Arrows can go through horse when riding it.

When shooting an arrow while riding a horse, the horse should take damage rather than the arrow going the horse and nothing happening.

How to reproduce

Start by obtaining a bow and some arrows, find a horse and tame it
Ride the horse and shoot an arrow through the horse while riding it, nothing will happen

Observations: Arrows can go through horse while riding it.
Expectations: It should take damage.