size and this can effect the severity of the symptoms a dog may experience as well as their prognosis.

Adrenal gland tumour: Less commonly, a tumour might form in the adrenal glands, causing them to overproduce cortisol.

A third way that Cushing’s disease can develop is as a result of high-dose steroid medication – this is known as iatrogenic Cushing’s disease.

Steroid medications are a vital treatment protocol for many conditions and are commonly used in pets to help reduce inflammation or to address problems with the immune system. When used correctly, steroids are safe and few side effects occur. However, dogs that are medicated with high doses of steroids for a prolonged period of time can sometimes develop iatrogenic Cushing’s disease.

If your dog is on medication and you suspect Cushing’s disease, never change your dog’s dosages before speaking to your vet.

Symptoms of Cushing’s Disease in Dogs

Regardless of the cause, Cushing’s disease results in the same symptoms. The condition is slow to develop, sometimes making it difficult to spot the early signs. Symptoms of Cushing’s disease include:

Increased thirst and urination: This is the most common symptom that owners tend to notice. Many owners will first suspect a problem because their dog suddenly starts to need to go to the toilet in the night, for example.

Hair loss: This might occur on the flanks, tail, neck and perineum.

Skin changes: The skin might become thinner, scaly, and slow to heal. You might also notice dark-coloured spots on the skin, and your dog may be more prone to skin infections.

Muscle weakness: Your dog might find it more difficult to move around as they usually do, struggling to climb stairs or jump onto the sofa for example.

Panting more than usual: The muscles used for breathing are affected by weakness too. This can cause your dog to pant more.

Weight gain: Increased cortisol levels can result in a bigger appetite, leading to weight gain.

Swollen stomach or ‘pot-belly’: Many dogs with Cushing’s disease will start to sag or appear bloated around the abdomen. This is partly due to an increase in fat within the abdominal organs, and partly because the muscles of the abdominal wall become weaker and eventually shrink in size.

Lethargy: You may notice drowsiness or a lack of energy in your dog.

Are There Specific Dog Breeds Prone to Cushing’s Disease?

Any breed of dog can develop Cushing’s disease, but some breeds are more prone to it than others.

Small breeds such as poodles, dachshunds and yorkshire terriers are thought to be at a higher risk of developing Cushing’s disease.

A study published in the Journal of Small Animal Practice (JSAP) in 2022 identified seven breeds that were more at risk of Cushing’s disease compared with cross-bred dogs. These included:

  • Border terrier
  • Staffordshire bull terrier
  • Bichon frise
  • Miniature schnauzer
  • Lhasa apso
  • Yorkshire terrier
  • Jack Russell

Diagnosing Cushing’s Disease in Dogs

If you notice any of the symptoms of Cushing’s disease in your dog, even if they seem otherwise well, you should make an appointment with your vet.

To help your vet make a diagnosis, it’s helpful to make a note of how much your dog is drinking by measuring the amount you put in their bowl, and seeing how many millimetres are left at the end of the day.

As well as giving your dog a physical full body check and asking about their symptoms, your vet will need to carry out tests, such as blood and urine tests, to confirm their diagnosis. It can take a bit of time to diagnose Cushing’s disease.

Treatment for Cushing’s Disease in Dogs

There are a few different options for managing Cushing’s disease in dogs, and the type that is right for your pet will largely depend on the cause of your dog’s Cushing’s disease.

In most cases, medication can be used to manage the levels of cortisol in the body and reduce the symptoms.

Depending on the size and location of the tumour, there may also be specialist surgical options to remove it.

Both treatments have advantages and disadvantages. The suitability of these options will vary from dog to dog, and availability of specialist treatment will vary between practices. Have discussions with your vet to determine what will be best for your dog’s individual needs.

If the disease has been caused by steroid medication, your dog will first need to be gradually and carefully weaned off the existing medication according to your vet’s instructions – it’s very dangerous to come off of steroid medication too quickly.

Medication for Cushing’s disease is life-long, and requires regular monitoring, so it can be expensive to treat. Asking for a written prescription from your vet and ordering your dog’s medication online can help to make it much more affordable.

How Long Can Dogs Live with Cushing’s Disease?

Prognosis and life expectancy for a dog with Cushing’s disease will vary depending on each dog’s individual condition.

Most dogs who are medicated tend to respond well, going on to live a long, healthy life (provided they have no other health issues). Once they start treatment, some of the symptoms of Cushing’s disease can improve within just a few weeks, and others a few months.

While some dogs with Cushing’s disease can live without any treatment for some time, it is likely to reduce your dog’s quality of life, with symptoms progressing and worsening over time.

Left untreated, dogs with Cushing’s disease are also at a higher risk of developing diabetes, high blood pressure, pancreatitis, kidney and urinary tract infections and pulmonary thromboembolism (blood clots in the lung).

It’s important to discuss your dog’s treatment and any potential side effects or risks with your vet.

What Can I Do for My Dog with Cushing’s Disease?

It’s important that you regularly monitor your dog at home, noting down any new or changing symptoms. Keeping track of how much water your dog drinks every now and then will also be very helpful; make a note of how much they drink in a 24-hour period every one or two weeks.

You’ll need to arrange regular check ups with your vet, where you can relay your observations, and your vet can carry out their own checks. Blood tests are often necessary to monitor your dog’s cortisol levels and make sure their level of medication is right.

Even if your dog continues to drink excessively, never restrict their access to water. They may continue to drink more than they did before, even after starting treatment. Also make sure that your dog always has access to somewhere they can go to the toilet.

Wrapping Up

Cushing’s disease is fairly common in adult dogs, and so it’s good to have an understanding of the symptoms associated with it so that you’ll be able to spot them if they arise. If you do notice any of the symptoms of Cushing’s disease, make an appointment to see your vet. Once diagnosed it’s important to discuss all your options with your vet to make the right decision for your dog’s individual circumstances.

Animed Veterinary Nurse, Beth Walker
Sign up for Animed emails