I don't generally indulge in these hot threads, but there's just something sticking in my craw. Where you're from/have lived or what meat is acceptable to eat has nothing to do with the post at all. It's about shooting to 'dispatch,' as you so coldly put it, someone's pet for munching on your garden ONE TIME. That was no first warning. The horse's owner riding on your land and the horse showing up on it's own are two completely seperate instances.
The fact that you find it okay to shoot to kill a PET that was NOT threatening your livestock is disgusting. That was not the only choice at all, which is what makes the whole situation sickening. It has nothing to do with being a horse lover or not, it has to do with being compassionate not only to the animal, who was doing nothing wrong in it's mind, but to the owners. You used that animal's life as a message. How much more cruel can you get?
For the record, I don't condone shooting ANY animal, pet or wild, unless it is absolutely necessary in order to protect your animals, so you can't throw that argument in my face.
I hope it was worth the bills you're going to have to pay when they sue the pants off of you. Because there's no way in hell they aren't going to win.