Cushing’s disease in dogs (also known as hyperadrenocorticism) is named after Henry Cushing who first described the disease in humans in 1912. It is one of the most common conditions affecting a dog’s endocrine system and mostly occurs in smaller dogs aged over seven years. The disease causes dogs to produce excessive amounts of cortisol, which helps regulate the body’s metabolism and immune system. Too much cortisol can impact a dog’s entire body.
Cushing’s Disease in Dogs |What causes it?
There are two different types of Cushing’s. The first is adrenal dependent hyperadrenocorticism (ADHA). This occurs when a tumour on the adrenal glands causes them to overproduce cortisol. The second type is pituitary dependent hyperadrenocorticism (PDHA). PDHA is the more common of the two forms, and the most common cause is benign tumours in the pituitary gland, accounting for up to 85 per cent of cases. The pituitary is known as the master gland because it controls the hormone release from other endocrine glands, including the adrenal glands. In most cases of PDHA, the tumours cause it to overproduce the ACTH hormone, which stimulates the adrenal glands to produce cortisol. Excessive use of some steroid-based medicines (mostly used to treat allergies, some cancers, and immune disorders) can bring about an onset of the disease, even after the steroids have been stopped.
Cushing’s Disease in Dogs |What are the symptoms?
There are numerous signs and symptoms which can point to Cushing’s disease in dogs, and as these are shared with many other illnesses — for example, diabetes and urinary tract infections — it can be tricky to identify.
● Increased thirst/appetite.
● Increased urination or night-time urination.
● Distended (pot-bellied) abdomen.
● Loss of hair.
● Recurring infections.
● Muscle weakness.
● Panting even when resting.
Cushing Syndrome in Dogs |How is it diagnosed?
If you suspect your dog might have Cushing’s disease, your vet will test his blood and urine for levels of cortisol. If he suspects Cushing’s, he may also order two further tests: ACTH stimulation test, in which the function of the adrenal glands is measured, and a dexamethasone suppression test to measure how cortisol levels change when injected with dexamethasone. Once a diagnosis of Cushing’s has been confi rmed, a test to determine which form, either ADHA or PDHA, will be in order.