Handling and Restraint: As stated above, domestic mice and rats generally tolerate gentle handling, though both may bite if startled or handled roughly. Mice are more likely to bite than rats under these circumstances. In fact, mice housed alone are more likely to be aggressive with a handler than those housed in groups. Cage territoriality (possessiveness) may be exhibited by some pet rats. We have encountered a large number of pet rats, normally docile in nature, that attack the fingers hands of a handler opening and entering its enclosure. This aggressive behavior is not noted when attempts to pick up these rats are made outside of their enclosures.
Mice: It is customary to pick up a pet mouse by gently lifting it up by the tail and placing it into a cupped hand. If a more secure hold is necessary (giving medications or food orally), the handler may grasp or pinch as much skin as possible over the neck, just behind the head. The mouse can then be picked up and turned over on its back by rotating the wrist. The tail can be restrained by gently grasping it with the other hand, or between the fourth (ring) and fifth (pinkie) fingers of the same hand.
Rats can be lifted by their tails but great caution must be exercised in doing so. The skin of a rat's tail can easily tear, so it is best to grasp only the base of the tail. Furthermore, suspending the entire weight a rat by its tail is, no doubt, painful for the rat. Therefore, this practice should be only momentary. Tall-lifting a rat that is grasping a fabric (wire mesh, etc) may injure the tail and may also break or tear the toenails. The best way to pick up a pet rat is to place one hand over the back, just behind the head, gently grasp it around the rib cage, and lift it upward. The rat can then be gently cradled against the handler's body, using minimal restraint.
Potentially aggressive or known vicious rats and mice can be captured and restrained using gloves and small towels to protect the hands of the handler. Cage-aggressive rodents should be allowed to come out of their enclosure before an attempt is made to pick them up.
Housing: Proper housing is a major factor in the maintenance of healthy mice and rats. The psychosocial well-being of the animals must be a primary consideration. Mice and rats can be housed within enclosures made of wire, stainless steel, durable plastic or glass. The last 3 materials are preferred because they resist corrosion. Wood and similar materials should not be used in construction of enclosures because they are difficult to clean and cannot withstand the destructive gnawing of rodents.
The construction and design of the enclosure must ensure that the resident(s) cannot escape. Furthermore, the enclosure must be free of sharp edges and other potential hazards. The enclosure must be roomy enough to allow the rodents to pursue normal movement and breeding activity, if the latter is desired. Visual security (a place into or under which the rodents can retreat for privacy) should be provided, as well as exercise wheels for optimum mental and physical health. Rats, in particular, tend to be burrowers and seem to enjoy hiding under things for extended periods. Enclosures should be easy to clean, well lighted and adequately ventilated (see vital statistics for preferred temperature and relative humidity ranges). Bedding must be clean, nontoxic, absorbent, relatively dust-free and easy to replace. Shredded paper, hardwood shavings and processed corn cobs are preferred bedding materials. Tissue paper or cotton are often supplied to breeding rats for nest-building material. Cedar shavings should be avoided as the aromatic oils in the cedar are toxic to animals. Pet mice and rats seem most comfortable when they are spared exposure to excessive noise, needless excitement and confusion, and other similar or perceived stresses. Sudden environmental temperature changes should also be prevented because pet rodents do not tolerate them well.
Mice can be aggressive toward one another, so great care should be taken when housing more than one mouse within the same enclosure. Newly assembled male groups and new males entering established territories, in particular, are likely to fight, so it is wise to always house male mice separately. Domestic female mice seldom fight unless they are defending their nests. Rats are more communal and, in contrast to mice, several males and females may be housed within the same enclosure, provided that it is roomy enough. In fact, young rats are raised by the group and nursing responsibilities are shared between females. These nursing females may fight among themselves. Males may occasionally bother the young, but aggression between rats is generally infrequent (in contrast to mice). Every effort to prevent the escape of pet rodents should be made because they can be a tremendous nuisance when allowed the "run of the house ." Escaped rats tend to eventually return to their enclosures, whereas escaped mice tend to fend for themselves within the home and do not return to their enclosures.
Hygiene: The frequency with which the enclosure should be cleaned depends on its design, the materials out of which it is made, and the number of rodents within . As a general rule of thumb, however, the enclosure and all cage "furniture" should be cleaned and disinfected once weekly. The food and water containers should be cleaned and disinfected once daily (Roccal: Winthrop). More than one set of containers should be maintained, and the soiled set should be washed in a dishwasher, if possible. Vigorous scrubbing of the enclosure and "furniture" with hot water and soap and a thorough rinse should be followed by the use of a disinfectant. Vinegar is often required to remove the scale deposited by rodent urine.