I breed Amrican Bulls (got 6). I had sort of the same issue with one that was a house dog and used to go on a tie out to get some fresh air while the kids were outside. I changed to a harniss (sp) when he was tied and (knock on wood) haven't had a problem with it since. We use (vet approved) children benadryl and baby asprins with ours and have for years. Good Luck!
Any idea what blood lines you have on him?
Any idea what blood lines you have on him?