Rats are usually housed in either open-topped or individually ventilated (IVC) “shoebox” cages. These cages are usually constructed from plastic and have a metal lid which houses the food pellets and a water bottle. Some caging systems have automatic watering devices. Both food and water are generally provided ad lib. Animals are usually transferred to a similar, cleaned and disinfected or sterilised cage on a regular basis. The frequency of cage changes depends upon the cage type, type of bedding, and number of animals housed in the cage, but usually is carried out once a week. To minimise the risk of exposing animals to rodent pathogens that could be present in the facility, the cage changing may be undertaken in a cage-cleaning station.