Introductions

Whenever you have current pets and want to bring in a new one, you should always do proper introductions between them. It is so much easier and better for everyone involved to try and do things as smooth as possible from the start instead of waiting to see if something happens and then trying to fix it.

So you already have a rat or a few and want to bring in a new friend. How should you go about it?


Step One
First I highly suggest doing a proper quarantine so you do not expose your current rat(s) to outside viruses, health issues or parasites. It is so extremely important. And you would feel awful if you harmed or killed your rats because you couldn't be bothered with this step.
Read my post on quarantine for more info


Step Two
Secondly never just assume things will go well. Yes most of the time with a proper intro everything will be fine, but not always. And there is no way to tell how either rat will react. They could be the sweetest rat ever, they could have done awesome with other intros in the past, etc... but things can still go wrong.

So have a plan just in case things do not go well. This would include:

• Having a spare cage. Which I suggest anyways in case of emergencies, temp cages, hospital cages, etc...
• Have a backup plan incase they do not get along. Will you still keep all rats? Do you have the cage/space for them? Can you afford and are ok with neutering?

Step Three
Be 100% sure of everyone's sex. Pet stores often make mistakes. Check, double check, and feel very very confident before ever putting anyone together. 


Step Four
I highly suggest you take into consideration the ages of your rats.

I do not suggest introducing babies to adults. Size difference matters alot and babies may not be able to hold their own in a fight. Babies also tend to be much more energetic and hyper then adults, they also have not yet mastered social graces. This means that the baby will likely annoy the adults, the adults will tell them to stop, the babies will not understand or listen- and this leads to fights.

IMO I'd wait to introduce babies until they are older then 8 weeks old. 12+ weeks is even better. So perhaps 8 weeks for females, 12 weeks for males. Even older if there is any past history of aggression or concern.

Also it is important to keep in mind the age of all males involved. At around 4 months+ males may go through a hormonal shift. For many males this is fine and they are still lovely. But for some males this sparks aggression. In that case the only thing you can do is keep them separate or neuter.

So if you rats are younger then 4 months old just be aware things can change and watch for it.


Step Five
My actual Intro method!

I will be honest, I almost never properly intro my females. I have a good size group of females (11 at the time of writing this) and they all get along very well. I think the group size helps actually. 

I still do suggest doing proper intros with females but I wanted to be honest.

1.) Take the rats to an empty bathtub. Use a type of messy food- chocolate syrup, yogurt, baby food, etc... It should be extra yummy. Mine prefer sweet over savory. Put a good amount of the food on them. On their backs, butts, etc.. they don't need to be drenched in it but a good amount for sure. This does two things- it helps mask their smell while also giving the entire meeting a very positive experience. They will likely bathe themselves and perhaps bathe one another even.

2.) If that goes well - no fights. Then you can give them a quick bath together to wash off the food. Then put them in a small warm space with lots of towels to dry off. I prefer a cat carrier. This also helps mask the smell and bonds them over the bath experience.

3.) If that goes well. Then you can put them in the cage together. First the cage needs to be super deep cleaned. Get into every corner and nook. Vinegar is your friend. Also clean everything going inside the cage- dont forget food dishes, water bottles, beds, toys. Everything needs to be deep cleaned or new.

The idea is to have no smell left of the current rat(s). In some cases I would even suggest cleaning around the cage and/or moving the cage into a new neutral room for a few days/weeks.

4.) When putting stuff back in the cage I suggest making it alittle bit bare so if there is a fight no one gets injured on something. I would also go with multiple food dishes, water bottles and beds. All placed on different levels/sides of the cage. This will help to prevent fights.


What to watch for:

There will likely be displays of dominance, spats, nosily squabbles. Those are all fine and normal. Let them work that out on their own. But if there is any blood or injuries I would separate at once.

If at any time there is blood or injuries separate at once and stop trying for that time.


If things go wrong....

Keep them separated for sure. I'd start looking into and ask your vet about neutering if they are male.

But just because things go wrong at first doesn't mean you have to give up all hope!

I have successfully reintroduced two males who were seriously fighting, like wanting to kill each other.

But some notes- They were brothers who had lived together a long time with no real issues before. Things only began when I tried introducing them to my other males. They fought with them and then began to attack each other.
Secondly it was more territorial aggression rather than hormonal.

Each case is unique and you have to weigh your options and decide what is best.

Reintroducing rats that began to have aggression:

If things go wrong or if aggression just starts up, I would first separate them. Try to figure out what the aggression is from if you can.

Is it possibly hormonal? (neuter)
Territorial? Fighting over space, food, toys, beds? (perhaps a bigger cage is needed.)
In my rats case I blame the presence of sharing a rat room with females as the key and then having the other males on top of that. (not all males have issues with either of these)

Keep everyone far apart. I know some suggest cage switches and putting the cages near each other- for me personally I don't feel it works with severe issues of aggression. It will only lead to more stress for the rats as they will be on high alert.

I prefer to keep everyone separated for several weeks.

Then go back and do all the intro steps as if they were meeting for the first time. But this time I definitely would clean around the cage as well as putting the cage in a different neutral room. Not forever maybe but for a while atleast. This is because the rats scent is likely still all around where the cage is kept and removing the smell and making it neutral ground is the key.

I would also try to fix whatever issue could be causing it- such as getting a larger cage perhaps, adding more food/water dishes, etc.. In my case it meant leaving the boys in a different room forever.