One pig biting another

Question
 We recently adopted two pigs from the local animal shelter. The shelter told us that Sugar Plum and Bon Bon are females, about two years old and had lived together before coming to the shelter. We have had them for about three weeks and they seemed to get along well until about three days ago. Sugar Plum now chases Bon Bon around the cage and bites her rump. She then sometimes mounts her. They are both making odd noises that we have not heard previously. Sugar Plum seems very agitated. Nothing in their environment has changed. What do you think? I am afraid that we really have a male and a female and they are trying to mate! Any suggestions? Thank you for your input!

Answer
Hello Sophie,

I'll send you a link to check gender, just to be sure. It's possible that Sugar Plum came into heat. Some sows become a bit more aggressive when they are in heat. Usually that only last a day however. It concerns me that this has lasted for 3 days. I would recommend taking her to the vet for an exam. She may have a reproductive problem (such as ovarian cysts or tumors) that is throwing her hormones out of whack and making her irritable. Do double check their genders though. If they have been missexed, that may solve the who problem.

http://cavyspirit.com/sexing.htm

-kkat
http://www.geocities.com/abyssinianguineapigs