Mice are small rodents found naturally in nearly every part of the world, including parts of Antarctica. There are around 40 different species of mouse, ranging in color and size dependent on their environment.

Mice are often thought of as pests because they can damage crops and spread diseases through their parasites and feces. But, they are an important part of the ecosystem, including as a source of food for small mammals, reptiles and birds.

The gestation period for female mice is less than a month, with an average litter size of about six babies. Baby mice, or pups, are born with their eyes and ears closed and with no hair. They are weaned at around three weeks old.

Mice, just like dogs, are supplied to pet stores by mass breeders, who aggravate the problem of these species’ overpopulation and the resulting abandonment and abuse. Shipped to distributors in small, cramped containers that are breeding grounds for parasites and viral and bacterial infections, mice often reach the pet store ill, malnourished, and/or pregnant. Small animals represent a small profit for pet stores, and their deaths represent a minor loss. Their living conditions in pet stores generally reflect this.

Prospective guardians of mice should keep in mind that they may require veterinary treatment and that this can be as expensive for them as it is for cats or dogs.

Mice are social but territorial animals. A lone, caged mouse will languish, but two or more crowded together without adequate space may fight.

A 15-gallon aquarium or a wire enclosure of equivalent size is a minimum requirement for two animals, and you should never mix males and females or different species.

If you are determined to have a mice, adopt – don't buy. Adoption is a far better choice than supporting a pet store. Like all other companion animals, mice are often abandoned to local humane societies and animal shelters.

You will need to provide mice with a habitat with the following specifications:
  • Bedding material at least 1-inch thick but no cedar or pine shavings, as these are toxic to small animals
  • No direct sunlight or drafts
  • Fresh food and water, but no cheese, milk, or other animal products—clean the feed dish daily and the water bottle before each refill
  • A mineral block, for honing teeth
  • An exercise wheel
  • Paper towel rolls, shelves, tree branches, old socks, etc. for toys and chewing