43 
THE HORSE'S FOOT. 
Y. Etiology .—Hoof bound, says H. Bouley, is not a simple 
fact, produced by a unique cause acting always in the same man¬ 
ner ; it is, on the contrary, a very complex one, to the production 
of which a great number of causes of various character and in¬ 
tensity contribute with simultaneous or successive effects. 
The hygrometic condition of the horny substance is a princi¬ 
pal feature in the etiology of the disease. It is when the hoof 
loses by evaporation the moisture which it should contain that 
it contracts as all organic substances do, and its flexibility returns 
when by a sufficiently long immersion in a liquid, the moisture 
that it has lost is recovered. Observation proves that this dis¬ 
ease often finds the conditions of its presence in circumstances 
which induce dryness in the part. In such cases the foot has the 
property of retracting, to an extreme degree, especially towards 
its posterior extremity, where the frog is situated, constituted as 
it is of a softer and more depressible substance than that of the 
wall. The same phenomenon takes place in the living 
structure that is observed upon the hoofs of dead feet; 
a phenomenon which cannot even be prevented by filling 
their cavity with plaster. During life the hoof is con¬ 
stantly permeated by a current of fluids which penetrate it 
from its depth to the surface. It is the serous fluid that the hoof 
is continually absorbing by the hygroscopic properties common 
in living tissues, which counterbalance the tendency of the foot 
to retract upon itself and keep it in the dimensions required for 
the perfect reception of the parts it covers. So long as the 
equilibrium is preserved between the loss of this fluid by evapo¬ 
ration and its renewal through the perspiration of the keratoge- 
nous apparatus, the hoof preserves its physiological form; but 
if this equilibrium is destroyed by an excess of the loss, then the 
condition occurs for the retraction of the hoof and the infliction 
upon the parts underneath of an excessive and painful pressure. 
This explains why, as proved by observation, lameness in gen¬ 
eral and that of contracted heels especially, are more frequent in 
warm than in moist seasons. Long standing in the stable is also 
an efficient producing cause. The feet become dry upon a con¬ 
stantly dry bedding, and here also the influence of inaction must 
be taken into account. The disease is commonly found in stabu- 
