Sexing Guinea Pigs
Being able to tell whether your guinea pig is male or female is essential. Not only does it prevent surprise litters, but it also helps you make the best choices for housing, bonding, and long-term care.
Mis-sexing is unfortunately is quite common, particular if guinea pigs come from petshops, ads online or even breeders.
Always be 100% certain of your new piggy's gender before you introduce them to an existing herd. If in doubt, find your nearest exotics vet or guinea pig rescue.
💡 Tips for New Owners 💡
Check Early! Guinea pigs can breed as young as 2-3 weeks old, so correct sexing early is essential.
Get a Vet’s Help: If in doubt, always ask a guinea pig–savvy vet or experienced rescue to double-check.
Don’t Rely on Guesses or Google Images: Only an experienced, in-person genital examination can confirm your piggy's sex.
Sexing Baby Guinea Pigs
It's important to sex any baby guinea pigs before they are 3 weeks old!
Males can become sexually active from just three weeks of age (yes, really!). Young boars are capable of impregnating their mothers and sisters, so if you have new babies in your care, identifying and separating any males from females within the first few weeks is crucial.
Sexing can be tricky in very young guinea pigs as their genitals become more pronounced over time. If you’re ever unsure, it’s always best to ask an experienced rescuer or an exotics vet to confirm.
Don't make a guess, make sure your piggies' sexes are 100% confirmed!
How to Hold Your Guinea Pig for Sexing
- Sexing piggies is easier with two people — one to hold, one to check!
- Be gentle but firm, keeping calm and quiet.
- If they wriggle or become stressed, give them a break and try again later. If they stay too anxious, you may need the assistance of an exotics vet to confirm the sex instead.
- Sit with your guinea pig on your lap or a towel-covered table. Avoid placing them completely on their back, as this is distressing and uncomfortable for them.
Safe handling:
- One hand across the chest for security.
- Keep them upright and close to your body.
- Support their bottom with your other hand.
Once secure, you’ll be able to check their sex safely.
Identifying Males & Females
♂️ Males (Boars)
- Look for a small “i” shape
- The dot = penis
- There will be a noticeable space between the penis and anus.
- Feel above the genital area → you should be able to feel a ridge under the skin. Push down here and the penis may extrude (can be tricky in babies).
- It's easier to tell features in older males than in newborns.
Testicles won't be visible in males until around 6 months of age. In mature males, this presents as two bulges either side of the anus.
Desexed males will have no testicles, but will still have the obvious male “i” shape of the penis, perineal sac and anus.
♀️ Females (Sows)
- In females, look for more of a “Y” shape. Gentle pressure above the area or spreading the area apart does not reveal a penis.
- No Testes: Females never have testicles, and the genital area will appear flatter compared to males (though not so apparent in baby guinea pigs).
Desexed females will have no noticeable differences to their physical genital area.
Important:
- Both male and female piggies have 2 nipples just above their genital area! So don't rely on those as a way to tell your piggy's sex.
- Generally speaking, males (particularly adults) are bigger and heavier in size than females, but this can vary, and shouldn't be a way of telling your piggy's sex!
NEED SOME HELP?
If you're ever in doubt about your guinea pig's sex, it's always best to check with an experiences professional. Your nearest exotics vet or guinea pig rescue will be able to help you out with confirming whether you have a male or female.
Remember, don't guess, get it confirmed!
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