Horses have two main instincts when they are faced with a situation that they find frightening.
One is fright. This when the horse runs away from the threat, by either spooking or simply getting away from the thing scaring it.
The other is fight. This is when the horse stays and tackles the thing it is frightened of head on. It often bucks or rears when it sees what is scaring it.
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.
to bite
Bolt.
To run
flight or fight and if it is afraid it is going to have a flight instinct
They run away or bolt.
Scatter in groups.
run away
Horse will Flee
For Howrse it's answer is Flee.
instinct