I second pflady’s comments. Not all horses can go barefoot, just the way not all horses have high withers or can grow a long, sexy forelock. It’s in the genes. I currently own a Morgan and have the same problem with her. I tried twice to let her go barefoot–it’s usually healthier and definitely cheaper–but she goes instantly lame. Thanks to a knowledgeable farrier, she’s fine now in all kinds of footing.