pregnant pigs

Question
About eleven moths ago (July) I got my first guinea pig. Then two weeks later we got another guinea pig. They were both girls. A couple of weeks ago though we saw some concerning behavior and now we think our first pig is a girl and the other is a boy. We also belive she is pregnant because she tries to bite me when i touch her stomach area. The one that we think is a boy though is becoming pear shaped. I need a answer to which one is pregnant and what to do? Also they are both older than six moths and I have heard guinea pigs usually die if they have not had a baby before they are six months. Will they be ok if one of them is indeed pregnant?

Answer
Hi Seb,

Before you panic ... you need to confirm whether either of them is a male. If they are both females - neither could be pregnant as the last time they would have been in contact was males was last July, and guinea pigs are pregnant for 68-72 days so the babies would have been born a long time ago. This is quite simply a case of picking them up and turning them over so you can look between their legs - as you have two, you can compare them. If you press low on the stomach of a male guinea pig, it will encourage his penis to come out (they usually tuck them away).

If one is a male, then the other one will almost certainly be pregnant, however - I would expect they would have mated well before now - and several litters would have been born in 11 months if they were living together. If one is male, you will need to house him in another cage as he will be constantly mating with the pregnant piggy causing her stress, and once she gives birth he will mate with her straight away - before her body had a chance to recover, meaning the second pregnancy would be unlikely to result in a successful birth. You may find that they are both males in which case you can breathe a sigh of relief!

Not all guinea pigs (like cats) like their stomachs being touched, so a piggy is likely to nibble you when you touch theirs even if it doesn't hurt. Signs of pregnancy are similar to those in humans - increased appetite and thirst, decreased movement and weight gain. Guinea pigs' babies sit either side of their stomach rather than underneath it, so a pregnant guinea pig looks like an aubergine/eggplant from above. In the final stages of pregnancy, you will be able to feel (and maybe even see!) the babies moving around. If you want to know for sure, take your piggies to a specialist small animal or exotic pet vet, or a rodentologist.

It is considered dangerous for guinea pigs to have their first litter over the age of six months - this is because the pelvic bones will have fused, and if the passage is too narrow the piggy will not be able to deliver the babies. However, there is a high mortality rate during all guinea pig births - especially amongst the babies - and a guinea pig over 6 months but under 1 year can still do a very good job of delivering a litter. It's all down to luck, really. If you do find that you have a pregnant piggy on your hands I'd suggest you find yourself a vet who is good with guinea pigs. He or she will be able to monitor the pregnancy for you, and let you know if the pelvic bones start to widen towards the end, as would be expected. You can have the vet on the phone during the birth - coaching you, in case you need to help deliver the babies - and if you live nearby and things do seem to be going wrong, you would be able to rush your piggy in for surgery. I would not recommend a c-section unless it is absolutely vital as it is unlikely that your adult female would make it through the anaesthetic.

Good luck, I hope this helps, and if you need anything else ... just ask!