This horse had a form of white line disease. White line disease is rarely seen in Western states because the climate is dry; it is more likely to occur where wetter environments are more conducive to the opportunistic bacteria or fungi that cause this progressive disease. My client had been led to believe that nothing could be done to successfully address her horse's condition and was not inclined to participate in any special treatment. When the owner is involved, it typically takes less time to eradicate white line disease, but in this case it took nearly two years to regrow the healthy hoof wall.
As I continued to care for this horse, every time I came out to replace the shoes, I recessed the affected horn a little at a time to remove the dead hoof wall. In order to avoid the exposed area, I was only able to put one nail on the lateral side, either in the toe or the back of the hoof. And because this horse shuffles, causing dramatic wear that put additional stress on the already compromised hoof, I used thicker-than-normal shoes.
The white line of a horse’s foot can be seen on the bottom of the hoof. It is the whitish area between the outside hoof wall and where it meets the sole. If the hoof is damaged or weakened by trauma caused by injury or even improper shoeing, fungus and/or bacteria may infect the foot, eating away at the horn and causing the layers of the hoof wall to separate. White line disease (also known as stall rot, hollow foot, wall thrush or seedy toe) is a progressive condition, which if left untreated can cause severe lameness.
The best ways to prevent white line disease are to practice good hygiene by picking your horse’s hooves daily, and having them trimmed regularly and kept well balanced by a professional farrier. Qualified farriers are trained to recognize the signs and symptoms of white line disease, which may present as small cavities in the white line or a seedy-looking toe. If white line disease is suspected, an equine veterinarian should be consulted to confirm the diagnosis and prescribe treatment, as well as to ascertain whether the condition may be the result of some underlying problem that also requires treatment.
When recognized and treated early, white line disease is quite manageable, and most horses can return to work without a layoff. But if the deterioration has become very severe, treatment can be more challenging — special shoes, boots or even a cast may be required, as well as a lengthy period of time to regrow healthy horn.
It was once thought that white line disease could be treated topically. But modern research has shown in the lab that while topical treatments may be seen to alleviate the infection, several of the various types of fungal spores causing the condition are not eliminated. Today, treatment is primarily effected by debriding (removing) the infected portions of the hoof wall. In order to eradicate the infection, the debrided areas of the hoof must not be covered, but left exposed to light and air to prevent further growth of the pathogen. These areas must also be kept very clean, which is typically accomplished by soaking the foot in a chlorine-based solution.
Because debriding weakens the hoof wall, if the boney column and frog are not properly supported secondary issues, such as laminitis, may occur. Rocker shoes or other therapeutic shoe modifications may be used to reduce the amount of pressure on the hoof by balancing the hoof wall breakover.