Ideal as small pets, mice are entertaining to watch, easy to care for, and make very few demands on their owners. They are a bit skittish and harder to handle than some of the larger rodents such as rats, but they can learn to take food from your hand and, if trained from a young age, can be held. As nocturnal animals, mice will be most active at night and sleep through the day. They are great for people who work during the day.
Common Name(s): Mouse, house mouse
Scientific Name: Mus musculus
Adult Size: 5 to 7 inches (including tail), weighing up to 2 ounces
Life Expectancy: 1 1/2 to 3 years
Mouse Behavior and Temperament
Mice are social animals and like living in groups. A pair of females is the easiest arrangement, although larger groups are fine if you provide the cage space. Do not let pairs of males to live together unless they were littermates, never separated, and have a large enough cage that they can have their own space. Unfamiliar males are very likely to fight. Avoid keeping males and females together unless you want lots of mice in a short amount of time.
Mice that are not accustomed to handling or handled roughly may bite. However, most pet mice will become quite tame given time, patience, and perhaps a little bribery. At first, allow the mice time to get acquainted with their new environment. Once the mice are calm, start spending more time near their cage, and quietly talk to the mice to get them used to your voice.
As the mice become comfortable or curious with your presence, start offering some favorite tidbits (try millet or sunflower seeds) by hand. Once the mice are taking treats from your hands, they may start walking on your hands, or you can start trying to pick them up. You can even train them to recognize their name.
When picking up a mouse, try scooping it up by cupping your hand under the mouse, but do not squeeze or tightly grasp the mouse's body. If holding a skittish mouse, you can try holding the base of the tail with one hand while supporting the mouse's body in the palm of your other hand to prevent the mouse from jumping off your hand and possibly injuring itself.
A relatively short fall can cause injuries. If you hold the mouse further down toward the tip of the tail, you may break the tail off, or the skin may come off the tail. It is best to hold the mouse just above your lap or some other soft surface in case it falls or jumps.
If you are going to allow your mouse time outside the cage, you will need to mouse-proof the room. Ideally, keep them contained in a large, shallow plastic storage box, small wading pool, or some other confined space.
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Housing the Mouse
The size of the cage you will need depends on how many mice you keep together. For a pair or small group of females, a 2-foot square cage is ample space. Mice will appreciate a cage with multiple levels, as they do like to climb, and it should be fairly tall.
Glass aquariums and wire cages are the best types of cages for mice. Aquariums will need a tight-fitting mesh lid. It is also important to remember that ammonia and other fumes will build up faster in an aquarium or plastic-sided cage than in a wire cage.
Mice need to mark their territory, so if their cage is thoroughly disinfected too frequently, they may become distressed. A good compromise is to leave a bit of the old shavings or litter in the cage at each cleaning, so their scent remains. Do a thorough scrubbing and disinfecting only when necessary.
Wire cages with horizontal bars are nice because they provide lots of climbing opportunities on the sides of the cage, and it is easier to affix furnishings, platforms, and toys to the sides of the cage. Make sure the bars are no more than 1/4-inch apart. Mice can escape (or get stuck trying to escape). Avoid using cages with wire mesh floors; solid flooring is a lot easier on the mice's feet.
Modular plastic cages meant for hamsters are well suited for mice but are challenging to clean and are sometimes poorly ventilated. A determined mouse might even chew through the plastic.
They universally love running on wheels, tunneling, and toys, including:
- Wood blocks and houses
- Small cardboard boxes
- Cotton ropes
- Paper egg cartons or paper towel or toilet paper tubes
- Small willow balls
Put the cage near you, where there is a lot of human activity to make taming easier. Keep the cage out of drafts, away from direct sunlight, and out of reach of other household pets.
Watch Now: Tips for Taking Care of a Pet Mouse
Specific Substrate and Nesting Needs
Provide a deep layer of aspen shavings or some other suitable substrate in the cage. Avoid cedar and pine shavings due to the strong volatile oils released from these woods (especially cedar). Also, give nesting material like strips of facial tissue, soft paper towel, or hay. Mice will shred it and build their nests from it.
A nest box should be provided and can be store-bought or homemade. Small cardboard boxes are fine, although they will be shredded over time and will need replacement frequently. Clay flower pots, either with holes cut in them or placed on their sides, can also be used, as can PVC plumbing pieces you can find at the hardware store. Clean out nesting material every month or two (frequent changes may be too disruptive).
Food and Water
Mice should be fed a formulated rodent pellet that contains moderate to high levels of protein. Pellets are available for mice and are completely balanced, but this is a monotonous diet. Grain and seed-based loose blends provide more interest to the mice and are readily eaten. Your mice may just pick out their favorite bits and leave the rest, leading to an imbalanced diet. Feed 2 tablespoons per mouse per day. You can feed it all at once or spread it out between two feedings daily.
Supplement pellet food with small quantities of fresh fruits and vegetables (1 teaspoon per mouse) with greens, apples, and carrots a couple of times a week. If a particular food item causes diarrhea, discontinue feeding it. Sunflower seeds are a favorite treat, but they are fatty, so provide sparingly.
Avoid feeding junk foods such as candy and potato chips, and never feed chocolate, as it is toxic to mice and other small pets.
For treats, you can give cooked pasta, whole-grain bread, or crackers with peanut butter. Commercial treat sticks make a good treat, but only very occasionally, as they are often sugary. For water, a gravity-fed water bottle with a dispenser is preferred, as it can't tip and keeps the water clean. A shallow food bowl of ceramic or porcelain is the best choice, as they are difficult to tip, won't get chewed up, and they are easy to clean.
Common Health Problems
Tumors are common in mice; usually, they are malignant and deadly. Signs include a visible lump or swelling accompanied by lethargy or weight loss. Most tumors can be surgically removed but are likely to recur.
Another severe and common health condition in mice and other pet rodents is wet tail, a gastrointestinal ailment caused by an overpopulation of bacteria in the digestive tract. It can progress quickly and may be fatal if left untreated. Symptoms include diarrhea, lethargy, lack of appetite, and difficulty walking. An exotics veterinarian can treat the condition with antibiotics.
Purchasing Your Mouse
Mice are one of the most affordable pets, costing $5 to $10. Most pet stores carry them. Look for a pet store or breeder that separates males and females at a young age. Mice can reproduce by about 6 to 8 weeks of age, although this is very stressful on the female and not recommended.
When picking out your mouse, look for an alert animal with a smooth, clean coat and pink, clean skin on the ears and tail. The eyes and nose should be free of discharge, and the mouth and anal areas should be clean and dry. Their breathing will be relatively fast, but should not be labored or noisy. Check their cage, make sure it is clean, and droppings look normal (not watery).
Similar Pet to the Mouse
If you're not sure whether a mouse is the pet for you, there are some similar animals you may want to consider:
Otherwise, check out other small rodents that could be your next pet.
Machholz, Elton et al. Manual Restraint And Common Compound Administration Routes In Mice And Rats. Journal Of Visualized Experiments, no. 67, 2012. Myjove Corporation, doi:10.3791/2771
Theobromine. PubChem, National Library of Medicine, 2020
Diseases And Disorders Of Mice. Merck Veterinary Manual
Selecting A Mouse. MerckVeterinary Manual