I had adopted a dog (Libby) who really needed lots of desensitization, and lots of work--but oddly I found her very easy to figure out and work with. So while you might think she was my challenge, she wasn't . ---As much as we fell in love instantly with each other--Wilson is my challenge dog. You have seen all the pictures of this boy--and he is funny beyond funny--but figuring out his communication has been a challenge. He does not communicate like other dogs I have had--he would be very easily misunderstood in another household I think. It is difficult to describe his oddities--but he has made me think about doggie communication in a very different way than my other dogs ever have. And I looooves the boy--seriously loooove the boy.