DISEASES OE THE HOKSE. 425 



of the horn-secreting powers of the sensitive sole, or upon a separation 

 of the horny from the soft tissues which maintain its vitality. 



Punctured wounds of the foot, accompanied by 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 dilferent conditions under which pumiced 

 sole may appear: First, where free exudation separates the horn from 

 the other tissues, or where the process of inflammation arrests the 

 production of horn by impairing or destroying the horn-secreting 

 membrane; secondly, where depression of the coffin bone causes pres- 

 sure upon and arrests the formation of horn; and, thirdl}^, where the 

 elevation 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 la3^s bare the tissues 

 beneath and impairs the animaPs value temporarily. Recovery takes 

 place after a few weeks b}'^ the tissues horning over, as in injuries 

 attended b}' the same process. Depression of the coffinbone is not 

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

 change in the bone takes place slowl^', 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 rapidl}^ crumbles away and the toe of the bone 

 com.es through. In many of these cases the soft tissues remain uncov- 

 ered for months. When they are eventually covered it is A7ith a thin, 

 slightl}^ 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 ground, and hence it is that these animals are gen- 

 erally incurable cripples. 



In the majority of cases where 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), ])ut 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 

 away of the horn b}'^ the smith when apx^lying the shoe, thereb}^ keep- 

 ing the sole at this point too thin. 



