What is a Quarter Crack?
A quarter crack is a full thickness hoof wall defect located in the quarter of the hoof between the toe and heel of the horse’s foot. The quarter crack originates at the coronary band and extends at an angle toward the ground. Quarter cracks can be a common cause of foot lameness or decreased athletic performance in race and sport horses.
What are the Causes?
Causes of quarter cracks may include trauma to the coronary band; preexisting damage to the sensitive tissue under the hoof wall from infection; limb conformation; abnormal hoof conformation; short shoes; or an abnormal landing pattern when the foot strikes the ground. For example, many horses will contact the ground asymmetrically, impacting first on one side of the hoof and then loading the opposite side (this type of landing pattern is generally related to conformation). Disproportionate forces placed on one side of the hoof wall over time often result in the formation of a quarter crack due to the increased pressure.
What are the Treatment Options?
For a successful quarter crack repair, it is necessary to determine the underlying cause of the crack and to correct it with appropriate shoeing. After the cause is addressed, the defect should be stabilized. Providing stability and strength to the hoof wall defect allows the horse to perform without pain while the quarter crack heals. A full thickness hoof wall crack can be thought of as a fracture. Treatment includes inserting stainless steel wires to stabilizethe crack. An acrylic composite combined with fiberglass is applied to the outer hoof wall over the crack to further stabilize the defect and form the “patch” which can be seen on the horse’s foot.
The type of shoes the horse wears plays a significant role in the successful treatment of a quarter crack. Bar shoes are effective in increasing the ground surface of the foot, providing support and decreasing the independent vertical movement at the heel bulb on the affected side. Aluminum shoes that are applied with glue also offer several advantages. Glue-on shoes allow the foot to be trimmed and shod to the most suitable foot conformation, there is no need for concern over nail placement in the hoof, and they provide increased support. Glue-on shoes are ideal in racehorses.
The importance of determining the underlying cause, trimming the feet properly, and applying the correct shoe cannot be overemphasized when repairing a quarter crack. Correcting any existing hoof abnormality along with improving the landing pattern of the horse is as important as the repair itself.
By Stephen O’Grady, BVSc