pharmacological agents or special equipment. For purposes of this discussion, only nonpharmacological means of restraint are addressed.
The method of restraint chosen should reflect the purpose of restraint, the period and degree of restraint, maintenance requirements, and the degree of discomfort imposed on an animal. For example, if the research protocol requires that an animal be chronically restrained but does not require strict immobility of the animal, this might be achieved in the animal's home cage by using a jacket and tether system, rather than a more confining primate chair. Animal restraint for periodic weighing, examinations, or testing can be achieved by training the animal to enter a transfer cage, rather than be hand-captured, netted, or chemically immobilized. Pole and collar systems also avoid hand capture and close restraint (Reinhardt 1995).
To achieve the restraint objective best, a balance between maximizing the safety of the procedure and maximizing the comfort of the animals should be struck. If animals are to be chaired for long periods, careful attention should be paid to chair design. A chair that allows the animal to assume a natural sitting or perching posture is preferable to a chair that constrains an animal in an unnatural position. Appropriate use of padding and soft surfaces with restraint devices can also reduce the incidence of injuries, such as decubital ulcers.
The use of restraint equipment does not necessarily preclude an animal from participating in an enrichment program. Manipulable objects and foraging devices that will not become entangled with a tether can be provided to animals that are maintained on a tether. In fact, a tethered animal can be housed with visual, auditory, chemical, and even tactile contact with another without compromising its safety. Similarly, a subject restrained in a chair in a procedure room might profit by having its usual cagemate placed in a cage in its view. Chair-restrained animals can also be provided with enrichment devices attached to the chair. Group housing of animals that are caught daily is still possible if the animals are trained to enter a transfer box (Clarke and others 1988; Reinhardt 1992a) or present themselves for pole and collar capture (Reinhardt 1995).
When deciding on a mode of restraint, the investigator, veterinarian, and IACUC should consider multiple criteria. Does the device provide the minimal restraint required to achieve the research objective? Is it safe for animals and personnel? Are its design and construction appropriate to the age, size, behavior, and normal posture of the animal that will be restrained? Has due consideration been given in the design of the equipment to the animal's comfort, such as use of padding and wide straps and the elimination of sharp or abrasive surfaces? How long will the animal be required to remain in restraint on a single occasion? Will the period of restraint be supervised by trained personnel? Is the animal adapted to the method of restraint and thoroughly trained to the apparatus? Finally, what specific procedures will be used to accomplish these goals, and who will carry them out?