*2.2. Search Strategy*

The search strategy aimed to locate published studies in English. An initial limited search of Medline was undertaken to identify articles on the topic. The text words contained in the titles and abstracts of relevant articles, and the index terms used to describe the articles were used to develop a full search strategy for Medline. The search strategy, including all identified keywords and index terms, was adapted for Scopus and Web of Science database searches. The three databases were searched in May 2019 using the developed search strategies (see Supplementary Table S1) and the search was updated in March 2020. Key concepts used for searching were "mice", "blood sample", "welfare" and "blood sample quality". Reference lists of all studies selected for critical appraisal were screened for additional studies. Contact with study authors was undertaken where necessary to clarify findings or seek further information. Studies published from database inception were eligible for inclusion.
