missing fur

I bought two breeder mice about two weeks ago. Both are white with red eyes, one is male the other is female.

I just noticed today while refilling their food bowl that the little girl had a patch of fur missing behind her neck. Kinda looks like the little boy was nibbling on her neck.

Do they do that with breeding? The little boy has a very small patch missing on his shoulder blade which leads me to believe rough play. But does that all coincide with breeding?

Thanks all!

It could be the rough play theory or could it be their allergic to something?
Maybe someone who know more about mouses will be more help then I am.

It could be a rough play/mating thing but it may also be patchy skin/fur from too much protien. I'm more into rats but I know I've had a breeder male that grabbed the females so hard behind the head/shoulder area when mating that he slashed them rather badly (he was soon out of a job let me tell ya!) Keep an eye on them, perhaps take a look at the protien percentage they are eating and see how it goes.

Well, diet wise I am using a mixture of soy/wheat ceral, rasin bran, cherrios, puffed wheat, dried fruit and nuts, a dog food (kibble and bits). The recipe is on this site and it called for a senior dog food with less than 20% protien. Well at the store i was at I couldn't find a senior food with less than 20% protien so I bought the kibbles and bits and that has 21% protien. They've been on that diet for a little under a week.

I haven't noticed any fleas/mites/ticks.

They're cage is cleaned out weekly and I am using a sample bag of carefresh. The only new thing I've added other than the diet is a new wooden hide that i got from a friend. She doesn't have any problems with mites/fleas/ticks, so I don't think that could be the problem.

I noticed the patch has grown just a bit on the back of her neck. When I did when refilling their bowl was took out all the dog food, just in case....

I am really hoping it was due to rough play...cause I am not sure of what type of treatment to follow other wise.

Kibbles N Bits isn't even good enough for dogs, not to mention mice. Too many by-products and rendered things, EW. You want to look for a high-quality dog food, such as Wellness Senior, Eukanuba, Nutro Ultra, etc. They don't need any dog food if you feed a good lab block diet(Mazuri, Harlan, etc), unless you want to toss some in as a treat.


I use a bit of the wellness or science diet for the mice every so often, but they mainly get grains and their lab blocks(Mazuri 9F).

A good preventative measure to take would be to go to Tractor Supply or another feed store in your area(preferably a Purina Mill so you can get lab blocks in bulk while you're there), and get a tube of 1.87% ivermectin paste. It's made for horses, and should cost around $5-$6. Give them a dose orally the size of half an uncooked grain of rice. Do that once per day for 2-3 weeks. That will get rid of any mites/lice they have on them as well as the main internal parasites if they have those.

I do this as a precautionary step to ensure any new mice I bring in, don't bring bugs in with them. Makes for healthier mice, bigger litters, healthier babies, and a non-infected colony. :)