Collapsed heels are a common problem in horses, particularly Thoroughbred racehorses, and can cause decreased performance and lameness. Because little is known about the mechanism behind this condition, a group of researchers from The Royal Veterinary College, in London, U.K., recently examined the relationship between collapsed heels and hoof deformation. Farrier Peter Day, Dipl. WCF, presented their findings at the 2013 International Equine Conference on Laminitis and Diseases of the Foot, held Nov. 1-3 in West Palm Beach, Fla.

Horses’ feet experience forces as high as 2.5 times their body weight when galloping—equivalent to a car crashing down on their foot every time it hits the ground, the researchers said. Fortunately, horses have developed several anatomical features that allow them to cope with these high loads, one of them being how the hoof deforms when loaded. "Hoof deformation (basically, a change in hoof capsule shape) is a shock-absorbing mechanism," Day explained.

In horses with collapsed (underrun) heels, the heels are lower and have a different shape than normal heels, which can impair their ability to deform when under load.

"We hypothesized that hoof deformation will be decreased in feet with collapsed heels compared to normal feet," he said. If this proves true, horses with underrun heels will not be able to cope with high loads as well as horses with normal feet, and other musculoskeletal structures (e.g., the navicular bone) will come under more load and be at increased risk of injury