How To Introduce Pet Mice

Step-by-step guide on introducing new pet mice to an existing group

1. Quarantine the new mouse for two weeks - Keep the newcomer separate for 14 days to ensure no signs of illness before introductions begin.

2. Begin gentle scent swapping - Place a teaspoon‑sized amount of bedding near each enclosure (not inside) for around 20 minutes. This allows both groups to become familiar with each other’s scent without overwhelming them. Afterwards, remove the bedding and take each mouse out of their enclosure one at a time.

3. (Optional) Add a tiny dab of vanilla essence - Place a micro‑dab at the base of each mouse’s tail. This isn’t essential, but it helps blur individual scent differences so everyone smells similar.

4. Use a completely neutral space for introductions - Choose an area that none of the mice have ever used before to prevent territorial behaviour, such as a bathtub.

5. Watch for normal bonding behaviours - Typical, healthy interactions include:

• sniffing

• some chasing

• humping

• squeaking

These are all part of establishing hierarchy.

6. Remove mice immediately if you see concerning behaviour - Stop the session if you observe:

• blood drawn

• repeated, intense chasing

• one mouse being singled out

• consistent tail wagging (agitation)

This may mean the introduction is rushed or the mice are not compatible.

7. If all is calm, continue in the neutral space for around an hour - Stay nearby and monitor their interactions.

8. Move them to a smaller neutral space - Transfer the group to a glass tank or carrier and observe for another hour. If they are:

• resting together

• not chasing

• not squeaking repeatedly …you can move to the next step.

9. Prepare the main enclosure - Deep‑clean the enclosure so no existing scent remains. Wash toys, hides, and accessories. Set up the enclosure with minimal items:

• no wheels

• no hammocks

• no ropes

• no toys

• Use multiple water bowls to prevent resource guarding.

• You may add cardboard tubes, but ensure they are open at both ends so no mouse can be cornered.

10. Observe closely for several hours - Stay nearby and monitor. Using a camera linked to your phone overnight is helpful in case any major squabbles occur.

11. Slowly reintroduce enrichment over the next few months - Add toys, hammocks, ropes, and other enrichment gradually, not all at once. Adding too much too quickly can trigger territorial disputes and force you to restart the process.

Final note - Some mice simply do not bond, even when every step is followed correctly. If repeated attempts over time are unsuccessful, it is kinder and safer to keep them in their existing groups.