In this disease the white line disintegrates as the result of infection caused by bacteria, yeast, or fungus. The infection starts at ground level and works its way up the white line to the coronary band. The region commonly affected is the toe back to the quarter. The loss of horn creates a hollow space between the hoof wall and the sole that becomes mealy or "seedy."
Eventually, a deep recess, filled with cheesy material and debris, develops between the sole and hoof wall. White line disease seldom occurs in barefoot horses on pasture. Like many other hoof conditions, it is a disease of domestic horse management. The typical horse with white line disease is given limited exercise, bedded in damp wood shavings, kept in a wet stall, and exposed to frequent wet-to-dry episodes such as daily wash-downs or walks in wet grass. With advanced disease, special shoeing techniques are required. All predisposing conditions should be corrected.
Canker is a chronic infection of the horn tissue of the foot. It begins at the frog and progresses slowly to involve the sole and sometimes the wall. The disease is rare and is found almost exclusively in tropical climates.
Canker develops in horses who stand in mud, or in bedding soaked with urine and feces, and who do not receive regular foot care. The cankerous horn tissue of the frog loosens readily, and when removed discloses a foul-smelling, bleeding corium covered with a curdled-white discharge. Treatment consists of moving the horse to a clean, dry stable, or preferable a dry rocky pasture. Remove the shoe and thoroughly clean the frog. Apply a drying agent and bandage the foot to prevent contamination. Consult your veterinarian for best treatment regimen. Because canker often involves the corium, treatment is generally prolonged.
Thrush is a painful infection involving the frog. It is characterized by a black discharge along with poor growth and degeneration of the horn. The disease can be caused by a number of bacteria, but Fusobacterium necrophorum seems to be the most common. Treat the foot as described for canker. The prognosis is good when the sensitive structures are not involved. If a wrap needs to be applied, the foot is first picked clean and then washed and dried as needed. Medications are covered with gauze sponge secured with a layer of rolled gauze. If padding is needed for protection, roll cotton or two to three sheets of cotton are used to wrap around the foot. next, rolled brown gauze or stretch gauze can be used to secure the sheet cotton. This is applied in figure-8 fashion to make the sheet cottons lie falt across the bottom of the foot. Finally, elastic tape or duct tape is applied to provide additional support and protection, and secure the bandage in place. It is very important to have the ground surface of the foot wrap flat, rather than convex or bulging.