Mousekeeping

Enrichment

One of the biggest problems new mouse owners have is a lack of enrichment. Mice need a lot of it. Being confined all day every day can get boring, and without things to do, mice can become stressed and/or depressed.

Chewing - When It's Stress and the Importance of Teeth Wearing

One primary sign your mouse is bored is that they'll chew on things they're not supposed to, like the bars or plastic of their cage or their cagemates. Stressed mice might fight or bite each other!

However, if you notice bite marks on things like igloos/homes and food bowl edges, note this is a normal behavior. Mice do this to wear down their teeth. Like most rodents, mice's teeth never stop growing, and in order to keep it short (and thus be healthier for the mouse), mice will chew on hard things.
This is why it's important to give your mouse toys to chew on!

Wheels

Wheels are a staple of small mammal enrichment. Small mammals LOVE to run, even wild ones! It's their primary form of exercise.
When it comes to choosing a wheel, get one that's appropriate for your animal's size (so they can actually turn it) and small enough to fit in their enclosure.

Wheels come in several types:

• Plastic/Silent Wheels - Wheels made of solid plastic. These can often be too small for larger mice, though. They're good picks otherwise. Mice run the risk of developing wheel tail from these. Recommended if you can find the right size.
• Wire Mesh Wheels - Contrary to popular belief, mesh wheels are perfectly safe! These cheaper wheels are easy to come by, just make sure you get the right size. Mice run the risk of developing wheel tail from these.

• Bar Wheels - The actual unsafe wheels. Feature bars with gaps that require a mouse to perfectly time their footfalls- and if they don't they risk injury. Mice run the risk of developing wheel tail from these. Don't get these if you can avoid it.
• Disc/Flying Saucer Wheels - A modern and popular alternative to standard wheels, though they take up a lot of horizontal space. These wheels cause less strain to be put on a mouse's spine, often allow for multiple runners, and don't run the risk of mice flipping upside down. It's important, however, that you get one that isn't too steep. Mice are very unlikely to get wheel tail and scoliosis from these. Highly recommended.

If your mouse's wheel is squeaking, oil it using cooking oil. Mice love licking this stuff up, they think it's delicious.

Wheel(y) Tail

Wheel tail or wheely tail is a condition that comes about in a few ways. A mouse naturally lifts their tail while running (and some do all the time) and wheel tail is when they curve it up towards their back. Whether or not its dangerous has yet to be discovered, but its considered a defect in show, and many rather avoid it.
Wheel tail can come from:

• Use of a wheel that is too small
• Overuse of a wheel (defintion of overuse varies on the mouse- mice run a lot and it's normal!)
• Genetic factors
• Habit
• Any combination of the above

Again, it's not conclusive whether or not wheel tail is hazardous to health. Mice can live long and healthy lives with wheel tail- my boy with very severe wheel tail lived to 4 years old and died of old age as opposed to any health conditions! Many mice just do it because its normal for them, even when not on a wheel.

Wheel tail isn't serious, but keep an eye on your critters who have it. Many may develop a curved spine, which is where the real issue with wheels comes in.

Developed Scoliosis

Mice with a wheel too small or who overuse their wheel may develop wheel-induced scoliosis, where their back arches upwards and is similar to a humpback. Like human scoliosis, sometimes it's not much of a big deal (though I think my own "minor scoliosis" back would beg to differ). In older mice, the condition may be something you can't really do anything about, and it's better to just let them live out the rest of their tiny little life. As long as it doesn't hinder the movements of a mouse and it doesn't cause them pain, I wouldn't worry too much about it.

The best way to prevent scoliosis is to make sure your wheel is the proper size and that your mouse isn't overusing it (defintion of overuse varies on the mouse- mice run a lot and it's normal!). Flying saucer wheels are the best way to go as they have a very low chance of your mouse developing scoliosis! Make sure your mouse's back is mostly flat when they're running, not curved.
Sometimes, scoliosis will develop even with a properly-sized wheel and a normal amount of use.

Toys

Other than wheels, mice should have plenty of toys! These can be standard small mammal toys, safe dog toys (make sure to remove any squeakers and other small parts), and safe parrot toys. Anything a mouse can chew on, climb on, rip up, or hide inside!
Good toys include:

• Storebought sticks
• Tunnels - Critter/habitrails, cardboard tubes, woven grass tunnels, etc.
• Wooden chews (bonus if they're hanging!)
• Ladders + other climbables
• Swings
• Woven grass chews (bonus if they're hanging!)
• Lava cube/grinding block chews
• Paper towel/napkin pieces
• Cut squares of soft fabric (they use these for their nests very often!)
• Safe strings + small ropes

I highly recommend getting wooden parrot toys for your mice! Avoid plastic ones, since mice may accidentally swallow the plastic.
My mice have a wooden flexible parrot ladder connected by both ends to the ceiling of their primary enclosure to form a wobbly, swing-like U shape. It's close enough to the ground where they can climb on and off it, but doesn't touch the ground so it can wiggle a bit! They love chewing on it, climbing on it, and very often will sit on top of it and watch the humans outside.
Of course, I have more than one toy, this is just an example. Please give your mice more than one!

Other Mice

Mice are social animals, and female mice should never be housed alone! Note that non-neutered males should never be housed with other mice unless you want a litter (or several) or a bloodbath. Neutered males are safe to house with females and sometimes other neutered males; neutered males, especially those neutered later in life, may still show signs of aggression and be territorial towards other mice!

If you have a female, always get her a companion or two. Non-neutered males can and should be housed completely alone.
Not giving a female mice a companion will almost always result in her developing depression; it's not humane!

Introductions can be done in a few ways, like in neutral territory, by putting mice in opposite containers next to each other where they can see and smell each other, then being swapped in between those two cages every now and again, and so on.

Fighting mice is never a good thing, but there's a difference between fighting and arguing. All mice argue, just like humans, and this (at least in my experience) normally manifests as loud squeaking. As long as no one is drawing blood, this is okay! Don't worry about two mice arguing, it's going to happen and that's just how it is. You can break them up if you want, generally do this by gently blowing on them so they run off to hide.

But always give your females buddies, be it another female or a neutered male! It's good for their health and very important! Just make sure to triple or quadruple check your mouse is actually the gender you think it is, and ensure that no non-neutered males are housed with any other mouse.