There are three forms of Cushing's Syndrome and they are treated differently.
1. Pituitary dependent: Dogs are treated with either Lysodren® or the newer drug, Vetoryl® (trilostane). Both are very good at treating the condition. Lysodren® does have side effects such as an upset stomach but can be managed with 5mg of prednisone several times per week.
2. Adrenal Tumors: Adrenal tumors are surgically removed to treat this condition. If surgery is not available, management can be attempted by using the above listed drugs.
3. Iatrogenic Cushing's Syndrome: The offending oral or injectable corticosteroids have to be stopped. This is difficult because without corticosteroids a medical condition could worsen. With exogenous corticosteroid therapy, the adrenal glands stop making glucocorticoids. If corticosteroids are suddenly removed, the animal may go into shock. For this reason the animal must be tapered off of steroids over a long period of time. The adrenal cortex also produces mineralocorticoid agents, the most common being aldosterone which is needed for sodium regulation. This sometimes is needed to be added to the therapy via Percorten® injections every 26 days.