413 



sues more or less exposed. It is not confiued to beiug a complication 

 of laraiiiitis, but may be seen whenever the necessary conditions for 

 inducing it are present. "Williams has described the horny-tissue un- 

 der these circumstances as being ''weak, cheesy, or spongy, like mac- 

 erated horn, or even grumous," and this certainly conveys a good idea 

 of its appearance and general characteristics. This crumbling horn 

 when critically examined shows almost an entire absence of the cohe- 

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

 are irregular and granular iu appearance. Pumiced sole depends upon 

 an impairment of the horn-secreting powers of the sensitive sole, or 

 upon a separation occurring between the horny and soft tissues which 

 maintain its vitality. Tbe normal sole physiologically maintains a 

 proper thinness by crumbling off in scales as it passes beyond the life- 

 maintaining influence of the i^roducing tissues, and anything which 

 prevents, suspends, or destroys this influence causes the crumbling proc- 

 ess to become excessive. 



Punctured wounds of the feet, whe re accompanied by any consider- 

 able destruction of the soft or horn-secreting tissues, present the same 

 peculiarities in this respect in the immediate neighborhood of the in- 

 jury. Bruises of the sole are occasionally followed by this change in 

 the horn where the exudation has been excessive and has separated it 

 from the living tissues. True, in these cases we rarely see the soft tis- 

 sues laid bare, for the reason that new horn is constantly secreted and 

 replaces that undergoing the process of 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 pro- 

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

 brane: secondly, where depression of the coffin bone causes pressure 

 upon and arrests the formation of horn ; and, thirdly, where the eleva- 

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

 induces the same condition. Pumiced sole, as it results from simple 

 exudation and separation of tissues, is of no importance, for the reason 

 given above iu connection with bruises ; but where 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 tempora- 

 rily. In these cases recovery takes place after a tew weeks' time by the 

 tissues horning over, as iu injuries which have been attended with the 

 same process. Depression of the coffin bone is not a sufficient cause 

 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 con- 

 vex from the 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 entirely 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, 

 and when they eventually become covered it is with a thin, slightly ad- 



