That's a very sad story. I do think unfortunately that this is normal dog behavior. It sounds like basic predation to me. Smaller dogs go after gophers, squirrels and birds. Bigger dogs go after bigger prey.
Now as to whether this dog might consider a yorkie prey - that's an open question. It sounds like you have a secure fence and at least you are aware of the potential danger.
__________________ If you love something, set it free. Unless it's an angry tiger. |