 Generally when two or more rats from the same litter are of the same sex they live together with no disruptions but with the occasional friendly tussle and play fight . Although it is possible that rats from different litters can be integrated together , the integration process can be easy or hard . Several measures have to be taken to provide security for both rats . Techniques for integration include bringing them to neutral ground so they do not become territorial . The process of integrating is easiest with two rats of young age , generally less than six months old . The process of integrating is most difficult with two or more adult male rats , as adult males are the least likely to accept new cage mates , especially after an alpha has been established . Unless there is an issue integrating rats together , owners should always keep them in a group of at least three , as rats live in packs and a pack starts with three animals . 
