What creature is a blind person's best friend? Janet Burleson of North Carolina would say it's a horse. Two years ago, the retired horse trainer decided to train miniature horses to guide the blind. The horses have excellent night vision, a good memory and a 25-to-35-year life-span-much longer than a guide dog's. The horses wear sneakers so they can walk indoors. Burleson used her pet, Twinkie, as her guinea pig. In May, Burleson's Guide Horse Foundation will give Dan Shaw of Maine the world's first guide horse.