Density and morphologic features of primary epidermal laminae in the feet of three-year-old racing Quarter Horses

Abstract

Objective - To quantify the density of primary epidermal laminae (PELs) around the solar circumference and evaluate the relationship between regional PEL density and hoof capsule morphology in horses. Sample Population - Forefeet from nine 3-year-old Quarter Horse cadavers. Procedures - Data pertaining to gross features of hoof morphology and PEL variables, including number, density, and distribution patterns around the perimeter of the hoof wall and number of bar PELs, were collected. Tissues of the laminar junction were examined histologically. Results - No significant differences were found between left and right forefeet with respect to gross hoof morphologic measurements. Mean ± SD number of PELs, including those at the bars of the hoof, was 551 ± 30. Primary epidermal laminar density in the toe was significantly higher, compared with that in the quarter and heel regions, and was higher on the lateral aspect of the foot, compared with the medial aspect. Feet were significantly wider on the lateral aspect of the foot, compared with the medial aspect, as measured across the widest point of the solar surface. Histologic examination revealed atypical laminar morphology at the toe. Conclusions and Clinical Relevance - Variations were detected in PEL density and morphology around the solar circumference of hooves from 3-year-old racing Quarter Horses. A better understanding of relationships between laminar density, laminar morphology, and gross morphology of the hoof capsule in different populations of horses may aid practitioners in diagnosis and treatment of disease involving the hoof wall in horses.