452 DISEASES OF THE HORSE. 



selves are irregular and granular in appearance. Pumiced sole de- 

 pends upon an impairment of the horn-secreting powers of the sensi- 

 tive sole or upon a separation of the horny from the soft tissues 

 which maintain its vitality. 



Punctured wounds of the foot, accompanied with any considerable 

 destruction of the soft tissues, present the same peculiarities of horn 

 in the immediate neighborhood of the injury. Bruises of the sole are 

 followed by this change when the exudation has been excessive and 

 has separated the horn from the living tissues. True, in these cases 

 we rarely see the soft tissues laid bare, for the reason that new horn 

 is constantly secreted and replaces that undergoing disintegration. 



Laminitis presents three conditions imder which pmniced sole may 

 appear: First, when free exudation separates the horn from the 

 other tissues, or when the process of inflammation arrests the pro- 

 duction of horn by impairing or destroying the horn-secreting mem- 

 brane; second, when depression of the coffin bone causes pressure 

 upon and arrests the formation of horn ; and, third, when the eleva- 

 tion of the sole compresses the soft tissues against the pedal bone 

 and induces the same condition. 



Pumiced sole, from simple exudation and separation of tissues, is 

 of little importance for the reason given above in connection with 

 bruises; but when suppuration occurs in restricted portions of the 

 foot in conjunction with laminitis, it always lays bare the tissues 

 beneath and temporarily impairs the animal's value. Recovery takes 

 place after a few weeks by the tissues " homing over," as in injuries 

 attended by the same process. Depression of the coffin bone is not 

 sufficient within itself to cause pumiced sole ; for, if the relative 

 change in the bone takes place slowly, or if the horn is thin, the sole 

 becomes convex from gradual pressure and the soft tissues adapt 

 themselves to the change without having their function materially 

 impaired. But when the dropping is sudden and the soft tissues are 

 destroyed, the horn rapidly crumbles away and the toe of the bone 

 comes through. In many of these cases the soft tissues remain 

 uncovered for months. When they are eventually covered it is with 

 a thin, slightly adherent horn that stands but little or no wear. The 

 sole being now convex, the diseased tissues bear unusual weight by 

 coming in contact with the gi-ound, and hence it is that these animals 

 are generally incurable cripples. 



In most cases in which the sole is raised to meet the pedal bone and 

 pumiced sole occurs it is due not to pressure of the bone from 

 within (for the tissues are capable of adapting themselves to the 

 gradual change) but to impaired vitality of the sensitive tissues from 

 the inflammation and to the constant concussion and pressure applied 

 from without during progression. To this is to be added the paring 



