Recent research by Simon Curtis, PhD, BSc(Hons), FWCF, a farrier based in Newmarket, England, has revealed how weight-bearing and loading affect hoof wall growth, compression, and overall hoof shape.
During a presentations at the 2017 International Hoof Care Summit, held Jan. 24-27 in Cincinnati, Ohio, Curtis shared how farriers might apply his research findings and provided practical applications for trimming and shoeing adult horses. He encouraged the audience of farriers to help develop focused trimming and shoeing techniques based on his research outcomes.
Hoof Shape Change Overview
Curtis’ previous findings indicated that loading in foal feet varied among different parts of the hoof, whether medially, laterally, dorsally, or caudally. Wherever weight-bearing and loading was greatest, hoof growth was reduced and while more compression occurred.
“I don’t see any reason to believe that that phenomenon that we recorded isn’t going on in mature horses,” said Curtis. He believes that loading and weight-bearing are important factors in why hoof shape changes and asymmetrical hooves develop in mature horses.
“If we now know that hoof compression is an actual fact and can be measured, can we use that knowledge of hoof compression to alter growth?” he posited. “Can we now apply that in our work in a more focused way?”
Curtis said age is the biggest factor on hoof shape early on in a horse’s life. Hoof shape change in the first four months is significant, and any change in the dorsal hoof wall angle can carry on for the first few years and perhaps for the entire life, he said.
Breed is another factor. It’s easy for farriers to see the differences in hoof shape between a Thoroughbred, Shire, and an Arabian, he said. Additional factors affecting hoof shape include hoof wear, farriery techniques, and plastic deformation of the hoof capsule, among others. Changes to the external shape are more cosmetic, while changes on the inside have a more long-term impact on the hoof capsule.
Curtis stressed the importance of occasionally examining extreme cases to understand certain principles that help farriers better understand more typical cases.
He shared a cased study of a rescued Miniature Horse that exhibited severe fetlock varus (toed-in) conformation, which caused him to stand completely on the outer wall. Many considered him beyond help at only 18 months old. Curtis helped the horse using an acrylic shoe that offered a lateral extension (on the outside of the leg) and a medial lift (on the inside of the leg) to even loading. Still, this horse must stay shod in that manner for the rest of his life and requires frequent foot care.
Another case study involved a non-Thoroughbred teaser stallion, whom Curtis weighed and placed on a pressure mat to determine his loading pattern before trimming him. The horse toed-out slightly, and his loading patterns revealed significant pressure on the frog but none on one heel. These surprising findings underscore the information that a pressure mat can provide farriers, he said.
Curtis altered the horse’s hooves using a polyurethane to elevate the toe on one foot and the heel on another foot. Then, the horse was then placed back on the pressure mat.
“We shouldn’t be surprised that when we elevate the heel in this case, there is more loading on the heel, but it’s also tipped the toe into the ground,” he said. “Where we elevated the toe, there is a lot of direct pressure there and it’s thrown it back on its heel and increased the heel loading in the frog.”
The third case study that Curtis discussed was a successful retired European Arabian racehorse stallion. , He was naturally varus and, due to running along a fence in hopes of gaining access to neighboring mares, had worn his feet down. Shoeing helped correct the shape and gave him some lateral support with more metal on the outside of the shoe.
“And if you look at that foot and if we just think in those terms, it creates more leverage there, that creates more loading and pressure on the hoof wall,” said Curtis. “Where you have more loading, in effect, you get less hoof growth. However, our experience is that by shoeing in this manner we gain hoof growth. Therefore, we must be altering stance and thereby unloading the lateral wall, encouraging growth.”
When it’s not possible to trim the hoof symmetrically, Curtis tries to shoe as symmetrically as possible to help balance the limb.
He shared a variety of stories about how he trimmed and shod cases by thinking about how loading, hoof growth, and compression would be affected, and he encouraged the audience to start doing the same thing in their farriery practices.