"Caution: Show Horses"

Today I was driving on I35 and saw a horse trailer that said "Caution: Show Horses." First of all, I want to know if such a sign is for when the trailer is moving or still? Or maybe both? Are show horses dangerous like attack dogs? Should people stay clear of the trailer because of their razor sharp manes? Or is it that our pure ugly humanness will damage the horses if they see us? Or is it for when driving because the owner thinks we'll be less likely to ram his precious trailer when we see that it has show horses in it? Because really, I try to run regular horses off the road, but I'd totally pause for the show horses? As we used to say back in the day, shah!