Hello, we recently (on march 1st) adopted a rescue dog who we and several others believe is a shih tzu and terrier (Border or Jack Russell) mix. He is great with us but is a bit overly protective. For example my husband gave my daughter a hug and he started to growl and bark. He also is not doing to well with guests who come to the house. When we first got him he would not aggressively bark at guests or would stop after the guest gave him a treat. Now, however, I assume that because he has got very attached, he feels that house guests are trying to hurt us. He barks and growls at any new people and we are worried it might escalate to biting. We also took him to the vet where he squirmed a lot when they were trying to microchip him and the vet told us he might have been abused in the past because he is scared of restraints. Any tips or advice on how we get him to not be so aggressive with our house guests and be less protective of us?