How to Tell a Male From a Female Guinea Pig

Guinea pigs are wonderful household pets. Owners usually want to know the sex of their guinea so that an appropriate name can be chosen. Owners of multiple guinea pigs must know the sex of their animals in order to avoid unwanted litters.

Instructions

Difficulty: Moderately Challenging

1. Consider the age of the guinea pig. If it is less than two weeks old, determining the sex will be difficult. You might want to wait until after two weeks of age. Any sexing done before two weeks should be checked again after two weeks.
2. Turn the guinea over, supporting it very well and making it feel secure.
3. Look at the genital area. Male guinea pigs do not have an obvious penis (nor is their scrotum as large as in rats or mice). Both males and female have a Y-shaped vent. In females, it looks like a perfect Y. If there are any wrinkles at the top of the Y, this could mean that there is a penis underneath that area. In males, the Y tends to look a little more like an “i,” with the section inside the top of the “y” being more bumpy.
4. Press right above the genital area, at the top of the Y. If something begins to protrude, this is the penis and your guinea pig is a male. If nothing immediately protrudes, move your finger around a little and press in various places to see if you can get anything to protrude. You will need to make sure you’ve adequately ruled out the possibility of a penis lurking under the surface before you declare your guinea pig to be a female.

Tips & Warnings

• Don’t worry overly much about hurting your guinea pig when you press your finger on it. As long as you are trying to be gentle, you won’t hurt it. Guinea pigs often squeal as if they are in pain just because they don’t like being on their back and they like to complain as loudly as possible!
• Compare your guinea pig to photos (see Resources).
• To be sure about the sex of your guinea pig, take it to a vet who specializes in small animals (not just cats and dogs).
• Don’t rely too heavily on what the pet shop says. Most people who work in pet shops don’t have enough experience working with small animals to be able to accurately determine their sex.