OklahomaHorses Magazine Nov/Dec 2020

12 OklahomaHorses • November/December 2020 Hoof Anatomy To understand white line disease better, a basic understanding of hoof anatomy is important. The hoof is made up of several layers. From outside to inside, they are the hoof wall, hoof horn and the laminae. The hoof wall is hard, and if damaged, it must regrow as it is unable to repair itself. In white line disease, the damaged hoof wall must be regrown. Underneath the wall is the horn. The horn is attached to the laminae, and these are attached to P3 (coffin bone). The hoof is nourished by the coronet band at the top of the hoof. All growth of the hoof wall is from the coronet band down. The wall and the horn meet the sole at the bottom of the hoof. How It Occurs It is suspected that white line disease begins when there is a defect in the hoof wall. This may occur from being in wet conditions for extended periods of time, trauma to the hoof or an unbalanced hoof that creates a small amount of separation in the wall. Opportunistic pathogens, primarily fungal in nature, take advantage of the defect and begin to proliferate. This leads to a blackish-grey colored discharge and foul odor. The infection continues to eat away at the hoof, creating lameness and potential rotation of P3. Treatment Treatment of white line disease is dependent on the severity of the disease. Really mild cases are often easily treated by trimming back the affected area, and the horse is usually able to maintain work during treatment. If the infection has damaged the hoof wall further, it is best to debride (remove) the affected wall. Small areas can easily be removed, and the horse’s affected foot can be soaked in chlorine- based treatment. If a large amount of the hoof wall is removed, shoes that are able to support the foot are applied. These can range from supportive shoes to clogs. Radiographs can be used to determine the extent of the damage to the white line. A black line can be seen in the wall of the foot that is the area of damage and separation. Radiographs can also determine the integrity of P3 and if there is any rotation (founder). Treating white line disease is most successful when caught early. More advanced cases require aggressive treatment and have a worse prognosis. Consistent quality farrier work can help prevent and catch white line disease. IDENTIFYING AND TREATING WHITE LINE DISEASE WRITTEN BY: Grace Owen, DVM Equine Medical Associates | Edmond, OK I f you have spent much time at all in the horse industry, you may have heard the term white line disease, but what exactly does that mean? White line disease is an infection that causes separation of the wall and the sole of the horse’s foot. The white line of the horse’s hoof is the narrow band of lighter colored hoof that you can see on a freshly trimmed hoof, where the hoof wall and the sole join. The separation is usually first seen at the white line, but the affected area is actually the area where the hard outer wall and middle layer contact each other. The disease is more common in front feet but can also occur in hind feet. Left untreated, white line disease may progress to substantial damage in the supportive structures of the foot and may result in laminitis and significant discomfort. Early detection and prevention of white line disease is important for positive outcomes. This radiograph shows white line disease (dark area) in the front foot of a donkey. The white line separation extends upward the length of the nail. Radiographs help determine how much of the dorsal wall may need to be removed. Soaking in OxiClean can help reduce the infected area.