14 <strong>LABORATORY</strong> <strong>ANIMAL</strong> <strong>MEDICINE</strong> <strong>AND</strong> <strong>SCIENCE</strong> - <strong>SERIES</strong> <strong>II</strong>35. Section title H<strong>AND</strong>LING, RESTRAINT, and IDENTIFICATIONRats and mice are routinely handled during cage changeouts, genderdetermination, clinical and experimental observations, and forexperimental or technical procedures. Proper techniques for handlingand restraining rats and mice minimize distress to the animals, lessenthe risk of injury to either the animals or their handlers, and preventtransmission of disease.36. “Gentling”Frequent handling of animals to familiarize andaccustom them to human contact is referred to as“gentling.” This is performed prior to experimentalmanipulations and will minimize or eliminate stress,struggling, or the tendency to bite. Most routine andresearch manipulations occur during the daily lightphase, when these nocturnal animals would typicallybe resting or asleep. By talking quietly to a rodentwhen approaching and opening a cage and movingone’s hand slowly around the inside of the cagebefore grasping it, will decrease the likelihood ofstartling it. A startled animal will react by biting ordefensive behavior.37. Short term restraintRats and mice may be picked up by the base of thetail, using the thumb and forefinger, for short periodsonly; for example, moving them quickly from one cageto another. The animals must not be picked up by thetip of their tails because they may twist about andinjure the tip which may slough off. Mice, if heldsuspended by the tail for longer periods, will “crawlup” their own body and tail in an attempt to bite theirhandler. Some strains of rats (e.g., Fischer rats) andmice are aggressive and difficult to restrain, requiringgreat skill and patience on the part of their handlers.38. Scruff hold39. Two-handed holdA scruff hold is one method for restraining both rats andmice. To scruff a mouse, grasp its tail and place its frontpaws on a rough surface, such as the wire top of acage. This allows it to grip the wire and diverts itsattention. Then grasp the skin on the scruff of the neckwith the thumb and forefinger of the other hand andsecure the tail between the little finger and palm of thehand. To scruff a rat, hold it in place by the base of itstail. With the other hand, press down gently and firmlyover the back of the animal and gather up the loose skinover the neck and back. “Scruffing” may pull the skintight over the thorax and prevent adequate expansion ofthe chest and lungs in both species, so handlers shouldmonitor animals for signs of respiratory distress.
V-9042 RATS <strong>AND</strong> MICE: Care and Management 15Another method for restraining a rat is shown here. Thehandler uses thumb and forefinger to encircle thethorax, taking care to place them behind the rat’s elbow.This hold should cause the forearms to cross andprotect the handler's fingers from being bitten. The otherhand is used to grasp the base of the tail, furtherstabilizing the animal’s hindquarters. The sameconcerns regarding restriction of chest expansion andhindrance of breathing apply for this technique.40. Other methods41. Restraint devicesBlunt thumb forceps may be used to pick up mice bythe scruff of the neck when concerns for sterility andworker safety exist. Forceps are dipped in adisinfectant solution before each use, therebyreducing or eliminating the likelihood of diseasetransmission from one animal or one cage to another.If chainmail or leather gloves are worn, care should betaken to avoid excessive squeezing of the animalsand to prevent injury to the incisor teeth should theanimal bite the glove.This image shows one example from the variety ofcommercial restraint products designed to facilitatesome procedures, such as tail vein injections or bloodpressure measurements. Animals should be held inthese restraints for the minimum amount of timenecessary to perform a procedure (2).
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