Definition. - This condition is simply a sloughing of a portion of the skin of the coronet, together with a portion of the immediately underlying soft structures.

Causes. - This form of quittor has its origin more often than not in contusions, punctures, or wounds of the region severe enough to cause death of a small portion of the tissues. In this case the low vitality of the parts does not allow of the dead portion being removed piecemeal by a process of phagacytosis, as is usually the case with similar injuries elsewhere. Instead, the tissues around, aided by a process of suppuration, cast the offending portion off as a slough. It is the wound remaining after the slough which we may really regard as a quittor. In this connection may be considered as causes blows from falling shafts, self-inflicted treads, or treads from other horses, overreach, etc. On the other hand, simple or cutaneous quittor may occur without ascertainable cause. In this case we can only explain its appearance, as we did that of simple coronitis (see p. 231), by attributing it to septic infection through a wound or a blow that is able to inoculate the skin, yet which is insufficient to cause pain, or in any other way attract the attendant's notice. Meanwhile, the spot of infection thus started spreads, and the end result is an abscess in the coronary region, again accompanied with necrosis and sloughing of more or less skin and other tissue, which terminates by discharging its contents and leaving behind a wound which again constitutes a cutaneous quittor. Thus, as with simple coronitis, anything lowering the vitality of the parts, and so favouring infection of the skin, may bring about a quittor. Walking through much water in the winter months, through the dirt and mud of our streets, through melting ice and snow, or through anything in the nature of a chemical irritant, may be looked upon as a cause.

Symptoms. - Whether commencing from an ascertainable injury, or beginning at first unnoticed, cutaneous quittor is characterized sooner or later by the appearance of an inflammatory swelling, usually confined to the seat of injury. Heat and tenderness are present, and the animal is lame.

Later the inflammatory swelling becomes more profuse, the animal is fevered, and the symptoms of lameness increased. Poulticing is at this stage perhaps resorted to. By its means the process of suppuration is aided, and the swelling (at first tense and hard) either becomes gradually softened, its contents discharged, and a simple abscess cavity left behind, or the suppuration runs immediately round the necrosed structures, and casts them off bodily as a slough. This latter condition is always manifested, where the hair does not hide it, by the colour of the skin. At first this is only red in colour - the angry red of an inflamed spot. As its intention to slough away becomes evident, the red gradually gives way to a gray, or even blue-black appearance, while from around it oozes a slight discharge of pus, yellow in colour and non-offensive, or blood-stained and dark in appearance, and foetid to the smell.

Almost invariably these symptoms are added to by a more or less diffuse and oedematous swelling of the lower portion of the limb, extending in some cases to as high as the fetlock or the upper third of the cannon.

With the casting off of the slough the phenomena of inflammation to a great extent subside, the pain ceases, and the case under ordinary conditions commences to mend.

Pathological Anatomy. - In its early stages the condition of simple or cutaneous quittor is really a condition of acute coronitis (see p. 229), and consists in an inflammation of the subcutaneous tissue, and the more superficial portions of the coronary cushion. The tissues implicated are destroyed outright, become infiltrated with the inflammatory exudate and escaped blood, and act as a source of irritation to the still living tissues around. Under the irritation the latter, as we have said before, cast the necrosed portion away by a process of sloughing.

Always, however, it is found that the portion to be sloughed off, while easily separated from the tissues adjacent to its sides, is closely connected on its lowermost or deeper face with the structures below, and cannot be torn away without haemorrhage and the causing of acute pain.

Prognosis. - With wounds about the feet our forecast should always be guarded. Even with this, the most simple form of quittor, no decided opinion should be given until the progress of the case warrants one in reasonably assuming that complications are absent. Once this point is decided, a favourable prognosis may be given.

Complications. - With cutaneous quittor various complications may arise, according to the extent of the invasion of the septic matter. Necrosis of tendon, of ligament, or of cartilage, caries of the bone, or a condition of synovitis and arthritis may be met with. As these complications are equally common to sub-horny quittor, we shall reserve their description until dealing with that condition. Treatment (Preventive). - Immediately after the infliction of an injury in this position, more especially if it is such as to lead one to judge that necrosis will follow to any large extent, the patient should be rested. Ill effects may then be probably warded off by having the foot immersed in a cold antiseptic solution, and afterwards bound with an antiseptic pad and bandage.

Curative. - When the condition has gone undiscovered until commencing necrosis and suppuration are plainly discernible, then the wisest course we can follow is to do all we can to hasten removal of the necrosed portion.

This is best done by promoting the suppurative process by means of warmth or stimulant applications.

To this end hot poultices, or, better still, hot baths, should be resorted to. Under their influence a greater supply of blood is directed to the still healthy tissues enabling them to actively continue the inflammatory processes necessary to the detaching of the portion necrosed, while, at the same time, the pus organisms, stimulated by the heat, are stirred into greater activity, and the readier accomplish their purpose of destroying the adhesion still existing between the necrotic portion and the surrounding living tissues.

When prolonged poulticing or bathing cannot be practised, then the swelling should be stimulated with a sharp cantharides blister, repeated, if the case demands it, at intervals of a few days.

Should the swelling show distinct signs of pointing, and an abscess is plainly the condition to be dealt with, its contents should be liberated by a free use of the knife. In this connection it is important to insist on the fact that the opening should be made large enough. One bold incision from the uppermost limit of the swelling down to the coronary margin of the wall is usually sufficient.

Even when pointing is not very evident, and suppuration is plainly more or less diffuse, benefit may still be derived from the use of the knife. In this case a deep scarification of the part is indicated. Three, four, or more vertical incisions are made in the swelling, and from them obtained a flow of blood mingled with a small quantity of pus from several different centres. By this means sloughing of the diseased portion is quickly obtained, and nothing but an ordinary open wound left for treatment. It should be mentioned, however, that when sloughing can be in any way induced to take place naturally it is better to allow this to take place. Even when the necrosed portion is freely movable, and only adherent by its base, it should not be forcibly removed, but left to the slower but more effectual action of the tissue reactions. If torn forcibly away, we in all probability leave in the bottom of the wound remnants of the dead tissue, which, being small and consequently less productive of inflammatory phenomena, are not so readily sloughed as the larger portion. These remain as centres of infection, and prolong the case.

Once a suitable slough has occurred, the after-treatment is simple. It consists in dressing the wound with reliable antiseptics, and maintaining the parts in a healthy condition until Nature completes the cure by repairing the breach. Solutions of carbolic acid, of perchloride of mercury, of zinc chloride, or of moderately strong solutions of copper sulphate, are all of them useful (see also treatment of coronitis on p. 236).

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.