With a horse (and people too), the panic reaction has 3 stages. The first is a rapidly rising response to fear. The second is when the fear response is no longer increasing but is steady. The third stage is a diminishing response to fear.
I think I meet 4 or 5 people a year who tell me that their horse hates men. Almost always the horse is a mare. They tell me how cranky their horse behaves when handled by men.
We study the behaviour of horses interacting with other horses and then write books and give lectures on horse herd behaviour, as if our observations are definitive. Is it that simple? Are horses that simple?