14 MOUNTED INSTRUCTION ' " 



where it is of but little consequence. It consists in the inflammation 

 of a small part of the coronary band and adjacent skin, followed by- 

 sloughing and suppuration, which in most cases extends to the neigh- 

 boring sensitive laminae. Injuries to the coronet, such as bruises, 

 overreaching, and calk wounds, are considered as the common causes 

 of the disease. Still, cases occur in which there appears to be no 

 existing cause, just as in other forms of quittor, and it seems fair to 

 conclude that subhorny quittor may also be produced by internaf 

 causes. 



Canker: Of the foot is due to the rapid reproduction of a vegetable 

 parasite. It not only destroys the sole and frog, by setting up a 

 chronic inflammation in the deeper tissues, but prevents the growth 

 of a healthy horn by which the injury may be repaired. The essential 

 element in the production of canker is the parasite ; consequently the 

 disease may be called contagious. As in all other diseases due to 

 specific causes, however, the seeds of the disorder must find a suitable 

 soil in which to grow before they are reproduced. It may be said, 

 then, that the conditions which favor the preparation of the tissues 

 for a reception of the seeds of this disease are simply predisposing 

 causes. The condition most favorable to the development of canker is 

 dampness — in fact, dampness seems indispensable to the existence and 

 growth of the parasite ; the disease is rarely, if ever, seen in high, dry 

 districts, and is much more common in rainy weather than in dry 

 seasons. Filthy stables and muddy roads have been classed among 

 the causes of canker, but it is very doubtful whether these conditions 

 can do more than favor a preparation of the foot for the reception of 

 the disease germ. 



Corns: A corn is an injury to the living horn of the foot, involving 

 the soft tissues beneath, whereby the capillary blood vessels are rup- 

 tured and a small quantity of blood escapes which, by permeating 

 the horn in the immediate neighborhood, stains it a dark color. If the 

 injury is continuously repeated, the horn becomes altered in character 

 and the soft tissues may suppurate or a horny tumor develop. Corns 

 always appear in the sole in the angle between the bar and the outside 

 wall of the hoof.' In many cases the laminge of the bar, of the wall, 

 or of both, are involved at the same time. The fore feet are almost 

 exclusively the subjects of the disease, for two reasons: first, because 

 they support the greater part of the body ; secondly, because the heel 

 of the fore foot during progression is the first placed upon the ground 

 whereby it receives much more concussion than the heel of the hind 

 foot, in which the toe first strikes the ground. It may be said that all 

 feet are exposed to corns, and that even the best feet may sufi^er from 

 them when conditions necessary to the peculiar injury are present. 

 Among the causes and conditions which predispose to corns may be 

 named high heels, which change the relative natural position of the 

 bones of the foot and thereby increase the concussion to which these 

 parts are subject; contracted heels, which in part destroy the elas- 

 ticity of the foot, increase the pressure upon the soft tissues of the 



