I have a three year old pure bred Maltese who has always had issues with separation anxiety from me and barking uncontrollably. In the process of trying to train him out of that, for the last couple months he has started to become aggressive. He used to love every single person who walked in the door, the problem was with jumping and licking and barking, but three times now in the past couple months he has been very suspicious at the start when they walk in, and when they reach for him, he starts barking at a very high pitch (sounds like screaming) and trying to hide himself, growling even. I'm very afraid he is going to bite someone. This is all new, and has only happened with females. He has never been isolated from people or other dogs, we just have had issues with the anxiety and barking for a long time. Advice is appreciated, will be talking to the vet about this as well but thought I would see what other advice I could get.