answer:I grew up in a rural area in Illinois (some 50+ years ago, before “factory farming” was the norm) and I have heard of this. It’s called savaging. I did a little research when I saw your q, and I found this article to shed some light on the behavior. I also came across some interesting non-cited info in this Wikipedia article. It cites anecdotal evidence that sanitary conditions and a comfortable environment can reduce the occurrence of cannabilastic savaging. Is there another sow available who can nurse the survivors? I might be wrong, but I don’t think nursing them with a sow from another breed will affect their purebred status, as long as a healthy diet is provided.