Introducing Rats 

This is never an easy task. It may take up to several weeks or you may find that you are stuck with two rats living in separate cages for the rest of their lives. Your going to need a lot of time, effort and patience.
A lot depends on the age of the rat and the personality, The easiest introduction are between 2 younger rats. Adult females tend not to get on with the younger females. Adult males fair better with younger baby males. Remember baby rats need to be supplemented with a high protein food so you may find it to be a problem if introduced to a new colony at too young an age. The best ages to introduce new rats are between 7 to 10 weeks. They won't be able to cope with the behavior of the dominant one if they are any younger.
The first step is to put the rats cages next to one another. Leave enough space so they can't get at each other but are able to smell each other's scent. You can then put each rat in their opposite cages just for a moment so they have each others smell in each other cages.
The next step is to introduce them on neutral territory somewhere where neither of their smells are. Be ready with a water spray just in case they need separating. Don't let them out for more time than necessary. If they seem to be getting on, you could then introduce them to a play area where there are both smells. Again be ready with the water spray as this time they may fight. If all goes well at this stage you are ready for the final introduction. Clean the cage you intend putting them in very thoroughly unless it is a new cage. Rearrange the cage completely. Apply Vanilla essence on them so they smell the same and see how they get on. If this fails , you must repeat the whole method and try again. You can usually tell within minutes whether they are going to get on.


Another way of introducing is to rub vanilla essence on both rats and introduce them on neutral territory. They may fight, if so separate them and try again. Keep repeating this as often as you can. eventually they will have no alternative but to get on with one another. Put the vanilla essence on their genital area, this will take away most of their smell. Good Luck!