So sorry to hear about Kiefer, I'm glad the bites aren't any worse, and hope they stay that way. As for "why" the dog turned? I don't know, for some reason the dog felt threatened, I bet though. Who knows, maybe the vet will have an answer for you on the "whys" when you return today, and, a suggestion of how, and if, you can bring the two dogs back together again. Good luck!