Skip to main content

Use of Restraint in Vertebrate Animal Studies

This page provides NC State's policy on the use of restraint in live vertebrate animals. The method of animal restraint used to achieve a particular objective in an experimental protocol should be chosen to minimize distress to the animal. Restraint is defined as limiting or restricting the normal physical movement of an awake, non-anesthetized, non-sedated animal. Physical restraint is the use of more than momentary 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.


Restraint devices should be suitable in size, design, and operation to minimize discomfort, pain, distress, and the potential for injury to the animals and staff. Mechanisms of restraint could include tethers, slings, DecapiCone restrainer, cylinder restrainer, or any other device that limits animal movement.

Any restraint that is part of the scientific objectives of the study must be described in the protocol.

Momentary Restraint

Momentary Restraint such as that used for withdrawing blood or administering an injection — does not need to be included in the Exceptions section of the Application for Vertebrate Animal Use (AVAU).

Prolonged Restraint

Prolonged Restraint such as metabolism cages/stalls — should be avoided unless it is essential for achieving research objectives and is specifically approved by the IACUC.  There is no one set duration to define “prolonged” for all species or types of studies. As the duration of restraint increases, a concomitant increase in attention should be given to alternatives to restraint, to the endpoint criteria for the restraint, and to monitoring the health and well-being of the restrained animal. The restraint must be described based on the species and scientific rationale and must be justified in the Exceptions section of the AVAU.

Prolonged restraint is subject to the following considerations:

  • Prolonged restraint must be the minimum required to accomplish the research objectives. Alternatives to physical restraint should be considered.
  • A description of the restraint device, duration of restraint, and a plan for routine monitoring must be included in the AVAU, including clinical signs of pain and/or distress that will be monitored and the amount of time that will be allowed to elapse before intervention if distress develops.
  • Animals placed in restraint devices should be acclimated and given training to adapt to the equipment and personnel. These details are to be included in the protocol and any animals that fail to adapt must have criteria for temporary or permanent removal from the study.
  • Veterinary care must be provided if lesions, illness, or severe behavioral changes indicating distress are observed.
  • It is the responsibility of the Principal Investigator to ensure that the animals are monitored at appropriate intervals by adequately trained individuals.

Restraint Stress

Restraint stress such as prolonged restraint in non-acclimated animals — can be approved with justification as a category E procedure if it is essential for achieving the research objectives.


  • National Research Council. 2011. Guide for the Care and Use of Laboratory Animals: Eighth Edition. Washington, DC: The National Academies Press.
  • National Research Council (US) Committee on Guidelines for the Use of Animals in Neuroscience and Behavioral Research. Guidelines for the Care and Use of Mammals in Neuroscience and Behavioral Research. Washington (DC): National Academies Press (US); 2003.

Approved 2/18/2021