396 DISEASES OF THE HORSE'S FOOT 



is plainly seen to be subsequent to the diseased processes 

 in the bone. For that reason, and also for the reason that 

 the condition has come to be known by the name we have 

 given, we give it special mention, 



Si/mptoms and Diagnosis. — Even when the condition 

 arises as the result of fracture, the ordinary manifestations 

 of such a lesion are absent. By reason of the situation of 

 the parts within the hoof we are unable to detect crepita- 

 tion, and the resulting lameness is perhaps — in fact, 

 nearly always is — neglected until such time as any heat or 

 swelling caused by the injury has disappeared, in which 

 case we are denied what evidence w'e might have obtained 

 from that. All that is presented is lameness, and lame- 

 ness that is at times excessive. But with the lameness 

 there is nothing distinctive. The foot is tender on per- 

 cussion, and the gait suggestive of foot lameness, that is 

 all. We are unable, therefore, to make an exact diagnosis, 

 and the condition goes for some time undetected. 



Later, however, changes in the form of the hoof and 

 the coronet begin to appear. The skin of the coronet, 

 especially in the region of the toe, becomes more or less 

 thickened and indurated, and the same remark applies to 

 the subcutaneous tissues. The most marked change, how- 

 ever, is the alteration in the shape of the hoof. The wall 

 protrudes at the toe in a manner that has been termed 

 ' buttress-like,' and has given to the condition one of its 

 names. This, of course, entirely alters the contour of the 

 horny box. From being more or less U-shaped, it ap- 

 proaches nearer the formation of the letter V, the point of 

 the V being at the toe. 



In the later stages the coronary enlargement is plainly 

 seen to be due to an extensive formation of bone. It is, in 

 fact, a reparative callus, and the reason it reaches so large 

 a size is probably to be accounted for by the pull of the 

 extensor pedis upon the detached pyramidal process. As 

 might be expected, this displacement of the fractured por- 

 tion, with its effect of giving greater length to the extensor 

 pedis, leads to a backward displacement of the os coronae 



