LAMENESS IN HORSES. 483 
riant fibre, and which possess light and near-the-ground action, 
may be said to be predisposed to contracted feet. On the other 
hand, heavy horses — such as are used by agriculturists and 
brewers, &c., are subject to disease or anormality the opposite 
of contraction. Thin hoofs, of weak fibre, broad and flat, and 
sometimes sprawl even, are prone to disease of laminae, and to 
become pumice. Colour has been said to have some influence 
to a disposition to contraction. Blaine insists upon the dark 
chestnut being its favourite subject. The texture and colour of 
the hair may have an influence over its correlative tissue, the 
hoof; and certain colours may prevail among light or well-bred 
horses, or among horses of certain countries. Farther than this 
I can perceive no connexion between colour of coat and con- 
traction of hoof. 
The Causes of Contraction, i. e., of pure contraction , 
are either direct or indirect. I shall consider the latter, as 
being the more influential, first. In order to render the nature 
and operation of this set of causes intelligible, it will be neces- 
sary to premise an observation or two on the physiology of the 
foot. Made, as this organ is, for the double purpose of sup- 
porting the weight of the horse’s body and moving under it with 
elasticity or spring enough to ward off concussion, its structure 
is such as to enable its component parts to possess certain 
motions, one upon the other, so that the effect of the whole to- 
gether may be, expansion of the foot during the imposition of 
weight and the force of action upon it : retraction of the parts 
taking place the moment such weight or force of action ceases 
to be in operation. This faculty of yielding or expansion it is 
which, while it answers the purpose of a spring to the animal 
body, acts counter to that tendency inherent in the hoof, from 
the nature of its composition, to shrink or contract within itself. 
What is called the spread of the hoof as the wall grows down- 
ward, is owing to this expansive property; and this spread, as 
we know, is, in the natural or unshod hoof, more conspicuous in 
the outer quarter than in the inner. So long as there exists 
nothing to prevent this function of expansion f rom going on un- 
interruptedly, and it continues to receive the necessary primum 
mobile , so long there will be no contraction. This accounts for 
our hardly ever seeing a contracted hoof in a state of nature. 
But the period arrives for the horse to be shod, and now what 
happens? From the very moment the shoe is nailed to the 
hoof is its faculty of expansibility more or less impaired. It 
can no longer, under the same force or weight, yield or expand 
to the same degree it did before. The consequence is, a slow 
but gradual change in its form takes place. Instead of con- 
tinuing the open-heeled and expanded foot it originally was, 
