University of Oulu

Swan J, Boyer S, Westlund K, Bengtsson C, Nordahl G and Törnqvist E (2023) Decreased levels of discomfort in repeatedly handled mice during experimental procedures, assessed by facial expressions. Front. Behav. Neurosci. 17:1109886. doi: 10.3389/fnbeh.2023.1109886

Decreased levels of discomfort in repeatedly handled mice during experimental procedures, assessed by facial expressions

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Author: Swan, Julia1,2; Boyer, Scott3,4; Westlund, Karolina5;
Organizations: 1Research Unit of Biomedicine, Department of Pharmacology and Toxicology, University of Oulu, Oulu, Finland
2Biocenter Oulu, University of Oulu, Oulu, Finland
3Chemotargets SL, Barcelona, Spain
4Global Safety Assessment, AstraZeneca R&D, Södertälje, Sweden
5ILLIS Animal Behaviour Courses, Stockholm, Sweden
6Independant Consultant, Strömsund, Sweden
7Sweden Operations, AstraZeneca, Södertälje, Sweden
8Department of Animal Health and Antimicrobial Strategies, Swedish National Veterinary Institute (SVA), Uppsala, Sweden
9Institute of Environmental Medicine, Karolinska Institutet, Solna, Sweden
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.6 MB)
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Language: English
Published: Frontiers Media, 2023
Publish Date: 2023-08-18


Mice are the most commonly used laboratory animal, yet there are limited studies which investigate the effects of repeated handling on their welfare and scientific outcomes. Furthermore, simple methods to evaluate distress in mice are lacking, and specialized behavioral or biochemical tests are often required. Here, two groups of CD1 mice were exposed to either traditional laboratory handling methods or a training protocol with cup lifting for 3 and 5 weeks. The training protocol was designed to habituate the mice to the procedures involved in subcutaneous injection, e.g., removal from the cage, skin pinch. This protocol was followed by two common research procedures: subcutaneous injection and tail vein blood sampling. Two training sessions and the procedures (subcutaneous injection and blood sampling) were video recorded. The mouse facial expressions were then scored, focusing on the ear and eye categories of the mouse grimace scale. Using this assessment method, trained mice expressed less distress than the control mice during subcutaneous injection. Mice trained for subcutaneous injection also had reduced facial scores during blood sampling. We found a clear sex difference as female mice responded to training faster than the male mice, they also had lower facial scores than the male mice when trained. The ear score appeared to be a more sensitive measure of distress than the eye score, which may be more indicative of pain. In conclusion, training is an important refinement method to reduce distress in mice during common laboratory procedures and this can best be assessed using the ear score of the mouse grimace scale.

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Series: Frontiers in behavioral neuroscience
ISSN: 1662-5153
ISSN-E: 1662-5153
ISSN-L: 1662-5153
Volume: 17
Article number: 1109886
DOI: 10.3389/fnbeh.2023.1109886
Type of Publication: A1 Journal article – refereed
Field of Science: 413 Veterinary science
Funding: This research was performed as an internal research project at Global Safety Assessment, AstraZeneca R&D, Södertälje, Sweden, which was closed in 2013.
Copyright information: © 2023 Swan, Boyer, Westlund, Bengtsson, Nordahl and Törnqvist. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.