Chances of mating

Question
Last night my male (who will be neutered next week) powered his way through a barrier and got in with my two adult unspayed females.  I was in the room (but my back was turned) and am pretty sure he was only in for a few minutes.  Now *he's* been purring, but what got my attention was some annoyed squealing.  Both females are rescues--one I was told had had babies, but not the other, and I am aware of the risk as the younger one is about 1.5 years old.  I examined both closely. According to a book I have, a female's organs will be slightly swollen and loose when in heat.  Both girls looked ordinary, and clean--I also didn't see any sign of the "plug" males create--I have only read about it but assume it must be somewhat visible if breeders know about it.  Since females are only in heat about once every 16-18 days, since they did not appear to be behaving in a receptive manner, since I heard angry noises, and given their appearance immediately after taking the boar away, is there much likelihood that he could have gotten one pregnant?  Obviously I will be watching the girls closely just in case (I do have a good vet).  Also, while many sourses talk about pelvic bone fusion, another expert on this site said she'd never encountered it in over 8 years of breeding/handling  and thought it was most likely to happen with females 3+.  I am beside myself because I don't want to bring more into the world, or hurt my unbred girl.

Answer
Hello L.,

It sounds like you are most likely in the clear. Plugs really aren't too visible if the male does it right, alot of them are a bit uncoordinated and miss. However, the plug is usually only inserted after several matings anyway. Pelvic bones don't actually fuse, they harden. When sows are pups, the pelvic bones are flexible but as they age they harden. This DOES take place at around 1 year. Some sows can still deliver safely, but that's rare and I wouldn't depend on it. Keep the date in mind of when he escaped and plan for a C-Section at 65 days. That way you have a good chance of saving mom and pups. It does sound like they are ok though. If they were in heat, they would have been receptive and not screaming at him for being near them. Your best bet is just to keep a close eye on them both and treat them both like they are currently pregnant just to be safe. Good luck!

-kkat
www.geocities.com/abyssinianguineapigs