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On Keeping Pet Mice

This is the main information service we try to provide. There are many sources with differing advice on keeping pet mice. Experience usually works best, but we will endeavour to give a few tips on common problems people encounter when trying to keep mice either as pets or for breeding.

The boy dilemma





Girls living together

Boys and girls living together

The boy dilemma

Most of us have had problems integrating boys to successfully live together. Just let me say now, that it can actually work. Here is, we have found, the only way to do it successfully.

Firstly - you require more than two boys (preferrably more than three) in a good size cage for them to live together. This way, there is an overload of testosterone long enough that no one knows who is in charge, and it confuses them long enough for them to get used to each others' smells. Eventually, a complex social structure and hierarchy will develop, and either everyone is in, or one or two are cast out (and you'll usually find them curled up in a corner by themselves). It depends very much on how many there are.

Secondly - give enough wheels and houses that fighting is minimised. Boys squabble. It's simply a fact. You'll know when it's particularly vicious or life-threatening if there is a lot of bleeding from one or more mice, or if you notice that they are, when fighting, going for the neck. Biting behind the neck is, in the wild, a killing attack, so separate them immediately if you see this happen (not to be confused with grooming). Ordinarily, they go for the tails first. If they fight, pull out the agressor for a bit (NOT the one being attacked), give him reassurance and put him back in. If he persists, put him in time out for half an hour (no longer). Otherwise you can try running him under the cold water tap - they hate it, and it usually silences even the most agressive tendency. **Be careful if they are fighting, however, when you pull one out. He might mistake you for another mouse and try to bite you. They won't always do it, just be careful.

Thirdly - the smell. A lot of boys living together tend to smell less than one boy living alone. Nevertheless, clean the cage regularly (twice a week), to minimise smells. If you are introducing new boys into a group, clean the cage out thoroughly, disinfect it, scrub it and put fresh litter in. Then throw all the boys in at once. Be prepared for some squabbling. An extra boy upsets the social order, and they have to re-establish the hierarchy.

Tips and Tricks:

* One way to encourage harmony is to give each boy a thorough bath, and put a spot of vanilla essence on each of their heads. It masks their scents long enough to get used to each other.

*If you know who the dominant male is (he will usually be the one attacking newcomers, and the one with the biggest testicles), always pull him out first if you go to play with them. That way, the others see he is on top (as he gets special treatment). Believe it or not, mice have an unnerving ability to sulk, and sometimes turn to attacking each other to get attention from you.

* An easy way to encourage boys to live together is, if possible, try to get three or four boys from the same litter who have lived together all their lives. They have never known what it is to live alone, and usually love each other very much. As they get older, a complex social order will develop, but it is rarely vicious. It also gives you a good size group if you want to include other boys later. Just clean the cage thoroughly (as described above), bath them, and throw them all in together. It might work. It might not. Boys are usually unstable toward one another, which is why so many have problems living together.

---Be aware: a boy you have taken out of the main group for breeding will try to assert dominance as soon as he is returned, as his testosterone levels are higher. Watch them carefully, as this is sometimes especially brutal. If it is very bad, you may have to separate them permanently (which is why it's a good idea to have a main stud for a while, before breeding from more). Unless you trust your boys implicitly. Again, the more time you spend with them, the better they'll be, because they'll listen to you if tell them to stop. Try the tricks I listed above, and see if it works.


Give your mice enough room to play, sleep, have a wheel, a water bottle and a food bowl. The more mice, obviously the bigger the house. The plastic 'Geo' brand houses come in all sizes and colours, and are well worth the price you pay for them. Be careful with them, though, they won't take too much punishment. But look after it, and it should last for years.

Mice love cages especially. They feel closer to their people, and they spend hours climbing all over the bars - it's good exercise as well as entertaining to watch. Be careful buying bird cages - some of them are too large and the mice will simply walk out between the bars. Proper mouse cages are advised - and they also come in huge varieties (varying in price).

The other alternative is a fish tank. A medium to large fish tank is the best thing to keep a group of boys in - extremely easy to clean, and there is a lot of space. Also, if they can't climb out - you can leave the lid off, and have easy access to your mice all the time.


A few don'ts:

* Don't under any circumstances use sawdust - it causes serious respitory diseases and can kill your animals

* Try to avoid wood shavings as well - most wood shavings nowadays are pine, and while it's not too bad here in Australia, pine shavings give off very strong fumes that can also cause respitory illness and lung disorder (I, and others, have found that wheezing and sneezing have virtually stopped since we stopped using shavings). A lot of people do use it, and it's fine for rats, but mice are infinitely more fragile. In an emergency, it's fine, but try to avoid it. An easy way to tell - if you smell anything when you open the packet of shavings, that's the pine fumes. The stronger the fumes, the stronger the smell.

* If you use tissues for bedding - change them frequently.

* Be picky about using straw. The mice love it, that's true, but be sure where it came from. Straw, as many people know, can contain pores, and has an annoying tendency to go mouldy. I recommend lucerne hay or straw - unfortunately very expensive. Best if straw was avoided altogether.

Okay, so what CAN we use??

As far as I know, we have only come across two types of bedding which is suitable:

* Lucerne pellets. (Commonly sold in Aus as Natty Cat in the supermaket). It's natural, easy to clean, and smells okay. The mice have a tendency to eat it, but that's fine, it won't hurt them, it's only grass. It's the absolute best bedding.

* Recycled newspaper cat litter is okay too, but keep an eye on it. As the mice will eat it, I'm not convinced that the extraction of inks from the paper is enough not to hurt them. For mice younger than about 4 weeks, use lucernce, because they WILL eat it.

Food & Water

You can pretty much feed them anything and be satisfied that they'll eat it. There are some serious breeders who have detailed menus about what their mice eat from day to day. It isn't necessary.

Any pet store now is likely to sell small animal food. Just go in and ask for mouse food (or alternatively, guinea pig food), and they'll show you the packets.

Things to watch:

* A lot of guinea pig mixes have an excess of grasses (we call it roughage) - this is okay for the mice, but be sure to supplement it with some fresh vegetables or fruit a couple of times a week, otherwise they won't be getting all the required vitamins and minerals.

* Sometimes you'll get a packet with weevils in it - don't despair. Tip it all into a baking tray and bake it in a hot oven for a few minutes, alternatively, nuke the lot in the microwave. That'll get them thar' weevils!!

Stuff mice love (and should get often):

* dog biscuits - great for their teeth and they taste good

* celery

* millet seeds

* sunflower seeds (a few mixed into their food is good - too many will make them fat)

Change the food at least every two days. Wash the dish so that any faeces in the bowl are gone (unfortunately we can't train our mice not to crap in the food bowl), and refill it.

Water bottles are the best thing to get for your mice. The Ferplast bottles are a bit expensive, but they last for ages. They glass 'test-tube' type bottles are also good. Water dishes are fine also - but be aware of a few things:

- They will kick crap into it, so empty and refill it whenever it gets grotty (with nursing mothers, this can be as often as every hour!)

- don't use anything porous (such as terracotta), the water will leak out, obviously.

Contrary to popular belief, mice can, and do, kick crap into their water bottle. This is a particular problem with the ball-bearing bottles. It isn't usually intentional (though I have actually seen a mouse do it out of spite). The mice pile bedding around it, and in so doing, fill it up with garbage. The water then leaks all into the cage, and before you know it, you have wet bedding, and wet mice! If this happens, clean out the cage, and suspend the water bottle just a touch higher, so that it's not so easy to kick stuff into it.


All mice love to play. The philosophy here is very simple, try to spend even just a little time each day with your mice. You get best results by spending about half an hour to an hour every day with them. Unfortunately, the more mice you have, and the busier you are, it's not always possible to do that. In that case I recommend that you rotate who gets to spend time with you. That way everyone has a turn. Also, just acknowledging them sometimes when you walk past, or putting your hand in the cage for a few minutes will be enough to keep them interested. Mice left alone like goldfish end up being as personable as goldfish. Not pets at all. They'll run away from you when you come near, and at worst, will bite out of fear if you try to pick them up. Get them used to you from day one, and your mice will be escaping from the cage - just to be with you!!!!

Girls living together

You can usually keep as many girls together in a cage as you like (as long as it's big enough). Five or six is a good number, but anything under that is okay too. Two are happy together, as are three (although sometimes one invariably gets outcast).

The Hierarchy

Girls develop a strict hierarchy in the cage. A group of more than two will squabble for the alpha position. Don't be alarmed if some squabbling ensues. They will sort it out after a few days, and then order will be restored. If you find that a particular mouse is fighting viciously with another (ie, causing serious injuries), sit them in a clean carrier (a small box) overnight with just some bedding, and you'll find that by morning, they'll be curled up together fast asleep. They work out their differences (and probably bond while in disgrace). Reintegrate them into the big cage and that fighting should cease. I've done with girls and desexed boys, and girls together, and it has almost always worked. Girls are less likely to seriously injure one another in battles for dominance than boys, so stick with it. Adding new mice to the cage will always involve some squabbling, as the hierarchy is then upset by the newcomer, but again, they'll work it out. Mice are the only animals I've ever seen fight it out for the bottom of the ladder. Number six and seven in a cage of seven will fight for number six in the hierarchy. It's quite fascinating to watch, and usually not dangerous. Keep an eye on them. if it's still happening in a week, separate them. Simply put, you can't win them all. Very importantly, do not, if it can be avoided, leave a mouse on its own for too long. You'll find that it will become depressed and unhappy (especially girls). However, a mouse that has been outcast by itself for a while will become so desperately lonely that it will be friends with almost anything you put it with. This has been tried with particularly vicious girls, and once re-integrated have begun grooming others with reckless abandon - they're just so happy to see others!!

* Never, under any circumstances, put a baby mouse (ie. younger than 10-12 weeks) in a cage with several adults. Babies are less able to defend themselves against attacks for dominance. If you want to keep babies, leave them separated in a cage together until fully grown - or if there is only one baby you want to keep, with the mother until fully grown (unless it's a boy - then you will have to separate it after about 5 weeks - as they can become fertile and ready to reproduce as young as this). For advice on keeping fathers with the litter, see my Breeding Info page. Mother and baby can both be incorporated into a cage at about 8-9 weeks, as the mother will (hopefully) go some way to protecting the baby, but it's a risk. try to avoid it.

Boys and girls living together

Can I just take this opportunity to say how much I don't recommend this. There are so many risks involved (ususally to the babies), that it simply isn't worth it. A boy mouse in a cage with one or two girls will be very protective of his 'harem', and will usually love them a great deal. A boy in the cage is of no interest to the heirarchy of the girls, and he won't be involved in internal struggles for dominance. The boys' fighting is purely territorial (and with girls - purely for mating). He'll be above it, and outside it. Truth be, he will live (very) happily with them, but unless you want and endless supply of baby mice, don't leave them together.

A desexed boy, if done young, is a good companion for girls in most cases. Not interested in mating, they'll bond with him as 'the odd one out', but he still won't be involved in their dominance struggles. If a boy is desexed older, he will likely not forget that he is a boy and still try to mate with them when they are on heat. This is okay, but I have experienced some boys who get very territorial with the girls and viciously attack them. They don't stay there very long, as separating them has been the only way to restore harmony.