last night we started our new agility classes and murphy starting barking aggressively to the trianer. he told us not to come back next week unless we have a muzzel on him. do any of your dogs wear a muzzel? i'm so worried about murphy's fear aggression. it is getting worse. now he barks and lunges at anyone who approaches me. it is getting out of control. i'm worried sick about it. what do i do?? i just talked to a trainer who recommened that we put him down. i just can't even let myself think of that.