322 
ON EXPANSION OF THE HORSE’S FOOT. 
experiments ; but the heel and the base of the frog also descended 
very considerably, indeed greatly, under continued pressure, and 
they continued to descend until the heels of the foot touched the heels 
of the shoe, beyond which there was no descent. As pressure was 
applied, the coronet could also be seen and felt to bulge all round, 
as also the lateral cartilages and the upper and back parts of the 
heels, which became hard and swollen. 
Observations .—The expansion of the lateral cartilages is, I 
think, a point so evident, that it hardly requires proving : we may 
see this action going on in all heavy low-heeled horses, and this 
expansion when in excess is, I consider, a cause of ossification of 
the cartilages, and consequent lameness, by pressure, or confine¬ 
ment of the elastic materials within the hoof; but such horses 
often work pretty well, or perhaps quite sound, until they are called 
upon for an extra degree of exertion, when pain and lameness are 
the consequences. Query, whether a bar-shoe, or a shoe with 
sprung heels, would afford any relief, by allowing a certain degree 
of motion of the foot in another direction] That the elastic tissue 
expands round the coronet is also, I think, pretty evident in practice, 
as we may see by the bulge which takes place whenever an ac¬ 
cident happens at the coronet, and the difficulty in healing it on 
account of the motion which goes on at that part. It is probable 
where this yielding action of the hoof, downwards and backwards, 
cannot take place, being prevented by the fixing of an iron shoe to 
the foot laid firmly to the heels, that both the expansion of the 
lateral cartilages, and also that round the coronet, may take place 
to a greater extent. It may be from this reason that we frequently 
observe horses having small feet with prominent lateral cartilages 
and coronets, as if these parts were performing more than their due 
share of work in the economy of the foot. Elasticity must go on 
somewhere, or concussion and destruction will be the result; and 
when one set of apparatus is put out of use, others must perform 
more work, or the machine will perish. 
20 th Experiment. 
Several experiments were made with a view of perceiving, by 
making a fissure in the hoof and applying a shoe sprung at the 
heels, or one laid flat to the heels, what would be the effect when 
pressure was applied. 
Result .—In each case I found the crack close, proving that, when 
motion or yielding backwards could go on, it would do so. 
21s/ Experiment. 
Subject, a heavy carriage-horse, with a good foot, moderately 
concave. 
