White line disease affects what part of the horse? Earn the Mane-U Horse Health Badge! 1. White line disease affects what part of the horse? any white area on the horse the inner layer of the hoof wall the gum line above the teeth an area just in front of the hoof’s epidermal laminae Loading… Share this:ShareFacebookTwitterPinterestLinkedIn Related Related posts: 5 wound questions that could save your horse T/F Horses can eat pumpkin? How long is the horse’s small intestine? How much water does a horse drink daily?