Scientific name -- Canis lupus familiaris
Size -- 2' at the shoulder (modern breeds vary)
Diet -- carnivore, favors small animals.

The relationship between humans and dogs goes back centuries.  They were probably first domesticated around 13,000 BCE.  It is thought that the social behavior of wolves made this relatively easy, compared to cats, and that their hunting skills made it beneficial to both creatures involved.  There are hundreds of dog breeds with a variety of shapes, colors, and sizes.