Cushing’s syndrome is a disorder that seriously affects your dog’s health, vitality and appearance. Also known as hyperadrenocorticism, it is one of the most common endocrine disorders, occurring mostly in middle aged and older dogs.
Dogs with Cushing’s syndrome produce excessive amounts of cortisol, an important hormone that helps regulate the body’s metabolism. This can have harmful effects on other organs and on the ability of the body to regulate itself.
Cortisol is produced by the adrenal glands, two small glands located in the abdomen next to each kidney. A hormone called ACTH controls the production and release of cortisol from the adrenal glands. ACTH itself is produced by the pituitary gland, a pea-sized gland located at the base of the brain.
The concentration of cortisol in the blood of a healthy dog varies as the body's demand for cortisol fluctuates; for example during a period of stress or illness, the production of cortisol by the adrenal glands is increased. Once the period of stress has passed the cortisol concentration in the blood returns back to normal.
Cushing’s syndrome will usually occur as a result of a tumour - often benign – most commonly in the pituitary gland or sometimes in an adrenal gland. Regardless of the cause, a dog suffering from Cushing’s syndrome will develop a combination of clinical signs which may be mistakenly associated with the ageing process.
Most dogs with Cushing’s syndrome (80 - 85%) have a benign tumour of the pituitary gland.
The tumour cells produce large amounts of the hormone ACTH, which in turn stimulates adrenal glands to overproduce cortisol.
In 15 - 20% of cases, Cushing’s syndrome is caused by a tumour of one (or very rarely both) of the adrenal glands, which produces excessive amounts of cortisol.
Irrespective of the cause of Cushing’s syndrome, the result is always the same – more cortisol is produced than is actually needed by the body. This results in the slow development of a combination of clinical signs that are associated with Cushing’s syndrome.