White line disease sneaks up on you without warning–one day your horse is fine, and the next day the farrier is digging a crater in your horse’s foot, dumping what seems like handfuls of soft, crumbly hoof horn on the floor. You might ask, what the heck is white line disease? Why is it such a big deal? Your horse isn’t even lame, although you fear he might be soon with that new crater in his foot.
This ugly mess called white line disease might not be a big deal initially, but left untreated it can undermine large amounts of your horse’s foot (or feet), resulting in lameness and instability of the coffin bone within the horse’s foot. Bill Baker, DVM, of Equine Associates in Hawkinsville, Ga., discussed the disease and its treatment at the recent Bluegrass Laminitis Symposium, held Jan. 25-28 in Louisville, Ky.
"White line disease doesn’t seem to occur without some sort of mechanical stress (such as long toes or hoof damage from previous disease or injury)," he began. "The only known certainty (about its cause) is that a breach in the hoof wall has to occur for the disease to occur. (Opportunistic bacteria and/or fungi then invade the defect and begin destroying hoof wall from the inside, starting at the bottom and working their way up.) There is no breed, age, or sex predisposition to this disease. It occurs in anything from Minis to drafts, donkeys, and mules. It may invade one foot or all four feet.
"Most cases are diagnosed with physical exam findings," he went on. "You see a small breach or crack in the hoof, explore it a little with a hoof knife and find cheesy, soft, white horn.