Some frequently asked questions about Cushing’s disease and Cushing’s syndrome in the dog

Cushing’s disease is also known as hyperadrenocorticism, and is a health condition that is caused by the body producing excessive amounts of their natural corticosteroid, cortisol. Cortisol is produced by the adrenal gland, and when the adrenal gland produces too much cortisol for any reason, this can lead to a fairly wide range of symptoms and changes in your dog’s health that should not be overlooked.

In this article, we will provide answers to some of the most frequently asked questions about canine Cushing’s disease, its diagnosis, and what it means for affected dogs. Read on to learn more.

What is Cushing’s disease?

Cushing’s disease or hyperadrenocorticism is known by various other terms too, including pituitary-dependent hyperadrenocorticism, or PDH. The condition occurs when the dog’s adrenal gland produces too much cortisol, a naturally occurring corticosteroid. Cortisol is a necessary part of a healthy body, allowing for the management of blood sugar levels, for the metabolism of fat, protein and carbs, and to control the immune system.

However, when the adrenal gland produces too much cortisol, the body will begin to show a range of symptoms related to this that can, in some cases, be fairly severe.

It is important to note that Cushing’s syndrome, while similar in name to Cushing’s disease, is actually treated as a different condition that is only found in around 15% of cases of Cushing’s disease.

What causes Cushing’s disease in the dog?

In the case of Cushing’s syndrome, the condition is caused by a tumour growing on the dog’s adrenal gland, which leads to an excess in the body’s production of cortisol.

Cushing’s disease itself is present alongside of most cases of hyperadrenocorticism, and this is caused by the growth of a tumour on the pituitary gland, which will in turn lead to an excessive production of adrenocorticotropic hormone, or ACTH. ACTH is the hormone that stimulates the body to produce corticosteroids, and a problem with the pituitary gland will lead to an over production of these, due to their increased ACTH hormone levels.

Both Cushing’s disease and Cushing’s syndrome generally occur as a result of tumour growth or other internalised problems without an external cause, however, a form of the condition called latrogenic Cushing’s can also occur if the dog is prescribed long term corticosteroids by the vet, such as prednisolone and prednisone for other conditions.

What are the symptoms of canine Cushing’s disease?

The symptoms of Cushing’s disease in the dog are generally systemic, meaning that they will affect many areas of the body at once, rather than being concentrated in one area. They can also be fairly wide and varied, and so you should keep an eye out for any or all of the following symptoms in combination:

• Increased appetite.
• Weight gain.
• Increased thirst.
• Increased urination.
• An apparent enlargement of the dog’s abdominal cavity.
• A loss of muscle mass in the hind limbs, or apparent muscle weakness.
• Alopecia or loss of hair, across various parts of the body.
• Hyperpigmentation, or darkening of the skin.
• Thin, fragile skin.
• Difficulty moving normally, or loss of the full range of movement.
• Lumps and bumps just under the skin.
• Lethargy.
• Pancreatitis.
• A tendency to catch minor infections, and problems shaking them off.
• A tendency to sleep during the day and be more active at night.
• Irritability and possibly, snappishness.
• Panting that is not related to exercise.

How is canine Cushing’s disease diagnosed?

If you observe some of the above symptoms in your dog, you will need to take them along for the vet for tests, and to confirm diagnosis. Your vet will usually run a range of tests on your dog, including a complete blood panel to look for high levels of cholesterol, liver enzymes and white blood cells, as well as running a test to measure the body’s cortisol levels.

Urine testing is also used to identify the ratio of cortisol to creatinine in the urine.

How is canine Cushing’s disease treated?

Treating and managing Cushing’s disease on an ongoing basis will depend on what is causing the condition. If the dog is suffering from latrogenic Cushing’s due to steroid medications, reviewing the dog’s steroid usage and seeking alternatives can help.

For naturally occurring Cushing’s disease, your vet will need to identify whether the condition is being caused by excessive cortisol, or excess corticosteroids. However, prescription of a medication called Lysodren, which works on the external areas of the adrenal glands is the usual course of treatment, as this medication also controls the pituitary glands as well.

Dogs diagnosed with Cushing’s disease will generally need to be tested for cortisol and corticosteroid levels a couple of times per month, in order to monitor the dosage rate and how effective the medication is proving to be.