10 Tips for Dealing with Aggression & Fighting

  1. Request littermates or cage mates when submitting animal orders for male mice. 
  2. Combining males from different litters is only appropriate at weaning (3-4 weeks).   
  3. Males may be combined at weaning age (3-4 weeks), but should not be combined at older ages.  
  4. 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.   
  5. Separate group-housed males which are fighting; at the very least remove the dominant male (the mouse lacking wounds). 
  6. 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. 
  7. Housing density of mice can affect aggressive tendencies.   
  8. Change gloves frequently and disinfect gloved hands between cages to reduce scent transfer that can lead to increased aggression. 
  9. Providing environmental enrichment such as nesting materials, Nestlets  and Shepherd Shacks (Shepherd Specialty Papers) can help alleviate stress and aggression. 
  10. Provide treats such as chocolate balls. The aroma has been proven to reduce stress.