Implementing strategies to reduce singly housed male mice

Area of Science:

• Laboratory animal science
• Animal welfare
• Research methodology

Background:

• Single housing of male mice is common in research facilities.
• Social isolation negatively affects animal behavior and molecular outcomes.
• Ethical and scientific considerations necessitate alternatives to single housing.

Purpose of the Study:

• To reduce the incidence of single housing for male mice.
• To evaluate the effectiveness of two implemented strategies: 'companion mouse' and just-weaned male grouping.
• To assess the impact of these strategies on aggression levels.

Main Methods:

• Implementation of a 'companion mouse' strategy.
• Implementation of a just-weaned male grouping strategy.
• Monitoring of housing status and aggression incidence over three years.

Main Results:

• A progressive reduction in single-housed male mice was achieved.
• The reduction in single housing reached 42% over a three-year period.
• No significant increase in aggression was observed between grouped mice.

Conclusions:

• The 'companion mouse' and just-weaned male grouping strategies are effective in reducing single housing of male mice.
• These methods improve animal welfare without compromising research integrity.
• Successful implementation demonstrates a viable approach for other animal research facilities.