The problem with prion diseases is that they are transmissible through various types of animals.

The big BSE (Mad Cow) scare in Great Britain was caused, IIRC, because farmers destroyed sick sheep, and rather than disposing of the bodies, they processed them into cattle feed, which infected the cows.

Prions are very difficult to destroy, even with high temperatures, so don't feed potentially sick animals (or people) to your pigs if you intend to eat those pigs later.