4 ANATOMY AND PHYSIOLOGY OF THE HORSE ? S FOOT. 
more a hoof is pared the faster it grows/’ which, though 
containing a little truth, is derived from imperfect obser¬ 
vation, and when applied in all its force is certain to produce 
most mischievous effects. It is certain that when a hoof 
becomes excessively long its rate of growth is diminished, 
probably because the foot is imperfectly exercised, and the 
circulation in the coronary cushion is less active. The inter¬ 
vention of shoeing doubtless diminishes the resistance that an 
unnatural development of the hoof offers to its rapid growth, 
by periodically substituting a mechanical action for the con¬ 
stant deperdition it suffers in the unshod state. In proof of 
this, it may be observed that the dimensions a hoof which 
has been allowed to grow for twelve months may acquire 
without being worn or interfered with by instruments, is 
scarcely equivalent to twice its ordinary length, while the 
quantity of horn removed in twelve successive shoeings is 
very much more considerable than this length, as it only 
requires some six or seven months for a mark made at the 
top of the wall to arrive at its lower border : showing that 
the hoof has grown as much in six or seven months when 
relieved periodically of its excess of horn as it did in twelve 
when untouched. 
Nothwithstanding these facts, it is also certain that the 
converse is much nearer the truth, and that “ the more a 
hoof is pared the less it grows.” This is easily comprehended 
when we call to mind its structure; how the upper part of 
each fibre is occupied by a tuft of blood-vessels engaged in 
furnishing the material from which the horn is formed, and 
that the newly generated horn is soft and moist. Removing 
the external hard, dry, protecting hoof exposes this soft 
elastic horn to desiccation—it loses its moisture and shrinks; 
each tube or fibre becomes lessened in diameter and presses 
on the vessels in its interior; these consequently decrease in 
calibre and only permit a greatly diminished flow of blood 
through them, and hence a partial suspension of the growth 
of these fibres. The evil effects of this removal of the 
external horn may be further increased by the morbid pro¬ 
cesses it induces in the capillary tufts, which may set up a 
reaction against the inflexible restraint imposed upon them 
by their constricted sheaths, and become congested, or even 
inflamed, and the horn, produced in infinitesimal quantity, be 
very defective in quality ; while the vitality of the whole 
foot, which is insufficiently protected by its attenuated 
covering, is thereby compromised, and pain and defective 
nutrition in the organ are the precursors of disease and altered 
gait, leading sooner or later to the destruction of the animal. 
