Fancy mice (“fancy,” in this context, means “hobby”) are domesticated breeds of the common or house mouse (Mus musculus). The terms “fancy” or “feeder mice” are often used interchangeably by retailer, and are in fact the same variety of mouse.
Fancy mice is a term used to describe mice that have been selectively bred for pets or for show. They can vary greatly in size, from small pet mice that are approximately 16-18 cm (about 6 inches) long from nose to the tip of the tail, to show mice that measure 30 cm (12 inches) nose to tail. Pet mice weigh about 25-40 g but large show mice can weigh up to 100 g. As fancy mice have a different process of natural selection than their wild cousins, they come in a wide 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 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.
The first written reference to mice kept as pets occurs in the Erya, the oldest extant Chinese dictionary, from a mention in an 1100 BC 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 found the National Mouse Club in Victoria England, with its first official show held in London that year. Since that time, mouse clubs have formed worldwide. Shows are held so competitive breeders can display their mice, where they are judged in 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. Mice are generally nocturnal, but do not have the proclivity towards biting when disturbed like hamsters.
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 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 afraid of rats, which often kill and consume them. In the wild, mice are able to co-exist with other small rodents. 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 or a commercial paper-based material. Despite popular belief, mice can be given newspaper for nesting, as the ink is soy based and nontoxic. They should not be given cedar shavings, as the oils in the wood are unhealthy and can cause breathing difficulties. Similarly pine shavings can cause respiratory problems. If odor is a serious concern, ask your pet retailer for essential oil-free scented bedding. Recent research suggests that these oils are likely the source of bedding allergies and respiratory conditions, and suggest that oil-free pine or cedar may be used without health risk. Small hide-a-ways or 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 provide stimulation as well as exercise.
Food for fancy mice can range from specially formulated feed mix to kitchen scraps, and is usually very inexpensive, although the later should be avoided as it may not provide a balanced diet. Laboratories keep mice as experimental subjects almost uniformly use a product called lab block, a scientifically formulated blend. Dry dog food is another good option when lab block is not available, as it offers balanced nutrition for a mouse and keeps their teeth conditioned. In order to kept variety in their diets, mice also eat oats, oily seeds, clean eggshell, breakfast cereal, and stale bread. Fruits and vegetables can be offered occasionally. Mice generally chew wood and other hard substances in order to keep their teeth from growing too long. As mice and rats have similar diets, some pet mouse owners choose to feed rat food, as many other mixes are too high in protein, and try to recreate homemade rat food by adding more seeds, grains, and oats which are more healthy for the mice than traditional hamster food.
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 in their food. If a water source is provided, then a gravity bottle feeder is necessary for maintaining the cleanliness of the water supply.
A healthy fancy mouse will live on average 18-30 months, depending on the genetic disposition. Like most mammals mice are susceptible to mites, ticks, and other skin parasites, as well as internal parasites. The cage should be cleaned regularly, and preferably treated with anti-mite spray. Mice can also over-groomed when stressed, leading to skin irritations and fur loss. Older mice are susceptible to tumors, especially breast cancer in females. Persistent problems should be referred to a veterinarian, although finding a vet with expertise in treating mice can be difficult.
It is not natural for a mouse to allow itself to be handled by humans. However with training a mouse can be conditioned to handling, although some are more accommodating than others. The best way to pick up a mouse is on the palm of your hand. Retrieving a skittish mouse from a cage can be frustrating; they frighten easily and often hide. One way to retrieve the mouse is to coax it into a cardboard tube placed in the cage, then pick up the tube. Picking up a mouse by its tail should be avoided as it can cause stress and injury. Once out of the cage many enjoy running along their owner’s arms, investigating pockets, or just sitting on the owner’s lap and grooming. Some mice also tolerate gentle petting. Care must be given as mice have poor eyesight and may try to lean over 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 rarely bite, except when they are hurt or frightened. Unfortunately mice cannot be house trained and will often defecate and urinate while being handled, especially if they are nervous. The feces of a healthy mouse consist 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.