How to Tell a Male From a Female Guinea Pig

At first glance, male and female guinea pigs look very similar. Both genders of these cute rodents have a stocky, round body with no tail and a large head with a short nose. They're cute, soft, and they are curious pets that you can even play games with.

Portrait of red guinea pig, close up.
How to Tell a Male From a Female Guinea Pig
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Although their coats can be a variety of colors, there are no obvious sex-related differences such as hair length or color. To tell the difference between a male and female guinea pig, you'll have to take a closer look at their body parts. Some veterinarians treat guinea pigs so if you're nervous or unsure about identifying guinea pig gender take your pet to your vet for a checkup.

About guinea pigs

First of all, it might help to know that a guinea pig is neither related to pigs nor natives of the country of Guinea! There are no wild guinea pigs, and no one is sure how they got their common name. Encyclopedia Brittanica explains that they were domesticated as a food source for ancient Incas. Europeans compared them to pigs, thus the pig in their name.

The guinea part of the name may have derived from the cost of an animal (one guinea for an animal), or from them being transported to market from ports in the country of Guinea. GuineaPigCare.com says that guinea pigs originated about 5,000 B.C. from South America. Since their scientific name is Cavia porcellus, many people call them Cavies. The lifespan of a guinea pig is about nine years.

Sexing baby guinea pigs

When baby guinea pigs are first born, they are known as pups. The females are sows, and the males are boars. Like most rodents, guinea pigs are prolific breeders, and they become sexually mature and able to reproduce in a matter of weeks. Sexing baby guinea pigs may be important to do as early as you can so you can prevent your guinea pigs from breeding and producing more than you can handle!

When guinea pigs are first born, their genitals have a small, doughnut-shaped ridge of skin protecting the rectum. This makes it difficult to see the genital area. As they grow, it will be slightly easier to tell the difference.

Nipples on male guinea pigs

Male guinea pigs do have nipples, so the presence of nipples alone is not enough to tell you whether you have a guinea pig boy or girl. According to GuineaPigCare.com, sows have larger nipples than boars, but the boar's body size is somewhat larger than the females. To determine guinea pig gender this way takes a comparison, and maybe between a handful of animals.

Both genitals have a Y-shape, but the male's genitals are likely to look more like the vertical shaft of the letter i, and at the very top of that line is a speck that looks like the dot of an i. If you have your guinea pig upside down in this position and are holding him firmly but very gently, try giving him a gentle press on the belly just above the genital opening. If you have a male, you should be able to feel the penile shaft just under the skin. If you press again, you may be able to cause the penis to extend from the opening just a little.

Female guinea pigs

The genital area of female guinea pigs should appear slightly swollen and also bumpy. You may have to use your fingers to gently pull the skin to the side to see the Y-shaped opening.