White line infections are quite common in the horse causing moderate to severe lameness. Most resolve once ventral drainage is established or when infection bursts out just underneath the coronary band.
However in this case the infection grumbled on for several weeks despite drainage at the solar surface and at the coronary band. In order to resolve the infection the dorsal hoof wall was removed and the infected laminae underlying it were resected and the area was flushed.
The resulting wound was dressed and flushed regularly until an horn producing epithelial layer completely covered it. The hoof defect was then repaired with an acrylic filler enabling the horse to return to full work. Please watch the following video which charts the progression of treatment of the problem and subsequent healing of the wound.