Rodent Toe Clipping Template

Purpose

The regulations contained in the Guide for the Care and Use of Laboratory Animals stress the importance of proper animal identification in sound research and humane animal care. The Guide , as well as a number of other sources, lists many acceptable identification methods for most common laboratory animal species.

One method of identification that has been used for rodents is toe-clipping. This method involves removal of phalangeal (toe) bones of one toe on one or more limbs. The different digits removed code the identifier.

Because toe-clipping can alter the gait or weight-bearing ability of a rodent's rear limbs, the Guide limits its use to justified instances. According to the 1996 edition, toe-clipping "should be used only when no other individual identification method is feasible and should be performed only on altricial (hairless) neonates." The IACUC has adopted the following policy in accordance with these guidelines:

Guidelines

• Investigators considering using toe-clipping as a means of rodent identification must first show that they have considered alternative methods of identification.
• The investigator must provide the IACUC with a justification of why toe-clipping is necessary for identification of his or her rodents, including a discussion of why alternative methods are unsatisfactory. For example, a requirement for permanent marking of rodents, and a requirement for early determination of genotype are justifications for toe-clipping.
• Toe Clipping should not be considered a suitable identifying technique for animals used in some behavioral studies as it may reduce grip strength.
• Toe-clipping without anesthesia is limited to rodents within the first week of life and must be limited to one digit per extremity.
• A proposal to use toe-clipping in an IACUC protocol must be discussed by the IACUC.

Information on alternative means of rodent identification is available from the ARC, and on this site .

Template

Toe clipping will be used in unanesthetized neonates less than 7 days of age as a means to obtain tissue for DNA analysis and to provide permanent identification of individual pups. Other means of permanent identification are not useful at this age. To prevent distress the mother is moved to another cage during the toe clipping of the pups. The foot is dipped in ice cold ethanol for 10 seconds to provide local anesthesia before removing the toe. A sterile scalpel, razor blade, or scissors is used to cleanly remove the last bone of a maximum of one digit per limb. Silver nitrate or direct pressure is used on the tip of the tail to effect hemostasis and the animal is returned to the cage once hemostasis is verified. When toe clipping has been completed all pups are collected into a nest and the mother is returned to the cage. If the mother urinates during the transfer process, urine should be smeared on the pups to camouflage the scent of human handling.

References

1. ALAT Manual, American Association for Laboratory Animal Science, 1998:page 57