When walking behind a horse you should do what Stand 6 feet behind the horse Speak softly so the horse knows you are there Be extremely quit so you won't spook the horse?

You shouldn't be behind the horse, if at all possible. Otherwise, if you have to go directly behind a horse and there is no other option, you should always let the horse know your there. Run your hand along his/her back and rump, speaking softly as not to startle her but loud enough that she can hear it. If you are 6ft behind a horse, the horse could easily still kick you if it is big enough or it could back up to make a hit. If you be extremely quiet, it WILL spook the horse; the horse can hear MUCH better than you can and WILL hear you, regardless of how quiet you are being.