• All the following techniques are acceptable forms of identification; some require IACUC approval.  Individual identification of animals plays a critical role in accurate record keeping. There are several optional methods of identification of rodents. Proper restraint plays an important role in most of these techniques.

  • Metal ear tags are inexpensive and don't require anesthesia for application (although this may facilitate proper placement) but the animal must be securely restrained. The tags need to be appropriate size for the species and should be applied to the distal 1/3 of the pinnae. If placed correctly they generally last for at least 6 months. There is a possibility of local infection and implantation sites should be monitored occasionally.

  • Ear notch punch is another identification option. It is inexpensive and permanent, the animal must be securely restrained but no anesthesia is required if the animal is less than 3 weeks of age. Ear clipping remnants can usually provide enough DNA for an initial PCR screening.

  

• Tattoo is an acceptable technique and offers a permanent means of identification. Disadvantages include initial cost of equipment, some skill and experience is needed and the need for anesthesia. Good for long term studies, especially in rats.

• Electronic Transponders are a recent option. Anesthesia is not required, but may facilitate placement, as this only requires a subcutaneous injection. Initial cost for reader is high but this is useful method for accurate identification. Toe clipping is a traditional method of identification and has the added benefit of high quality tissue sample for analysis. However, the IACUC discourages toe clipping because it has the potential to cause pain and distress and might alter the gait, weight-bearing ability of a limb, and ability to feed.

• Toe clipping can be considered under the following conditions: 1) Alternative methods of identification must first be considered. 2) A written explanation of why it is necessary is required, including a discussion of why alternate methods are unsatisfactory. This will be considered and must be approved by the IACUC. 3) It should only be performed when mice are less that 12 days of age and is generally limited to only one digit per extremity. Mice should be anesthetized, but topical anesthetics are acceptable. Sharp sterile scissors should be used and the foot should be cleaned with a dilute betadine solution.