It may be true that a dog is a man's best friend, but if you are a serious dog owner, you are probably a serial dog owner, having embraced not one but a succession of canine companions, each of them memorable in their own particular way, and each marking a particular epoch in your own life. We remember which dogs our children teased (and which generally suffered the abuse nobly), the ones that chewed the furniture and peed on the rugs, the ones that...