I have been able to tame a wild horse that no longer runs away from me when I come near it. The problem is that he goes missing all the time and he usually ends up back near the twin peaks stables. Pressing down on the controller makes Link whistle, but the house doesn't come when I do it. Is there a way to make a horse come when you whistle?
There are 2 steps when it comes to taming a horse in a Breath Of The a Wild. The first is breaking the horse. This involves getting on its back and making it obey you and the second is registering the horse to give it a saddle. It is the second step that will end up making the horse come to you when you whistle. Since the dueling peaks stable is the place that most people will find a horse, I'll use this as an example.
Start by taking the wild horse that you wish to claim, over to the stables. Jump on its back and talk to the guy standing at the counter facing the outside of the stables. He will give you a speech and eventually let you register the horse that you are sitting on. This process will cost 20 Rupees. Once complete, choose to take the horse with you. Your horse will now have a saddle and will come to you when you whistle.
Keep in mind that the whistle only does so much. If you are half way across the map, your horse won't hear you and as a result, will not come to you. This is the best you can get to make a horse come when you whistle, at least until they decide to add some magical ocarina or something to the game.