I had a Paint mare with this in a hind hoof. She had injured her coronary band as a filly. It was totally superficial. There is nothing that will make it go away as it is a scar that continually grows out. It never gave my mare a problem. I showed her in halter, showmanship, western, english, trail, and over fences. Your farrier or vet can validate whether this is a coronary injury.