In the world of dreams the rules of reality do not necessarily apply. Each dream is unique and it's a direct link to the soul and spirit. Psychology provides its own theories on what dreams mean, but so did tradition and the study of dreams for thousands of years before any relevant science had developed.
Dream Meanings - Horseriding
If you dream that you are riding a horse, then your wishes will come true. If, however, you are dismounting a horse then you will have problems and distress.