Human-directed artificial selection in fancy mice has created a variety of colors and patterns. These include black, chocolate, blue, white, cream, lilac, red, fawn, champagne, cinnamon, golden agouti, silver agouti, silver and dove. All mouse standards fall into one of five categories: Selfs (one solid color all over), Tans (mice of one solid color on the top with a tan belly), Marked either in Even or Broken patterns (spotting of a standard color on a base of white) and a miscellaneous category.
Mice as pets
The first written reference to mice kept as pets occurs in the Erya, the oldest extant Chinese dictionary, from a mention in an 1100 B.C. version. In Europe the breeding of fancy mice became popular through the introduction of Japanese stock in the early 17th century. By 1895 Walter Maxey founded the National Mouse Club in Victorian England, with its first official show held in Lincoln that year. Since that time, mouse clubs have formed worldwide. Shows are held so competitive breeders can display their mice, where they are judged on color and behavior.
Mice are kept as pets in many countries for a number of reasons: Fancy mice are relatively small, inexpensive, clean, and can learn to enjoy regular handling. Female mice are popular with many owners since they tend to cohabitate with other mice better than males. Additionally, the urine of female fancy mice does not contain as strong of an odor as that of the male mice. Bucks can fight with each other, unless they are introduced at a very young age, and they produce urine with a strong, musky smell. Some people, however, prefer the personality and curiosity of male mice. It is a good idea to keep fancy mice in groups of at least two if possible, as mice are sociable animals. However, if a buck and a doe of breeding age are put in the same cage it is possible for them to reproduce at a maximum frequency of once every three weeks.
Caging
Glass aquariums or cages with wire bars and plastic flooring, are the most common types of housing. A span between cage bars of less than 9 mm (0.35 in) prevents young mice from attempting to escape by forcing themselves through the bars, where they may get stuck. This can also help prevent predatory pets such as cats from killing and eating the mice.
Mice are naturally cautious of rats, who may kill and consume them. This rat behavior is known as muricide (Tattersall, Smith and Nowell 1997). The mouse cage is strongly recommended to be cleaned every couple of days to stop it smelling and disinfected properly every 2 weeks to prevent infection and disease. In the wild, mice are able to co-exist with other small rodent species (Moro and Morris 2000). Compared to larger mammals, the mouse's small body makes it difficult to regulate body temperature effectively. Thus, drafts and large fluctuations in temperature can adversely affect the health of mice.
The best products for in cage bedding are aspen wood shavings. There are also paper pulp based products available, as well as a variety of recycled products, though newspaper products may contain inks, dyes and other chemicals from the paper making process. Cedar and pine, even kiln-dried, should not be used as they release aromatic oils that damage the respiratory system and can cause or make worse chronic respiratory disease. Recent research suggests that paper pulp beddings may allow very high concentrations of ammonia to build up in cages, especially those with little ventilation. (Vanderlip 2001, ISBN 978-0-7641-1812-8). Small hide-aways and toys (such as a cardboard tube) are good to have in the cage. Commercial toys are also available. Mice love to run on a wheel, which provides stimulation as well as exercise.
Feeding
Food for fancy mice can range from specially formulated feed mix to kitchen scraps. Carrot, spinach, tomato, and lettuce are usually very inexpensive, although the latter should be applied sparingly as it may not provide a balanced diet. Laboratories keeping mice as experimental subjects almost uniformly use a product called lab block, a scientifically formulated blend originally designed for mice in laboratories. Dry dog food is another good option when lab block is unavailable, as it offers balanced nutrition for a mouse and helps keep their teeth conditioned. In order to keep variety in their diets, mice can also eat oats, oily seeds, clean egg shell, breakfast cereal, and stale bread. Fruit and vegetables are part of a more natural and healthy diet. Mice often chew wood and other hard substances which keeps their teeth from growing too long; salt licks are also an option. As mice and rats have similar diets, some pet mouse owners choose to feed rat food. Although it is common practice to feed pre-mixed diets designed for other rodents, for the longevity of the animal it is best to feed mouse designed diets. Diets for hamsters, for instance, are known to contain higher protein than what is required for mice or rats. Home made diets can be blended using grains, rice, oats, seeds (such as peanut, sunflower, and pumpkin), as well as a number of other ingredients.
House mice primarily feed on plant matter, but they will also accept meat and dairy products. They will drink water but require little of it, relying mainly on the moisture present in their food. If a water source is provided, then a gravity bottle feeder is necessary for maintaining the cleanliness of the water supply. They will eat their feces to acquire nutrients produced by bacteria in their intestines in a behavior they share with rabbits and guinea pigs called Coprophagy. House mice, like other rodents, do not vomit.
A healthy fancy mouse will live on average 18 to 30 months, depending on genetic predisposition. Like most mammals mice are susceptible to mites, ticks and other skin parasites, as well as intestinal parasites. The cage should be cleaned regularly, and preferably treated with anti-mite spray. Mice are particularly sensitive to drafts and may pick up colds and other flu-like conditions. Mice can also over-groom when stressed, leading to skin irritations and fur loss. Older mice are susceptible to tumors, especially breast cancer in females as the mammary tissue is distributed around much of the body. Persistent problems should be referred to a veterinarian, although finding a vet with expertise on treating mice can be difficult.
Like people, fancy mice can become obese if they overeat and do not get enough physical activity. This can lead to them developing life-threatening cardiovascular disorders and diabetes as well as arthritis. Unfortunately overfeeding is common as they require little food. Activity aids such as tubes and wheels are great for ensuring mice get enough exercise, as well as mental stimulation. Mice also love to climb, and a wire cage with horizontal bars is perfect for this. A mouse set loose for exercise should be carefully observed, as they tend to scurry into a hiding spot and can be difficult to retrieve.
As rodents, mice must gnaw to keep their incisors from growing too long. Overgrown teeth can cause occlusion (blockage) of the mouth, which in extreme cases can lead to starvation. Hard foodstuffs, small pieces of wood or specially prepared blocks can suit this purpose, although some mice can grind their teeth together ("bruxing") to keep them short. In rare cases a mouse may not be able to gnaw effectively, either from malformed incisors or jaws, and so their teeth must be trimmed by a vet.
Mice self-groom and do not need to be bathed, unless they have a skin condition which requires special treatment.
Also, like people, mice can get diarrhea. For humans in developed countries with access to clean water, this is usually not a very big deal. For mice though, it is. Once a mouse gets diarrhea, since they are so small, they can very easily lose too much liquid, dehydrate, and die.
Handling
It is not natural for a mouse to allow itself to be handled by a human. However with time, a mouse may acclimate itself to accept human handling. The best way to pick up a mouse is by gently grabbing the base of the tail, and if necessary, supporting the body with the palm of the hand. Retrieving a skittish mouse from its cage can be frustrating; they frighten easily and often try to hide. One method of retrieval is to coax the mouse into a cardboard tube placed in the cage, then pick up the tube. Grabbing a mouse by its body should be avoided, as it can cause stress and possibly damage internal organs.
Although mice are small animals and care must be taken to avoid injury, they are also surprisingly robust and inquisitive. Once out of the cage many enjoy running along their owners' arms, investigating pockets, or just sitting on the owner's lap and grooming. Some mice also tolerate gentle petting. Care must be taken as mice have poor eyesight and may try to lean too far over an edge and fall. Care must especially be taken when being handled by small children as they may be overly rough. Fancy mice very rarely bite, except when they are hurt or very frightened.
Unfortunately mice cannot be house trained and will often defecate and urinate while first being handled, especially if they are nervous. The feces of a healthy mouse consists of a solid pellet a few millimeters long and can be discarded easily. However their urine is quite pungent, particularly with males, and may stain fabric. It is handy to keep sanitary wipes close to the cage.
Breeding
Mice have a rapid reproduction rate; the gestation period is approximately 18 to 21 days. The typical litter size is 4 to 12 young. In some instances, up to twenty young have been born. Males can mate with the female as soon as the litter is born. Female mice should not be bred before 12 weeks or after 8 months; doing so can be very dangerous, and some mice can die while giving birth. Females come into heat around every five days, so the pair can be kept together for up to ten days. Baby mice, pinkies also called pups, are born blind, naked, and deaf. Their eyes are closed and their ears are stuck to the sides of their heads. Mothers may eat any dead or sickly offspring. Pups begin to grow hair at two to four days. Ears open at three to five days, and the pups will start vocalizing. Eyes open at 14 days, and the babies will start exploring the world around them. At three weeks old they look like miniature versions of adult mice. At four to five weeks the pups will be able to breed.
