When you blow into a goat horn, the nearest saddled horse that belongs to you will reveal their location by yelling and glowing for a couple seconds. If you can't see them, you will hear them from up to 1,000 blocks away!

This gives a use to the Goat Horn where it was orginally designed to be more of a social / cosmetic item.

You can also install this as a mod for Fabric on Modrinth.