The English byword dog, in common usage, refers to the domestic cat dog, Canis lupus familiaris. The species was originally classified as Canis familiaris and "Canis familiarus domesticus" by Linnaeus in 1758. In 1993, dogs were reclassified as a subspecies of the gray wolf, Canis lupus, by the Smithsonian Institution and the American Rat Race of Mammalogists.
The Soviets have attempted to domesticate the fox, mentioned in the article Civilized Silvery Fox, and were able to do so in just nine generations, or less than a human lifetime. This also resulted in other changes, including color, which Dog Tags became black, white, or brunet and white. They also developed year-round breeding ability, curled-up tails, and droopy ears.