Breeding, separating mice

Question
my mouse had a litter of 5 sadly 2 of them were eaten by another female mouse that i have. i have now separated them and the mom is so nice. after about a week i started to pick her up and play with her more and i noticed a bump near one of her nips. I don't know if its a tumor. i hope not because she seams to be such a great mom. Also my other female seems to be quite aggressive towards my 3rd female (still quite young) and i noticed a bite on the young ones side. i don't have anymore cages. the 2nd one i am using for mamma. last but not least i think my male mouse might be to old. he has a little balding spot near his rump and i have only seen him try to breed once. I'm fairly new to mice. i have bred rats before. (so much easier to breed in my opinion)

Answer
Dear Nathan,

Mouse breeding should be left to experienced private breeders. It is far more complex than breeding rats, because male rats can live in groups, while male mice often end up having to each have their own cage. That means having as many cages and as many adoptors as you have males. Five is a very small litter; you can usually expect 10-12 and it can be up to 18. Mice should be bred through proven lines and bred for health and longevity. There are mice in shelters because people breed more than they can house; and even worse, sweet little pet mice get fed to snakes, experimented on, or "set free" where they have no idea how to survive.

Your male may be too old, but don't trust him.

I hope it was the aggressive mouse who killed the pups, if she did. It is also quite possible that the pups died for some other reason. It is normal for mice to eat dead bodies. So my suggestion is to put the less aggressive mouse in with the mom and pups. The aggressive one can live alone. I assume the male lives alone too. The three cages should be near each other, so no one is lonely. They do communicate too high for us to hear.

The mom mouse should go to the vet to have her lump checked out, but this can probably, and thus should, wait till the pups are about 12 days old, so they can travel with her. Mice do get mammary tumors often, but it could be an abscess; and the vet could then lance it and give her antibiotics.

I wish all of the mice the very best of luck. I do recommend that you not breed.

Squeaks,

Natasha