Murine rodents that is, more specifically Rattus norvegicus the fancy pet rat.

A lot of rat websites have instructions on how to introduce rats to one another. I think most of them that I have read do have great suggestions. This is my experience with rat introductions.

Once a proper quarantine time has passed and you are certain none of the rats are harboring any diseases, put their cages so close to one another that they touch. Keep them this way for at least a week; close enough that the rats can touch one another through the bars.

After one week take them out of the cages and switch them. Let them explore one another's homes; just don't do it while the occupant is home. This way they get to know one another but there is no threat to them.

A day or so after the switch and explorations of each other's homes let them out together in a neutral territory and see how they get along. Neutral territory can be a bathtub, a bathroom, a couch, a playground, any place you want it to be. Just make sure that the place you choose doesn't hold the odor of another rat. This way, again they don't feel threatened.

If they get along ok in a neutral area, then it may be time to let them live together. If they don't seem to get along at first then keep them in separate cages for another week but let them out daily/nightly to play together and keep allowing them to visit one another's cages.

Before putting them in the same cage, be sure to thoroughly disinfect and change the bedding in the cage that will be the home for all of them. All territorial markings must be removed so that none of them perceive those odors as a threat to them.

Some people recommend putting vanilla extract on all the ratties before sending them all to the new group home. That will mask the scent of all of them, they may think they belong together if they all smell the same. I personally have not needed to use the vanilla extract method but it's harmless so there's no reason not to use it if you want to.

When introducing males to one another it's a good idea to bring in a young, prepubescent male to live with an older one. That way the older male will not feel threatened by a "child." He's much less likely to attack a baby than another adult.

There will be squeaks scuffling, wrestling, lots of staring contests, and pushing matches. They must establish their "pecking order." If there is no bloodshed then as tough as it may be for the humans, you must stay out of it. Let them work it out on their own but do watch them for signs of real aggression.

If you are introducing new rats to those older rats who've lost their cage mates through a death in the family. Keep in mind that sometimes you will run across the stubborn rattie who never wants to accept a new family. It doesn't happen often and you can't know ahead of time whether bringing a new rat into the family will work. Sometimes older rats never get over the death of their cage mate but other times they perk up and begin acting young again. It can make them very happy to have a new cage mate. It may not work out but it's always worth a try to bring home that new rat for the older lonely one.

Jan McArthur, R.V.T.