Group and Single Housing of Male Mice: Collected Experiences from Research Facilities in Sweden
Swedish Centre for Animal Welfare, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden
Department of Animal Environment and Health, Swedish University of Agricultural Sciences, 532 23 Skara, Sweden
Department of Animal Science and Technology, AstraZeneca, 431 83 Mölndal, Sweden
Centrum för försöksdjursverksamhet, Uppsala University, 752 37 Uppsala, Sweden
Department of Comparative Medicine, Karolinska Institutet, 171 77 Stockholm, Sweden
Department of Pharmaceutical Safety, Swedish Medical Products Agency, 751 03 Uppsala, Sweden
Department of Physiology and Pharmacology, Center for Molecular Medicine, Karolinska Institutet, 171 77 Stockholm, Sweden
The Swedish 3Rs Center, Swedish Board of Agriculture, 551 82 Jönköping, Sweden
The Swedish National Committee for the Protection of Animals Used for Scientific Purposes, Swedish Board of Agriculture, 551 82 Jönköping, Sweden
Department of Integrative Toxicology, Karolinska Institutet, 171 77 Stockholm, Sweden
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Received: 30 October 2019
Revised: 15 November 2019
Accepted: 18 November 2019
Published: 21 November 2019
The mouse is the most commonly used mammal in scientific research, and housed in research facilities around the world. Mice are a social species, but when housing male mice together in a confined environment in the laboratory, aggression is often observed and can be problematic. Fighting or trying to avoid fighting can be stressful. Furthermore, fighting can lead to injuries which can sometimes be fatal. Mouse aggression is therefore a significant welfare problem and has implications on the 3Rs (Replacing, Reducing, and Refining animal use in scientific procedures and education). In this study, we used a survey and workshops to collect the experiences of animal technicians, veterinarians, and researchers at Swedish research animal facilities relating to mouse aggression and what methods of preventing aggression they practice. Both group housing and single-housing as a consequence of aggression was perceived as problematic and stressful for the animals. In line with current recommendations from the literature, participants perceived that aggression occurred less if mice were grouped with litter mates at an early age, that nesting material was transferred at cage cleaning, and disturbance was kept to a minimum. Experience from practice will play a valuable part in developing guidelines for group-housed male mice.