■ 425 



between the tenth and twentieth days either from exhaustion or 

 pyemic infection. 



Gangrene occurs in the periosteum as the result of excessive detach- 

 ment from the bone and compression due to excessive exudation. 

 Other parts of the sensitive tissues are subject to the same fate occa- 

 sionally, and at times large territories will be found dead. 



Pumiced sole is that condition in which the horny sole in the neigh- 

 borhood of the toe readily crumbles away and leaves the sensitive 

 tissues more or less exposed. It is not a complication of laminitis 

 only, for it is seen under other conditions. Williams has described 

 the homy tissue of pumiced sole as " weak, cheesy, or spongy, like 

 macerated horn, or even grumous." This crumbling horn, when 

 critically examined, shows almost an entire absence of the cohesive 

 matter which unites the healthy fibers, while the fibers themselves are 

 irregular and granular in appearance. Pumiced sole depends upon 

 an impairment 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 different 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, thirdly, 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 lays bare the tissues 

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

 place after a few weeks by the tissues horning 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 



