White line Disease in Horse

White line Disease in Horse has been described as a keratolytic process on the solar surface of the hoof that is characterized by progressive separation of the inner zone of the hoof wall. The separation occurs in the non-pigmented horn between the stratum medium and stratum internum.

White line Disease in Horse is also known as Seedy Toe. It differs from laminitis in that it does not involve the sensitive tissue beneath the hoof wall. It usually begins at the solar surface of the hoof and most frequently affects the toe region but can originate in the quarter or heel. The disease progresses to varying heights and configurations proximally toward the coronary band but never involves the coronary band. It has numerous other names such as seedy-toe, yeast infection, hoof-wall disease, environmentally induced separations, onychomycosis, and Candida.

Etiology

• Mechanical stress on the hoof wall with long toes and poor hoof conformation
• Environmental condition such as excessive dryness or moisture that affect the inner hoof wall attachment
• Selenium toxicity
• Bacteria or fungal infection

Clinical Signs

• No lameness to variable degree of lameness
• In the early stages the only noticeable change may be a small powdery area located just dorsal to the hoof wall/sole junction.
• Sole pain with hoof tester
• Occasional heat
• Increasingly flat soles
• With time the hoof separation enlarges and the hoof wall growth may slow and be of poor consistency.
• Exploration of the inner hoof wall often reveals a separation that is filled with white/gray powdery horn material and debris
• White line disease can also be a secondary problem following extensive subsolar or sub-mural abscesses that can occur with chronic laminitis

Treatment

• Therapy for white line disease is directed toward protecting and unloading the damaged section of foot with therapeutic shoeing combined with removing the hoof capsule over the affected area.
• Topical disinfectants/astringents are often applied after hoof wall resection.
• Systemic medical treatment is considered unnecessary in most cases and is of no value without resection of the damaged hoof wall.
• Correction of predisposing hoof capsule distortions such as long toes and low heels is essential.
• In mild to moderate cases, local debridement and regular shoeing to protect the sole are often all that is required
• A full support bar shoe is recommended to protect and unload the damaged section of foot if extensive removal of the hoof wall is required.
• Acrylic repair should only be considered after all tracts have been removed and the defect is solid to avoid trapping infection beneath the composite
• The feet should be kept as dry as possible and the hoof wall defects should be covered with a light bandage to keep them clean.
• The duration of treatment depends on the amount of wall removed, but most horses can return to work when the surface of the defect has cornified.
• Recurrence of white line disease is possible and good foot care helps prevent the disease

Prognosis

Most horses with white line disease have a very good prognosis with local debridement and corrective shoeing.