The Flying Sandwich is, sadly a recognised and real concern for many animal diseases. The Swine Fever outbreak in 2000 was I think due to thisIts not my theory, they have enough documented cases of snap being found in German laybys and dead boar then found nearby.
My berufsjaeger pal Rene is for the last few years an official boar cadaver searcher using his trained hounds in the Rheinland Pfalz area of Germany. He told me this.