Boy the Wandering Dog by Marshall Saunders

King Harry, as he said, had never been trained as his grandmother was, for he had been stolen when he was a puppy, but he inherited enough trailing instinct to do pretty good amateur work, and we dogs were always setting him tasks, and were surprised at his cleverness in picking up a trail.

One night, shortly after my conversation with him about his grandmother, we gave him something to do for our owners. We thought at first that there was going to be a serious case, but in the long run it turned out more happily than we thought it would.