By Christa Lesté-Lasserre
Logic tells us that a kick from a shod horse is going to hurt a lot more than one from a barefoot animal. That’s why some farm managers insist on horses going barefoot on the hindlimbs if they’re pastured with other horses. But there’s never been any science to confirm this logic—until now.
A recent study by Swiss researchers has confirmed that a kick from a horse with metal shoes comes with a much greater risk of fracture to another horse’s long bones than a horse with plastic shoes. And that risk is significantly minimized if the horse has no shoes at all.
“Kicks by shod horses are clearly more dangerous than kicks by barefoot horses, so the concept of keeping horses barefoot on the hindlimbs in group pasture settings seems justified,” said Michelle Jackson, PhD, of the University of Zurich Vetsuisse Faculty Equine Surgery Clinic.
Proper herd management using behavioral clues and recommendations by behavior specialists can also help reduce injury risk in group pasture settings, regardless of shoeing status, she added.
In their study, which was a doctoral thesis for colleague Miriam Sprick, DrMedVet, Jackson and colleagues investigated the effects of hoof strikes against horses’ leg bones in a laboratory setting at the Swiss Federal Laboratories for Material Science and Technology in Dübendorf. Jackson presented the work at the 2017 Swiss Equine Research Day, held April 6 in Avenches.
They took 32 radius bones (located just above the knee) and 32 tibia bones (located just above the hock) from cadavers of horses with healthy skeletal systems. They then subjected these bones to automated strikes with a machine that simulates the strike of a horse’s hoof, equipping the machine’s striking point with four kinds of material: an aluminum shoe, a steel shoe, a polyurethane shoe, and a barefoot horse hoof. The strikes occurred at 8 meters per second—estimated at the same speed at which a horse would naturally kick. If the bone did not break, the researchers tried again, at a higher speed: 13 meters per second.
They filmed the strikes with high-speed cameras and then checked the interior damage using X ray and computed tomography scans.
They found that at 8 meters/second, aluminum strikes resulted in damage 81% of the time, and steel strikes damaged the bone 75% of the time, she said. However, no damage occurred at this speed with polyurethane or bare hoof strikes.