Understanding how quarter cracks occur is critical to managing the injury, not to mention keeping the horse going.

Wellington, Fla., farrier Curtis Burns classifies quarter cracks into three categories — concussion, rotational and blunt trauma.

Concussion. A quarter crack that is caused by concussion is typically seen in racehorses.

“In racing, 90% of it is concussion-related issues,” he told attendees at last spring’s North Carolina State University’s Equine Health Symposium. “I think of horseshoes as mechanics and how the shoe allows the foot to settle into the ground, instead of a pancake hitting the ground.”

Rotational. A range of things — from their job to their conformation — can cause this type of quarter crack.

“In the show horse world, I look at rotation,” Burns says. “These horses are coming off jumps that are 5 feet or more sometimes, and they’re already making a left-hand turn before they get to the ground.”

Although the jumps are high at times, concussion doesn’t generally play a role.

“I’m not going to worry as much about how the horse is hitting the ground as much as it’s turning left or right,” he says. “You’ll notice that if you follow the tubules…