CANKER. 393 



of canker; but it is very doubtful if these conditions can do more than 

 favor a preparation of the foot for the reception of the disease germ. 



All injuries to the feet may, by exposing the soft tissues, render the 

 animal susceptible to infection; but neither the injury nor the irrita- 

 tion and inflammation of the tissues which folloAv are sufficient to 

 induce the disease. 



For some unknown reason horses with lymphatic temperaments — 

 thick skins, flat feet, fleshy frogs, heavy hair, and particularly with 

 white feet and legs — are especially liable to canker. 



Symptoms. — Usually, canker is confined to one foot; but it may 

 attack two, three, or all of the feet at once ; or, as is more commonly 

 seen, the disease attacks first one then another, until all may have been 

 successively affected. When the disease follows an injury which has 

 exposed the soft tissues of the foot, the wound shows no tendency to 

 heal, but instead there is secreted from the inflamed parts a profuse, 

 thin, fetid, watery discharge, which gradually undermines and de- 

 stroys the surrounding horn, until a large part of the sole and frog is 

 diseased. The living tissues are swollen, dark colored, and covered 

 at certain points wath particles of new, soft, yellowish, thready horn, 

 which are constantly undergoing maceration in the abundant liquid 

 secretion by which they are immersed. As this secretion escapes to 

 the surrounding parts, it dries and forms small, cheesy masses com- 

 posed of partly dried horny matter, exceedingly ofi^ensive to the sense 

 of smell. When the disease originates independently of an injury, 

 the first evidences of the trouble are the offensive odor of the foot, the 

 liquid secretion from the cleft and sides of the frog, and the rotting 

 away of the horn of the frog and sole. 



In the earlier stages there is no interference with locomotion, but 

 later the foot becomes sensitive, particularly if the animal is used on 

 rough roads, and, finally, when the sole and frog are largely destroyed 

 the lameness is severe. 



Treatment. — Since canker does not destroy the power of the tissues 

 to joroduce horn, but rather excites them to an excessive production 

 of an imperfect horn, the indications for treatment are to restore the 

 parts to a normal condition, when healthy horn may again be secreted. 

 In my experience, limited though it has been, the old practice of strip- 

 ping off the entire sole and deep cauterization, Avith either the hot 

 iron or strong acids, is not attended with uniformly good results. 



I am of the opinion that recovery can generally be effected as surely 

 and as speedily with measures wdiich are less heroic and much less 

 painful. True, the treatment of canker is likely to exhaust the 

 patience, and sometimes the resources, of the attendant; but after 

 all success depends more on the persistent application of simple 

 remedies and great cleanliness than on the special virtues of any 

 particular drug. 



