Put some small rocks in an empty soda can and tape it shut. When you rattle it or throw it into the air behind the photographer most horses will point their ears.
try clucking or whistling! maybe play some music or interesting sounds (animals, door bells, squeaky toys, etc.)
I like making really weird or scary sounds!😂
I usually sprinkle dirt or dust down
Ry video taping a horse neighing then playing it full volume (assuming for pictures)
Try throwing some dust or small rocks up in the air or holding some treats