I have a yorkieshire 2 chihuahuas and a 5 month old pitbull. We brought Sandy our GR into our family 2 months ago. A friends if mines couldn't keep get so I decided to take her because I already knew she was a good dog to begin with and knew them both. The problem is that she has become aggressive with my Yorkie she growls at her even tries to bite her whenever she comes near me and at the beginning she was ok with them but now my yorkie also tries to fight back and that makes it worse. I do see that they are both jealous and want my attention but also Sandy gets aggressive whenever my pitbull starts to pick on my.yorkie cause he's too playful! I wish they would get along especially because she's very small next to Sandy and i'm afraid she might end up hurt. A friend of mines advices me to get Sandy a muzzle should I or not?? If anyone can give me advice I really would appreciate it Thank you!