How to Sex Spiny Mice?

Care Basics
Housing
Equipment
Sexing
Grouping

Quite many people have told me about surprise litters, when they have left one or more males with the females by mistake. All in all, many say that sexing spiny mice is difficult. Well, it wasn't that easy for myself at first.

When sexing grown up mice, rats or gerbils you usually check if the animal has testicles; if there aren't the animal is naturally a female and if there are, it is a male. With spiny mouse males the testicles are quite small, so that the male goes for his great joy in with the females. But is the owner that happy?

Sexing the above-mentioned rodents, you usually compare the distance between the anus and the sex organs, which is usually longer with males than with females. Of course, this works with spiny mice as well - as long as you know how long the distance should be with males and females of different ages. Mice, rats and gerbils get usually so many babies that you can tell the sexes apart by comparing the babies (unless a large litter is all of the same sex). Spiny mouse litters are so small (1-4 babies) that comparing doesn't often work.

Here's the problem, but where's the answer? Check if your spiny mouse has nipples or not. If it has, it is a female. If not, it is a male. You can see the nipples as "rows of dots" both sides of the belly, the ones nearest the sex organs can be seen best. You can sex even a few days old spiny mice by the nipples. Young spiny mice have their nipples showing better than adults have.

There is one thing you should always remember before starting to check the sex of your spiny mouse: remember that you NEVER lift a spiny mouse by the tail. You have to turn the mouse over or look under the belly using some other method. You can put the mouse on a show box lid and try and look under the belly through the lid - you can do this with adults, not with young ones who may fall down. The tail of a spiny mouse is really fragile and it does not stand lifting. I myself have one spiny mouse bought from a pet shop with a broken tail, broken due to wrong handling.

On to next part - Grouping.

Text by: Tiina Andersin