Fighting with cage mates

[simonsmom]

My girls are 20 months and have lived together since they were around 6 weeks. I've never had problems with them (they fight with other rats but not each other) until recently.

My girl Xena has been fighting with all my other girls. At first I thought it was just one girl but I've caught her fighting with 3 now. There is always a lot of squealing, wrestling, standing up at each other and her chasing the others. It's not playing, they haven't played in months. Today I stopped a fight and the victim had a large wound on her shoulder. There was never wounds before so it's getting worse.

Physically she seems fine. There hasn't been any changes. Same cage, same belongings, same routine, same location. The only changes recently in the household are we have a new baby (4 weeks old), but their routine hasn't changed at all I've been very careful with that, and we lost one of their cage mates 6 weeks ago. Her change of behaviour didn't start until recently.

I have no clue what to do about it. She can't live on her own, but she won't stop attacking the other girls.

 

[Velo]

You could try a time out cage to help show her that beating them up is wrong.
When you see her being mean, you put her in a small cage or carrier, with nothing in it, for ten minutes.

Otherwise... Could she be trying to hide illness or injury? Has she been getting less out time and/or attention from you?

 

[simonsmom]

I'll try the time out cage. I don't think she is trying to hide anything. I can't find anything wrong and she was at the vet last week when this started. She seems to be fine, but I could definitely be wrong.

She has been acting completely normal with me. She is a biter (not aggressive, she bites first sniffs later). It's just the other girls she is having issues with. I've kept her routine the same as it's always been. So she's been getting as much out time as normal and time with me.

I did find this bump though. It's blue and wasn't there yesterday that I noticed. It's about the size of a pencil eraser.

 

[jorats]

That looks like a little cyst.
But, have there been any changes recently? New rats in the home? If not, this could be a symptom of pituitary tumour. Behaviour changes can be a neuro issue. Keep an eye on her for more symptoms like paw clubbing, porphyrin, change in appetite, sleeping more, puffy.
But in the meantime, I also suggest a time out cage for her.