THRUSH. 383 



leather soles should be used ; these may be moveable, and used 

 only while the horse is in the stable. 



"When, from the intrinsic cause already referred to, or from 

 some habit of body (cachexia), with swelling of the legs, or 

 grease, the cure becomes a difficult matter, purgatives, dress- 

 ing with calomel, tonics if necessary, regular exercise, and great 

 cleanliness, will be necessary. 



CANKER 



Differs from thrush in the nature of the diseased secretion, in 

 its course and tractability. It usually commences in the frog, 

 and rapidly extends to the sole, and even the sensitive laminae ; 

 but it is not a rare thing to see it commencing in any other 

 part of the plantar surface, or of the laminated structure of the 

 wall, excited by a wound, prick, or other injury. It much 

 resembles grease of the leg, both in its nature and the class of 

 animal it attacks ; and very frequently both conditions are co- 

 existent. I have investigated the condition of the parts micro- 

 scopically, but have failed to detect any malignant characteristic.. 

 The papillse are enlarged by engorgement, or by hypertrophy, 

 but show no trace of cancer or malignant disease ; nor of lym- 

 phoid or tubercular deposition, as in some cases of foul in the 

 feet of horned cattle. In some instances such bodies, like the 

 sporulcs of a vegetable parasite, are to be seen under the micro- 

 scope ; perhaps further research will demonstrate that canker is 

 due to the presence of a cryptogam. 



The characteristic symptoms of the disease are strongly 

 marked, and consist of an abundant foetid, colourless discharge 

 from the frog, which is large, spongy, and covered by pallid, 

 stringy prominences of a fungoid nature, intermixed with offen- 

 sively smelling, semi-dried, cheesy masses of matter, composed 

 of imperfect horn cells. It seems as if the various constituents 

 of the horn were in an uncombined state ; the sulphur, which 

 is a natural constituent, being secreted as sulphuretted hydro- 

 gen, giving the characteristic foetor to the whole secreted mass ; 

 the horny matter imperfect, and floating in an abundant 

 liquid material ; the secreting villi enlarged, scantily covered by 

 a thin pellicle of horn, giving them superficially a while appear- 

 ance, whilst underneath they are turgid, congested, and humid. 



