Becoming aggressive terrier / havanese
I adopted a very mute, tame, terrier/havanese mix as a puppy. Three years later my now 3 1/2 year old has become nippy, barks at everyone and everything and has even taken to biting visitors. We have three, all rescue dogs. Ranging from 9 to 9 months. They all play. Get along with each other, but increasingly we are having serious issues. I was told to just put him down. He is a family member and you just don't or can't do that, yet! What should and can I do?