There seems to be some disagreement among hoof-care professionals as to the extent of the sole’s role in weight bearing. The suggestion that the laminar attachment of P3, with transference of the horse’s weight to the hoof wall, is not its major means of support is as absurd as suggesting the sole should take no part in weight bearing.
The consequence of laminar attachment breakdown and P3’s loss of support is evident when a horse suffers from laminitis. When the foot sinks into the ground, the load will inevitably be spread to the sole and the frog, in all but the hardest of surfaces. However, even on hard surfaces or if shod, the outer edge of the sole provides support to P3.
The attachment of the sole to the hoof wall, via the white line, gives the perimeter of the sole stability, and provides a “ledge” for the border of P3 to rest on. The support provided by this ledge is reduced in a number of situations. These relate to the thickness of the sole and the integrity of the white line junction or because of abnormal forces, either to the distal hoof wall or from the tip of P3.
It was a particular laminitis case that first drew my attention to the importance of this. By the time I attended this case, P3 had sunk in both front feet and the hind feet also were badly affected. For 5 weeks, the horse appeared to be…