684 



OPEKATIONS ON THE FOOT. 



Fig. 519.— Changes of Structure of the Os Pedis in old cases of Chronic Laminitla. 



well as in its form, and becomes denser and more brittle. (Fig. 

 6ld). One might suppose that as the disease progresses, the os 

 pedis would become pressed backward more and more toward the 

 sole, in consequence of its giving way under the pressure. This, 

 however, is not so. As the old normal walls disappear, the new 

 horn yields to the pressure from forward, the heels rise, the os 

 l^edis resumes its horizontal direction, and the danger of hernia 

 of the bone diminishes, and a hypersecretion of the hoof is even 

 noticed toward the point where the hernia would have taken 

 place, in the middle of the pumiced sole. 



We have, so far, supj)Osed that chronic laminitis is always 

 manifested by the presence, between the internal face of the wall 

 and the podophyllous surface, of a mass of abnormal hoof. But 

 there are cases, after hemorrhage, and especially after serous 

 exudation, where, instead of it, a cavity is found — a seedy toe. 

 There is also an entire separation between the os pedis and the 

 wall. But the horny production, that of the podophj'llous tissue 

 especially, is not sufficient iu amount to fill up the whole space, 

 there being hoof only upon the podojDhyllous tissue. There is 

 then a sound wall formed, separated from the old one by a vac- 

 uum, which is often filled by a dry mass derived from the blood 

 and serosity, mixed with the horny cells. But more frequently 



