Reasons for performing study: Surgical stripping of the hoof wall results in a wound that heals remarkabley well. In contrast, lamellae recovering from laminitis are often deformed. Investigating lamellar wound healing may aid understanding of laminitis.
Objectives: To document temporal changes in the lamellar basement membrane (BM), dermis and epidermis after surgery.
Methods: Wall strips were made in the dorsal hoof wall midline of 6 mature horses. Immunohistochemistry was used to document changes in the basement membrane (BM) and detect proliferation of epidermal cells in lamellar tissues harvested at intervals. A conforming metal plate was screwed to the hoof wall to maintain alignment of the wound edges.
Results: Wall stripping caused lamellar tips to snap and remain behind in the dermis along with the majority of the lamellar BM and some lamellar basal cells. Three days later the BM was intact and new lamellae had been reconstructed by proliferation of surviving epidermal cells. By 5 days the surface of the stripped zone was covered with yellow epidermis that subsequently thickened and hardened. Eventually the hoof wall deficit was replaced by new wall growing down from the coronet. The conforming metal plate and post operative analgesic ensured minimal lameness.
Conclusions and potential relevance: In wall stripped lamellae the BM survives virtually intact and is used as a template for proliferating cells, from snapped-off lamellar tips, to migrate and quickly achieve repair to near normality. In laminitis epidermal dysadhesion and lamellar BM destruction occurs and lack of a functional BM template may explain the prolonged and abnormal repair of affected lamellae.