Mike, a lot of people (and dogs) do have a lot of side effects from prednisone. If it is not helping (and for that matter helping a lot), I think that you are doing the right thing to wean off of it. The only reason to put up with horrible side effects from any drug is if it does so much good that it is worth it. Side effects like you are telling us about are too bad to tolerate. I would think that it could kill you if you kept it up. Other people may do ok on that much.
I think that the fluid retention would kill me. If I eat pizza, my blood pressure will soar. If I took a drug that caused fluid retention, I don't think I would make it.
I am very glad you are getting off of it.