CAUSES OF HOOF CRACKS
Hooves generally crack under pressure from some sort of trauma. The forces contributing to the crack can originate within the hoof---if there are balance problems from poor or neglected farriery work, for example, or conformation issues that place unusual strains on the hoof wall. And, of course, cracks can be caused by external traumas---any single serious blow to the hoof can cause injury, and cracks may also develop due to repeated concussion, such as the horse who gallops on unforgiving footing or who stomps at flies incessantly on hard ground.
Genetics also plays a role in the strength and thickness of a horse’s hoof walls--some horses are simply more prone to cracks than others. “A strong foot can withstand or overcome a lot of adverse factors, but a weaker foot may not be able to handle it,” says Steve Norman, a farrier from Georgetown, Kentucky. “Some horses just have more structural integrity in the feet, and certain breeds have stronger feet than others.”
Finally, one type of hoof wall defect---horizontal cracks that run parallel to the ground---is almost always caused by an abscess that drained through the coronary band and temporarily disrupted the formation of horn, creating a gap. Horizontal hoof cracks generally are not serious and will grow out without causing problems. “Horizontal cracks are usually the result of an injury or a gravel abscess that blew out at the coronary band,” says Moshier.
“Horizontal cracks are not normally lameness related, even though the initial cause of that crack could have been a lameness-causing abscess or foot injury,” he adds. “The crack itself is nothing to worry about. It will eventually grow out.”
Horizontal cracks that run parallel to the ground are almost always the result of an abscess that drained through the coronary band and disrupted the formation of horn.
As the horizontal hoof crack nears the ground, your farrier may take steps to stabilize the “loose” piece so it does not break off prematurely. “Sometimes at that point I take out the unattached wall below the crack,” says Moshier.