I slaughter hogs, i've seen this in many hogs before. All possibilities that you've gotten so for is a chance. In the hogs that i slaughter its a rupture of the abdominal wall and her intestines drop. From your photos that is given i see a young fawn with her, which leads me to assess this. During pregnancy she was able to give birth to a healthy one but then her inner wall was weak and the rupture happened. Sad part in the this is, if she happens to get pregnant again, chances are that neither one will make it. If she does she is very fortunate.