The strong association between sheared heels and a spontaneous quarter crack is hard to ignore. Although inappropriate farriery may play a role, limb conformation and the landing pattern of the horse appear to be the dominant factors causing this type of hoof capsule deformation.

The importance of determining the underlying cause and implementing the appropriate farriery cannot be over emphasized when managing a quarter crack associated with a sheared heel. The repair of spontaneous quarter cracks will be of little value, and the defect will have a tendency to recur, unless the cause is identified and rectified.

Introduction

Sheared heels as a clinical entity and a cause of lameness were first described in the veterinary literature 35 years ago1.

A sheared heel is defined as a hoof capsule distortion resulting in a proximal displacement of one quarter/heel bulb relative to the contralateral side of the hoof2. The disparity between the lateral and medial quarter/heel bulb is generally 0.5 cm or more and is measured from the coronet to the ground or to the shoe.

When the weight of the horse is not distributed uniformly over the entire hoof during the landing and/or weight-bearing phase of the stride, one section of the foot, usually a heel bulb and accompanying quarter, receives a disproportionate amount of the total load. This repetitive disproportionate load causes the proximal displacement of the heel/quarter of the hoof capsule while the increased compressive stresses placed on the submural tissue in this area predispose the foot to various…