180 MANUAL OF MODERN FARRIERY. 



should seldom be pared witli a knife, but merely rasped 

 down to a level surface. This is peculiarly applicable to 

 the inner heel. The hind feet are seldom affected with 

 corns, because they are stronger than the fore-feet, and 

 less subjected to concussion ; and even where corns do exist, 

 they do not produce lameness. 



CANKER. 



Canker consists of a separation of the horny substance 

 from the sensible fleshy and bony portion of the foot, 

 caused by the growth of fungus matter shooting up and 

 occupying parts of, or the entire sole of the foot and frog. 

 It is induced either by a puncture, bruise, corn, quittor, or 

 thrush, more commonly proceeding from the latter than any 

 other cause. It seldom attacks high-bred animals, being 

 almost always confined to the heavy breed of cart and dray 

 horses, which class seem to have a constitutional predisposi- 

 tion to this complaint. Those which have previously had 

 grease are peculiarly liable to canker, and especially those 

 which have thick heels. Persons experienced in breeding 

 have long ascertained that grease and canker follow certain 

 blood, and have thus established the fact of these complaints 

 being hereditary. Besides the hereditary predisposition of 

 work-horses to canker, in order to give him foot-hold, it 

 becomes necessary to raise the heels of the hinder feet 

 so much that all pressure on the frog is done away with, 

 which has the effect of destroying its functions, and con- 

 sequently rendering it liable to disease. 



But canker is produced chiefly from the very ponderous 

 shoes with which these horses are furnished, and the large- 

 ness of the nails with which they are necessarily attached 

 to the feet, together with the strain to which the animals 

 are subjected in drawing and sustaining heavy weights. 



