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.
Mice and rats: how to handle
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 also 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 toe nails.
The best way to pick up a 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.