Chapter 22

DISEASES OF THE LATERAL CARTILAGES

A. WOUNDS OF THE CARTILAGES.

To a consideration of this we shall devote but little space. It is sufficient to say that any wound in the region of the coronet should always be given the most careful attention. More particularly should this be so when it is ascertained that the wound has involved one of the lateral cartilages. Wounds of non-vascular bodies such as these are always slow to heal, and, by reason of their slowness, invite septic infection. In many cases, in fact, it happens that they do not heal at all. Instead, the injured part becomes necrotic, is unable to cast itself off, and remains as a centre of infection in the depths of the wound, thus constituting what is known as a quittor.

Apart from this, it will be remembered that the internal face of the cartilage is in intimate contact with the pedal articulation, especially anteriorly. Wounds in this situation are, therefore, likely to penetrate the joint, giving us as a complication of the injury the conditions of synovitis and arthritis.

Immediately a wound is inflicted in this position, attempts should be made to insure thorough asepsis of the part. When possible, by far the better way of accomplishing this will be to wholly immerse the foot in a tub of cold antiseptic solution, and keep it there for an hour three times daily. During the time the foot is out of the solution the wound should be protected with a pad of carbolized tow or other suitable dressing, and wrapped in a linen bandage or clean bag. If unable to use the bath, then antiseptic solutions of more than moderate strength should be freely applied to the wound and the adjacent parts, a carbolized or other antiseptic pad placed over it, and the bandage adjusted as before. Repeated injuries to the cartilages, even if not attended with an actual wound, are apt to bring about their ossification and end in the formation of side-bones.

B. QUITTOR.

_Definition_.--A fistulous wound of the foot, usually opening at the coronet, and variously complicated according to the structures invaded by its contained pus. For the reason that quittor is in every-day veterinary nomenclature _usually_ associated with necrosis or other abnormal condition of the lateral cartilage, we include its description in this chapter.

_Classification_.--It has been customary with Continental authors to classify quittor according to the extent and position of the diseased process. There were thus distinguished:

_(a)_ The _Simple_ or _Cutaneous Quittor_, in which had occurred nothing more than necrosis of a portion of the coronary skin and the structures immediately underlying it--that is, the superficial portion of the coronary cushion.

_(b)_ The _Tendinous Quittor_, in which not only the immediately subcutaneous tissues were attacked, but also portions of tendon and of ligament.

_(c)_ The _Sub-horny Quittor_, in which the diseased process had invaded the deeper portions of the coronary cushion, and continued a downward course until the laminal tissue below the upper margin of the wall was involved, or any other case, no matter what the starting-point, in which pus existed within the horny box and was discharging itself by a fistulous opening.

_(d)_ The _Cartilaginous Quittor_, in which a portion of the lateral cartilage had become attacked and rendered necrotic.

We believe that--in this country, at any rate--the word 'quittor' is usually held to indicate one or other of the two latter conditions, and probably the last of these; and that the two first are held of small account, or hardly of sufficient gravity to allow of the word 'quittor' being applied to them. In fact, by defining quittor as a 'fistula,' or little pipe, we have ourselves already indirectly restricted the use of the word to the two latter conditions, for in those varieties known as Simple or Cutaneous and Tendinous, the wound is generally broad and open, or, at any rate, superficial, and can scarcely be strictly described as 'fistulous.' In the two latter, however, a true fistula exists. These, however, have only one essential difference, and that consists simply in the position of the lesion and the structures it has attacked. In the main the symptoms will be the same, the disease in each case about equally serious, and in each the same essentials of treatment will have to be regarded.

In our opinion, therefore, a lengthy classification serves no useful end, and we think matters will be simplified by considering quittor under two headings only--namely, 'Simple or Cutaneous' and 'Sub-horny,' and discussing the other varieties as simply complications of either of these two.

1. SIMPLE OR CUTANEOUS QUITTOR.

_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 hæmorrhage 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.

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.

Any other diseased condition of the foot in which suppuration is present may in like manner terminate in quittor. In complicated sand-crack, suppurating corn, or in ordinary pricked foot quittor may be a sequel. In these conditions the pus formation either goes unnoticed or is neglected, and after seriously invading the sensitive structures within the hoof, breaks out at the coronet. Again, too, as with the simpler form of quittor, and as with coronitis, we may always regard as a predisposing cause the action of excessive cold in promoting septic infection of the wound when occurring at the coronet.

_Symptoms and Diagnosis_.--Where the fistulous wound has had its starting-point in an injury to the coronet diagnosis is, of course, easy. The history of the case explains it. Nothing in this instance remains but to probe the opening, and ascertain its direction, depth, and extent.

An animal with the wound thus open at the coronet, and freely discharging its contents, may, if no serious complications exist, walk tolerably sound. It is only when put to the trot that symptoms of lameness are apparent.

It may so happen, however, that we first see the case when the symptoms are wholly those arising from a painful suppuration within the horny box. This occurs when the original injury has taken place at a more dependent position than the coronet. Either from violent blows upon the hoof, puncture from below, from corn or from sand-crack, or any other causes we have enumerated, suppuration is occurring deeply within the hoof, with as yet no opening upon the coronet.

Even when an opening has already occurred on the coronet, the same condition of sub-horny suppuration may be met with in cases when the opening of the fistula has by some means or other become occluded. Granulation tissue, for instance, may have temporarily closed the mouth of the fistula. The pus, instead of continuing its discharge thereat, is made to burrow in other directions.

In either of these cases pain is excessive, the animal walks on three legs, the foot is painful to percussion, and grave constitutional disturbance is noticeable. The presence of pus is immediately suspected, and, in the absence of any indication of an opening having existed at the coronet, searched for at the sole. It may or may not be found. If found it is given exit, and the case ends as one of ordinary pricked foot, of suppurating corn, or some other condition equally simple when compared with quittor. In those cases where the pus is not discovered at the sole, one adopts the expectant treatment of poulticing. This, if pus is present, is followed by a painful swelling of the coronet. At one point there forms a hot and tender enlargement, with the hairs on it standing straight up from the skin, which latter is seen below red and inflamed in appearance.

Later, the abscess--for abscess it is--discharges its contents, the opening is explored, and we find that in extent it is not confined to the coronary region, but that it is deep enough to constitute a true sub-horny quittor.

This discharge of the abscess contents may take place at a well-defined spot on the coronet, or it may ooze out at the junction of the wall with the skin. In appearance the discharged pus varies. When the softer structures only are attacked it is thick, and yellow or white in colour; when bone is involved it is ichorous; and when attacking the horn itself black or gray. It may or may not be extremely foetid, and often it is mingled with blood.

When evidence of a previous opening upon the coronet is plain, then it is not considered wise to attempt a paring of the sole. Instead, poulticing is at once resorted to, to induce the discharge of the pus through its original channel. Once this has occurred a fistulous wound remains, which is open for treatment upon one or other of the lines we shall afterwards indicate.

COMPLICATIONS--_(a) Necrosis of the Lateral Cartilage_.--This is the so-called 'cartilaginous quittor' of other writers. In all probability it is the condition generally understood when the word 'quittor' is used by one practitioner to the other. Its tendency to keep the disease existing in a chronic form renders it of grave importance, and for that reason we give it first mention among the complications.

It may occur as a sequel either of cutaneous or of sub-horny quittor, and may result either from actual wounding and infection of the cartilage, or from an attack on it of septic matter originating elsewhere.

Unless there has been discovered a fistula, which on probing is seen to lead direct to the position in which we know the cartilage to be, we know of no precise means by which the existence of this condition may be diagnosed. When free from other complications, the horse with his foot in this state may travel fairly sound. This is so when the necrosis is situate in the posterior half of the cartilage, in which case the irritation set up by the disease is confined to the comparatively non-sensitive tissues of the cartilage itself and the fibrous mass of the plantar cushion. When attacking the anterior half of the cartilage, the close contiguity of the joint renders the disease of a more serious nature. It is then that we have acute pain, and with it extreme lameness, for in this position it is more than likely that we have involved either the synovial membrane of the articulation or the tops of the sensitive laminæ. It will be remembered that here the synovial membrane protrudes as a small sac between the antero- and postero-lateral ligaments of the joint. More or less easily then it is bound to come into intimate contact with the septic matter attending the necrosis of the cartilage, and so share in the inflammatory processes, afterwards communicating them to the interior of the articulation.

With necrosis of the lateral cartilage is always swelling and thickening of the skin and subcutaneous structures of the coronet. This is the greater the longer the disease has been in existence. Upon the swelling is seen the mouth of the fistula, or it may be the mouths of several, and from them all a discharge of pus.

The mouth of each fistula is generally filled with a mulberry-like granulation tissue, standing above the level of the skin, and bleeding easily if touched. The exuding pus is thin and pale gray in appearance, gritty to the touch, and generally free from pronounced smell. At other times its colour is reddened with contained blood, and floating in it are tiny particles of a pale-green substance, which when picked up and rubbed between the fingers are seen to be small fragments of the diseased cartilage.

Should the mouth of a fistula become occluded with the granulations filling it, and the discharge prevented from escaping, it soon happens that we have close to the fistula that has closed a tender fluctuating swelling. This points and breaks, and pus is again discharged from another opening. In this manner is accounted for the multiplicity of scars and fistulas seen on the swelling of an old-standing quittor.

The continued, inflammation thus kept in existence has the effect of rendering the skin and subcutaneous tissues in the neighbourhood greatly thickened and indurated. This in time leads to a tumour-like enlargement, and causes the structures of the coronet to greatly overhang the hoof. At the same time the constant inflammation has made its stimulant effects noted in a great increase in the growth of the horn of the wall.

Although more abundant, however, the quality of the horn is deteriorated. The perioplic ring has become obliterated, and the varnish-like appearance of the healthy wall destroyed. Cracks and fissures in its surface are numerous, and sometimes deep enough to lead to exposure of the sensitive structures beneath, complicating the quittor with a sand-crack of a peculiarly objectionable type.

_Pathological Anatomy of the Diseased Cartilage_.--The bulk of observers appear to agree in the statement that in quittor the necrotic cartilage is pea-green in colour, and recognise it by that characteristic. In size the necrotic portion thus recognisable varies from the tiniest speck to a portion the size of a horse-bean. Commonly, however, it is about as large only as a pea. It is seen to be more or less detached from the rest of the cartilage, to which it is adherent by one of its extremities only. In general appearance we can best liken it to the split half of a green pea, whilst others have compared it with the green sprouting of a seed. The portions of cartilage nearest the necrotic piece are also slightly green in colour, thus indicating that here also the diseased process has commenced. This peculiar change of colour in the affected cartilage is of great importance to the surgeon. It enables him when operating to distinguish with some degree of certainty those portions of the cartilage which are healthy and those which are not.

_(b) Necrosis of Tendon and of Ligament_.--This complication of quittor is, as we have said before, treated by other writers as a distinct form of the disease, and described by them under the heading of Tendinous Quittor.

This simply means, of course, that the diseased process has extended to either of the flexor tendons, to the tendon of the extensor pedis, or, perhaps, to the ligaments of the pedal articulation.

Of the flexor tendons, the perforans is the one commonly attacked, by reason, of course, of its more superficial position. At times, however, especially when its aponeurotic expansion is diseased, the necrosis of the perforans spreads until the aponeurosis is eaten through and the phalangeal sheath penetrated. Septic materials gain entrance thereto, and commence to multiply. In this way the flexor perforatus is invaded, and comes to share in the diseased process.

The extensor pedis is usually attacked by extension of the disease from a necrotic cartilage, or results from the infliction of a severe tread in a hind-foot. In this case the diseased structure has nothing between it and the articulation, the synovial membrane in one position actually lining its inner face. The result is that a condition of synovitis is easily set up, and the case aggravated by that and by arthritis.

With the flexor tendons attacked pain is always very great, and lameness is excessive. This, however, is not sufficiently characteristic to enable us to determine the precise seat of the necrotic changes. Later, however, a tender but hard enlargement made its appearance in the hollow of the heel, which enlargement, later still, became soft and fluctuating. At this stage there is also considerable swelling along the whole course of the tendons, as high up as the knee or the hock. The foot is carried forward with all the phalangeal articulations flexed, and in many cases the limb is unable to take weight at all. Manipulated after the manner of examining the tendons for sprain, this swelling is found to be extremely painful. The animal flinches from the hand, and shows every sign of acute suffering. This condition may, in fact, be mistaken for sprain, and is only to be distinguished from it by carefully noting the history of the case--first, the appearance of the swelling in the hollow of the heel, and, secondly, the _after_-swelling of the upper portions of the tendons.

The formation of the abscess, the after-discharge of its contents, and the final establishing of a fistula, are processes greatly prolonged in this form of quittor. It will readily be understood why this should be so when one remembers the depth at which the suppurative process is going on, the thickness of the metacarpo-phalangeal sheath, and the resistant nature of the material of which this latter is made, and which must be penetrated before the condition becomes observable.

After the opening of the abscess, which usually takes place in the hollow of the heel, there is left the fistulous wound which obstinately refuses to heal. Or it may be, again, that there are several of these fistulas, each opening in the heel, and the mouth of each marked by a small, ulcer-like projection. The discharge continually oozing from these keeps the heel constantly wet with a thick purulent discharge, which is nearly always blood-stained, and very often foetid.

This constitutes what is known as tendinous quittor in its worst form, for more often than not there is associated with it inflammation of the navicular bursa, caries of the bones, or arthritis of the pedal articulation.

With the extensor pedis attacked matters are not quite so grave, in spite of the fact that the articulation is closely situated thereto, for in this case the more superficial position of the diseased structure allows both of readier exit of the discharges and of easier removal of the necrosed portion and after-treatment of the wound.

_(c) Caries of the Bones_.--Portions of the os pedis, more especially of its wings, and therefore usually occurring in conjunction with necrosed cartilage, become carious in quittor. In many cases it is impossible to say with certainty when this has occurred. In a few instances, however, the exuding discharge gives evidence of what has happened. It is thin, but extremely offensive, with the characteristic odour of decayed bone or tooth, and with a feel that is gritty with contained particles of broken-up bone. If, with a discharge of this nature present, the probe also conveys to the fingers the sensation that bone is reached, then diagnosis may be sure.

_(d) Ossification of the Cartilage_.--This may take place in part or in whole. It, of course, constitutes Side-bone, a fuller description of which will be found in a later portion of this chapter.

_(e) Penetration of the Articulation_.--This may occur either as a result of the suppurative changes or as an accident in excision of the diseased cartilage. Unless it is followed by a severe purulent arthritis, it is not so grave a complication as at first sight it would appear.

_(f) Synovitis and Arthritis (Purulent)_.--Should this complication arise, the case is a most serious one. Beyond here mentioning the fact that it may occur, we shall not dwell on it. Fuller consideration is given to it in