will male mice get along?

Question
Dear Natasha,
I was sold four male mice from a pet store on Thursday and was told that males can live together well. I now know this may not be entirerly true!! (after doing a bit of research which I perhaps should have done beforehand but I trusted the pet shop). The store kept my 4 mice for me in a cage (away from other mice)over the weekend as I was away. I collected them yesterday and they all seemed calm and fine- no scrathces etc. But I put them in their new home yesterday and after about an hour one mouse decided to chase another mouse (with loud squeaking). I saw this happen about 8 times over the space of 5 hours. Is this a lot? It was one particular mouse chasing the same mouse from what I could see and the other 2 are fine. The chaser or bully does not appear to bite the other mouse and stops chasing after about 5-10 seconds. I have seen the chaser and the victim play quite happily together too and all 4 mice sleep together. Do you think the chasing is a problem or that they will be fine? I don't want to remove the chaser unless I have to, and I hope that they can all be friends!

Thanks in advance, Rebecca

Answer
Dear Rebecca,

It is indeed true that in most cases male mice can't live together and will even fight to the death. The pet store attendant was very remiss in telling you it was fine. Trying to be charitable to them, if the male mice at the store were always quite young, there may never have been a problem.

However, you and the little boys may be in luck. If you have litter mates who have never been separated, sometimes it works.

A little chasing and squeaking is absolutely fine. My criteria for when to separate fighting mice are the follows. Separate if one of the following is true:

1. If there is blood.

2. If a mouse becomes depressed. That would be if he became far less active, possibly lethargic, began losing weight or not eating.

3. If someone is being denied access to nest, food, water, or wheel.

4. If the chasing becomes constant over more than two weeks.

If you do decide to separate, unlike with girls you probably will be making a permanent decision about who lives with whom. This is because once the brothers have been separated, they may never get along again. If there is one mouse who gets along with the most aggressive mouse, take those two out to live together. It is best to put him with the least aggressive, most submissive mouse. It is then far more likely that those two will get along; and if a problem occurs later, the most likely that the submissive mouse might be able to be reintroduced to the others.

You might decide to take the aggressive mouse out alone. If you have any mouse living alone, the cages should be within a few feet of each other so they can still communicate. I don't know what they say between cages, but they do communicate in a frequency too high for us to hear.

Best of luck.

Squeaks n giggles,

Natasha