Physical or Prolonged Restraint of Laboratory Animals

Last Review Date: September 11, 2020

I.  Purpose/Scope

The University of Montana Institutional Animal Care and Use Committee (IACUC acknowledges that physical restraint of an awake, un-anesthetized animal may be necessary due to the scientific goals of certain studies. The IACUC has adopted the following guidelines to outline the minimally acceptable standards for physical restraint of laboratory animal species for experimental purposes.

II.  Policy

It is LAR policy to meet or exceed all federal, state, and local regulations and guidelines and to comply with all institutional policies and procedures as they apply to the use of animals in research.  Personnel must attend any applicable training in animal care and use, occupational health and safety, equipment operation, and SOPs prior to performing activities outlined in this SOP or work under the direct supervision of trained personnel.

III.  Physical or Prolonged Restraint

It is sometimes necessary to restrain animals for husbandry and research purposes, both to accomplish treatment or scientific objectives and to ensure the safety of the animal and the human handler. However, because prolonged restraint can be stressful and has the potential to cause harm to the restrained animal under certain circumstances, it is critical that considerable care and training are employed. Prolonged restraint should be utilized only when other means are not feasible and only following a determination by the IACUC that the objectives justify the procedures. Convenience alone is not deemed sufficient justification for prolonged restraint.

The Guide provides the following definition for physical restraint: “Physical restraint is 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 manipulations.” Animals are restrained for brief periods, usually minutes, in many research applications. Restraint is assumed to involve immobilization and some limitation of normal postural adjustments.

Prolonged restraint is defined as a physical restraint of a conscious animal lasting longer than 15 minutes (Guidelines for the Care and Use of Mammals. Neuroscience Research Council, 2003). Although the criteria for prolonged restraint vary according to species and type of restraint, it is generally considered to involve periods of more than 15 minutes.

A.  Restraint that does not require justification in an AUP.

1.  Brief (< 15 minutes) physical restraint that is part of normal animal-handling
     practices (e.g., moving mice from one cage to another).

2.  Brief physical restraint (<15 minutes) for procedures such as substance
     administration or sample collection (e.g., restraint of an animal to draw a blood

B.  Restraint that does not require justification in an AUP but does require description:

1.  Brief mechanical restraint (< 15 minutes) of animals by personnel trained in the
     use of the device (e.g., rabbit or mouse restrainers to give injections or collect
     blood samples).

IV.  Guidelines

A.  The following should be considered when restraint is required:

1.  Alternatives to physical restraint should be considered. Systems that do not limit
     an animal’s ability to make normal postural adjustments (e.g., subcutaneous
     implantation of osmotic pumps in rodents or backpack-fitted instrumentation)
     should be used when compatible with protocol objectives.

2.  The period of restraint should be the minimum required to accomplish the
     research objectives.

3.  Animals to be placed in restraint devices should be given training to adapt to
     the equipment and personnel.

4.  Animals that fail to adapt to training should be removed from the study in
     consultation with the Attending Veterinarian.

B.  When prolonged restraint is proposed in an AUP, the protocol must include the

1.  A description of the restraint device.

2.  The duration the animal will be restrained.

3.  A description of how the animal will be acclimated and trained prior to the

4.  A description of how the animal will be observed during the procedure.

5.  If the duration of prolonged restraint limits the ability of the animal to access
     food and water > 6 hours, the protocol must also include:

a.  A description of when food and water will be given

b.  How body weight will be monitored

c.  How hydration status will be monitored

V.  Personnel Training

Any person using restraint procedures on an animal, even if for brief periods of time, must have received formal training and demonstrate proficiency (to someone who has already been trained) prior to carrying out these techniques unsupervised. If mechanical restraint devices are employed, they must be appropriate for the species, employ designs of known safety, and be in good working order. The device should be appropriate for the stated objectives (e.g., to minimize self-inflicted harm). Training must include practice in putting an animal into the device, as well as removing it safely.

VI.  Animal Monitoring

If the restrained animal can potentially hurt itself while restrained, or if restraint is employed to prevent possible interference with potentially dangerous catheters or other instrumentation, then monitoring must be continuous. Notations documenting this monitoring should be recorded each half-hour, at a minimum. In general, continuous monitoring may be advisable if the period of restraint exceeds 4 hours. Even for shorter periods between 1-4 hours, monitoring at periodic intervals may be required to ensure the wellbeing of the animal. Indirect monitoring by a camera may be utilized if the observer can respond to an emergency in a timely manner. A description of the monitoring procedures, including a statement about the frequency and duration of monitoring, must be included in the AUP.

VII.  Complications

Regardless of the length and frequency of restraint, close attention should always be given to the possibility of complications arising from restraint procedures. These problems initially could seem relatively minor, such as small abrasions or edema, but care must be given to preclude the possibility of exacerbation or infection. Food and water intake between periods of prolonged restraint should be monitored and body weights records should be maintained, especially in young or growing animals. The Attending Veterinarian or her/his designee have the authority to terminate the restraint procedures at any point should there be signs of complications that may compromise the animal’s wellbeing. Records of any complications must be maintained and be available to the IACUC upon request. The investigator must notify the AV to evaluate any clinical concerns and to determine if treatment is deemed necessary.