Food and Fluid Restriction in Animals

Language in the revised Guide for the Care and Use of Laboratory Animals (1996) requires careful monitoring of animals that are on food or fluid restriction.

"When experimental situations require food or fluid restriction, at least minimal quantities of food and fluid should be available to provide for development of young animals and to maintain long-term well-being of all animals. Restriction for research purposes should be scientifically justified, and a program should be established to monitor physiologic or behavioral indexes, including criteria (such as weight loss or state of hydration) for temporary or permanent removal of an animal from the experimental protocol . Restriction is typically measured as a percentage of the ad libitum or normal daily intake or as percentage change in an animal’s body weight.

Precautions that should be used in cases of fluid restriction to avoid acute or chronic dehydration include daily recording of fluid intake and recording of body weight at least once a week--or more often, as might be needed for small animals, such as rodents. Special attention should be given to ensuring that animals consume a suitably balanced diet because food consumption might decrease with fluid restriction. The least restriction that will achieve the scientific objective should be used. In the case of conditioned-response research protocols, use of a highly preferred food or fluid as positive reinforcement, instead of restriction, is recommended."

The following items are the minimum requirements for all protocols that use food or fluid restriction.

1. All protocols that require the use of food or fluid restriction must be specifically justified. In most cases this has already been accomplished. If justification has not been given previously, please provide justification with your next animal protocol review. The animal use protocol should include a description of procedures to be used to monitor animals on food or water restriction.
2. All animals on food or fluid restriction should be weighed at least once every seven days. Rodents should be weighed more frequently. As long as the information is easily retrievable it may be kept as part of the regular research records.
3. Animals on fluid restriction should be monitored for daily intake and assessed for dehydration by an experienced observer. Daily intake and state of hydration should be recorded and made available for review.
4. You should establish (in written form) criteria for the temporary or permanent removal of an animal from the experimental protocol. These criteria should be available in the laboratory for review and should be made a part of your protocol during the next animal protocol review.

Please ensure that you are following the guidelines in this letter. Failure to do so could affect Rutgers’ accreditation as an animal research facility.

Distributed to faculty using animals as a memo from Dr. Curtis on August 26, 1997.