Dwarf

Rat

The name Fancy Rat is derived from the phrase "to fancy" (to like, or appreciate). Specially bred as pets Fancy Rats now come in a wide variety of colors and coat types. Commonly recognized standards include: Berkshire, Hooded, Capped, Variegated, and Irish or English Irish. Domesticated rats are physiologically and psychologically different from their wild relatives and consequently make good pets.

http://en.wikipedia.org/wiki/Dumbo_rat#Body_types.