My dogs were sitting in another room and I went to help my son with his dogs. He had just dyed them green, and I wanted to help him breed them. So I fed each of them some rotten flesh, and they made a puppy. The puppy instantly went after me and killed me. After I respawned, I collected my stuff and went back. His dogs didn't hate me, so eventually I tried breeding them again, exactly the same thing happened again. The puppy went crazy on me and killed me. The second time especially, I'm certain I didn't do anything to activate hostility. The parent dogs didn't attack at all.