Introducing rats to one another
CARRIER METHOD
If you keep rats for many years, some will die and you’ll probably want to introduce baby rats, called “kittens” in the UK, in order to prevent your remaining rat from living alone.
For years I dreaded introducing rats to one another. The babies look so small compared to the adults and even the most mellow human-loving buck can be difficult to introduce to new babies. My rats are largely peaceable, with in-season does bickering occasionally but no outright fights among them. Even so, I am always of the power and speed of adult rats.
With the right procedure, introductions can go smoothly. A word of warning: Buck adult-adult introductions can be quite tricky and should be avoided. Intact adult male rats do not take well to strangers. A perfectly calm, friendly buck will turn into a a puffed up, adrenaline-fed hell-raiser the moment he sees an intruder and new rats can inflict serious injury to one another, even death. Of course, there’s always someone who will tell you about their rats that got along without any difficulty. They’ll say that it just takes a little time (and of course their own expertise!). But what they won’t tell you is that, often enough, adult buck/buck introductions fail spectacularly. Even if the rats don’t kill one another, gashes on the belly and across the testicles are seriously intended, bode badly for the future peace of the cage, and are expensive to treat. I’ll be writing shortly about how stress in cages shortens the lives of “beta” or “omega” rats, but for now, I want to give you tools on how to introduce rats, not the perils of when it goes wrong.
Not all introductions are difficult. Let’s start with the easiest of introductions: kitten-to-kitten. Kitten to kitten introductions are generally very easy. You can introduce babies from different litters at any time up until ten or twelve weeks without much trouble. Breeders typically mix eight week old rats from one litter with a similar age from another litter without any need for special introductions. The same may be true with 10-14 weeks rats. Though the 14-week old is likely going to pull rank with younger kittens, and playfighting may put your heart in your throat, it would be unusual to see a big problem.
However, by the time they are juveniles, which is anytime from about thirteen weeks upward, you should be a little more respectful of the need for measured introductions. Some people will introduce young rats on neutral ground—a sofa or dry bathtub on which a towel has been laid. The idea is that such a space is nobody's territory and therefore the rats may simply get used to each other without feeling any need to defend. I don't do it this way. This advice, as well as any that involve bath tubs, vanilla extract or other strong smells, is not the best advice. It may have been the best we had at once time, but now the preferred method of introductions is the "Carrier Method".
Start carrier method in the middle of the day when rats will naturally be most sleepy. Prepare a small cage (and I do mean small) with two water bottles either end and a LOT of food distributed throughout. Now, put in the rats to be introduced, whether it is a single individual to a single individual or a group to a group. When I say "small cage”, the rats need to be in a space that allows them to be shoulder to shoulder and still lie down. “Small” is a relative term, depending on how many rats you are introducing. In the case of a few rats, a carrier will do. For 10 bucks, you'll need a hamster cage.
It should look crowded, like in this video, and this isn’t even as crowded as it can be!
Once you've put them all in, walk around your house, holding the carrier. This is to distract them from fighting. If you see them eating, that’s a good sign. Rats tend not not eat when frightened. By contrast, rats do groom themselves when frightened. So, if they are eating, that’s a good sign. Walk around with the cage if it isn’t too cumbersome to do so. Rats in transit tend not to fight. Keep them moving until they seem more relaxed.
Later, you can just sit down with the carrier near you. Hear squeaking and fussing? Walk around with the carrier to distract them from this. You may see a rat pinning down another rat, or forcibly grooming another so that the poor victim is squeaking lightly. That can happen and mean very little (though mine don’t do this) or it can be a signal that you may have some work to do. Either way, move the cage again. If a rat is really being aggressive with another, you may need to intervene. Do not do this with your bare hands! Get a towel or oven gloves or anything, but do not ever break up a rat fight without protection. It is a sure way to get bitten.
Add food often and if you can’t get even a mouse-sized water bottle through the holes in your carrier, chop up vegetables and fruit like cucumber, carrot and apples as a source of moisture and scatter them on floor of the carrier. You don’t want the rats to be hungry. If they are overweight already, don’t worry about it for now. You can deal with that problem separately once they are all getting along well.
How long you keep rats at each stage of the carrier method varies. Some people keep the rats in a carrier for a few hours or overnight. I've had mine in a carrier for as little as 5 hours to as long as 12 hours before moving them up. I've been known to keep a cage of rats in the bedroom over the first few days of their introductions. We want to see the rats in close contact, keeping each other comfortable in a kind of “rat pile”, and the small cage works well to encourage this.
Do not leave them in a small cage for a long time, and do monitor the temperature getting too warm inside the carrier. If you can’t move them them up to a larger cage/carrier within twelve hours, at least swap them into an identical one that has been cleaned and aired.
I like using barred cages rather than plastic carriers as I can see the rats and also the ventilation is so much better. The cage I prefer is a ridiculously small barred cage that an ill-informed manufacturer thought would be acceptable for a mouse,Not good for mice, but ideal for introductions. It is 43cm (17”) wide x 26cm (10”) deep and 26cm high.
From stage 1 (carrier or show tank for a few rats) to stage 2 (small mouse cage) is quick, even half a day. I may even start with the mouse cage depending on the number and temperaments of the rats being introduced.
You may find it is only another day or so before you can move them into to a single story rat cage like a Savic Ruffy. The Ruffy is 80cm x 50cm x 30cm. The reason I like it is that it is a single level cage. Rats aren’t going to be climbing up to retreat from others, which means they will be at less risk of attack. I’ll post soon about why this is the case, but for now, just know that a single level cage is important in introductions.
You are certainly not going to be able to walk around with such a cage, but you can position it somewhere in your house where it will be easy to keep track of how they are doing.
Just as in the earlier cases, you give them thick layers of soft bedding, but not any hammocks. If you put a hammock in too early, you may find that some get into the hammock and some do not. Again, you want to see them huddled altogether, once you have a consistent rat pile (a day or two), add a hammock that is large enough for them all to fit, then another, then maybe a little house over several days. You can add a 12” wheel to the Ruffy or a cage with similar height without difficulty, too.
Once they are sleeping together and look like nothing much is stirring I personally move to a larger cage. ( my SRS, but only half of it), and start again. However, you may find you need to move to a cage that is only a little bit bigger before making the final leap to their final cage, the one in which you intend to keep them.
You can go much faster if it is a totally nothing event, and usually I do, but some people take a week to get from carrier to the final cage in which they will be keeping their rats (or at least one half of it). If you must pause a while at the stage 3 stage (a single story Ruffy), that’s fine. Give it a few days, even a week if you must.
I do let my rats out of their introduction cages to play with me on my play tables. I don’t believe they have to be housed in a small, then smallish space 24/7 for introductions to go well. I say this as a breeder who does introductions quite often, maybe 4-6 times a year when I introduce rats to one another after a litter has matured. I’ve never had time out on a table playing with me result in injury, though of course I supervise it. Anything can happen, though if an argument is going to happen it is usually in the evening, when rats are most active. So, get them out during the day to stretch their legs.
Rats will play fight and will have occasional grumbles but it is natural for them to live in groups and they usually get on. If you have a particularly difficult situation, you may need to create alternative groupings or even neuter/spay a rat or rats. I’ll be writing more about this later. Generally speaking, with the a few tips and tricks, you’ll get there!
Be warned that you may have to "reintroduce" rats on occasion. For example, if you've had one out of the group for days or weeks at a time or when the "alpha" rat dies. You also need to remember that not all rats will get along. Imagine living in a cage with someone you were afraid of! That isn't a sustainable situation and sometimes introductions fail. If so, keep two cages. You may be able to try again later.
