The library system has all sorts of books about dogs: training dogs, dog health and personal stories about dogs. Mutts by Brian Kilcommons and Michael Capuzzo [636.7009 K48] is the book about most American dogs. It is an appeal for adopting shelter animals and an explanation of why mutts make such good pets.
Dogs are the most genetically plastic mammals, ranging in size from five pounds to nearly 300 pounds. Dogs were the first animal domesticated by humans, and a case can be made that dogs cooperated in this. Many later species were domesticated with the assistance of dogs. Any animal that lives in herds was domesticated with the help of dogs.