Some work on hard surfaces can help increase the loading rates of a horse’s internal structures, but too much or repetitive hard-surface work can lead to musculoskeletal damage. Ideally, horses should work on a variety of surfaces with minimal hard-surface exercise, most researchers agree. But sometimes, that’s not an option.
“Police horses spend a majority of their time on city streets and other hard roads, for example,” said Amy L. Barstow, MRCVS, PhD candidate, of the Royal Veterinary College in Hatfield, Hertfordshire, the U.K. “So do leisure horses sometimes, especially in periods of drought like the U.K. is having right now. Not all owners have access to soft arena surfaces. So, finding a practical solution to this problem was necessary.”
Barstow and colleagues recently investigated a pour-in polyurethane sole packing materials for that purpose. They found that it helps reduce certain forms of vibrations and forces in the hoof, at least in their introductory study. The theory is that when the polyurethane absorbs the shock from the hoof impacting the ground, it prevents it from traveling further up the musculoskeletal system where it could cause wear and tear injuries.
The researchers tested five sound horses in four shoeing conditions: standard steel shoes and standard aluminum shoes, both with and without a farrier-applied polyurethane sole pack. They used a high-range accelerometer connected to each front foot to measure vibration and forces as each horse trotted in hand in a straight line across hard ground.
They found that peak impact deceleration force was 30% lower in each kind of metal shoe when combined with the sole-packer, Barstow said. Meanwhile, total vibration signal power (a kind of vibration force within the foot caused by the shock of hitting the ground) showed to be 46% lower in aluminum shoes when the sole-packer was applied and 32% lower when it was applied with steel shoes (compared to the shoes alone). Finally, they noted a difference of 58% in the maximum vibration signal power (the same vibration force, but in its maximum force at any given moment) between aluminum shoes with and without the sole-packer, and of 35% with regard to the steel shoes with and without sole-packers.
It seemed clear in this pilot study that deceleration forces and various vibration forces dropped significantly when the polyurethane sole-packers were added to the metal shoes, regardless of whether the shoes were steel or aluminum, Barstow said.
“Our results suggest that using sole-packers could be a way to help minimize musculoskeletal injuries related to the shock that occurs when working on hard grounds,” she said.
However, she and her colleagues also noted some individual variations. And in fact, some horses might even be less comfortable with the sole-packers applied than without not.
“At this point it really is an individual decision that requires good cooperation with the farrier and a good familiarity with the horse to know if he’s feeling better or worse with the sole-packers,” Barstow said. “Our study supports its use, but more research is necessary before making general recommendations.”
The study, “Effect of A Pour in Synthetic Sole Packing Material (Sole‐Packer) on Foot–Surface Impact Vibrations In The Live Horse,” was published in the Equine Veterinary Journal.