IACUC Policy 013: Mouse Tail Biopsy

1. Purpose: The IACUC encourages the use of the least invasive method of tissue sampling.  If tail biopsies are to be used, they should conform as follows (unless sufficient justification is provided by the researcher):

2. Policy:

2.1 Tip of tail tissue biopsy for genotyping (generally 2-3 mm of tail is removed with no more than 5 mm). Sampling may be conducted no more than twice and if re-sampling is needed from the same mouse, no more than five (5) mm in total of the distal tail should be harvested.  2-mm samples have been found to be adequate for genotyping.  In this situation, other tissue sources should be considered for harvest (e.g., ear pinna).  

• General anesthesia or local analgesic is recommended but not mandated in mice up to 21 days of age.  General anesthesia or local analgesic is required when tail biopsy is performed on animals older than 21 days of age.
• Local anesthesia by immersion of the tail tip in ice cold ethanol for 10 seconds prior to biopsy may provide sufficient anesthesia for the biopsy procedure. General anesthesia with isoflurane may be used safely for chemical restraint and procedural analgesia.  

2.2 Tip of tail cut for blood collection (generally 1 mm of skin is cut and no more than 2 mm to avoid contact with bone). Any bleeding at the tail tip must be controlled (hemostasis) following the biopsy.   Hemostasis can usually be achieved by direct manual pressure with clean paper towel or gauze on the end of the tail.  If direct pressure does not stop the bleeding, the use of hemostatic agents [e.g., styptic powder (Kwik-Stop ®)] is recommended and should be readily available as a precautionary measure.  

• Analgesia is recommended if greater than a total 5 mm of tissue is removed at one time or multiple blood collections.