Shape, orientation and spacing of the primary epidermal laminae in the hooves of neonatal and adult horses (Equus caballus)

Circumferential and proximodistal variations in the morphology of the prima ry epidermal laminae of six neonatal and five adult equine feet were docume nted. Three parameters were quantified: interlaminar spacing, the orientati on of the laminae with respect to the overlying wall, and any angulation wi thin the laminae themselves ('internal angle'). In adult feet, the laminae were most closely spaced at the dorsum, the spacing increasing gradually to wards the heels. in foals there was a nonsignificant trend for the dorsal l aminae to be more widely spaced than those in more caudal parts of the foot . In both age groups, the dorsal laminae were almost straight (mean diverge nce from linearity at all sites 2 degrees), and were oriented at approximat ely 90 degrees to the tangent to the overlying wall (mean orientation for a ll sites 91 degrees). At the quarters, the laminae were in general oriented caudally relative to the tangential position from their epidermal to their dermal ends (mean orientation of > 90 degrees at 12 of 16 sampling sites, where an orientation of > 90 degrees defines a 'caudally directed' orientat ion) and, in general, had a bend within their length (mean absolute value o f internal angle for all sites 9 degrees). At the heels there was greater v ariability in the data for both laminar orientation and internal angle. Ove rall, the foal feet showed greater mediolateral symmetry and less proximodi stal variation than did the adult feet. In both age groups, rapid spatial c hanges in laminar morphology were closely associated with the position of t he margins of the third phalanx. Copyright (C) 2000 S. Karger AS, Basel.