still nobody's bitch
This picture bounced around the web within the last year or two and its of a dog that didn't know how to react to its owners' death. It apparently would not leave the body and paramedics (from what I think I remember) had to bring the dog with them since it wouldn't let them take the body very far from it.
Having had dogs, I can certainly attest to their loyalty. It may be biological, something in their blood that makes them loyal to their leaders, but I think there's nothing wrong with that.
I think that it is biological, and it's why they were domesticated so much earlier in our history than cats were.