sorry i don't know what they are but am really interested to find out, i have a long haired satin BEW with the same thing, she has 1, shes a retired breeder about 19/20 months old, she is okay though it does not bother her.

 

They look like warts. Some of the 'hairless' mice I used to breed had them too and had no ill effects. They didn't grow to be very big at all. If they start to increase in size rapidly then I would assume the worst, but if they stay like that then she should be fine. Of course if you're worried you should consult a vet, as I am going from personal experience of a few thousand mice but of course have no way to be positive one way or the other about your doe.

 

 

I can't say for sure what these growths are, but I've had two older mice that had them identical to the larger one on your [Shadowrunner's] mouse. One obese brindle had one on her belly that never changed or caused harm. But an elderly buck had one on his back that stayed stable for several months and then sprouted more smaller growths ON the original growth so that it looked like a cluster of grapes. I let it go and one nite it ruptured or something (maybe even he tore it off by accident?). I found him in the morning cold, pale and half-unconscious from massive blood loss. Whatever these things are, I would keep a close eye on them.