itchy dog!

My dog is itchy! She does not have fleas. When we first got her a few months ago, I think she got bitten by some ants, and was itching constantly, the vet gave us some prednizone, which helped a lot. But it made her pee a lot, and I have heard that prednizone is not good for for dogs for long term use. She doesn't take it anymore.
I guess I suspect she may still be allergic to something, because her skin seems normal and not irritated. She eats dog food that is supposed to be good for allergic dogs.
ANY IDEAS??? (We live in Arizona)

Heather,
One of my family's dogs was recently found to be allergic to the preservatives in her dog food. We switched, and no more problems. Does your dog's allergy food contain preservatives? Just something you might want to look in to.

[This message has been edited by dogncatluvr (edited August 08, 2000).]

Thanks dogncatluvr...
She has been eating Solid Gold food for two months which is preservative free.
This morning I gave her a bath with Avo-derm.
Today I am going to start adding The Missing Link supplement to her food. Has anyone had any luck with this???