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.”
Researchers believe that unequal load (due to poor limb conformation, for example) continually placed on one heel, over time, changes the hoof wall’s shape (the wall straightens and the heel contracts). As a result, there is less expansion of that side of the heel when it impacts the ground, “overstressing” the affected quarter. A hoof wall defect will likely occur, and these often develop into full-blown quarter cracks.
“When at all possible, a horse with a spontaneous quarter crack and sheared heels should be taken out of competition (and) have the shoe removed for a brief period of time (to) let the coronary band ‘settle’ into a more normal position before attempting to repair the quarter crack,” advised O’Grady.
Unfortunately, this is not always possible with competitive horses, and in these cases the underlying problem is often not addressed appropriately.
“The goal of treatment is to improve the landing pattern, unload the affected heel, and let the heel bulb settle into a more acceptable position," O’Grady relayed. "Various trimming techniques and tools such as bar shoes and rim pads are recommended when treating these horses, and some horses will need to be looked at every four to six weeks.”
O’Grady concluded, “Provided a skilled, invested farrier is involved as well as a committed owner, quarter cracks can be successfully treated. In knowing there is a link between sheared heels and quarter cracks, avoiding quarter cracks can be achieved.”
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.