How To Tell the Sex of a Guinea Pig

Deciphering whether your guinea pig is male or female can be very important if you are getting more than one and deciding whether you should put them in the same cage. If it is less than 2 weeks old, however, you might have some difficulty determining between boy and girl. You could either simply wait until it is a bit older or you could attempt to find out, then when it is a little older, check again to be certain. The male’s scrotum usually becomes a lot more noticeable as it reaches maturity. All the process really requires of finding out whether you have a boy or a girl is getting the guinea on its back and examining its “privates”.

To get the guinea pig on its back, pick it up and carefully turn it over on its back, supporting its head and rear end with your hands. Then take a close look at its genitals. Both a male and female have basically “Y” shaped parts, though you can usually see a round-shaped dot on the top of the “Y” in males, which can therefore look more like an “i”. Sometimes, though, the dot can disappear within some folds of skin. As a result, even if you think you have a female, apply gentle pressure on either side of the top part of the “Y”. If it is in fact a male, a small nub, or the penis, will pop out. Sometimes it does not protrude immediately, so you might have to apply gentle pressure in multiple areas around its genitals until you can be absolutely sure it is a female. With older males, though, there is also swelling on each side of the “Y”.

It is very important to know exactly whether your guinea pig is a boar (male) or a sow (female) because of the many risks associated with a pet guinea pig becoming pregnant. Also, some pet stores might sell two supposedly same-sexed guinea pigs together, when in fact they are anything but, so you should still check to make sure even if they are being labeled as “same-sex” at the store. If they do turn out to actually be of the opposite sex, separate them immediately, even if you do not believe that the female is pregnant. Another fact that should be noted is that both sows and boars have nipples, so never let that be the determining factor.


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