About rodent identification

There are several methods—both temporary and permanent—available for identifying research mice and other small animals.

Temporary identification

A felt tip marker can mark the ear or tail for several days. Dyes may be used to color a patch of fur; which will generally last several weeks, however restricted to albino and light colored animals. Another method is to shave a patch of fur on the back or side of the animal.

Permanent identification

Methods for permanent rodent identification include ear punching, ear tagging, and subcutaneously implanting a numerically coded transponder microchip.

Permanent identification methods

Ear punching

Ear punching is commonly used for identification of rodents and involves using a special punch to either produce a small (0.5 to 2 mm) notch near the edge or to punch a hole in the middle of the ear. Always test before animal use. The cutting edge of the punch should be disinfected or the entire punch should be autoclaved.

Ear tagging

Ear tagging requires a special applicator to place an “earring” or metal tag with an identification number in the pinna of a mouse or rat’s ear. Since tags are relatively large and mouse ears develop quickly, ear tagging is primarily used on weanling and older mice. The applicator tip and ear tags should always be disinfected before use.

Subcutaneous implanting

Subcutaneous implanting an RFID microchip is a method of permanently identifying an animal. Microchips are about the size of a grain of rice and transmit a unique alphanumeric code to the RFID. The codes are easily distinguished by the electronic reader. Since the implants are relatively large, it is not recommended for newborn mice. Implanting is ideal for identifying rodent weanlings and adults.