“We might have known the ideal or optimum interval time between trimming and shoeing for a long time, but only more recently has science enabled us to better understand why,” said Kirsty Lesniak, SFHEA, PGCHE, MSc, BSc (Hons), a senior lecturer of equine science and equine postgraduate program manager at Hartpury College University Centre, in the U.K.
In their study, Lesniak and colleagues compared 17 hoof length and angle measurements from 26 predominantly stabled riding horses of mixed breed, age, and height. They took the measurements before and after farriery, following a four- to six-week period of growth since the last farrier treatment.
During that period, the hoof grew such that the angles began to change, which could negatively impact soundness, Lesniak said. If left untrimmed, that hoof growth and angle change could result in the heels and back of the hoof becoming loaded with too much weight. However, farriery work in this population of horses maintained healthy angles when performed within four to six weeks.
“The greater the duration between being trimmed or reshod, the longer the toe becomes in relation to the heel,” Lesniak said. “This forces the hoof-pastern axis into a broken back angulation and places more of the horse’s body weight toward the palmar aspect (the back) of the foot and even to the unsupported region behind the heels.
“As the interval length increases, this leads to changes in hoof conformation and limb posture,” she continued. “The increased palmar loading results in an increased strain on the deep digital flexor tendon. Strain on the deep digital flexor tendon transfers to the laminar junction via the distal phalanx. Therefore, as the strain increases, so does the risk of injury to the body of the tendon, its insertion point, and the laminar junction.”
Fortunately, however, horsemen throughout the ages have determined the correct shoeing interval through observation and experience, she said. Although each horse varies some, science now confirms what horsemen have adhered to for centuries.
“During the era when horses were vital for transport, agriculture, and the military, a horse out of action because of a lost shoe was very costly,” Lesniak said. “Therefore, refitting or replacement of the shoe before it got to the point of being loose or lost was an important pre-emptive strike.”
The study, “Does a 4–6 Week Shoeing Interval Promote Optimal Foot Balance in the Working Equine?” was published in Animals.