If you think a hangnail is painful, then it’s easy to imagine how a horse with a quarter crack must feel. Luckily, there is a warning sign to help owners catch it early–a sheared heel.

What is the link between sheared heels and quarter cracks? According to Steve O’Grady, DVM, MRCVS, a private equine practitioner from Marshall, Va., at the 12th Congress of The World Equine Veterinary Association, held Nov. 2-6, 2011, in Hyderabad, India, “It is very rare to see a spontaneous quarter crack that is not associated with sheared heels on the same side of the hoof.”

Sheared heels are distortions of the hoof capsule that result in an upwards displacement of one heel bulb compared to the other. Typically, the disparity between the two heel bulbs is 0.5 cm or greater, measured from the coronary band down to the ground or shoe. Quarter cracks originate at the coronary band and extend through the full thickness of the hoof wall, making the hoof unstable and often inflamed.

Treating quarter cracks is a time-consuming and often frustrating challenge, as many cracks require consistent treatment. And as O’Grady explained, treating the cracks themselves often doesn’t address the root of the problem: “Although various materials and techniques exist to treat quarter cracks, unless the cause of the hoof wall defect is determined and addressed through basic farriery, none of these treatments will be successful