Hmm, I think he has Jack Russel in him based on the face, but I don't know why I jumped to the conclusion that he might have Tibetan Spaniel in him...Oh! Maybe he has a bit of Nova Scotia Duck Tolling Dog in him! Heh, that would be a little odd to see, but I've seen a dog recently who was a pure bred Duck Tolling Dog, and she looked a little like your dog, only bigger. What makes you say that you know for a fact he has chihuahua? I would think he has more of a Jack Russell face, but then again, I can't see his face too well.