Cushing’s Disease in Dogs
Reviewed for accuracy on January 6, 2020 by Sarah Wallace, DVM
Just like humans, dogs’ hormones can sometimes get out of balance. One example of hormonal imbalance that usually affects middle-aged and older dogs is Cushing’s disease, also called hyperadrenocorticism, which means excessive cortisol production caused by an abnormality in either the adrenal gland or pituitary gland.
What is Cushing’s Disease?
Cushing’s disease is a condition in which your dog’s body makes too much of a hormone called cortisol. Cortisol is normally produced in times of stress; it is also known as the fight or flight hormone. The breakdown of body fats and sugars to prepare for stress is a good response in short bursts, but prolonged exposure to the cortisol hormone creates a long-term breakdown process in the body. As a result, it can ultimately weaken the immune system and leave your pup vulnerable to additional infections and diseases.
There are two main types of this condition that affect dogs:
- Pituitary dependent: This type is caused by a tumor in the pituitary gland in the brain and is the most common type of Cushing’s disease. The pituitary gland is what tells the adrenal glands to produce and secrete cortisol. 85% of Cushing’s disease cases are caused by pituitary tumors.
- Adrenal dependent: Caused by a tumor in the adrenal glands, near the kidneys. 15% of Cushing’s disease cases are caused by adrenal tumors.
Clinical Signs and Symptoms
Because there are many non-specific clinical signs that result from chronic exposure to cortisol, Cushing’s disease can be quite difficult to diagnose. Some signs to look out for:
- increased thirst, appetite, and/or urination
- saggy belly
- lethargy and weakness
- hair loss, darkening of the skin or recurrent skin infections
- poor wound healing
- excessive panting
Diagnosing Cushing’s Disease
Because Cushing’s has similar symptoms to a few other conditions, it can be difficult to diagnose. Several blood tests are necessary to identify the disease and determine whether the adrenal or the pituitary gland is the source of all the trouble.
Some diagnostic testing may include:
- ACTH stimulation test
- Low dose dexamethasone suppression test
- High dose dexamethasone suppression test
- Endogenous ACTH level
- Ultrasound of the belly to check for adrenal tumor
In addition to these tests, X-rays and MRI can also be useful in making a diagnosis.
Just like the symptoms and diagnosis, the treatment of Cushing’s disease is varied and complex. If the condition is due to a tumor on one of the adrenal glands, then surgery can be an option if the tumor is benign. However, it is possible that the adrenal tumor is malignant and may have spread elsewhere in the body.
In other cases where surgery for an adrenal tumor is not recommended, or in cases of pituitary tumors, prescription medications may be necessary for the rest of the dog’s life. Without treatment, symptoms may persist indefinitely and infections of the skin and urine may reoccur indefinitely. Although not a fatal disease, treatment is generally encouraged to improve the quality of life for your dog. It’s best to come up with a plan alongside your veterinarian, since treatment is unique to every pup.
Dr. Kait Link, DVM, is a veterinarian and co-founder of Treat, an innovative vet practice. Treat is reinventing pet care, offering instant access to affordable in-home veterinary care, training, and grooming. Book in under a minute or chat free anytime. Download the Treat app at treat.co.