White Line Disease

Description

White line disease, is caused by infection from bacteria, yeast, or fungus that causes the loss of horn at the juncture between the laminae and the inner hoof wall.

As the horn disintegrates, it creates a hollow space that becomes mealy or "seedy." As the breakdown continues, the mechanical loss of the attachment between the laminae and the inner hoof wall may result in displacement of the coffin bone, at which point the horse begins to show discomfort and may become lame.

Seedy toe is most commonly noted as an unexpected hoof wall separation discovered by the farrier during routine hoof care.

Symptoms

• A small powdery area along the hoof wall/sole junction usually noticed by the farrier
• Tender soles when checked with hoof testers
• Warmth in the foot
• Slowed hoof wall growth
• Bulge above affected area at the coronary band
• Discomfort when horse puts weight on hoof

Causes

Seedy toe seldom occurs in horses that are unshod and on pasture. Instead, it occurs most often in horses that are shod, given limited daily exercise, kept in damp stalls, and are exposed to frequent wet-to-dry situations, such as walks in wet grass.

When the bacteria, yeast, or fungus invades the hoof wall, the infection begins at ground level and works its way up the white line to the coronary band.

Excessive toe length, poor hoof conformation, clubfoot, and damage to the hoof wall may be contributing factors.

Vascular damage associated with chronic laminitis, and trauma from a localized blow to the hoof causing vascular damage will also lead to separation of sole and hoof wall leading to possible abscesses and other infections that result in seedy toe disease.

Prevention

Prevention of seedy toe is difficult because the exact cause is unknown. Having a farrier examine each foot when the horse is shod is important.

Any abnormality involving the sole/wall junction should be assessed and treated. Proper trimming and shoeing offers some protection.

Monitoring horses that have previously had the disease is important because it may suddenly reappear.

Treatment

Correcting the primary cause of the hoof wall separation is the first step in treatment. Supporting the foot with therapeutic shoeing is important if the hoof wall is extensively damaged.

In some cases, removal of the outer hoof wall to expose the diseased area may be necessary. Debridement of the infected areas should take place over a period of time. The resectioned area should be cleaned daily.

A change in the horse's environment may be necessary. The feet should be kept as dry as possible, with clean, dry bedding and without turnouts in rainy or wet weather.

A well-balanced diet with the addition of biotin and methionine can be helpful. The shoeing schedule should be maintained at four week intervals until all signs of the disease have been eliminated and the hoof wall grows out. The veterinarian or farrier can give advice on exercise and work schedules depending on the condition of the horse.