Possible functions of equine hoof wall tubules were investigated in this study. Hydration tests were conducted on blocks of hoof wall tissue in order to test the hypothesis that hollow tubules facilitate the conduction of water vapour distally. Although water loss or gain was inhibited through the outer wall surface, the increase in surface area provided by medullary spaces was ineffective in facilitating hydration through the face with exposed tubule ends. Rather, hollow tubules appear to allow for a higher dehydration rate through their exposed ends. Analysis of medullary space indicates that the presence of these voids does not provide either a significant increase in flexural stiffness, or a decrease in thermal conductivity. These findings suggest that nonmechanical roles of hoof wall tubules are unlikely and, therefore, the hollow nature of tubules may be a reflection of manufacturing constraints in producing keratin fibres at steep angles to the coronary border.