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Office of Animal Welfare

Prolonged Physical Restraint of Laboratory Animals

Purpose

To define what duration of restraint qualifies as prolonged physical restraint, explain the appropriate use of physical restraint, and establish expectations for what information needs to be included in the IACUC protocol.

Definitions

Physical Restraint:
The use of manual or mechanical means to limit some or all of an animal’s normal movement for the purpose of examination, collection of samples, drug administration, therapy, or other experimental manipulation​1.

Background

Many research projects require brief periods of restraint for procedures such as examination, drug administration, or blood collection. Many species can be trained, through use of positive reinforcement techniques, to cooperate with research procedures or remain immobile for brief periods. However, it is sometimes necessary to physically restrain a conscious animal for a longer period in order to accomplish a research objective. The Guide distinguishes between brief physical restraint and “prolonged restraint,” and the University of Washington IACUC is responsible for evaluating the use of prolonged physical restraint and ensuring that appropriate steps are taken to minimize the potential for pain and/or distress.

Policy

The University of Washington IACUC defines prolonged physical restraint as physical restraint of an unanesthetized animal for:

A. 30 minutes or longer in a natural body position in which no body parts are completely immobilized (e.g., pig sling, primate chair restraint without head or limb fixation)

B. 15 minutes or longer in an unnatural body position and/or one or more body parts are immobilized (e.g., most rodent restraint devices, primate chair restraint with head fixation)

Restraint devices should not be used simply as a convenience in handling or managing animals. All restraint should be the minimum length required to complete research objectives. Prolonged physical restraint should be avoided unless it is essential for achieving research objectives and is specially approved by the IACUC. Systems that do not inhibit normal postural movements (e.g. subcutaneous osmotic mini pumps for infusions or back-pack infusion pumps) should be used when compatible with protocol objectives. When used, restraint devices should be specifically designed to accomplish research goals that are impossible or impractical to accomplish by other means or to prevent injury to animals or personnel.

When prolonged physical restraint is used as part of a research project, the following information should be provided in the IACUC protocol:

  • Description of physical restraint: Restraint devices should be suitable in size, design, and operation to minimize discomfort, pain, distress, and the potential for injury to the animal and the research staff.
  • Justification for use of prolonged physical restraint: Alternatives to physical restraint should be considered.
  • Duration and frequency of physical restraint: The period of restraint should be the minimum required to accomplish the research objectives and the maximum period of restraint must be described in the protocol.
  • Description of training or acclimation: Animals to be placed in restraint devices for prolonged restraint should be given training, with positive reinforcement, to adapt to the equipment and personnel. Animals that fail to adapt should be removed from the study. Prolonged restraint without training or acclimation must be justified in the IACUC protocol.
  • Monitoring of the animal during physical restraint: Provision should be made for observation of the animal at appropriate intervals. Frequency and method of monitoring must be described in the IACUC protocol.
  • Criteria for removal from restraint: This should include specific behavioral or clinical signs that would warrant removal from restraint (e.g. signs of distress). The presence of lesions, illness, or severe behavioral change often necessitates the temporary or permanent removal of the animal from restraint. Veterinary care must be provided if lesions or illnesses associated with restraint are observed.

Long-term restraint of nonhuman primates: As required by the Animal Welfare Act, if a nonhuman primate is restrained for a period greater than 12 hours, the nonhuman primate (NHP) must be provided with at least one hour of unrestrained activity on a daily basis during the period of restraint, unless continuous restraint is required by the research proposal and approved by the IACUC.​ Requests for long-term NHP restraint would require extremely strong justification within the protocol.

References

  1. Committee for the Update of the Guide for the Care and Use of Laboratory Animals, Institute for Laboratory Animal Research, Division on Earth and Life Studies, & National Research Council. (2010). Guide for the care and use of laboratory animals (8th ed.). National Academies Press.

Approval/Review Dates

Originally A​​​pproved: 06/15/2017
Last Reviewed/Revised by the IACUC: 05/18/2023

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