How do you know the sex of your mouse?


You adopted a Mus musculus, that is, a house mouse, or do you want to do it? Indeed, once tamed, it is an animal very appreciated for its affectionate side and its intelligence. Why sex his mouse? This seems especially important if you plan to adopt multiple mice.

Mouse reproduction

The house mouse reproduces all year round. In the wild, she can only hope to live for 3 months: this is why it is vital for her species to reproduce quickly. On the other hand, its life expectancy in captivity rises to 2-3 years.

The gestation period is approximately 21 days. The female, in optimal conditions, gives birth at a litter of 4 to 14 young, and she is fertilizable shortly after giving birth. A mouse therefore gives birth on average to forty young per year. The multiplication of mice is therefore very fast, and this is one of the reasons for its use in the laboratory, with its genetic proximity to humans.

A house mouse can reach sexual maturity as soon as four weeks of life, more frequently around five or six weeks. From 4 weeks, as a precaution, it is therefore essential to isolate the mice by sex.

Know the sex of your mouse

Baby mice are born hairless. It could be a boon to identify the sex of a baby mouse. However, the udders of the females are not yet visible and the testes of the males have not yet descended.

There would only remain the method of distance between the genitals and the anus, more important in the male than in the female. But a 3-day-old mouse is only 3.5 cm. Evaluating a difference that will play out in millimeters therefore seems a very difficult challenge. Suffice to say that it is not possible to sex a baby mouse.

Fortunately, the development of the mouse allows you to do so before the fateful fourth week of life. The udders appear around the 10th day of life: it looks like small holes on the lower abdomen, without hair. However, the male’s testicles may not descend. Since the penis is visible, this is why the anus – genitalia distance remains the most reliable technique for determining the sex of a mouse. The size of the animal will be sufficient for a reliable diagnosis from 21 days of life.

You should never grab a mouse by the tail and suspend it in a vacuum. Wrap her with both hands: you need to make sure her legs keep contact with a support when you pick her up.

Caring for your house mouse

The best way to protect your mouse from disease is to provide it with good living conditions, as well as a adapted diet.

Food and water must be renewed every day. The enclosures must be kept clean, free of the food reserves that it instinctively constitutes. Ideally, the cleaning is done without waking up the mouse, which sleeps during the day and lives mainly at night. The olfactory imprints that it disseminates in its place of life are fundamental: it is therefore necessary to change only the soiled parts of the litter.

Like any other pet, you need to observe your mouse every day and establish regular and gradual contact so that it gets used to you.