Cushing’s Disease: Treatment Instructions with Mitotane for Dogs

Treatment with mitotane (brand name Lysodren®) involves an initiating phase and a maintenance phase. The initiating phase arrests the disease and restores the dog to a more normal state.

Some of the clinical signs, especially increased food and water intake, should stop within the first 1–3 weeks. Other signs, such as a poor hair coat or a bloated abdomen, may take several weeks or months to correct. 

The maintenance phase represents the phase of long-term therapy. This phase lasts the rest of the dog's life. You must continually monitor your dog's food and water intake. Both should return to a normal level. 

Water intake should be less than 1 ounce per pound (66 ml per kilogram) of body weight per day, but do not limit water if your dog needs to drink more. The amount of food should also be measured each day. At least two feedings per day are preferred. 

Initiating Phase of Treatment

1) Give the prescribed dose of Lysodren once daily until directed otherwise or one of the following occurs:

• Your dog's water intake drops to 1 oz per pound (66 ml per kilogram) per day.
• Your dog's appetite returns to normal, or it takes 15-30 minutes to eat when it would normally take much less time.
• Your dog does not eat a regular meal.
• Your dog vomits.
• Your dog has diarrhea.
• Your dog becomes unusually listless.

2) Return for another ACTH stimulation test on the date specified by your veterinarian or when one of the above occurs. This test should be done early in the morning and will require your dog to be in the hospital for about 2–4 hours. If the test is still abnormal, the initiating phase will continue. If the test is normal, the maintenance phase will begin.

3) If loss of appetite, vomiting, diarrhea, or listlessness occurs, give prednisone as prescribed by your veterinarian and DISCONTINUE THE LYSODREN® TABLETS. If vomiting prevents oral administration, your dog must be seen by a veterinarian for administration of proper medication by injection. When you begin this treatment, please call us for consultation and instructions as a tapering dose will be prescribed.

4) Report any other changes in your dog's behavior that are out of the ordinary. This disease, and this treatment, can result in several abnormal behaviors. However, your dog can also have other diseases, independent of Cushing's disease, that occur at the same time. It is important to differentiate between conditions so that proper treatment can be taken.

5) Stay cautiously optimistic. Cushing's is a serious disease, but many dogs with this disease enjoy a greatly improved quality of life for many years.

Maintenance Phase of Treatment

Once regulated, your dog will take Lysodren® approximately once weekly; your veterinarian will determine the best dosing schedule for your dog. An ACTH stimulation test will be necessary about every 3-4 months to be sure that regulation is satisfactory. At the appropriate time, the specifics of the maintenance phase will be explained.