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IACUC Guideline II
Genotyping: Tail Clipping, Ear Punch, Ear Snip

Purpose
Specific Guidelines

Purpose:

The following procedures may be used to obtain tissue for genotype mice. Deviations from these procedures should be described in the IACUC protocol.

Specific Guidelines:

Tail Tip Amputation:
Cutting through the soft tissue in the tail of a young mouse is likely to be less painful than cutting through the more extensively mineralized bones and mature tissues in the tail of an older mouse. Therefore, tail tip amputation should be performed at as young an age as is feasible.

  1. Animals less than 3 ½ weeks of age: Amputation of tail tissue may be performed without general anesthesia.
  2. Animals older than 3 ½ weeks of age: General anesthesia* is required when tail clipping any mouse after 3.5 weeks of age. Bleeding must be controlled and the mouse observed until it recovers (about 3-5 minutes).
  3. Size of tissue sample: The total amount of tail tissue removed should be as small as possible. In most cases, ½ cm or less should be adequate.
  4. Control bleeding: The amount of blood loss is usually small when tails are clipped at the recommended age. If necessary, bleeding may be controlled by applying direct pressure to the tip of the tail. Styptic powder and silver nitrate are chemical cauterizing agents that may be used if necessary. Use of heat to cauterize the amputated end of the tail is discouraged.
  5. Repeated tail amputations: It is occasionally necessary to collect additional tissue from an animal in order to verify the genotype. Consideration should be given to using one of the alternative procedures listed below. If the animal is older than 3 ½ weeks, it should be anesthetized* for collection of tail tissue.

* Anesthesia: Anesthetic machines are available in the procedure areas of most of the animal facilities and should be used when anesthetizing mice with isoflurane. Personnel who are unfamiliar with the equipment should contact the Animal Resource Program office (865-1495) for training. Some additional portable anesthetic machines are available for those who don't have easy access to procedure areas.

Alternatives to Tail Snips

Ear punch - The small amount of tissue collected from 1 or 2 ear punches is often adequate for genotyping and may be performed on any age mouse without general anesthesia.

Ear Snip - Using a sharp pair of scissors, 2-3 mm may be snipped from the tip of the ear to collect tissue for genotyping and may be performed on any age mouse without general anesthesia.

Last Revised by the IACUC on 11/14/2005
Last Approved by the IACUC on 12/08/2008