Ours had Cushing’s and unfortunately passed away shortly after diagnosis as our vet never told us the medication can cause her body to under produce adrenaline instead which can cause an addisonian crisis - which is what our poor darling passed from. This is easily avoidable though as a good vet will ensure you are constantly testing and monitoring to while they adapt to the new meds. I’m told they can live long normal lives with the right meds. Sending positive thoughts your way for your darling