Prolonged Physical Restraint


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 experimental manipulation."2

Prolonged physical restraint: physical restraint of a conscious animal for 30 minutes or longer in a natural body position, 10 minutes or longer in an unnatural body position, or for any duration when a body part is fixed.

Natural position: a position in which the animal would normally engage.

Unnatural position: a position in which a normal healthy animal would not engage.

Fixed body part: restraint of a body part such that all movement is restricted (e.g. head post for neurologic testing)

IACUC Policy

  • Prolonged restraint should be avoided unless it is essential for achieving scientific objectives and is approved by the IACUC
  • Procedures involving prolonged physical restraint are classified as USDA category E
  • Restraint devices should not be considered a normal method of housing.
  • Prolonged physical restraint of a conscious laboratory animal must be avoided unless it is essential for achieving the research objectives and is specifically approved by the IACUC.  Alternatives to physical restraint should be considered.
  • 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.
  • Training and acclimation of the animals to restraint devices should be performed.  Animals that do not adapt to necessary restraint systems must be removed from the study.  
  • The purpose of the restraint and the duration should be clearly explained to the personnel involved with the study.
  • The period of restraint should be the minimum required to accomplish the research objectives.
  • Animals in restraint devices must be observed at appropriate intervals.  Such observations should be thoroughly described in the IACUC protocol.  Observations may include a physical examination, an evaluation of the animal's behavior, and/or an assessment of various physiologic measures, such as concentrations of hormones or blood glucose. 
  • Personnel involved in the study should be trained on the purpose of the restraint device and proper use.
  • Animals injured or ill as a result of the restraint must be evaluated by a veterinarian.

The IACUC Protocol must include:

  • Description of the restraint device.  A picture of the device may be uploaded in the attachments section for reference.
  • Scientific justification and consideration of alternatives for the restraint device proposed
  • Maximum duration of restraint specified
  • Monitoring procedures and methods described that minimize distress (e.g. acclimation plan)
  • Criteria for removing animals that fail to adapt or acclimate



  1. Code of Federal Regulations, Title 9 (Animals and Animal Products), Chapter 1, Subchapter A (Animal Welfare), Part 2, Subpart C, §3.81(d)
  2. National Research Council (2011). Guide for the Care and Use of Laboratory Animals, 8th Ed. Washington, DC: The National Academies Press.
  3. National Research Council (2003). Guidelines for the Care and Use of Mammals in Neuroscience and Behavioral Research. Washington, DC: The National Academies Press.


Approved: December 2012

Revisions Approved: October 2017, December 2019, June 2021