Christine, why has your pet been put on Prednisone? Prednisone does cause increased thirst and urination which should subside after the medication has been discontinued. Prednisone can cause the belly to be distended but that usually happens after they have been on the medication for a long period of time. I suggest you review her symptoms with your veterinarian because what you are describing could be indicative of other more serious problems. I hope all works out well for you both.