The fancy rat is a domesticated brown rat (Rattus norvegicus), which is the most common type of pet rat. The name fancy rat derives from the idea of animal fancy or the phrase “to fancy” (to like, or appreciate).
Fancy rats have their origins as the targets for blood sport in 18th- and 19th-century Europe. Specially bred as pets since then, fancy rats now come in a wide variety of colors and coat types and there exists several rat fancy groups worldwide. Fancy rats are commonly sold as pets in stores and by breeders.
Domesticated rats are physiologically and psychologically different from their wild relatives, and, when acquired from reliable sources (such as a breeder), they pose no more of a health risk than other common pets. For example, domesticated brown rats are not considered a plague threat, while exposure to wild rat populations could introduce pathogens like Salmonella into the home. Fancy rats experience different health risks from their wild counterparts, and as such, are less likely to succumb to the same illnesses as wild rats.
As in other pet species, a variety of colours, coat types, and other features that do not appear in the wild have either been developed, or have appeared spontaneously. Any individual rat may be defined one or more ways by its color, coat, marking, and non-standard body type. This allows for very specific classifications such as a ruby-eyed cinnamon berkshire rex dumbo.
Agouti-based colors include agouti, cinnamon and fawn. Black-based colors include black, beige and chocolate.
Commonly recognized standards include:
Berkshire – coloured top, white belly
Hooded – colour runs from full head down spine
Capped – colour on full head only
Variegated – a blaze, or short white strip on the forehead, with a fully colored head and splotches or flecks of color run down the back only
Irish or English Irish – In England the Irish is standardized by the NFRS as an equilateral triangle of white with a side that begins at the chest, or between the front legs, and where the point ends mid length. In the United States and elsewhere, clubs like the AFRMA distinguish this marking as the English Irish and allow for another standard Irish in which the rat may have white of an even or symmetrical nature anywhere along its underside.