Thanks for the update. Well, it certainly sounds as if they have everything covered, doesn't it:)
I suppose I understand why Benadryl was recommended although in my experience, it's not a medication which is effective for all dogs who suffer from seasonal allergies. In general, antihistamines don't work as well in dogs as they do in people especially if the allergies are pretty intense. But, having said that, they can help some patients and aren't harmful so, hopefully he'll be one of those who benefits.
Personally, I might have considered dispensed systemic steroids but I don't like to second guess in these types of situations since I'm not on scene.
I would agree that you should expect to see improvement within a relatively short period of time. Deb