Longridge, a couple years ago i posted a very similar story on here about our "miss piggy" she was great for a long time then all of a sudden all hell broke loose & she chased me running flat tack foaming at the mouth through 3 paddocks. I closed 3 gates & she threw all 3 off their hinges then patrolled round & round the locked house looking for me who was shut inside frightened. My young baby was stranded at my mother's house up the lane with me unable to go and collect her. I drove out to close the front gate on the mule & pig charged the mule, I threw a bucket of food which had no effect & she kept coming. I phoned neighbors to ome shoot this savage (& enormous) pig but they weren't home. Couple days later she was fine. Butcher couldn't take her & next heat same thing! Butcher said he hadn't seen so much fat on a pig before..she made the best sausages though.
There was a reason I had a designated pig paddock! in the same way as I have a designated ram paddock! Nothing and nobody has to go through them to get to anywhere else. After two heats, why wasn't she in pig? or was she too fat.
The first 'episode' happened around the time we were waiting for her to farrow. The piglets never really arrived to our knowledge & we weren't as experienced back then so we got a local pig guy (and owner of the boar we had used) to come give his opinion. He thought she had farrowed and eaten them. He said she was the most obese pig he had ever seen & suggested she likely only had 1-2 piglets with complications due to weight. He suggested digging a huge hole & shooting her. It was a couple days later she went psycho. We didnt try again. She had previously given us a really good litter when she was in better body condition. We were feeding bakery scraps & had 2 people feeding. One thought she always looked hungry! Basically she got grossly overfed and pretty much killed with kindness. A real shame and a big learning curve. That was about 4 years ago. We have 8 sows, 2 boars, a few porkers and usually a couple litters at same time now so have come a long way since then.