Our dog Avery is a 3 year old Dachshund/Yorkie mix that we adopted a little over a month ago. The history on him said that he had lived with other pets at one time, but his last owner before us was an older woman who lived alone. He seems to warm up to people very quickly. Not instantly, but quickly. He seems to love teenagers especially. He'll roll over for belly rubs right in front of them within 2 minutes of meeting them. The problem we're having with him is other dogs. This behavior seems to vary depending on whether it's my wife or me walking him. When I walk him, he doesn't pull toward other dogs. If my wife is walking him, he does pull. Once he meets the other dog, the reaction always seems to be the same. They sniff each other for a few seconds and then our dog snaps. We're at the point now where we just won't let him get close enough to sniff anymore for fear of the inevitable. You can see his tail start to stand up vertically when he gets close to sniffing distance. I know this is pretty much a telltale sign of trouble. I've wondered about the differences in his behavior when my wife walks him vs me walking him. Although he loves everyone in the family, she is his favorite hands down. Is it possible that he thinks he's protecting her from the other dogs on walks? We've talked about adopting another dog, but we don't dare until we can get Avery to the point where he can be nice to other dogs. Any thoughts?