Cushing’s disease, otherwise known as Hyperadrenocorticism refers specifically to an increase in cortisone due to a benign tumour of the pituitary gland. This disease affects a number of bodily systems, and signs of this disease vary considerably between cases. However, the most common signs are related to the urinary tract or the skin. Hyperadrenocorticism generally affects middle-aged to older dogs.
Symptoms and Types
- Increased thirst and urination
- Increased hunger
- Increased panting
- Pot-bellied abdomen
- Fat pads on the neck and shoulders
- Loss of hair
- Lack of energy
- Inability to sleep (insomnia)
- Muscle weakness
- Darkening of the skin
- Thin skin (from weight gain)
- Bruising (from thin, weakened skin)
- Hard white scaly patches on the skin, elbows, etc.
The most common cause of hyperadrenocorticism is a benign non-spreading pituitary tumour. Malignant tumours of the pituitary, which metastasize through the body, are a less frequent cause for hyperadrenocorticism. An even less common cause is a tumour of the adrenal gland (adrenal tumour – AT), but when it does occur, it may be benign or malignant.
Your veterinarian will perform a complete physical exam, including a blood chemical profile, complete blood count and a urinalysis.
Your veterinarian will also run tests to measure cortisone levels in your dog’s bloodstream. There are three tests for measuring cortisone which will help your veterinarian to diagnose hyperadrenocorticism: a urine cortisol creatinine ratio test, and two types of blood tests: a low-dose dexamethasone suppression test, and an adrenocorticotropin hormone stimulation test.
After your veterinarian has settled on a diagnosis, there will need to be further tests to see if it is being caused by PDH related tumours, or overgrowth of the pituitary gland. The high-dose dexamethasone suppression test is a blood test that may conclusively point to PDH caused hyperadrenocorticism by measuring cortisone levels in response to administration of the anti-inflammatory agent dexamethasone. A lowered, or unchanged cortisol level in response to the test will indicate Cushing’s disease.
Dogs with non-spreading adrenal tumours will be surgically treated in most cases. Medical treatment to stabilise your pet before surgery may be necessary.
Living and Management
If your dog is being treated with medications for this condition, you will need to be prepared to continue treatment for the life of your pet. You will need to be observant of any adverse reactions to medications. Signs of an adverse reaction are lack of energy, weakness, lack of appetite, vomiting, diarrhoea, and possible difficulty walking. If any of these side effects do occur, you should discontinue the medication, contact your veterinarian.
Once your dog has stabilized, you will need to return to the veterinarian for follow-up appointments at one, three, and six months, and then every three to six months after the first six months of treatment.