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A team of researchers at Michigan State University's (MSU) McPhail Equine Performance Center offers hope to horse owners facing underrun heel and flat-footed woes with a 16-month study examining the short-term and long-term effects of a specific barefoot trimming technique on hoof conformation.

In the study, seven previously barefoot horses were trimmed every six weeks with a technique that leveled the hoof to the live sole, lowered the heels, beveled the toe, and rounded the peripheral wall. The sole, frog, and bars were left intact.

"This study has shown that a group of school horses performed well and remained sound when trimmed so that the frog, bars, and sole of the foot were engaged in the weight-bearing function," explained Hilary Clayton, BVMS, PhD, Dipl. ACVSMR, MRCVS, the Mary Anne McPhail Dressage Chair in Equine Sports Medicine at MSU. "We believe it is important for these parts of the foot to contact the ground, not only to distribute the weight-bearing forces and to support the coffin bone from below, but also to provide the horse with proprioceptive input from receptor cells in the heels."

The first four months of the study established the hoof shape representative of the barefoot trim. From this baseline, morphological (shape and structure) changes in the hoof's response to the trim technique were monitored from months 4 through 16. At 0, 4, and 16 months, the researchers measured hoof morphology from lateral (from the side), dorsal (from the rear), and solar photographs, as well as lateromedial (side to side) radiographs.

As the study progressed, subjects showed palmar/plantar migration of the heels, meaning the heels shifted further back underneath the limb, with increased support length, heel angle, and solar angle of the coffin bone. "This research has shown that the feet do indeed adapt and become healthier," Clayton noted. "One of the interesting findings was that in response to weight-bearing on the frog and bars, the entire heel region migrated back underneath the limb, leading to an increased weight-bearing area and an increase in heel angle. These findings offer hope for treating underrun heels."

Horse owners interested in giving barefoot trimming a try shouldn't expect immediate results, Clayton cautioned. "It is important to realize that it takes a long time--months or sometimes even years--for a horse's hooves to adapt to being barefoot if the horse has been accustomed to wearing shoes for a long time," she remarked. "Owners who contemplate changing to a barefoot trim need to find a farrier who is trained and experienced in this manner of trimming, and they need to be prepared for a period of adaptation.

"There is great research potential in this area. One area where I would like to see more research is in comparing different types of barefoot trim in horses that live in different environmental conditions (desert vs. wet) and on different types of ground (hard, stony, sandy, soft)," Clayton added. "We know quite a lot about wild horses' feet and how they differ according to habitat, but less is known about managing the feet of domestic horses under different conditions."

This study, "Effects of barefoot trimming on hoof morphology," was published in the Australian Veterinary Journal. The abstract is available here.