One involves you pulling the shoes, trimming the feet and noticing a small cavity just inside the white line. Picking up a nail, you give it a scratch and a powder-like substance comes out. More scratching leaves you part way up the hoof wall. Another involves having a horse with hoof walls separating in the most distal part of the foot. While probing the separation, you discover that not only is it separated at the bottom, it goes much higher.

Lastly, you have a horse that’s having intermittent lameness. Its legs look good, the bottom of its foot looks good and it doesn’t respond to a hoof tester. Tapping on the hoof wall produces a hollow sound, though. A radiograph reveals a lucency (cavity). What these cases have in common is that you’re facing a white line disease (WLD) case.

Anatomy Of White Line Disease

One of the first places to describe WLD was in 1898 in the pages of Dollar and Wheatley’s Handbook of Horse-Shoeing. Apparently the condition was not very common back then. It burst on the scene in the mid 1980s when it almost seemed like it was an epidemic.

Burney Chapman, an International Horseshoeing Hall Of Fame member from Lubbock, Texas, prominently publicized the problem. That period lasted for about 3 years before subsiding with occasional cases showing up around the country. Nowadays, Southern Florida and Southern California have the highest incidence of grade three cases in the U.S. The combination of heat and humidity seems…