272 HORSE, SWINE AND POULTRY DISEASES 



condition. As a rule, the diseased and ragged portions of horn are 

 to be pared away and the foot poulticed for a day or two with boiled 

 turnips, to which may be added a few drops of carbolic acid or a 

 handful of powdered charcoal to destroy the offensive smell. The 

 cleft of the frog and the grooves on its edges are then to be cleaned 

 and well filled with dry calomel and the foot dressed with oakum 

 and a roller bandage. If the discharge is profuse, the dressing 

 should 'be changed daily ; otherwise it may be left on two or three 

 days. Where a constitutional taint is supposed to exist, with swell- 

 ing of the legs, grease, etc., a purgative, followed by dram doses of 

 sulphate of iron, repeated daily, may be prescribed. In cases where 

 the growth of horn seems too slow a Spanish-fly blister applied to the 

 iheels is often followed by good results. Feet in which the disease is 

 readily induced may be protected in the stable with a leather boot. 

 If the thrush is but a sequel to other diseases, a permanent cure may 

 not be possible. 



CANKER. 



Canker of the foot is due to the rapid reproduction of a vegetable 

 parasite. It not only destroys the sole and frog, but, by setting up a 

 chronic inflammation in the deeper tissues, prevents the growth of a 

 healthy horn by which the injury might be repaired. Heavy cart 

 horses are more often affected than those of any other class. 



Causes. The essential element in the production of canker is 

 the parasite; consequently the disease may be called contagious. 

 But, as in all other diseases due to specific causes, the seeds of the dis- 

 order must find a suitable soil in which to grow before they are re- 

 produced. It may be said, then, that the conditions which favor the 

 preparation of the tissues for a reception of the seeds of this disease 

 are simply predisposing causes. 



The condition most favorable to the development of canker is 

 dampness in fact, dampness seems indispensable to the existence 

 and growth of the parasite ; for the disease is rarely, if ever, seen in 

 high, dry districts, and is much more common in rainy than in dry 

 seasons. Filthy stables and muddy roads have been classed among 

 the causes 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 

 irritation and inflammation of the tissues which follow are sufficient 

 to induce the disease. For some unknown reason horses with lym- 

 phatic 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 



