An enclosed and locked build is best, however its good practice to craft and deploy a Hitching post and Trough. Once placed, simply dismount at the trough (or lead the horse to it using the in-game interaction menu). The horse will remain at the hitching trough and can only be mounted by yourself or your teammates on our modded servers.

Be sure to keep the trough stocked with food or the horse will perish from hunger in hours.