Researchers Evaluate Hoof Wall Tubule Density, Morphology

Could something as simple as hoof wall tubule (the keratin-based, tubelike structures that form the hoof wall) density provide veterinarians with clues as to a laminitic horse's prognosis? Not yet, but researchers are taking the first steps determine if it could be a possibility in the future.

Lisa Lancaster, MSc, PhD, DVM, of Lancaster Veterinary Services, in Denver, Colo., and colleagues at the Michigan State University College of Veterinary Medicine believe horses' hoof wall tubule density could have diagnostic or prognostic value for laminitic horses, but no data on that subject had yet been collected. So the team recently took the first step in examining their hypothesis, and Lancaster presented the results at the 2013 International Equine Conference on Laminitis and Diseases of the Foot, held Nov. 1-3 in West Palm Beach, Fla.

"We are all familiar with the hoof capsule distortion of chronic laminitis," Lancaster explained. "Previous research has shown that the horn cells (tubular and intertubular horn) are damaged in the laminar wedge tissue, a distinctive feature of chronic laminitis.

"However, we do not know if tubular characteristics differ between normal and acute laminitic feet," she continued. "Laminitis research has established that the laminae undergo pathologic changes before we see clinical changes in the horse. We wondered if there are corresponding subclinical changes to the tubules in the very early stages of disease."

Lancaster and colleagues examined histologic (microscopic) samples of hoof wall tubules from the toe and the quarter of 12 nonlaminitic horses' feet. The samples came from a variety of sources, including cadaver feet from race- and feral horses and live pleasure horses' feet.

This histologic image of one of the racehorse feet from Lancaster's study shows a tiny portion of the laminae at the inner edge and then tubules all the way to the outer wall.

Photo Courtesy Dr. Lisa Lancaster

The team found several important features in their study, including significant density differences between tubule from the toe and lateral (outer) quarter, and between tubule from the medial (inner) and lateral quarter. But, importantly, "this study … established a necessary baseline and comparison for future studies with laminitic feet," Lancaster concluded.

"We are all seeking ways to detect disease as early as possible—wouldn’t it be amazing if horn samples taken from routine trim appointments could tell us something about the health of our horses’ feet?" she said. "Even if future research reveals that distal hoof horn samples are not useful in laminitis detection, maybe we would find these samples useful for other aspects of hoof horn health. What if a prepurchase exam included hoof horn sample analysis that could establish a 'toughness' scale, indicating which feet were most resilient, most likely to contribute to long term soundness?"

Lancaster said future research in this area is warranted.

The study, "Equine hoof wall tubule density and morphology," was published in October in the Journal of Equine Veterinary Science

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.