SMPH Policy Number: 13

Policy Title: Genotyping and/or Identifying Rodents


Rodents to be genotyped and identified should have these procedures performed at the earliest practical age. Sample collection and identification should occur simultaneously.

Tissue sampling or identification via ear punching, or the application of an ear tag does not require anesthesia at any age.

If clipping the tip of the tail occurs at before 21 days of age, no analgesia or anesthesia is required and no more than 0.5 cm should be collected. Hemostasis should be ensured by application of a clotting agent or by pressure applied with clean gauze. If the tail must be clipped a second time or if it is clipped at greater than 21 days of age, then anesthesia or analgesia must be given during the procedure. Consult with a veterinarian for recommended analgesia and anesthesia.

Toe clipping is not a routine procedure, but may be approved if the following conditions are met. Large numbers of animals must be permanently and uniquely identified, and ear tags are not appropriate for this population. No more than the last segment of two toes from each back foot is removed. The procedure must occur at no later than 14 days of age. The severed toe should be used for genotyping if required, so that other tissue samples are not taken.

Role of the Investigator:

The investigator must include a written description in the animal protocol of proposed procedures, and ensure that their laboratory staff follow the approved procedures. The laboratory should be well organized so that lost samples do not occur and it is rare that an animal must have a second tissue sample collected.

Role of the Veterinary Staff and Laboratory Animal Resources (LAR):

The veterinary clinical staff will provide training and advice in these techniques upon request.

ACUC Oversight:

The ACUC shall review proposed protocols for conformity to these guidelines, and enforce compliance.

References :

Guide for the Care and Use of Laboratory Animals, NRC, 1996


Approved July 2003
Corrected October 2005