Oh, and to add to Dr. Cortex's suggestion: There are no DLC horses, from what I see on the Japanese sites. The game has been out for almost three years now, so if there were DLC you'd see it by now. You simply breed your horses to create better and better horses. (But how you end up with a fire-breathing dragon which I've seen on the Japanese community, I'm not sure...! Lots of breeding?!)