Q: I got a female rat that had her own cage in the pet store. She slept with me and had fun. After five months, I wanted to give her a friend, so I bought another female rat. I’ve had the new rat for one month, but my resident rat keeps getting aggressive toward it. She puffs up her fur, arches her back and swings her body sideways at the new female rat.
I have tried to put their cages next to each other, so that they cannot harm each other. And my resident rat is breathing hard through the nose.
I have tried switching cages for 20 minutes three times a day.
I introduced them to each other in the bathroom, because it’s a neutral place.
I also tried to spread a bit of peanut butter on the new female. My resident rat tried to lick the peanut butter off her, but the new rat made a scream and ran toward my feet to get away.
I have only been able to introduce my rats to each other for 5 to 10 minutes — but with fights.
I want the resident rat to like the new one. And the new one doesn’t attack first, she defends herself. What can I do?
A: It sounds like you’ve done everything possible to provide your rats with companionship and introduce them properly, but sometimes our pets have different ideas.
Rats are extremely social creatures and must have a same-sex rat companion, preferably one that is about the same age. Rats require the social interactions they experience with other rats. When they don’t have this necessary companionship, they can develop unhealthy or unnatural behaviors, such as imprinting too strongly on their human. After a while, as you’re experiencing, the rats no longer know how to interact appropriately with other rats.
Female rats are usually fairly easy to introduce, except in those instances where they’ve lived alone and have become overly protective of their space and their human. It sounds like this has happened with your original rat. As a result of her attachment to you, she is acting as though the new rat is an intruder and is exhibiting very aggressive behavior.
Because there is obvious aggression, a real risk of injury to one or both of your rats and your original rat has made it very clear that she has no interest in a rat companion, I recommend that you stop your attempts at introduction. Listen to what your original rat is telling you and allow her to live alone, but continue to shower her with lots of attention.
This means you need to immediately purchase a buddy for your new rat. Use the same careful introduction techniques you’ve already tried, and I’m sure you’ll have much better luck this time.