I would never shock a dog when they are running a track, that would be giving negative reinforcement for something you are doing.
There isn't much you can do for the yipping on track, some of them figure it out and quit on there own but that is about it.
X2
I've had several pups that grew out of it the're just exited, but had few that didnt. But i wouldn't shock when the're after a hog. Give em little more time with silent dogs good chance will grow out of it.