N. 
DISEASES FROM FAULTY CONFORMATION 163 
Take, again, the vice of contracted heels. Here, in the 
first place, we have a variety of causes tending to bring 
about the contraction. With the contraction, and its con- 
sequent pressure upon the sensitive structures in the 
region of the quarters and the frog, has arisen a low type 
of inflammation. The horn of the part has become dry 
and brittle. The exciting cause of its fracture is found in 
an excessive day’s work upon a hard, dry road, with, per- 
haps, a suddenly-imposed improper distribution of weight, 
due to treading upon a loose stone, or a succession of such 
evil transfers of weight due to travelling upon a road that 
is rough in its whole extent. 
In their turn, too, such defects of the feet as we have 
mentioned in the last chapter—as, for example, the foot 
with the pumiced horn, the foot with abnormally upright 
heels, or that which is upright on one side only, or crooked 
—each offers a condition which is predisposing to the for- 
mation of a sand-crack. In each case it wants but the un- 
even distribution of the body-weight, which, as a matter of 
fact, some of these conditions themselves give, to bring 
about a fracture. 
Apart from the predisposition conferred by conformation, 
must be remembered the simpler predisposing causes lead- 
ing to brittleness of the hoof. We refer to the after-effects 
4 of poulticing, the moving from pasture to stable, the 
igration from a damp to a dry climate, or the alternate 
hanges from damp to dry in a temperate region. Hach 
ay have a deteriorating influence upon the horn, render- 
g it liable to the condition we are describing. Excessive 
dampness alone, especially when the animal is called upon 
to labour at the drawing of heavy loads upon a rough road, 
is not infrequently a cause. In this case the wet, together 
with the constant friction of the sharp materials of which 
the road is made, serves to destroy the varnish-like 
periople. The wet gains access to the inner structures of 
the wall, the agglutination of the horn fibres is weakened, 
and fissures begin to appear. 
Other causes of sand-crack are purely accidental. An 
11—2 
“Ss Oo 
