IACUC / LARC STANDARD PROCEDURES

RODENT IDENTIFICATION

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). However, 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. See below for code.


• Tattoo is an effective method of permanent identification. Tattoos can be applied anywhere on the body but are most commonly applied either to the tail (adult rodents, often in the form of numbers) or to the foot pad (neonates, colored dots).

1. Electric tattooing
• An electric tattoo machine can be used to write numbers or symbols on the tail, ear, or footpads.
• Needles must be sterile and sharp. Needles should be changed between each group of animals or when the needle becomes blunted.
• Anesthesia (generally isoflurane) is required when tattooing adult mice with more than a colored dot.
2. Microtattooing
• Microtattooing systems utilize a hypodermic needle at one end of a stainless steel forcep and a small metal cup containing a tattoo paste at the other side of the forcep.
• By squeezing the forceps together, the needle penetrates the toe/foot pad, ear or tail of the animal and injects a deposit of tattoo ink in the animal.
• Anesthesia (generally isoflurane) is required when tattooing adult mice with more than a colored dot.

Note: If a rodent is tattooed as a neonate, the animal may need to be re-tattooed when older.

Follow manufacturer’s guidelines for procedures and recommended age for both electric tattooing and microtattooing. Tattooing may require special training. For information on training, please contact trainerIACUC@ucsf.edu

• Toe clipping can be used as a method of identification and collection of tissue for genotyping. This method 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 between 5-10 days of age and is limited to only one digit per extremity.
  4. Mice must be anesthetized. The foot should be cleaned with a dilute betadine solution and sharp sterile scissors should be used.

Ear notch punch code: