Whenever a horse is not moving, they are constantly spamming their idle sounds. This is especially apparent if you mount a horse and repeatedly make small adjustments; each time the horse enters its idle animation a sound will play.
This is because back when I contributed the fix for #29343, I incorrectly mapped some of the head idle animations to the wrong animation events, causing any idle animation to trigger the sounds. It turns out that these animations had no animation events, so I've added three new animation events to the horse behavior file that are called by the animations (two by idle_head1, and one by idle_head3).
Fix attached.

Attached Files:
Horse Fix.zip