- Request littermates or cage mates when submitting animal orders for male mice.
- Combining males from different litters is only appropriate at weaning (3-4 weeks).
- Males may be combined at weaning age (3-4 weeks), but should not be combined at older ages.
- Males shipped in separate compartments of the same shipping box or in individual boxes should not be combined upon entry into the facility as they may fight.
- Separate group-housed males which are fighting; at the very least remove the dominant male (the mouse lacking wounds).
- Males from some strains (e.g. SJL/J) are naturally aggressive toward their female mates and offspring and may need to be removed until pups are weaned.
- Housing density of mice can affect aggressive tendencies.
- Change gloves frequently and disinfect gloved hands between cages to reduce scent transfer that can lead to increased aggression.
- Providing environmental enrichment such as nesting materials, Nestlets and Shepherd Shacks (Shepherd Specialty Papers) can help alleviate stress and aggression.
- Provide treats such as chocolate balls. The aroma has been proven to reduce stress.