We just bought 3 Guinea pigs today - all 3 male. One ...

It is definitely possible that the pet store has not sexed them properly. Yes, they could be playing but I would keep the one seperate until you are absolutely sure of the sex. I would prefer you take them to an veterinarian that specializes in exotic small animals to verify the sex. It usually doesn't cost much at all and bring all three. Taking them back to the pet store still doesn't guarantee proper sexing.

Please review this site for further information and pictures:

Guinea pig sexing

Thank you,

Theresa

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Just so you know females may also commence in this mounting behavior aswell, but again a veterinarian should sex them if you are not able too just so you don't end up with unwanted pregnancies and babies.... Will you be keeping them all in separate cages later in life? How large is their cage if not?

Thank you

Theresa

__________________
If I was helpful please hit ACCEPT if you need more help just let me know.
In the case of an emergency please contact your veterinarian or emergency center.
Feedback is appreciated!

Thank you for your help. The links have very interesting information. We plan to keep all 3 Guinea pigs together. We bought the largest one level cage available at the pet store. Thanks again.