Sows will tolerate just about anything behind them when they are in heat. We used to test sows by pressing on their haunches with our hands and if they backed up, they were in heat. If they ran, well its obvious. Now this pervert must have waited until the sows were in heat, because if they were not in heat they would have been cranky and would have given the fellow a nasty bite. I heard of country sickos putting down several ears of corn in front of the sows while they were in heat to keep the sow distracted while the deed was occurring. Now the boar, he has a corkscrew like penis and the sow has ridges in her vagina that fits the boars penis like a wall anchor fits a screw. The boar and sows copulate and they even will do it for recreation while the sow is in heat. If the sow ain't in heat, they the boar gets eat up.
LMAO....Now that's information I could'a used in some bars when I was active duty !
I had to use a ear of corn with a treble hook and some 550 cord to get some of them sows off the dance floor !
Trolling for hogs was an EOD Olympic Sport ya know !
Stay safe !