An introduction to Cushing’s Disease
Cushing’s Disease, also called Hyper-Adrenocorticism, is a disease that affects dogs (as well as some other species). This condition is treatable, but it is important for you to know what the signs are, and what your dog’s prognosis is.
What is Cushing’s Disease?
Cushing’s Disease affects a dog’s adrenal glands. These tiny glands are positioned just next to the kidneys. With Cushing’s Disease, the adrenal glands become overly active and produce too many hormones, such as Cortisol (sometimes called Cortisone). Cortisol is a stress hormone, and important for an animal’s “fight or flight” behaviour. Excess Cortisol will have detrimental or even deadly effects on a dog, and can even lead to death.
What causes Cushing’s Disease?
There are three main types of Cushing’s Disease, each with its own cause.
- Pituitary gland tumour: This is the most common cause of Cushing’s. The pituitary gland is at the base of the brain. If a tumor develops on it, the pituitary gland will produce too much of the hormone ACTH, which will in turn stimulate the adrenal glands to produce too much Cortisol.
- Adrenal gland tumour: A tumour may develop on one of the adrenal glands, which will affect their function. This type of Cushing’s is more common in large breed dogs.
- Iatrogenic: If a dog is given too many steroid medications, this can lead to the development of Cushing’s Disease.
What are the Symptoms?
A popular memory aid for the symptoms of Cushing’s disease are the Five P’s:
- Polydipsia – drinking more water
- Polyuria – urinating more
- Polyphagia – increased appetite
- “Pot-bellied” appearance
Some dogs may seem lethargic, with a poor quality coat, hair loss (especially on the neck, flanks, and backside), and skin lesions.
The problem is that a lot of these symptoms are commonly mistaken for signs of aging, so it may take a while for an owner to notice that their dog isn’t well.
How is the Diagnosis made?
To diagnose Cushing’s Disease, your vet will need to perform blood and urine tests. If the results of these tests are unusual, the next step is the ACTH-stimulation test. In this test, the vet first checks the level of Cortisol in the dog’s blood, and then injects ACTH (adrenocorticotrophic hormone): this is a hormone that stimulates the adrenal gland. A few hours later, the vet will check your dog’s blood to see the amount of Cortisol in it.
Further testing will be required to discover the root of your dog’s disease; for example, ultrasound will help your vet check whether there is a tumour on the adrenal gland.
What’s the treatment for Cushing’s Disease?
The type of treatment depends on what is causing Cushing’s in a particular dog.
- Pituitary gland tumour: Your vet can prescribe medicine to help treat this. Keep in mind that your dog will probably be taking medicine for the rest of his/her life in order to control the disease.
- Adrenal gland tumour: To remove the tumour, your dog will need abdominal surgery. This surgery can be risky, but if successful, your dog should soon be happy and healthy again.
- Iatrogenic: As this is caused by excess steroid medication, your dog will gradually need to stop taking this medicine. This must be done in a controlled manner, as it is dangerous to just stop giving the medicine at once! Your vet can advise you as to the best course of action.
What’s the outlook for my dog?
Your dog’s prognosis depends on the kind of Cushing’s Disease that they have. If it is caused by a small, benign tumour, then the outlook is very positive, and medicine/surgery should allow your dog to live out the rest of their days in comfort.
If the cause is a large tumour affecting the brain, the prognosis is less positive. Dogs with malignant adrenal tumours also have a worrying prognosis. Fortunately, surgery for benign adrenal tumours is usually successful.
It’s important to ask your vet for their advice. They will be able to give you the information you and prescribe the correct care and treatment for your dog.
What dogs/dog breeds are prone to this condition?
Cushing’s Disease tends to affect older dogs, typically above eight years of age. Some dog breeds are more prone to the illness:
- Boston Terrier
- German Shepherd
- Dandie Dimont Terrier
- Yorkshire Terrier
Please note: The information in this article cannot be used to diagnose or treat an animal you suspect suffers from any diseases.