They run away or bolt.
A horse's first instinct if it is afraid is to run.
When a horse is frightened or afraid their first instinct is to Flee, run or get away. known as spooking.
to bite
Bolt.
To run
flight or fight and if it is afraid it is going to have a flight instinct
Scatter in groups.
run away
Horse will Flee
For Howrse it's answer is Flee.
First it will flee.
flee, runaway, yes i do play howrse