i have lots of horses myself and their most normal instinct is flight, they normally shy away from the thing that is scaring them or back away, they may also put their head in the air and their ears will flatten back.
there can be a leader but only sometimes they get afraid
When a horse is frightened or afraid their first instinct is to Flee, run or get away. known as spooking.
A horse's first instinct if it is afraid is to run.
Horse have a fight or flight instinct...normally flight!
to bite
Bolt.
To run
flight or fight and if it is afraid it is going to have a flight instinct
run away
They run away or bolt.
A welt on a horse is usually the symptom of an allergic reaction to something they have touched. If the welt is spreading, it is likely the horse's reaction is worsening.
Horse will Flee