Rodent Identification Policy

IACUC Policy: 018-06, Effective Date: 06/22/2007, Last Revision: 11/17/2023

Overview/Purpose

Individual animal identification is important for animal colony management, animal health/medical records, and for research data interpretation. This policy provides guidance on common methods of rodent identification.

Requirements

• Methods of animal identification that will be used must be outlined in the approved IACUC protocol.
• Study team members must be appropriately trained for animal handling and identification methods. Training is available free of charge through University Laboratory Animal Resources.
• Markers and Dyes - Short-term topical options which require reapplication (every 3-4 days) include nontoxic permanent markers to mark the tail, ear, or nontoxic hair/fur dyes or marking sprays to mark the fur.
• Ear punch/notch - Removal of a small (5mm or less diameter) section of the ear pinnae requires that the animal is firmly restrained, and instruments used must be sharp.
• Ear tags - Tags must be appropriately sized for the species and age. Proper placement is necessary to prevent auricular irritation or trauma.
• Microchip transponders - Aseptic technique must be used to insert (subcutaneous or intraperitoneal) sterile transponders.
• Tattoo - Tattoo devices are used to permanently mark the dermis of the tail, toes, or other sites as needed. Proper restraint or anesthesia is needed.
• Toe-clipping - The use of this method for identification is only appropriate when tissue samples are also used for genotyping purposes. Toe-clipping must be scientifically justified and approved by the IACUC when other individual identification methods are not feasible. Additional justification (including a list of all other methods that were evaluated and why they were dismissed) is required to obtain IACUC approval. Toe clipping must only be used in altricial pre-weanling rodents after the toes are no longer webbed and before they reach 8 days of age. Instruments must be sharp; only 1 digit may be removed per rodent; and the hindpaw must be used.

References

• 1. Wang, L. A primer on rodent identification methods Lab Animal 2005; 34: 64-67.
• 2. Castelhano-Carlos MJ, Sousa N, Ohl F, Baumans V. Identification Methods in Newborn C57BL/6 Mice: A Developmental and Behavioral Evaluation. Laboratory Animals 2010
• 3. Schaefer D, Asner I, Seifert B, Bürki K, Cinelli P. Analysis of Physiological and Behavioral Parameters in Mice after Toe Clipping as Newborns. Laboratory Animals 2010; 44:7-13.
• Paluch L, Lieggi C, Dumont M, Monette S, Riedel E, Lipman N. Developmental and Behavioral Effects of Toe Clipping on Neonatal and Preweanling Mice with and Without Vapocoolant Anesthesia. JAALAS 2014; 53(2): 132-140.
• Guidelines for Toe Clipping of Rodents. NIH. https://oacu.oir.nih.gov/system/files/media/file/2022-03/b9_toe_clipping.pdf
• Dahlborn K, Bugnon P, Nevalainen T, Raspa M, Verbost P, Spangenberg E. Report of the Federation of European Laboratory Animal Science Associations Working Group on Animal Identification. Laboratory Animals 2013; 47: 2-11.
• Bonaparte D, Cinelli P, Douni E, Herault Y, Maas A, Pakarinen P, Poutanen M, Santos Lafuente M, Scavizzi F. FELASA Guidelines for the Refinement of Methods for Genotyping Genetically-Modified Rodents. Laboratory Animals 2013; 47(3): 134-145.
• Roughan J, Sevenoaks T. Welfare and Scientific Considerations of Tattooing and Ear Tagging for Mouse Identification. JAALAS 2019; 58(2): 142-153.

Related IACUC Policy

• Tissue Sampling Policy for Rodents Genotyping