 Rats are highly sociable animals, living in large packs in the wild,
and so are best kept in pairs or groups. Solitary rats can become anxious
and lack confidence.
Rats are best introduced at a young age, preferably when they are under
10 weeks of age. When buying two or more rats to live together it is
not necessary to get rats from the same litter but it is best if they
are roughly the same age and size (and sex if you do not want to breed
them) and should have been living in a group community previously.
Although rats are best introduced at a young age, it is possible to
introduce older rats although older females are more easily introduced
than older males.
When introducing older rats this is best done by dabbing vanilla essence
on both rats to disguise their smells and introducing them on neutral
territory. With older males it is usually best to introduce the rats
gradually, first of all just letting them sniff each other, then introducing
them for short periods, working towards putting them together in the
same cage.
When introducing rats for the first time they may squabble a little
at first - there may be some chasing, squeaking, nipping, boxing, standing
and staring at each other or one rat may pin another down while it grooms
the its belly or sniffs its rear. This is quite normal and their way
of establishing their position within the social structure of the group
and unless serious injury or prolonged fighting occurs they are best
left to sort this out. If it is necessary to intervene and separate
the rats this is best done by throwing a towel over the top of them,
separating them with a book or a piece of cardboard, or whilst wearing
thick gloves to avoid getting bitten in the process.
Occasionally a very dominant rat may not accept living with another
but this is rare. | 
