What is Cushing’s Disease?
Cushing’s disease is a condition that can occur in dogs of all ages but middle-aged and older dogs have an increased risk of developing it. The disease occurs when the dog’s adrenal glands produce too much of the stress hormone cortisol.
Cortisol is a normal, necessary hormone that helps the body regulate blood sugar levels, metabolism, and stress response. However, when levels of cortisol become too high, it can lead to severe illness in dogs.
How common is Cushing’s Disease in dogs?
According to research published in 2009, it is estimated that canine Cushing’s Disease is diagnosed 1 to 2 times per 1,000 dogs every year.
What causes Cushing’s Disease in dogs?
The excess production of cortisol, which causes Cushing’s Disease, can occur naturally by tumors but can also occur as a side effect of other medications.
Pituitary gland tumor
About 80–85 percent of Cushing’s Disease is caused by a benign (non-cancerous) or malignant (cancerous) tumor of the pituitary gland. This pea-sized gland is found at the base of the dog’s brain.
A pituitary tumor causes an excess secretion of adrenocorticotropic hormone (ACTH) which travels through the bloodstream to the adrenal glands. The adrenal gland sees this excess ACTH and reacts by secreting cortisol. This is also known as pituitary-dependent Cushing’s disease.
Adrenal gland tumor
The other 15–20 percent of Cushing’s disease in dogs is caused by a benign or malignant tumor of the adrenal glands. As mentioned above, the adrenal glands are responsible for secreting cortisol and an adrenal gland tumor can lead to excessive production of this hormone. The adrenal glands are located next to the kidneys and an adrenal tumor can occur in one or both of them. This is also known as adrenal-dependent Cushing’s disease.
Iatrogenic Cushing’s Disease
Cushing’s disease in dogs can also be caused by an excessive or prolonged use of steroids. Using medications such as Prednisone and Dexamethasone for prolonged periods of time can lead to an excess of cortisol production. This is also known as Iatrogenic Cushing’s Syndrome.
Common symptoms of Cushing’s Disease in dogs
There are many symptoms of Cushing’s disease to look out for but any change in a dog’s behavior or appearance should be discussed with a vet.
Common symptoms include:
- Increased first (drinking more water)
- Increased urination
- Pot-belly appearance
- Excessive panting
- Increased appetite
- Hair loss
- Thinning skin
- Recurrent skin infections
- Lethargy
- Weight gain
How to diagnose Cushing’s Disease in dogs
There are a number of tests, that your veterinarian can perform, to diagnose Cushing’s Disease. They are usually used in combination with each other as there isn’t one test that can definitively diagnose Cushing’s Syndrome on its own.
Common diagnostic tests
- ACTH stimulation test
- Low-dose dexamethasone suppression (LDDS) test
- High-dose dexamethasone suppression (HDDS) test
- Urine cortisol : creatinine ratio test
- Abdominal ultrasound examination
- Urine analysis
- Bloodwork
How to treat Cushing’s Disease in dogs
There are several treatment options available for dogs with Cushing’s disease. Which option is best for your dog will depend on a number of factors such as their age, the type of Cushing’s Disease (pituitary-dependent Cushing’s disease etc.), or whether it’s a benign or malignant tumor present.
Treatment options for Cushing’s Disease
- Medication
- Surgery
- Radiation
How to cure Cushing’s disease in dogs
Adrenal/pituitary-dependent Cushing’s Disease
The only way to “cure” Cushing’s disease is to remove the tumor but this may not be an option in some cases due to the complexity and risks associated with the surgery.
Iatrogenic Cushing’s Disease
With the guidance of the vet, the steroid dosage will be slowly reduced and discontinued. This may, however, lead to the reappearance of the ailment the steroids were originally used to treat.
Can you prevent Cushing’s Disease in dogs?
Unfortunately, you cannot prevent dogs’ Cushing’s Disease if it is the result of pituitary tumors/adrenal tumors.
However, the risk of developing Iatrogenic Cushing’s Disease can be lowered by avoiding the prolonged use of steroids.
Final thoughts
Cushing’s Disease in dogs is most commonly seen in middle-aged and older dogs. It develops when your dog’s body produces an excess amount of the stress hormone, cortisol. This is usually due to the presence of a tumor but can also occur after prolonged use of steroids.
Symptoms to look out for include increased thirst/urination, excessive panting, pot-belly appearance, and hair loss/thinning skin. The most common treatment option is medication but other treatments include surgery and radiation.
Article sources
de Bruin, C. (2009). Cushing’s disease in dogs and humans
US Food and Drug Administration. Treating Cushing’s Disease in Dogs
