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Welfare and Scientific Considerations of Tattooing and Ear Tagging for Mouse Identification

Lookup NU author(s): Dr Johnny RoughanORCiD



This is the final published version of an article that has been published in its final definitive form by American Association for Laboratory Animal Science, 2019.

For re-use rights please refer to the publisher's terms and conditions.


Ear tagging is perceived as less painful or stressful than tattooing and therefore is generally considered less harmful or costly to welfare. However, ear tags are more difficult to read than tattoos and can fall out, and mice usually require restraint for the tag numbers to be read accurately. We assessed the welfare and scientific implications of tattooing by using a commercial device compared with restraint in a device versus ear tagging. Male and female BALB/c mice (n = 32) underwent procedures after 1 wk of tail or nonaversive (tunnel) handling to determine whether tunnel handling reduced anxiety. Pain was evaluated using both the Mouse Grimace Scale (MGS) and manual and automated behavior analyses; light-dark preference testing and voluntary interaction with the handler's hand were used to assess anxiety. Tail inflammation after tattooing was quantified using bioluminescent imaging, and ear tag and tattoo misidentification rates were estimated from volunteer staff records. Tunnel handling reduced anxiety compared with tail handling. According to the MGS, tattooing was not more painful than ear tagging but caused significant tail inflammation and more agitation and anxiety. However, all tattoos were read correctly without handling, whereas all ear tagged mice needed restraint, and at least 25% of the tag codes were misread. Handling stress together with identification errors at this rate represent potentially serious concerns regarding the scientific integrity of data from studies using ear tagging. These concerns are unlikely to arise with tattooing. Although tattooing was stressful, so were restraint and ear tagging. However, considering the other major advantages of tattooing, the total costs associated with tattooing were not substantially greater than for ear tagging.

Publication metadata

Author(s): Roughan JV, Sevenoaks T

Publication type: Article

Publication status: Published

Journal: Journal of the American Association for Laboratory Animal Science

Year: 2019

Volume: 58

Issue: 2

Pages: 142-153

Print publication date: 01/03/2019

Online publication date: 27/02/2019

Acceptance date: 02/04/2018

Date deposited: 10/11/2021

ISSN (print): 1559-6109

ISSN (electronic): 2769-6677

Publisher: American Association for Laboratory Animal Science


DOI: 10.30802/AALAS-JAALAS-18-000057

PubMed id: 30813985


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