CORNS. 



1065 



at intervals, the corn may appear stratified — layers of ecchymosed 

 horn alternating with unstained horn. 



Causes. The fact that the posterior parts of the hoof are oftenest 

 the seat of mechanical lesions is partly due to their greater mobility ; 

 the movement of the hoof is most apparent at this point, and rupture 

 of soft structures, therefore, more liable to occur. Then again, 

 the heels carry a larger proportion of the weight, and the horn 

 covering them is weakest. The more frequent occurrence of corns 

 in the inner heel and in fore feet must also be referred to the greater 

 weight borne and the more marked impact during rapid movement. 



Corns are favoured by long, weak fetlocks, and by defects in 



Fig. 566. — Three-quarter bear shoe, 

 a, Seat of the corn. 



Fig. 



567. — Ordinary three- 

 quarter shoe. 



formation, especially in the front limbs. In animals which stand 

 with the feet well apart, the inner heel is most generally affected ; 

 in the opposite conformation, the outer. Wide, flat feet with thin, 

 low heels are particularly exposed to bruising from pressure of the 

 shoe or from rough ground. The weaker the horn of the heels, the 

 more readily do such injuries occur : rings on the surface of the heels 

 suggest the existence of corns. Abnormally narrow feet are generally 

 affected with corns, and in contracted heels they are almost always 

 present. But wide hoofs are also liable to them ; in such case the 

 corn being an injury of the sole, whilst in narrow hoofs the bar is more 

 often affected. 



The principal external causes are faulty shoeing, especially 

 improper paring, the use of too short or too narrow shoes, or allowing 

 the shoes to remain on for too long a time. As corns are very rare 



