So I think my dog has hay fever. We've taken her to the vets as she kept scratching and ended with hives all over her. I was given antihistamines and we were giving her them when the weather was warm but I stopped when the weather cooled down. However she has started itching again. So my question is how often should I be giving her antihistamines? Do I just give her them daily now throughout all of the summer or is it to be used intermittently? Also is there any other tips for easing symptoms? Any advice you would be greatly appreciated.