Mouse

The mouse (house mouse, Mus musculus) is a small rodent with a pointed snout, large rounded ears and a long, almost hairless tail. Adults measure about 7.5-10 cm from nose to base of tail, with a tail of 5-10 cm, and typically weigh 11-30 g.

Pet mice, often called fancy mice, have short hair and come in many colours, from white through champagne to pink. Their voice is a high-pitched squeak. Mice are kept as pets and as laboratory animals.

Mice are native to India. They spread to the eastern Mediterranean about 13,000 BC and reached the rest of Europe around 1000 BC. This delay is thought to be because they need farming settlements above a certain size. From there people carried them to every part of the globe.

The first written mention of mice kept as pets appears in the Erya, the oldest surviving Chinese dictionary, in a version from around 1100 BC. Keeping them led to many strains of fancy mice with varied colours and a docile temperament. The pet mouse is descended from the Western European house mouse subspecies.

Domestication can change mice quickly. Captive-reared mice differed in boldness and activity patterns from wild-caught ones after just 4-5 generations.

Mice are mostly active at dusk and during the night, and they dislike bright lights. A captive mouse sleeps about 12.5 hours a day. They are good jumpers, climbers and swimmers, and can jump vertically up to 45 cm.

Mice often rear up on their hind legs, supported by the tail, when eating or looking around. The tail also helps with balance and with losing heat. Mice build nests from soft materials.

Males are territorial and mark their ground with urine. If two or more males share a cage they often become aggressive unless raised together from birth. In commensal house mouse populations, groups of usually related females breed cooperatively and nurse their young communally. Mice use scent for social communication and sense surfaces and air movements with their whiskers, and they do not perceive some of the colours people can see.

In protected environments mice often live two to three years, much longer than in the wild, where most live under a year.

Mice cannot vomit. They eat their own droppings to gain nutrients made by bacteria in their gut. A common mite, Myobia musculi, is found in the fur of house mice.

Older mice show rising levels of DNA damage in tissues such as the liver, heart and brain, which is linked to ageing.

This is general awareness only, not veterinary advice. Always consult a vet about your pet's health.

What is a fancy mouse?

It is the domesticated pet form of the house mouse. Fancy mice are bred in many colours and have a docile temperament.

How long do pet mice live?

In protected conditions mice often live two to three years. Wild mice usually live less than a year.

Are mice nocturnal?

They are mostly active at dusk and at night. A captive mouse sleeps about 12.5 hours a day.

Do mice smell?

Mouse urine, especially from males, has a characteristic strong odour. Males use it to mark their territory.

Can mice carry diseases?

Mice in general can transmit some illnesses, such as lymphocytic choriomeningitis, which is not commonly reported in people and is usually mild. Mice are not usually carriers of bubonic plague.

How quickly do mice breed?

Pregnancy lasts about 19-21 days and litters hold 3-14 pups, averaging six to eight. A female can have 5-10 litters a year.

Pups are born blind, without fur or ears. Their eyes open around 13 days and they are weaned at about 21 days.

Male mice sing ultrasonic courtship calls that are complex and have been compared to bird songs.

Mice have two thymus organs, one in the chest and a tiny second one in the neck.

Mice are the most commonly used mammal in laboratories, and have been used in research since the 1650s. They were also thought to be the main reason cats were first domesticated.