Morphology of the laminar junction in relation to the shape of the hoof capsule and distal phalanx in adult horses (Equus caballus)

The purpose was to investigate whether differences in equine hoof shape, wh ich are inferred to alter foot function, are accompanied by differences in morphology of the laminar junction. Ten fore feet from adult horses were se gregated into normal and low-angle groups, depending on the dorsal angle of the hoof wall. Twenty measurements of external hoof shape and four of the enclosed distal phalanx were tested for differences between groups, and for intragroup correlations. Three measurements of laminar morphology (spacing , orientation and degree of bend) were recorded for samples of up to 50 pri mary epidermal laminae at each of 20 sample sites. Sites were distributed o ver the foot in 5 circumferential columns and 4 proximodistal rows. intergr oup differences were investigated, as were correlations among sample sites of the laminar variables with the shape measurements. Results show differen ces in hoof shape between groups (but not bone shape) and laminar morpholog y. Six shape measurements are significantly different between groups: dorsa l angle, medial and lateral angles, lateral sole width, solar circumference , and dorsal length. In the normal group, shape measurements show patterns of correlation among regions of the hoof, and between hoof and bone measure ments. In the low-angle group, shape correlations occur largely within one region of the hoof (the heels) and in the bone measurements. Laminar spacin g tends to be nonsignificantly greater in the low-angle group, while varian ces for laminar spacing and orientation are significantly greater in this g roup. Laminar spacing correlates with bone width and coronary circumference (CC) of the hoof in the normal group, but only with CC in the low-angle gr oup. When taken as a whole, and interpreted in light of a model of foot mec hanical function, the results appear to indicate a deterioration in structu ral coherence of the foot in the low-angle group. Copyright (C) 2001 S. Kar ger AG,Basel.