Threatened mammals (including horses) have built in instincts for life preservation. When threatened, they can either turn and run or stand and fight. This is called the “Fight or Flight” reflex. Because horses are ill-equipped to fight (they have no horns, fangs, or other very effective fighting weapons,) they generally choose flight.
Predator species are born unfinished, unable to see or function – protected by a mother with teeth and claws. Prey animals, such as foals, are born fully finished with hair, open eyes, and well-functioning legs that can run with the herd in just a matter of hours. Their ability to run serves the flight instinct specifically. When alerted to danger, they can wheel and run in a millisecond.
In all instances of Pressure training, we expect a horse to try to “get away” from the pressure using Flight (from mild to severe). We prepare for (but don’t expect) the “Fight” response. When we encounter “fight”, it presents unique challenges. see Charging