636 OPEEATIONS ON THE FOOT. 



the caustics upon the fibrous tissues exposed to necrosis, or 

 ah-eady in that condition, a double salutary result is obtained ; 

 first, the transformation of the part, which is the seat of a pro- 

 gressive gangrene, into a chemical eschar ; and, again, promoting 

 the more active vascularization of the surrounding parts, and con- 

 sequently their increased power of healthy reaction ; conditions 

 twice favorable to the sloughing of the eschar, and the process of 

 repair following it. 



"When the wound has reached the os pedis, and this has become 

 carious, a portion of the sole is removed, so that the suppuration 

 can escape, the bone is scraped off, and a dressing of carbolized 

 alcohol applied, kept on by a thin shoe or slipper, with tin plates. 



"When there is a fistulous wound, through which synovia escapes, 

 yet not purulent, caustics are recommended. Solleysel preferred 

 these, but blacksmiths used them so carelessly that they soon 

 were discarded. Since, however, they have been employed again, 

 not in powder, but as trochiscus. Eey recommends the corrosive 

 sublimate in conic pencils, introduced to the bottom of the fis- 

 tula ; by them he obtains an eschar, a solid clot, from the synovia, 

 which closes up the wound and prevents the synovial flow, at the 

 same time stimulating the granulations which close up the fistula. 



We have already said that these measures must be used only 

 when the synovia is not purulent, as then the escape of morbid 

 liquids may be prevented. It is not then uncommon to see 

 abscesses forming at the back of the coronet ; generally not so 

 serious as is usually believed; not as much as those which take 

 place in front and which are due to suppuration of the articula- 

 tion. After the running out of those abscesses, sometimes the 

 wound of the foot assumes a better aspect, the symptoms im- 

 prove, and the animal recovers rapidly. Injections of a very weak 

 solution of tincture of iodine, as well as the baths of copper or 

 iron, are then very advantageous. Hertwig advises the introduc- 

 tion of a seton through the sesamoid sheath 



This treatment is not always sufficient, especially where the 

 lesions are deep. All the diseased structures must be then ex- 

 posed, and they must be removed and the wound changed into a 

 simple one, which, well dressed, wiU heal without difficulty. The 

 operation is required in proportion to the extent and nature of 

 the lesion, and if this is recent and comparatively superficial, if a 

 piece of the foreign body yet remains in the wound, or if its re- 



