I see you found emilyh’s post with horse photos so you have probably also seen what we put into that thread.
I don’t know the circumstances of the shot but your contest entry would benefit from a rim light.
Horse in a hard right turn, the camera is tilted. It’s not a horse’s most flattering side.
Pony through a hole could stand a little more light on the shadow side. I would prefer a bit more DOF to have the whole head in focus.
Horse in the sun desperately needs a lens hood and fill flash.