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Mice/fur loss, scabs, and fighting, in mice


Dear Natasha,

My two female mice have been together for over a year.  They were litter mates.  All of a sudden my black mouse is missing fur on her head and my black and white mouse has wounds all over her body.  There are no bugs.  I've already checked for mites or lice or anything like that.  Now they are squeaking at each other and the black one, with the missing fur, is chasing the black and white one around the cage.  I luckily had another cage and separated them for the night.  

Do I have to keep them separate or can I put them back together?  Also, what happened?  They were happy and now my two girls are fighting.


Dear Allie,

You can't see mites. In fact, all mice have a few mites all the time. They only flare up occasionally, usually due to some depression of the immune system (other illness, age, depression, stress) or exposure.

A trip to the vet is, of course, your best bet. I understand that that is not always possible.

Mites are not the only reason for fur loss or scabs, which is a good reason to go to the vet. But with both of these mites-like symptoms, it is pretty likely.

If the vet found mites, they would most probably give them each a drop of Revolution, which just goes on the back of the neck, nice and easy; and stays in the blood, killing ectoparasites, for a month. Very easy.

If you can't get to the vet, you may still be able to use Revolution. Although it is prescription only, you may find a vet who will let you have a kitten dose without prescription; or you may be able to get a vial from a cat or dog owner. All you have to do is put one drop on the back of the mouse's neck, gently rub it into the *skin* not the fur, and don't let it wash itself for ten minutes. Super easy.

If you can't get Revolution, treating for mites is less easy, but still possible. You will need to get a flea and tick spray from the company 8 in 1 (there may be other sprays as well, but this is what my breeder does and I used to do too). The following post is from a time before I knew Revolution could be safely used on mice, so the only option I offered mouse owners was the spray:

Please read my instructions carefully. If you have more than one  cage of mice, you must treat them all, and clean all cages as I describe. Another pointer I have learned since I wrote this: if you have anything you can't wash but don't want to throw away, such as wood, you can freeze it for two days to kill the mites.


The fighting is another question. Mice have all kinds of personality problems, similar to people. It is possible for an event or situation-- such as being driven nuts by mites- to provoke an emotional reaction or even personality change.  If this is the case, we can hope it is temporary.

If the chasing is not constant; they still sleep together; you don't observe any actual blood-drawing bites (very hard to know, since scabs can be from mites); neither mouse is prevented from accessing the wheel, food, water bottle, or nest; and neither mouse becomes depressed-- lethargic, inactive-- they can stay together. When you are in the room and they fight you can distract them by clapping your hands or shouting or blowing on them. You can also pick (either) one up to give the black and white one a break. But it is really best if they can live together.

If some of those conditions are present, however, then they must be separated. But do put the cages right next to each other so they do not get lonely. They actually communicate in frequencies we cannot hear. In that case, after the mites are treated, and the fur is growing in and the scabs healing,  you can reintroduce them and see what happens. The cage should be neutral, and the mice should each have a drop of REAL vanilla tapped onto their necks and rear ends.

Again, observe the same rules. If you have to separate them in the end, again, keep the cages next to each other.

Best of luck and health to them both.




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I can answer questions about raising mice and caring for them as pets, with knowledge from my 38 years of having fancy mice as pets. I have NO MEDICAL TRAINING and you should take a sick mouse to the vet; but if you simply can't, I will try to help you. I LOVE PHOTOS!!! I ALSO LOVE UPDATES! Let me know how the little tyke is doing later on, for better or worse, especially orphans. It also helps me to help the next person. Please first search first: use 'Natasha Mice Mouse' with whatever else your question includes. Or check out these links: **** YOUR FIRST MOUSE (my video; rough draft): **** TEN VIDEOS ON RAISING ORPHANS: **** SEXING MICE: **** And some GREAT MOUSE INFO SITES:


I have had mice for 40 years (since I was 5!). I raised them when I was a child but now I keep all females, and never fewer than three so that if one dies the others are not devastated, because they have each other.

I run Rats and Mice are Awesome on Facebook. The official name is Rats are Awesome.

B.A., M.A., M.A. in Linguistics: Yale University and University of Connecticut

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