Dwarf rats are like their cousins in most ways except for their smaller size. They are typically 1/3 the size of a standard rat, depending on their breeding. Some can be closer to 1/2 the size. They come in many fur types and colours and have excellent temperaments. The one huge difference is their urine odor. Dwarf rats seem to smell a lot less than standards. They have the same lifespan of 2-3 years.