Hi there, I'm Dr B and I'm happy to help you with your question today.

I think that it would probably be best to avoid prednisone, as it will worsen signs of cushings disease.

However, when you are between a rock and a hard place like this, cushings is the lesser of 2 evils, as long as you can live with the side effects.

My personal recommendation would be to look into chemotherapy for Biskit

The most commonly used chemotherapy for mast cell tumors is vinblastine, given IV once weekly for 4-6 weeks

I have used this in several dogs and have achieved a good remission with minimal side effects. Most dogs have little to no side effects from chemotherapy - it is much different from chemo in people. In dogs we use much lower doses which usually puts the cancer into remission, but does not cure it. However, this allows dogs to have a great quality of life while undergoing chemo

All of my owners that have decided to go forward with chemotherapy have been really happy with their choice. Its important that you understand that chemo is different than in people and that if dogs have side effects, it is usually mild nausea or diarrhea for 1-3 days after their chemo dose that is easily controlled with medications.

The major barrier is cost - an average round of chemo in my clinic costs anywhere from XXX-XXXX dollars depending on how many doses are given and if there are any complications.

(A round being all doses required to cause remission).

So, in short, I highly recommend that you speak to your veterinarian about chemotherapy, specifically vinblastine. If chemotherapy is not an option for you, then I would probably start Biskit on prednisone and just be prepared to handle the cushing's side effects. If you have any further questions, please reply to chat and I will be happy to come back and address them. I sincerely XXXX XXX the best of luck with Biskit ~Dr B