A hoof boot has a base, a heel captivator, and a pivoting mechanism that disposes the heel captivator to pivot relative to the base, preferably in a manner that allows the heel captivator at least three degrees of freedom of movement relative to the base. The heel captivator is preferably low in the rearmost portion, which provides clearance for the pastern bones of the equine lower leg to descend upon weight bearing during movement at various gaits. To reduce the possibility for bruising and chaffing of soft tissue around the pastern bones, and to help eliminate accumulation of debris, preferred heel captivators have an open mesh architecture. Heel captivators can alternatively or additionally be designed with fabric covered neoprene or other liners. Boots are preferably tightened using mechanically advantages laces.