Horses are animals in Harvest Moon: Tree of Tranquility that you're able to interact with. They're obtainable after Brownie Ranch is unlocked and upgraded once through shipping farm products (milk, eggs, etc.), however you'll need to make sure you have a barn to put them in. When you buy them, they start off as colts. They take 28 days to mature. Once your horse is mature, you will be able to ride it. It is one of the two animals you can use to ride around the island. You can ride your horse from inside and outside the barn, though it obviously can not go into any other buildings in the game.