Running Hogs!!!
Dogs that run them a few minutes and quit... hogs learn they can get away.
Rough dogs chewing on their butts... I'd run to if something bit me on the butt.

x2
Hogs learn they can get away...
I also believe evolution. In this case the easy ones get caught and the ones who stop to fight get caught and the ones who run before the dogs can get there to keep them bayed or caught will live to breed another day and mother nature does not make mistakes when culling.
If a species can't adapt it becomes extinct and the hogs aren't going anywhere any time soon.