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Keeping mice together

Mice are outgoing and social, and need the company of other mice. Never house them alone unless your vet specifically recommends it. Here's what you need to know about keeping mice together.

human hand holding mouse © RSPCA

Which mice can be kept together?

Mice form a complex social organisation within their groups. How each mouse fits within this social group can depend on their age, gender, position and reproductive condition.

House your mice in compatible single-sex groups. Take care with group size and composition, particularly when housing male mice in groups, to keep disturbance to a minimum - they can be aggressive towards mice they aren't familiar with. 


  • Ask the breeder to pre-group before weaning - this ensures the group is made up of mice who know each other, ideally siblings.
  • Keep the group the same - don't add or remove any mice. Upsetting the group's complex organisation by adding or removing even one mouse can cause intense, stressful conflict, which can affect the welfare of all the mice in the group.
  • Ensure males can't smell females, as this can increase aggression between male cage mates.

Keep a close eye on your mice after grouping them together and when you put them back in their cage after cleaning and keep checking regularly to make sure they're not getting aggressive.

Mice find social isolation and living on their own incredibly stressful, so this should only happen if your vet advises it. If it's necessary, make sure your mouse can see, hear and smell other mice of their own gender, and give them extra things to keep them occupied in their cage.

Keeping mice with other pets

Mice can find the presence and smell of other animals stressful. Keep your mice and their cage away from your other pets, and away from other rodent species such as wild rats and mice.

Always wash your hands and cage equipment properly before handling different species, and before handling mice from different cages.

Other rodent species don't make suitable companions for mice; they carry potentially fatal diseases that can be transmitted to mice and vice versa. 

Handling your mice

Mice are a prey species, and if they're not used to human interaction they can find handling very stressful. Gently get your mice used to you, as this reduces the stress they can feel when you handle them.

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