Canis lupus familiaris

The domestic dog (Canis lupus familiaris) is a canid that is known as man’s best friend. The dog was the first domesticated animal and has been widely kept as a working, hunting, and pet companion. According to recent coarse estimates, there are currently between 700 million and one billion dogs, making them the most abundant member of order Carnivora in the world.

http://en.wikipedia.org/wiki/Dog