Attitudes of laboratory animal professionals and researchers towards carbon dioxide euthanasia for rodents and perceived barriers to change.

Michael W Brunt,Daniel M Weary,Lucia Améndola

doi:10.1177/00236772211025166

Michael W Brunt, Daniel M Weary + Show 1 more

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https://doi.org/10.1177/00236772211025166

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Journal: Laboratory Animals	Publication Date: Jul 1, 2021
Citations: 10	License type: CC BY 4.0

Affiliation: University of British Columbia

Abstract

Evidence indicates that carbon dioxide (CO2) induces negative affective states (including anxiety, fear and distress) in laboratory rodents, but many countries still accept it for euthanasia. Alternative methods (e.g. inhalant anaesthetic) may represent a refinement over CO2 but are not widely adopted. We conducted an online survey of Canadian and European laboratory animal professionals and researchers (n = 592) to assess their attitudes towards the use of CO2 and alternative methods for rodent euthanasia using quantitative 7-point scale (from 1 (= strongly oppose) to 7 (= strongly favour) and qualitative (open-ended text) responses. CO2 was identified as the most common method used to kill rodents, and attitudes towards this method were variable and on average ambivalent (mean ± SD score on our 7-point scale was 4.4 ± 1.46). Qualitative analysis revealed four themes relating to participant attitude: (a) the animal’s experience during gas exposure; (b) practical considerations for humans; (c) compromise between the animal’s experience and practical considerations; and (d) technical description of the procedure or policies. Many participants (51%) felt that there were alternatives available that could be considered an improvement over CO2, but perceived barriers to implementing these refinements. Qualitative analysis of these responses revealed five themes: (a) financial constraints; (b) institutional culture; (c) regulatory constraints; (d) research constraints; and (e) safety concerns. In conclusion, concerns regarding the use of CO2 often focused on the animal’s experience, but barriers to alternatives related to operational limitations. New research is now required on to how best to overcome these barriers.

Highlights

Mice and rats are widely used in research; in 2017 nearly 7 million of these animals were used in the member states of The European Union[1] and 1.5 million were used in Canada.[2]
We found that CO2 continues to be a commonly used method of killing laboratory rodents, with nearly 50% of European and Canadian participants stating that this method was used most often in their facilities
It is reasonable to infer that many participants who use CO2 as a primary euthanasia method are not convinced that this method provides a good death

Summary

Introduction

Mice and rats are widely used in research; in 2017 nearly 7 million of these animals were used in the member states of The European Union[1] and 1.5 million were used in Canada.[2] Most of these animals were likely killed at the end of the study. In addition to considerations regarding the animal’s experience, preferred killing methods should have high reliability, non-reversibility, be compatible with research objectives and safe for the people performing the procedure.[3,4,5,6] Carbon dioxide (CO2) is the most commonly used method to kill rats and mice; in an international meeting on laboratory animal euthanasia held on 2016, many participants reported using CO2 to kill rodents.[7] This method is conditionally acceptable in Canada[3] and the USA,[5] and is listed as ‘appropriate’

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