Diseases of the Horse's Foot Part 43

The penetrating object is nearly always dirty--bacterially dirty, at any rate--and suppuration only too readily commences. Even should such a wound be inflicted by an aseptic body, infection would quickly ensue as a result of the wound gathering dirt from the ground, or even from admission to the joint of impure and bacilli-laden air.

_Symptoms and Diagnosis_.--This is one of the most serious conditions we are called upon to face when dealing with diseases of the foot, for in many cases it quickly ends in exhaustion and death of the patient, while in even the most favourable cases nothing better than a condition of complete and bony anchylosis is to be expected. The owner, therefore, should be warned accordingly.

As in the other joint affections, so here, we get all the symptoms of acute febrile const.i.tutional disturbance. The pulse, the temperature, the respirations, and the general haggard, 'tucked-up,' and distressed appearances of the animal all tell too plain a tale. Our patient is in constant pain, and the seat of the trouble is clearly enough shown by the constant pawing movements of the affected foot. If he has room to get up and down in comfort the animal adopts for long periods at a stretch the rec.u.mbent position, and is not upon his legs long enough to take the necessary amount of food to keep him going. Even when down, it is plain to see that the animal is not at rest. The pawing movement is still maintained with the foot, and every now and again the eyes are opened and the headed lifted to give a troubled look round. The appet.i.te, too, is capricious, and in many cases almost entirely lost.

In some slight degree the condition is less to be feared in a fore than in a hind foot--that is, so far as absolutely fatal results are concerned.

With the condition confined to one fore-foot, the animal is able to get up and down with a moderate degree of comfort. At intervals, therefore, he rises to take nourishment, and as soon as his wants are satisfied again lies down.

With the disease in a hind-foot matters are not taken so comfortably. The patient finds that with each day's increasing weakness the difficulty that at first he had to raise himself with only one sound hind-foot becomes enormously increased. The consequence is that he fears to go down, and the standing position is maintained until sheer weakness overcomes him, and he goes down, not to rise again without a.s.sistance.

If judiciously attended he is, of course, put in slings before this stage is reached; but there are instances, as in the case of a cart-mare heavy with foal, where the use of slings is most decidedly contra-indicated.

If doubt before existed as to the nature of the case, it is at a later stage dispelled by the appearance, generally in the hollow of the heel, of a hot and painful swelling. This at first is hard, but later fluctuates.

Finally it breaks at one or more spots, and there exudes from the opening or openings a purulent and oftentimes sanious discharge, which coagulates about each fistula after the manner of ordinary synovia.

With the discharge of the abscess contents there is some slight improvement in the symptoms. Here, with a suitable treatment, and with a patient of a particularly robust const.i.tution, the case appears to turn, and slowly but surely progresses towards the only end we can hope for--namely, a more or less painless anchylosis of the articulation.

In less favourable cases the purulent discharge continues, and (always a bad sign) becomes more or less chocolate-like in colour, distinctly thin, and stinking. The diseased process spreads until the ligaments of the joint, both by reason of their infiltration with the inflammatory discharges, and also on account of the ravages made on them by the invading pus, either greatly stretch or altogether rupture.

The joint, after its ligaments have been destroyed in this manner, is loosened, and the bones are now freely movable. Their manipulation gives to the touch a sickening, grating sound--in other words, we have crepitus.

This, of course, indicates that the articular cartilages have become greatly eroded by the inflammatory process, and so left what we may term 'raw' surfaces of bone to rub together. When the animal is put to the walk the toe of the foot is elevated, and the extreme mobility of the foot gives one the idea of fracture. With every step there is a peculiar sucking noise, comparable to that of a foot moving in a boot of water, and putrescent matter is squeezed from every opening each time the foot is put to the ground. Although we have seen cases even advanced thus far recover, it is questionable whether it is now wise to attempt to prolong life.

Slaughter is far more humane, and, in our opinion, except with a valuable brood animal, more economical.

If the animal is allowed to linger, other symptoms will nearly always present themselves before death occurs. Whether in slings or not, a careful watch should be kept upon the sound limb. For some time the patient stands upon it incessantly, but sooner or later it happens that a farther visit show us the animal standing with full weight on the diseased foot, and making painful pawing movements with what before was the sound. We immediately jump to the conclusion 'laminitis.' And so it is, but it is a laminitis brought about by pyaemia. This is indicated by the swollen and oedematous nature of the lymphatics of the limb. Plainly enough they indicate the road by which the poison has travelled. It is in this way: Pus and putrefactive organisms have gained entrance to the lymphatics of the original diseased limb. From these they have rapidly gained the blood-stream and set up infection elsewhere. In this particular instance it is demonstrated by the laminitis and lymphangitis of the previously sound limb. With the poison thus circulating in the blood-stream, we often also get spots of infection commenced in one or other of the more vital organs--notably the lungs or the kidneys. The end of our case is then either a gangrenous pneumonia or complications induced by a condition of widespread pyaemia.

With the animal in slings there are one or two other symptoms that call for attention. In many cases, especially with animals of a lymphatic and indolent nature, the use made of them is inordinate. The patient rests so continually in them that alarming swellings commence to make their appearance about the r.e.c.t.u.m, or in the case of a mare about the v.u.l.v.a. The animal must then be let down at regular intervals and again raised when rest is obtained.

A more alarming symptom still is when the animal, instead of resting in the slings by his b.u.t.tocks, casts his weight bodily into the belly-rest and hangs with a heavy head into the head-stall. This indicates complete exhaustion and a wish for death. Matters should therefore be explained to the owner, and his consent obtained for immediate destruction.

_Pathology_.--The pathological changes occurring in suppurative arthritis we shall pa.s.s over briefly. It is almost sufficient, in fact, to say that the whole of the joint becomes completely disorganized.

The synovial membrane becomes so tremendously thickened and injected as to be scarcely recognisable as such, the thickening in the later stages being due to large growths of granulation tissue which entirely alter the appearance of the membrane as we know it normally. In the early stages the contents of the joint are composed of thin pus and synovia. Later, as destruction of the synovial membrane proceeds, the flow of synovia is stopped, while the pus formation goes on until finally nothing but pus and dead tissue products fill the cavity.

If the suppurative process has commenced from within, the pus that is formed is, as a rule, thick and creamy, comparatively unstained, and free from marked odour. If, on the other hand, air has gained access to the joint, or the suppurative process has started from the materials introduced by a foreign body, the joint contents are thin, blood-stained, and stinking.

The inflammatory changes in the joint soon spread to the ligaments, and to the soft structures in contact with them. This means that the ligaments become infiltrated with inflammatory exudate, that the fibrous bundles composing them become separated, and that the ligaments are weakened and easily stretched. As a consequence, a certain amount of displacement or dislocation of the bones is allowed.

In like manner the inflammatory changes keep spreading until we have the periosteum next the ends of the bones affected. The periost.i.tis thus set up invariably takes the osteoplastic form, and as a result of this we have growths of new bone in the near neighbourhood of the joint. It is in the later stages of the disease--that is, when the pus has been evacuated and reparative changes commenced--that this osteoplastic periost.i.tis is most marked, and it plays a large part in bringing about the condition of anchylosis, which we shall afterwards describe.

Grave changes also occur in the articular cartilages. They quickly lose their peculiar glistening polish, their semitransparency is lost, and the natural tint of a pearl-like blue gives way to a dirty yellow. Later this is followed by erosion of the cartilages at such points as they happen to be in greatest contact. The ends of the bones are thus exposed, and their medullary cavities exposed to infection. As a result we get in them the changes we have already described under Ost.i.tis.

_Treatment_--_(a) Preventive_.--Seeing that many of these cases have their starting-point in stabs or penetrating wounds of the sole, we shall be concerned first with a consideration of the correct treatment to be adopted when we know the wound to have reached the articulation.

Only too frequently the treatment practised is that of poulticing. In other portions of this work we have pointed out the advantages that a continued antiseptic bathing has over the application of a poultice, the greater readiness with which the solution comes into contact with the deeper parts of the wound, and the far greater chance there is of maintaining water in an antiseptic condition than there is of keeping a poultice in the same state. There is no doubt, that in this case also, the cold or warm antiseptic bath is to be preferred to the poultice. It is questionable, however, whether even the bath is sufficient for our purpose here. We have in this case a deep punctured wound, and a wound that in every probability is infected with the organisms of pus or of putrefaction. It is a wound, moreover, which is likely to impede the thorough access to it of the solution in which the foot is fomented, on account of the flakes of coagulated fibrin which fill it.

The most rational treatment, therefore, if we get to the case early enough, is to irrigate the wound freely with a solution of carbolic acid in water (1 in 20), or with a solution of perchloride of mercury (1 in 1,000), injected by means of a gla.s.s syringe, or the pattern of syringe devised for quittor. This injecting should be done thoroughly, and by that we mean that several syringefuls of the solution should be injected, the joint after each injection being manipulated so as to distribute the solution as far as possible over it. When this is done the opening in the sole may be plugged with a little perchloride of mercury, or, better still, with a little piece of tow saturated with a concentrated solution of perchloride of mercury or a solution of iodoform in alcohol and an antiseptic pad of tow or lint placed over all. The foot should then be bandaged and encased in a boot or sacking protective. The bandage should be removed daily and the antiseptic pad changed. At each visit the animal's condition must be carefully noted. So long as const.i.tutional disturbance is slight, the foot appears comfortable, is free from marked heat and tenderness, and pawing movements are absent, and so long as the discharge on the pad appears non-purulent, free from marked odour, and small in quant.i.ty, then this dressing may be persisted in.

This treatment of open joint, preventive as it is of arthritis, is also indicated in the case of open navicular bursa. In several instances we have practised this treatment for the dressing of wounds implicating the bursae of tendons and the capsules of joints. It is also spoken of favourably by Mr. C.H. Flynn in the _American Veterinary Review_ for June, 1888, whose treatment is as follows: 'Place the patient in a clean, well-ventilated, and drained stable. Have all the litter removed, and insist on the stall being kept clean. Either place the animal in slings, or tie the head so as to prevent lying down. Clip the hair and cleanse the parts well. He prefers the corrosive sublimate solution (1 in 1,000). Should the wound be of two or more days' standing, inject the joint with the corrosive sublimate solution. Now dry the parts with a clean towel and sprinkle the wound with iodoform. Over this place a thick layer of absorbent cotton-wool, filled with iodoform, bandage securely, and keep the patient on a moderate diet, preserving the utmost quietude possible. Should the bandage remain in position and the animal free from pain, leave the bandage and dressing in place from five days to a week. Then change it, and should the discharge be little, do not disturb it, but renew the iodoform and cotton dressing, leaving it on for another week.'

Other treatments for the same condition are practised, in which the wound is dusted with powdered iodoform, with pota.s.sium permanganate, or with corrosive sublimate, or where the wound, instead of being dusted, has the corrosive sublimate applied in the form of a plug. In each case the preliminary irrigation with the corrosive sublimate solution is dispensed with. This, however, should on no account be omitted. In our opinion it const.i.tutes the very essence of the rationality of the treatment.

_(b) Curative_.--It may happen, however, and often does, that this first injection of an antiseptic is unsuccessful in preventing organismal infection of the wound. In this case grave const.i.tutional disturbance and other untoward symptoms such as we have already described quickly make their appearance.

The animal should now be placed in slings and preparations made for actively treating the wound with antiseptics. Whether we fail or not, we have the satisfaction of knowing that we have given to the patient the best and the only chance of recovery.

It should be remembered, however, and should be pointed out to the owner, that with purulent arthritis fully developed, with the grave const.i.tutional changes it occasions, and with the ever-present danger of a general septic invasion of the blood-stream, that the human surgeon under such circ.u.mstances offers to his patient the alternatives of amputation or probable death. With us no such alternative is possible. It is either return the joint to some semblance of its former usefulness, or destroy the patient.

In this case we advise the injection of the original wound, and also such fistulous openings as may have formed, with the 1 in 1,000 sublimate solution. Also, in order to avoid the sometimes abortive attempts of the antiseptic pad, to maintain a condition of asepsis around the wound, we advise the continual soaking of the whole foot in a cold antiseptic bath.

This may be either carbolic acid 1 in 20, or--what is less volatile, perhaps more effectual, and certainly more economical--perchloride of mercury 1 in 1,000.

It has been our good fortune, even when we have seen the foot almost detached from the limb by the devastating inroads of the pus, to see the suppurative process by this means gradually overcome, a reparative anchylosis set in, and the animal restored to good health and usefulness, if not to soundness.

Once the suppurative process is checked and anchylosis commences, it is good treatment to smartly blister the whole of the region of the coronet, the pastern, and the wound itself with a mixed blister of cantharides and biniodide of mercury, repeated at intervals of a fortnight. This prevents to some extent further infection of the wound, and a.s.sists also in promoting the changes that tend to anchylosis.

_(d)_ ANCHYLOSIS.

The word anchylosis signifies the stiffening of a joint. When one has read the serious changes occurring within the joint in the more serious forms of arthritis, it is easy to understand how it comes about. In suppurative arthritis, for instance, we have the synovial membrane destroyed, the articular cartilages partly or wholly obliterated, and the former boundaries of the joint entirely lost. If the animal lives, nature is bound to make repair of a sort. The synovial membrane and the articular cartilages utterly destroyed, as we have described, cannot again be replaced. Nature can only build again from such materials as are left to her. In this case the material is bone.

It must be remembered, however, that often the bone has been so diseased that spots of necrosis or caries within it are bound to remain unless moved by operative interference. Such diseased portions, when dealing with the foot, are beyond reach of the surgeon's knife, and we have no alternative but to allow them to remain. We get, therefore, in many cases, a condition of rarefactive ost.i.tis occurring side by side with a slowly progressive caries within the bone, while outside is occurring an osteoplastic periost.i.tis. The concurrence of these conditions leads in time to great increase in size of the parts, together with increasing anchylosis and deformity.

C. NAVICULAR DISEASE.

_Definition_.--Chronic inflammatory changes occurring in connection with the navicular bursa, affecting variously the bursa itself, the perforans tendon, or the navicular bone, and characterized by changes in the form of the hoof and persisting lameness. The disease is commonly noticed in thoroughbreds or in horses of the lighter breeds, and is but seldom observed in heavy cart animals. Usually it is met with in one or both fore-feet. Although of extremely rare occurrence, it has been noticed in the hind.

_History_.--To English veterinarians appears to belong the credit of discovering navicular disease. As early as 1752 we find one, Jeremiah Bridges, in 'No Foot, No Horse,' drawing attention to 'coffin-joint lameness,' and advocating for its treatment setoning of the frog. It appears, too, that Moorcroft, prior to his departure for India in 1808, was acquainted with what was then known as coffin-joint[A] lameness, having drawn attention to it in 1804 in a letter to Sir Edward Codrington.[B] In 1819 Moorcroft made it even plainer still that he was fully acquainted with what we now know as navicular disease. This we learn from a letter written by him to Sewell, in which he laid claim to being the originator of neurectomy. In this letter he says:

[Footnote A: The coffin-joint at this time included the navicular bursa.]

[Footnote B: Percival's 'Hippopathology,' vol. iv., p. 132.]

'On dissecting feet affected with these lamenesses, the flexor tendon was now and then observed to have been broken, partially or entirely, but more commonly to have been bruised and inflamed in its course under the navicular or shuttle bone, or at its insertion into the bone of the foot.

Sometimes, although seldom, the navicular bone itself has been found to have been fractured; at others its surface has been deprived of its usual coating, and studded with projecting points or ridges of new growth, or exhibiting superficial excavations more or less extensive.'[A]

[Footnote A: _Ibid_.]

_Pathology and Point of Commencement of the Disease_.--The exact position in which the diseased process starts has for a long time been a subject of discussion, and even now it is doubtful whether the point has been definitely settled. To mention but a few among many: We find Mr. Broad, of Bath, strenuously insisting on the fact that the disease commences in the interior of the navicular bone. Just as strenuously we find the editor of the journal in which the matter is being discussed, the late Mr. Fleming, a.s.serting that the disease commences in the bursa.[A] Others, too, hold that the disease commences primarily in the tendon. Wedded to this view was the discoverer, Mr. Turner, of Croydon; while Percival commits himself to the statement that it is either the central ridge or the postero-inferior surface of the navicular bone, or the opposed concavity in the perforans tendon, that shows the earliest signs of the disease. The observations made by Dr. Brauell, the first Continental writer to fully describe the disease, led him to the statement that neither the bone nor the bursa was the _invariable_ starting-point of the trouble, but that usually it commenced in inflammation of the bursa itself.

[Footnote A: Percival's 'Hippopathology,' vol. iv., p. 132.]

Without, therefore, committing ourselves to an expression of opinion as to the precise starting-point of the affection, we shall describe the pathological changes occurring in navicular disease as noted in (1) the bursa, (2) the cartilage, (3) the tendon, and (4) the bone.

1. _Changes in the Bursa_.--Upon the internal surface of the bursal membrane is first noticed a slight inflammatory hyperaemia, accompanied by more or less swelling and tumefaction, owing to its infiltration with inflammatory exudate. The portion covering the hyaline cartilage of the navicular bone has lost its peculiar pearl-blue shimmer, and become a dirty yellow.

Remembering that the bursal membrane is a synovia-secreting one, and bearing in mind what happens in ordinary synovitis and arthritis (with which, of course, this may be very closely compared), we shall first expect changes in the bursal contents. It is highly probable, though difficult of proof, that in the very early stages the chronic inflammatory stimulus has the effect of increasing the flow of synovia. In every case, however, where it can with any certainty be said that navicular disease exists, it is too late to meet with this condition. The disease has then progressed until destruction of the secreting layer of the bursal membrane has been seriously interfered with, and in this case we find a distinct deficiency in the quant.i.ty of synovia in the bursa. In advanced cases it is even found that the bursa is _absolutely dry_.

2. _Changes in the Cartilage_.--Directly that portion of the bursal membrane covering the cartilage is the subject of inflammatory change, the cartilage itself, by reason of its low vitality, soon suffers.

Under a process, which we may term 'dry ulcerative,' the cartilage covering the ridge on the lower surface of the bone commences to become eroded, and in appearance has been likened, both by English and Continental writers, to a piece of wood that has been worm-eaten (see Fig. 161).