I have a 8 month old Golden Retriever named Riley that has been "grabbing" our hands, legs, elbows, whatever is available with her mouth and though it's not "biting", she's none too gentle about it either. She does this when we try to pet her, simply walk along with her, put her leash on...But not always, she often behaves perfectly fine. We jerk our hands away and say "no" firmly but if she gets on a roll doing it there's nothing to do but walk away from her. It's like she becomes obsessed with doing it and it escalates to aggression. Help please!