Dog

Any member of the canine genus Canis, particularly the domestic species, Canis familiaris. Domestic dogs seem to have decended from the wolf or a wolflike ancestor.

Dogs were apparently the first animals to be domesticated, and domestication seems to have begun in various parts of the world at roughly the same time. Selective breeding by humans has resulted in myriad domestic breeds that vary widely in size (from the tiny Chihuahua to the huge mastiff), physical form (e.g., the short-legged dachshund and the flat-faced bulldog), coat texture and length (e.g., the sleek Doberman pinscher and the long-haired Afghan hound), and behavioral patterns (e.g., sporting dogs, toy dogs, and working dogs). The American Kennel Club now recognizes almost 150 breeds; other clubs, such as the United Kennel Club, recognize many more.