As a veterinarian and a farrier, Scott Morrison, a podiatrist and co-owner of Rood & Riddle Equine Hospital in Lexington, Ky., sees a lot of troubled feet and more than his fair share of quarter cracks. He thinks many of these problems can be attributed, at least in part, to the lifestyle many of these horses lead.

Pegging dysfunctional heel structure as the main cause of quarter cracks, often related to underrun heels paired with long toes, he cited year-round competition schedules requiring constant shoeing as a potential culprit. “Horses don’t get the time off that they used to. Now, whether it’s hunter/jumper or racing, the horses are always traveling and keep working, so they never get their shoes pulled and kicked out in a field for a couple of months, which does wonders for the morphology of the heel,” he said. “It’s probably one of the best things you can do for a foot intermittently that tends to be underrun.

“The hoof conformation is in their genes, and some horses’ conformation of hoof is to have a little more of a low heel and a fragile, delicate heel region, and if they’re not shod right or managed right, they’re the ones that commonly get the quarter cracks,” he explained. “For those heels, even more important than heel height and the angle of the hoof, is position of the heel. When farriers trim the heels back, it usually is a good thing. They’re trying to relocate the position of an underrun heel. Ideally, you want that heel position to be at the widest part of the frog. Shoeing them often and keeping the heel back at the proper position is one way to manage those feet.”

Morrison said that hooves with weak heel structure don’t typically do well with perimeter loading of the hoof wall and do better with a load-sharing approach that mimics the barefoot
condition. “Those feet will tell you that quick. If you make them 100 percent bear weight on the wall, you’ll see the wall fall and will get quarter cracks or even crushed heels,” he said. “You rarely see quarter cracks in barefoot horses. It’s mostly a secondary complication of a dysfunctional foot.”

He believes excess weight, insufficient exercise and turnout, frequent baths, liberal use of various hoof goos and cushy footing all contribute to hoof dysfunction in domestic horses. “Just standing in a stall all day really weakens a horse’s hoof. A hoof is amazing; it can absorb huge amounts of impact, absorb lots of shock from landing over a fence or galloping, but the same hoof can’t handle long-term, low-magnitude loads as well as it does short, abrupt, high-magnitude loads,” he said. “Just standing around all day in a stall on a weak structure, I think that’s how most horses’ feet become deformed and distorted.

“It’s exacerbated when we put shoes on the foot because all that weight is on the perimeter of the hoof wall and you don’t really use the frog, bars and sole,” he continued. “You see a lot of things on the market to mimic the barefoot condition with shoes. For most horses, you can’t just pull the shoes and go barefoot. They’d be crippled and out of work, so all these fancy things are trying to mimic the barefoot condition in a controlled environment to keep the horse sound at the same time.”