It is sometimes found that even with careful attention the wound left by the removal of the slough shows a marked disinclination to heal. The greater portion of the cavity becomes filled with granulation tissue, and the epidermis gradually closes round until all is covered except a spot of perhaps the size of half a crown or a crown piece. Here the regenerative process stops, and the wound obstinately refuses to effectually close. In such cases we have derived excellent results with the actual cautery. The animal is cast, the foot firmly secured by fastening it upon the cannon of another limb, and the animal chloroformed. A practical point to be remembered in this connection is that all necessary fixing of the limb is easier performed if the chloroform is administered first. With the patient thus secured we first of all ascertain by means of the probe whether or no the non-healing of the wound is due to the presence of a fistula. Decided in the negative, we take an ordinary flat firing-iron, and with it cut away a portion of the skin immediately around the still open wound, carrying our incisions deep enough to 'scoop' out a large portion of the new inflammatory tissue beneath. With the loss of pressure from beneath, occasioned by the removal of so much of the cicatricial tissue, the epidermis the more readily closes over the wound. To a large extent also this new growth of epidermis is helped by the renewal of the inflammatory phenomena brought into being with the cauterization. 2. SUB-HORNY QUITTOR. _Definition_.--A fistulous wound of the foot in which the lower and blind end of the fistula is situated below the level of the coronary margin of the wall. _Causes_.--These, again, will be practically the same as those mentioned in the cause of cutaneous quittor--namely, bruises, punctures, wounds--in fact, any injury upon the coronet severe enough to cause death of tissue and a suppurating wound. We may thus expect sub-horny quittor to follow upon treads, overreach, accidental injuries with the stable-fork, and kicks from other animals. Sub-horny quittor may also arise without original injury at all to the coronet. Either from a violent blow upon the hoof, or from the animal himself kicking violently against a wall, death of a portion of the sensitive structures takes place within the hoof, suppuration ensues, and the formation of quittor commences. With the escape of the pus at the coronet the quittor is fully formed.