I give Xena benadryl 2x a day EVERY day and don't see any end to it right now. Whenever I have tried to stop she has a major hives breakout that lasts for days and makes her miserable. A vet recently told me it's a very good long term medicine but it's only an anti-histamine, not an anti-inflammatory, so it really doesn't do anything except help soothe itching if your dog has already had a reaction to something. I guess that's when prednisone and the other prescription meds come in.
Mr. Eko, GSD 2/14/12
Xena, ABPT mix 11/30/12