Odd Scenario with Large Animal

I was with the family at a RenFest. Wife, kids and 2 young grandkids, one in stroller. I am carrying Glock 17(9mm) IWB.Family is relaxing on grass. TINY lady rides by on a LARGE (draft) horse. The horse starts to spook, and almost knocks a kid over. Lady tells the kid to watch out, horse spooks even more. Lady gets off horse. I get up and put myself between horse and family.Lady appears to have hard time controlling horse from ground. Horse looks more and more agitated. Horse starts moving erratically and heads toward me. I puff up raise my hands and contemplate my next move.I decided that my point of no return would be if the horse reared or bucked.Still not sure what would have been correct action? Do I draw and fire on the horse? 9MM vs large draft horse? Do I stand my ground and hope the horse backs off? Do I wait until the rider takes control?What would you do? via /r/CCW http://ift.tt/2eCzqLe