Because Cushing's disease in dogs is usually caused by a tumor on either the pituitary gland or the adrenal gland, the prognosis depends on the size and type of the tumor. The prognosis for dogs with smaller tumors is usually better than those dogs that have a large tumor, according to VCA Animal Hospitals.
Cushing's disease in dogs comes in three forms. One form occurs when a tumor develops on the dog's pituitary gland. This is the most common form of the disease and occurs in between 85 and 90 percent of all Cushing's cases, states VCA Animal Hospitals. The tumor may be malignant or benign and a benign tumor may be controlled with medication. A malignant tumor on the pituitary gland offers a less than favorable prognosis. Vets typically treat this type of Cushing's with Vetoryl or Lysodren and occasionally Anipryl may be used, although it is not as effective.
The second type of Cushing's is caused by a tumor on the adrenal gland. Benign tumors are often removed in a surgical procedure and although malignant tumors can be removed in this way, the prognosis is less favorable. In cases where surgery is not an option, the dog's health may be managed with medication.
The third type of Cushing's is caused by excessive cortisol production caused by the prolonged use of steroids. Treatment for this form of the disease requires the discontinuation of steroids and hormone replacement.