A Quarter Crack is a vertical split in the hoof wall at the widest part of the hoof, on the side between the toe and the heel. While it can be caused by damage to the coronary band (where the hoof and hair meet) or damage to the hoof wall from infection or other hoof problem, a Quarter Crack is most often the result of abnormal hoof or limb conformation causing an incorrect landing pattern. This puts excess force on the hoof, causing it to crack where it is weakest.
If the Quarter Crack is not all the way through the hoof wall, is not causing pain or lameness, and is not infected or bleeding, no treatment other than restoring the hoof and limb to proper balance may be necessary. However, if the Quarter Crack is more serious, it may have to be stabilized to prevent it from getting worse. This may involve treating any infection that is present, removing damaged hoof tissue, and preventing motion at the crack with such materials as screws and wires.
Deciding if and how to treat a Quarter Crack depends on many factors such as the type, location and degree of crack; the cost, time involved and use of the horse; and the expertise of the treating veterinarian and farrier. Ideally, a horse with a Quarter Crack is given time off to heal while the hoof split is stabilized but more aggressive forms of treatment may permit continued training and competing.