An inspiring and heartwarming introduction to the many roles of service dogs, from herders and sled-pullers to search-and-rescue, hearing, and guide dogs. Starting with lively and easy-to-understand explanations of a dog's senses, the author describes roles of canines long ago (such as the use of dog power to transport goods) and in contemporary times: from herders and hunters to police dogs, military dogs (including scout, messenger, and even parachuting dogs), search-and-rescue dogs, and traditional service dogs (the training and role of guide dogs, hearing dogs, canine assistants, seizure dogs, and therapy dogs). Vibrant illustrations throughout the book show a variety of breeds working in their jobs and helping people.