Sometimes I forget that not everyone is in redneckville (where everyone knows that most people are armed so they mind their own business) and that yes, calling the sheriff would be a good idea if this continues.
My grandma tells us a story about her uncle Jerry who was a South Dakota cowboy. One day a horse was picketed outside the house where he lived and a couple of teenage boys came over and started throwing rocks at the horse and making it run in circles around the picket. Jerry saw it and came outside. He wasn't an overly tall man but he was built like a brick wall. He laid his hand on the doorframe and bellowed: "THEM'S FIGHTIN' WORDS TO MESS WITH ANOTHER MAN'S HORSE".
Needless to say the kids lit out of there like he was actually after them.
And actually, the hot wire around the rubber trough (under the lip) shouldn't bother the horses or be dangerous as far as I know. It would give the dude a shock when he goes to grab under the lip and it would be kind of great to watch.
No matter how much you think you know about horses, there will always be one that'll come along and teach you something new.