Male guinea pigs should be about three to four months of age before being allowed to mate.

A female guinea pig's oestrus (heat) cycle lasts 16 days. She will only be interested in liaising with the boar for about eight hours during this time. Female guinea pigs get on quite well with their boar-beaus, so the easiest way to manage the romance is to leave the couple together until you are sure she is pregnant.

You can probably tell when the sow is in season as, during this time, she will regularly curve her spine downwards to elevate her rear end. In addition, you may find that she regularly mounts other female guinea pigs that she is living with. If you have a harem of females, a happy boar can service the needs of up to ten sows.