INFLAMMATORY AFFECTIONS 825 
coronary cushion, the ergots and the chestnuts, but some- 
times extending to that of the frog and the sole, characterized 
by a malsecretion of the affected membrane similar to that 
observed in canker. 
Causes.—The cause which we have indicated for canker— 
namely, a local specific one, is in all probability the one 
operating here. Apparently there is a variance of opinion 
as to whether the condition is actually canker or not. We 
think, however, that the character of the secretion of the 
affected membranes, the appearance of the growths, the 
manner in which they react to the hot iron, the comparative 
absence of pain, and other points of similarity, point to the 
fact that the two conditions are actually identical. In other 
words, the cause is precisely the same, and the only point of 
difference is the alteration in the point of attack. 
Symptoms.—Like canker, the disease is insidious in onset. 
In precisely similar manner the horn, and in this case the 
skin of the coronet, is underrun. Later there is the partial 
shedding and fissuring of the undermined horn and the 
exuding of the characteristic discharge—in this case not so 
watery as that of canker. The caseous material of canker 
is also present, as is a disposition to hypertrophy of the 
exposed sensitive structures. What horn is left becomes 
rough and irregularly fissured, and has been likened by 
some observers to deeply-wrinkled bark of an old tree. A 
peculiar characteristic of this condition is the state of the 
ergots and chestnuts. Here the keratogenous membrane 
participates in the diseased process, and their horn becomes 
dry and brittle, and readily splits into small fibrous bundles 
very similar to the fibroid growth described in canker. 
These excrescences are easily separated from the sensitive 
structures beneath, and the exposed surface is seen to be 
more or less moist, or even exhibiting a slight oozing of blood. 
Again, as in canker, the deeper layers of the sensitive 
structures appear to be normal, the horn-secreting layers 
being the only ones affected. According to Malcolm, the 
disease is in its nature equally as inveterate as canker, but 
it is easier to treat, on account of its more exposed position. 
