Cracker the Best Dog in Vietnam

In the book Cracker the Best Dog in Vietnam by Cynthia Kadohata, Cracker a dog going to the Vietnam war has to bond with her handler. She still remembers her previous owner a boy named Willie  and still feel loyal to him. Rick Hanski wants to whip the world so he decides to join the army as a dog handler, when he first met Cracker he wanted to switch dogs, but by the end they become friends and the best team in Vietnam.