790 
DISEASES OF THE FOOT. 
IV.—CORNS. 
The term “corn” embraces a number of diseased conditions of the 
posterior portions of the foot, and especially of the heels. The injury has 
its seat in the sensitive laminae of the quarters, in the sensitive bars, or 
in the sensitive sole. The condition has, therefore, been divided into 
three corresponding divisions. As a rule, it consists in bleeding at the 
surface of the horn, resulting from pressure or rupture. As long as the 
haemorrhagic spot remains uninfected, no inflammation results, but 
infection is followed by a pododermatitis, which may either be super¬ 
ficial or parenchymatous. In the latter case exudation occurs, in 
consequence of which this form has been termed moist corn, in contra¬ 
distinction to the dry form in which inflammation is absent. In the wall 
or sole, the bleeding is oftenest seen at the surface of the papillae. The 
blood in most cases is extravasated between these and the hoof-horn, the 
inner surface of which it saturates, and imparts to the newly-formed 
horn-cells a red colour. The red spots thus formed sometimes appear 
as fine points if bleeding be confined to isolated papillae, but generally as 
large red stains, which are only seen later when cutting out the foot— 
that is, after the coloured layers of horn have grown down to the free 
surface of the hoof. 
If the extravasated blood becomes infected, inflammation follows, and 
often proves serious—as, for instance, when pododermatitis parenchy- 
matosa extends from the bars to the fibro-fatty frog, in which it induces 
diffuse purulent inflammation. A troublesome condition may also be 
Produced by infection of the parachondrium and formation of a quittor. 
These two complications are unfortunately rather frequent. 
Causes. In consequence of the close union between the vascular 
laminae, and the horn, it results that, as bleeding occurs so easily, 
inflammation is seldom seen without haemorrhage. Traces of it are, 
however, sometimes seen in the heels. The horn of the sole then 
appears shining, semi-transparent, and coloured yellow, changes which 
point to inflammation of the hoof matrix. 
The fact that the posterior parts of the hoof are oftenest the seat of 
mechanical lesions is partly due to their greater mobility ; the move¬ 
ment of the hoof is most apparent at this point, and rupture of soft 
structures, therefore, more liable to occur. Then, again, the heels carry 
a larger proportion of the weight, and the horn covering them is weakest. 
The more frequent occurrence of corns in the inner heel and in fore feet 
must also be referred to the greater weight borne and the more marked 
impact during rapid movement. 
Coins aie favoured by long, weak fetlocks, and by defects information, 
especially in the front limbs. In animals which stand with the feet well 
