Laboratory animals are generally offered food and water ad libitumAd libitum Latin. At one's pleasure, free. In laboratory animals context: unlimited supply of food. Antonym: Restricted.. Mice are herbivores with a preference for grains but they are able to adapt to an omnivoreOmnivore An animal that eats both vegetable and animal matter. (Carnivore: meat eater; herbivore: plant eater). Both the rat and the mouse are omnivores. life style, meaning that in addition to grains, they can eat scraps of meat, dairy products and insects. CannibalismCannibalism Eating the flesh of dead or living (sick/injured) animals of the same species e.g. cage mates. This may occur when animals are injured (including surgical or self-inflicted wounds, see self-injury) or when animals are inactive for extended periods of time. may also be observed in mice.

CoprophagiaCoprophagia The consumption of feces by an animal directly from its own anus, often during an active phase. It meets a need for essential nutrients.

Mice will engage in coprophagia, which means they re-ingest stool. The alimentary canal is able to efficiently absorb a large quantity of vitamins, minerals, trace elements, and other nutrients on second passage.

Sensitive to dehydrationDehydration “Drying out” because of reduced fluid intake or excessive fluid loss. The degree of dehydration can be determined by gently pinching and twisting the skin and releasing it, allowing the skin to fold and flatten (the turgor test).

The daily food intake of the mouse is about 15 grams per 100 grams of body weight. Fluid intake is about 15 mL per 100 grams of body weight per day. Because of their unfavorable surface to volume ratio and their high metabolic rate, mice are extremely sensitive to fluid loss (dehydration). This can occur when the animal is sick or when it is placed under a heat lamp following surgery (see picture).