Cushing's Syndrome in Dogs

Has your dog been diagnosed with Cushing's Syndrome, also known as hyperadrenocorticism? Learn more about this condition, caused by a chronic overproduction of the stress hormone cortisol, its significance for your dog's health, and its treatment options.

What is Cushing's Syndrome?

Cushing's Syndrome, also called hyperadrenocorticism, is a relatively common hormonal disorder in dogs, occurring particularly in small breeds and older dogs (average age 8-10 years). It is caused by an overproduction of cortisol by the adrenal glands. Cortisol, which is similar to cortisone, is usually secreted by the adrenal glands in stressful situations to help the body cope with these stressful events. However, an overproduction of this stress hormone over a prolonged period has detrimental consequences for the body, which then trigger Cushing's Syndrome.

There are two causes of Cushing's Syndrome:

• A pituitary gland tumor, which is usually benign and secretes a hormone that stimulates the adrenal glands to produce too much cortisol. Such a tumor is responsible for approx. 85% of cases.
• A benign or malignant tumor of one or both adrenal glands that produces an excessive amount of cortisol. This occurs in approx. 15% of affected dogs.

Additionally, there is iatrogenic Cushing's Syndrome, which can occur when a dog is given a cortisone preparation prescribed by the veterinarian long-term to treat a specific illness. 

What are the Symptoms of Cushing's Syndrome and How is it Recognized?

The symptoms of Cushing's Syndrome are both very typical and very diverse. Especially in the early stages of the disease, they are often subtle and therefore not easy to recognize.

These classic symptoms constitute what is known as Cushing's Syndrome:

• Increased thirst and increased urine production (polyuria-polydipsia): Your pet may need to urinate at night, makes larger puddles, and empties their water bowl faster and more frequently
• A greatly increased appetite (polyphagia): Your dog starts begging or stealing food and never seems to be full
• Fatigue or lethargy due to muscle weakness
• Pot-belly: Your dog may develop a pot-belly, gain fat, and lose muscle
• Dermatological problems: typically, symmetrical hair loss occurs on the trunk and tail. The skin becomes thinner and darker and is more susceptible to infections.

Less commonly, other symptoms may also occur, such as excessive panting, infertility, or weakness in the hind legs.

In addition to these symptoms, there are also other, less visible complications which your veterinarian can detect, such as high blood pressure, urinary tract infections and stones, proteinuria (loss of protein in the urine through the kidneys), diabetes, pancreatitis, and thromboembolism.

How is Cushing's Diagnosed?

If your veterinarian suspects Cushing's Syndrome, they will recommend various tests to confirm the diagnosis and choose an appropriate treatment. The most important tests to confirm Cushing's Syndrome are hormonal blood tests to monitor adrenal function, such as the ACTH stimulation test or the dexamethasone suppression test.

Once the presence of Cushing's Syndrome has been confirmed, its origin must next be clarified: Is it caused by a tumor in the pituitary gland or in the adrenal glands? Sometimes the answer is already provided by the blood test, but often your veterinarian will perform one or more of the following additional tests:

• - Abdominal ultrasound: to determine if there is a tumor on the adrenal glands,
• - CT or MRI scan of the brain: to locate tumors on the pituitary gland.

All these tests are useful and crucial for your veterinarian to ensure that your dog receives the most appropriate treatment for their form of Cushing's Syndrome.

What are the Treatment Options and What is the Prognosis?

The treatment for Cushing's Syndrome depends on its cause. For pituitary Cushing's, treatment is usually medicinal. Surgical removal of the tumor would be an ideal solution. However, this is very rarely performed in practice, as the procedure is expensive and difficult, requires a specialized surgeon, and the affected animals are often already very old. The same applies to radiation therapy.

The most common treatment is therefore medicinal therapy with "Vetoryl", a medication that reduces the adrenal glands' cortisol production and must be administered lifelong. The dose must be individually adjusted for each dog and regularly checked through blood tests. The quality of life for dogs well-adjusted to the medication is very high. Life expectancy, however, depends on the tumor's development: if it is benign, as is usually the case, the dog can live for many more years; if it is malignant, life expectancy is shortened.

Treatment for Cushing's Syndrome originating from the adrenal gland is usually surgical, by removing the tumor. If it is removed early and completely, the dog is subsequently fully cured. Unfortunately, this procedure is also not without risk, so sometimes lifelong treatment with "Vetoryl" is the better option here too. Also with this form, the prognosis depends on the type of adrenal tumor, which is benign in approx. 50% of cases.

For iatrogenic Cushing's, treatment simply involves reducing the cortisone dose. The symptoms then disappear on their own.

How Can I Support My Dog?

In addition to medicinal treatment, it may be beneficial to adjust your dog's diet to minimize muscle mass loss. Highly digestible food with a high protein content is suitable for this.

Furthermore, Cushing's Syndrome can damage your dog's organs and make them more susceptible to inflammation. Therefore, you can supplement your dog's diet with Omega-3 fatty acids, which have a positive effect on inflammatory processes.

You can also administer food supplements with a high content of antioxidants and vitamins to support your dog's health and immune system and combat the premature cell aging caused by their illness.

And finally, it is important to always provide your dog with sufficient fresh water so they can quench their thirst and not become dehydrated.