Institutional Animal Care and Use Committee

Policy #2011-2

“Tail Clipping Mice and Rats for Genotyping([1], [2], [3], [4])” 

  1. Tail clipping requires prior approval by the Institutional Animal Care and Use Committee (IACUC).  
    • The procedure must be clearly described in Appendix 3 of the Animal Protocol. 
    • The PI must provide evidence that the procedure is conducted in the least painful &most humane manner possible. 
  2. Tail clipping is an acceptable method for genotyping rodents 5—21 days old(4). 
  3. For PCR, 2 mm of the distal tail is generally sufficient; no more than 5 mm is permitted. 
  4. Specific Age Requirements: 
    • 5-10 days old recommended age.  No anesthesia required. b.  10-21 days old(conduct as early as possible in this age range) 
      • Local/Topical Anesthesia is Required. 
        • Immersion of tail in ice cold alcohol for 10 seconds, OR 
        • Spray with ethyl chloride (topical freeze anesthesia) 
        • Hemostasis is generally spontaneous, but may require digital pressure or cautery; (especially older , i.e. close to 21 days of age) 
    •  22-35 days old -Anesthesia Required 
      1. General anesthesia is recommended & provides easier handling of mice & rats. ii.  Local anesthesia may be sufficient in the hands of an experienced handler. 
      2. Greater attention to hemostasis - cautery required in this age group (see 5.c.below) 
    • Greater than 35 days old General Anesthesia Required  
      1. Pain perception and ossification iscomplete at this age. 
      2. To avoid injuring the bone, limit tissue sample to 2 mm of the distal tail iii.  Hemostasis is critical and must include cautery (see 5.c.below). 
  5. Hemostasis: Animals must be monitored for 5 minutes after return to cage for any signs of bleeding from the amputation site. In addition: 
    • Mice &Rats 7-12 days little bleeding expected - apply digital pressure for a few seconds b.  Mice &Rats 12-21 days – digital pressure or cautery of amputated stump 
    • Mice & Rats greater than 21 days old Cautery Required. Use Silver Nitrate Stix, Quik-Stop powder or electro-cautery pen. 

Approved: 9/21/1011 

Reviewed and Reapproved: 4/29/2015, 10/20/2015 

[1] NIH-Animal Research Advisory Committee 

[2] Guidelines for the Genotyping of Mice and Rats 

[3] Guide for the Care and Use of Laboratory Animals - 2011 

[4] Hankenson FC, Garzel LM, Fischer DD, Nolan B, Hankenson KD. Evaluation of Tail Biopsy Collection in Laboratory Mice (Mus musculus): Vertebral Ossification, DNA Quantity, and Acute Behavioral Responses. J Am Assoc Lab Anim Sci 2008; 47(6):10-18. 

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