It is difficult to treat pituitary dependent Cushing's disease because the pituitary gland is hard to get to. These treatments selectively kill cells in the adrenal gland that are producing cortisol. With removal of all or part of the adrenal glands, supplemental cortisol must be followed conscientiously. Cushing's disease can also be induced by a veterinarian. Prednisone, a synthetic steroid, is often used to treat skin disorders and as an anti-inflammatory agent.
Steroids act like natural cortisol.
Long term use of steroids eliminates the need for cortisol production by the adrenal gland. With decreased function, the adrenal glands shrink in size. Slow withdrawal of steroids is normal treatment. Eliminating steroids abruptly can have fatal consequences. The variety of clinical signs makes Cushing's disease difficult to diagnose without further testing.