FRACTURE IN SITU (OS CORONÆ).
FIG. 158.—FRACTURE IN SITU (OS CORONÆ).
'The diagnosis was now that a fracture existed, and it was proposed to send the mare to grass for a few months. The consulting veterinary surgeon suggested that before doing so a blister might be applied to the coronet. This was done. The mare was found next day again on three legs. She had apparently been down during the night. In a few days the coronet increased again in size, and within a week "broke out" in two places.
'The opinion now formed was that, with a fracture and this additional cause of inflammation around the joint, it would be most economical for the owner to have her killed. This was done, and a post-mortem examination was made by Mr. Hunting and Mr. Willis.
WITH BROKEN PORTION REMOVED.
FIG. 159.—WITH BROKEN PORTION REMOVED.
'Post-mortem.—The foot, cut off at the fetlock-joint, showed extensive swelling all round the coronet. There were two wounds on the skin—one on the front of the coronet, the other on the inner side. From both pus and blood had escaped. They both communicated under the skin with a large abscess cavity. The abscess did not communicate with the joint. The pastern bone was sound. On separating the pastern from the coronet bone the articular surfaces were of a healthy colour, but the soft tissues immediately surrounding them were inflamed. On the centre of the articular surface of the coronary bone a thin red ring was noticed, and the portion of cartilage within it seemed raised. With the point of a scalpel this portion was lifted, and was found to be not only cartilage, but a layer of bone completely detached from the os coronæ. On removing the bones from the hoof the rest of the bone was quite normal, as was the pedal bone.
'Fig. 158 shows the articular surface of the coronet with the fracturein situ; and Fig. 159 the surface from which the broken portion is removed and laid to the side of the foot.
'Some interesting questions arise. How was the fracture caused? When did it occur? Between the broken portion and the main bone there was a layer of granulation tissue, so that it is certain the injury existed before the blister was applied, and it may possibly have existed from the commencement of the lameness.'[A]
[Footnote A: R. Crawford, M.R.C.V.S.,Veterinary Record, vol. viii., p. 478.]
2. FRACTURES OF THE OS PEDIS.
These also are a result of the causes we have before given. The os pedis is also liable to fractures from pricks, from treads in the region of the wings, and from the malnutrition and careless use of the foot sometimes following neurectomy.
It is interesting to note that, with fracture of this bone, lameness is nearly always excessive, but that at times it may be entirely absent. Crepitus is, of course, denied us, and in nearly every instance the case is only diagnosed when the lameness persists and pus commences to form, or when grave changes in the normal shape of the foot compel our attention to the parts. When it is the continued formation of pus that draws our notice to something more than ordinarily grave, it is in giving exit to the pus that the fracture is nearly always discovered.
Reported Cases.—Two interesting cases of fractured os pedis are reported by Mr. Gladstone Mayall, M.R.C.V.S., in theVeterinary Record, vol. xiv., p. 54:
1. 'The horse was brought in markedly lame on the off hind-foot, knuckling at the fetlock, and taking a long stride with the injured limb. There was a punctured wound at the toe. The horn was pared, and antiseptic poultices applied. Notwithstanding the antiseptic treatment pus continued to form. At the end of a week sufficient horn was removed to ascertain the cause of the constant suppuration. A movable object was found at the bottom of the wound, and a piece of bone as large as a sixpence finally removed. Recovery was uneventful.'
FRACTURED OS PEDIS.
FIG. 160.—FRACTURED OS PEDIS.
2. 'A filly was attended for a discharging fistula at the coronet. Externally it had all the appearances of a quittor. At first no history was given. The filly went scarcely lame at all, and had never been shod. Treatment with poultices and caustic injections was useless. Finally the filly was cast and the foot examined. A piece of bone, apparently part of the wing of the os pedis, was removed, and the case made a good recovery. Subsequent inquiries elicited the fact that the animal had kicked at and hit a gate-post, and it was judged that then the injury had occurred.'
3. 'The subject was a bay horse, nine years old, used for railway shunting. On August 7 he was found to be intensely lame of the near hind-limb, and, after inquiries, there was no evidence bearing on the cause, as is often the case, and at times this comes to light when least expected.
'I was called in consultation on September 2, and found him suffering acute pain, with great swelling around the coronet. The foot was examined thoroughly, and the diagnosis was fracture of the pedal bone, and immediate slaughter was recommended. However, that was not carried out, and he died on September 22.
'The post-mortem inspection revealed a complete fracture of nearly the whole of the articulating surface and the left wing of the pedal bone (as shown in Fig. 160).'[A]
[Footnote A: J. Freeman, M.R.C.V.S.,Veterinary Journal, vol. xxxi., p. 324.]
4. A further interesting case is reported by Mr. William Hurrell.[A] Here the cause was presumably galloping in the field, for the subject, a cart mare running out at grass with her foal, was suddenly found to be lame.
[Footnote A:Ibid., vol. v., p. 408.]
As the lameness continued to increase in severity, Mr. Hurrell was called in on August 1, and diagnosed the case as one of foot lameness. On this date the foot was pared out, and a large accumulation of pus discovered, Poulticing and antiseptic dressings were continued until August 16, when a movable piece of the os pedis was found at the toe.
On August 25 this detached portion of the bone was removed, and turned out to be the whole of the anterior margin of the os pedis, measuring 3-1/2 inches long, and varying in width from 1/2 inch to 1-1/2 inches. On September 20 the mare was working without lameness.
3. FRACTURES OF THE NAVICULAR BONE.
Hidden within the wings of the os pedis, and protected as it is by its tendinous covering and the yielding substance of the plantar cushion, the navicular bone is even less liable to fracture than either of the other bones of the foot.
The most common cause of fracture of the navicular is that of stabs or deep pricks in the region of the point of the frog (see p. 216). Following that, the next most common cause is violent injury. We thus find the navicular bone fractured, together with one or both of the other bones of the foot, when the foot is run over by a heavy vehicle. One such case is reported by Mr. J.H. Carter, F.R.C.V.S., where the horse's foot was run over by a tram-engine, in which the os pedis and the navicular were fractured in several places.[A] A further case is on record where a sharp blow on the front of the hoof was the cause. In this case the os pedis and other structures were uninjured, but the navicular bone was fractured into three large, and about half a dozen small, pieces.[B]
[Footnote A:Veterinary Journal, vol. xxxi., p. 246.]
[Footnote B:Veterinarianfor 1857, p. 73.]
Fractures of the navicular may occur, however, in which history of a prick or of a violent injury is absent. See reported case below.
As with fractures of the os pedis and the os coronæ, so with this exact diagnosis is difficult—we may say almost impossible. With a history of violent injury, however, some little regard may be paid to a continued heat and tenderness of the foot, and a distinct inclination on the part of the animal to go on the toe. Even when the fracture is the result of a prick, and the bone is plainly felt with the probe, we still cannot be positive as to fracture.
Reported Case.—'The animal was a Hungarian, a troop-horse in the 3rd Hussars (G. 15). On November 22, 1881, on the march from Norwich to Aldershot, the horse suddenly made a violent stumble, very nearly coming on to his knees. The rider declared that he put his foot on a stone. The accident caused great lameness in the near fore-leg, and the horse had to be led the remainder of that day's march. On the following day he was also led; but, after going some sixteen or eighteen miles, he was so lame that he was left at the nearest billet (in Edmonton). He was here attended by Mr. Stanley, M.R.C.V.S., of Edmonton, who pronounced it a case of navicular disease. I first saw the animal on December 1, 1881, and quite agreed with Mr. Stanley that it was a case of foot lameness, though, from the horse's former history, I could not think it a case of ordinary navicular disease. I diagnosed it a case of fracture, without displacement, either of the os coronæ or the navicular bone, but was more inclined to the former than the latter. This was after a full hour's examination. I failed to find any heat in, or any flinching by manipulation of, any part of the limb; but, in walking, the horse was excessively lame, going on the toe, and, indeed, trying if possible to keep the foot entirely off the ground.
'On December 6 the horse was sent on to Aldershot by rail. He was then walking better, though still very lame. My only treatment for a short time was to apply cold water constantly to the coronet and foot. For two hours daily this was done by a hose, the remainder of the time by a cold swab. On December 14 I applied a strong blister over the coronet, reaching up to the fetlock. This was washed off about the end of December. The horse was then not nearly so lame. I then resumed the cold-water treatment, and he got gradually better, and was sent to light duty on February 18, 1882. He, however, only attended one field-day, and was taken into the Horse Infirmary again on March 8, very lame. Again, there was an entire absence of heat or pain on pressure, but the same action, viz., going on the toe. I forgot to remark that he always pointed the toe of the affected leg when standing in the stable, and this symptom continued. I put him under the cold-water treatment for a short time, and about the middle of March again applied a strong blister over the coronet up to the fetlock. This was washed off about the end of the month, and was succeeded by the cold water again. Towards the end of April there was no improvement at all, and I applied for permission to destroy the horse. This was carried out on April 27, at the recommendation of Mr. Gudgin, I.V.S., Aldershot, and a Board of veterinary surgeons.
'On making the post-mortem examination I first thought the bone was only partly fractured or cracked, but on manipulating it, after its being in hot water a short time, I saw the fracture was complete.'[A]
[Footnote A: S.W. Wilson, M.R.C.V.S., A.V.D.,Veterinary Journal, vol. xv., p. 12.]
Treatment of Fractures of the Bones of the Foot.—It will be seen at once that in most cases anything in the way of bandaging is well-nigh useless. When the os coronæ is fractured, however, a little more may be added to the natural rigidity of the parts by enclosing the region of the pastern and the foot in a plaster-of-Paris bandage. The main treatment, however, in every case, will be a continual use of the slings for at least seven to eight weeks, by that means compelling the animal to give to the injured parts the necessary amount of rest.
With fracture of the os pedis, when such is caused by pricks and complicated by a flow of pus, then attention must be given to removal of the displaced piece of bone. The pus track is to be followed up with the searcher, sufficient horn removed with the knife, and the broken piece of bone removed with a scalpel and a pair of strong forceps, the operation to be afterwards followed up by antiseptic dressings to the opening. Until this is done the wound refuses to heal.
Fracture of the navicular bone, if in any way diagnosed with certainty, offers us an almost hopeless case, for it appears to be a commonly reported fact that attempts at reunion are rare. This, in all probability, is due to the pressure put upon it every now and again, when the animal's weight presses the bone between the os coronæ and the os pedis above and the perforans tendon below. Even should reunion take place, the resulting callus, interfering as it does with the movements of the perforans, leaves us a case of incurable lameness. When the fracture is complicated by the formation of pus, as in the case of prick, then the case, with the attendant purulent synovitis and arthritis, is even more hopeless still.
Diagnosis of fracture of either of the bones of the foot is, as we have said before, extremely difficult. It so happens, therefore, in those cases caused by violent blows, that anything approaching an accurate opinion cannot be given until some months after the injury. After some time we are met with unmistakable changes in the form of the foot, and are able to assume that the persisting lameness is due to pressure of a reparative callus within the hoof. In such cases the only treatment of any use is that of neurectomy.
[Footnote A: Properly speaking, we have in the foot of the horse butonejoint—namely, the corono-pedal articulation.
Although not a joint in the strict sense of the word, we, nevertheless, intend here to consider the navicular bursa as such. In this apparatus, although we have no articular cartilage proper, and no apposition of bone to bone, we still have a large synovial cavity, and in close proximity to it bone. We may, in fact, and do get in it exactly similar changes to those termed 'synovitis' and 'arthritis' elsewhere. Therefore, we include the changes occurring in it in this chapter, and hence the plural use of the word to which this note refers.]
Definition.—By the term 'synovitis' is indicated an inflammation of the synovial membrane. It may be either (a)SimpleorAcute, or it may be (b)PurulentorSuppurative.
In the simple form there is little or no tendency for the affection to implicate the other structures of the joint, whereas in the suppurative form the joint capsule, the ligaments, and the bones soon come to participate in the diseased processes, giving us a condition which we shall afterwards describe as acute arthritis.
(a) SIMPLE SYNOVITIS.
1.Acute—(Causes).—Simple or acute synovitis is nearly always brought about by injury to the joint—by blows or bruises, or by sprains of the ligaments. At other times it occurs without ascertainable cause, and is then put down to the influence of cold, or to poisonous materials (as, for example, that of rheumatism) circulating in the blood-stream.
Pathology.—Uncomplicated acute synovitis never causes death. The pathological changes in connection with it have therefore been studied in cases purposely induced, and the animal afterwards slaughtered. It is then found that, as in inflammation elsewhere, the synovial membrane is showing the usual inflammatory phenomena—that it is thick and swollen as a result of the inflammatory hyperæmia and commencing exudation. Later, the synovial fluid becomes increased in quantity, is thin and serous, and after a time is seen to be mixed with the inflammatory exudation poured into it. We then find that it has lost its clear appearance, has become thick and muddy, and has floating in it flakes of fibrin.
If the case progresses favourably these materials are soon absorbed and resolution occurs. In rarer cases the thickening and congestion of the membrane increases, and the articular capsule becomes so distended with the increased synovia and accumulated inflammatory discharges that a kind of chemosis occurs. In other words, there oozes through, without actual rupture of the membrane, a thin, blood-stained, and purulent-looking discharge.
It is an important point to note that in cases of synovitis the fringes of the synovial membrane become swollen and blood-injected, forming noticeable red elevations at the margins of the cartilages. It is then that the diseased condition soon spreads and runs into arthritis.
Further, it is important, especially with regard to the question of the degree of pain and lameness likely to be caused, to note that often granulations are thrown out upon the looser folds of the membrane. As these increase in size they come to form fringed and villous membranous projections inserting themselves between the bones forming the articulation. In such cases there is no doubt that the intense pain sometimes observed in these cases is due to pinching of these prolongations of the synovial membrane by the opposing bones of the joint.
Symptoms and Diagnosis.—Acute synovitis of a joint leads to heat of the parts, pain, distension of the capsule, and, where the joint may be easily felt, fluctuation. In the articulation with which we are dealing, however, these last two symptoms are not easily detected, for the surrounding structures—namely, the lateral and other ligaments of the joint, the extensor pedis tendon in front, and the perforans behind, together with the dense and comparatively unyielding nature of the skin of the parts—are such as to prevent distension and fluctuation becoming marked to a visible extent. We are able to diagnose the case as one of foot lameness, and, with a history of a severe blow or other injury, are able to assume that this condition, perhaps attended with periostitis, is in existence.
When other symptoms present themselves diagnosis may be more certain. The animal becomes slightly fevered, throbbing pains in the joint manifest themselves by irregular pawing movements on the part of the patient. The animal comes out from the stable stiff, even dead-lame, and the limb is carried with the lower joints semiflexed. The breathing is hurried and the pulse firm and frequent, while in a bad case patchy perspiration breaks out at intervals on various parts of the body. If with this we get a puffy and tender swelling in the hollow of the heel, our diagnosis may be certain at any rate as to the existence of joint trouble, although, from reasons we have given, we may not be able to mark its exact nature.
2.Chronic.—Simple synovitis may in many instances become chronic. In this case we have simply a pouring into the synovial capsule of serous fluid, and with it an increased quantity of synovia—this time with an absence of the usual inflammatory phenomena. Beyond the swelling of the capsule there is little to be noticed. The joint becomes perhaps a little weaker, but pain or tenderness and heat are entirely absent. Such a condition, by reason of the natural rigidity of the parts, is not to be observed in the foot, although at times it must most certainly occur. Examples of such a condition are to be found in bog-spavin, in hygroma of the stifle, and sometimes in the fetlock. From a study of these, we know that they may be induced by frequent attacks of acute synovitis, from repeated slight injuries or bruises, or from strains to the ligaments of the joint; or that they may be chronic from the outset. We know, too, that in such cases the synovial membrane becomes thickened, and that in places it may have extended somewhat over the edges of the articular cartilages. It is only fair to suppose that such changes occur also in the pedal articulation. In that case we may take it for certain that the natural rigidity of the surrounding structures has the effect of pushing the thickened membrane further between the bones of the joint than occurs in a like condition elsewhere, leading, of course, to a lameness that is marked in degree but occult as to cause.
In our minds there is no doubt that many of the occult and chronic forms of foot-lameness we meet with in practice are in this way to be accounted for. We may, in fact, explain them by suggesting either a chronic synovitis alone, or a synovitis complicated with periostitis.
Treatment of Synovitis.—If a joint has been injured, as we have suggested, by slight blows or other causes—in other words, if the injury is subcutaneous, and no wound is in existence—then there is no treatment which offers better results than does the continued application of cold.
At the same time, the animal should be slung, or, if non-excitable and inclined to rest, allowed at intervals to lie on a thick and comfortable straw bed, the cold fomentations during such intervals being discontinued. When the case is a marked one and the animal valuable, benefit will be derived from the application of crushed ice.
The animal's condition must be watched, and the case helped as far as is possible by the administration of a mild dose of physic, by saline drinks, and, when necessary, by the giving of small but repeated doses of Fleming's tincture of Aconite in order to relieve the pain. In a chronic case the repeated application of a blister is indicated.
(b) PURULENT OR SUPPURATIVE SYNOVITIS.
In this condition we have synovitis complicated by the presence of pus. Unlike the simple form, it shows a marked disposition to spread, and quickly involves the surrounding structures. Very soon the ligaments of the joint, the periosteum, the articular cartilages, and the bones are implicated. This, of course, constitutes a condition of acute purulent arthritis. Under that heading, therefore, the condition will be later discussed.
(a) SIMPLE OR SEROUS ARTHRITIS.
With an attack of simple synovitis it may be always assumed that the changes commenced in the synovial membrane, communicate themselves more or less readily to the surrounding tissues, and are not confined to the synovial membrane alone. We may thus have the inflammatory phenomena asserting themselves in the surrounding ligaments, in the periosteum, in the bone, and in the articular cartilages. It depends, in fact, upon the severity of our case whether we call it synovitis or arthritis. The two conditions merge so the one into the other that no hard-and-fast rule may be laid down whereby they may with certainty be differentiated. Such symptoms, therefore, as we have given for synovitis may be also read as indicating a condition of simple arthritis. The course of the case will be very similar, and the treatment to be followed identical with that just given.
(b) ACUTE ARTHRITIS.
Causes.—An attack of acute arthritis may commence with the affection of the synovial membrane, and spread from that to the other structures. In other cases the disease of the synovial membrane, and after it the disease of the joint, may be secondary to diseases commencing in the structures around the joint. This affection may therefore follow on a case of acute coronitis, a case of suppurating corn, a case of quittor, a severe case of tread, or may attend a case of laminitis.
Symptoms.—In our cases we get very little beyond a magnification of such symptoms as we have described under acute synovitis. The heat and the pain is perhaps greater, and the lameness more marked. It is rather to the constitutional disturbance we must look, however, for a confirmation of our opinion that arthritis is in existence. This is always severe, and of an acute febrile nature. The pulse is fast, thin, and thready, the respirations enormously increased, and the temperature high. The appetite is in abeyance, the animal quickly becomes what is termed 'tucked-up,' or greyhound-like, in the body, and patchy perspirations break out about him. The limb is held with the joints all semiflexed, and severe and intense throbbing pains are indicated by the frequent pawing movements the animal makes in the air. Manipulation of the foot is resented, and the agonizing intensity of the pain so caused is shown by the drawn and haggard appearance of the eyes.
In a favourable case the symptoms from now onwards may gradually subside. The appetite returns, the breathing and other signs of disturbance show a return to the normal, weight is placed on the limb, and resolution slowly but surely takes place. In many of these, our favourable cases, however, resolution is incomplete, and recovery only takes place at the expense of anchylosis of the joint, a condition we shall refer to later.
In unfavourable cases, and these unfortunately are only too common, the condition terminates in suppuration.
(c) PURULENT OR SUPPURATIVE ARTHRITIS.
Definition.—By this term we indicate an arthritis complicated by the formation of pus within the joint.
Causes.—The organisms of pus may infect the joint by extension of a suppurating process from without. For example, in the case of a suppurating corn, in quittor, in tread, or in the case of a suppurating wound caused by a prick, the pus formed may in many instances be very near the capsular ligament of the articulation. Under such circumstances, unless there is a free and unhindered flow of the pus from an outside opening, inroads will be made by it upon the thin capsule. The latter is quickly penetrated, and pus is admitted to the interior of the joint.
In other cases infection of the joint may proceed from within, from a poisoned state of the blood-stream. The condition occurs, for instance, in bad attacks of laminitis. We ourselves, too, have seen two cases where suppuration of the pedal articulation occurred in the septic pyæmia of foals, a disease known commonly as 'joint-ill,' and characterized by an infected state of the circulation. Cases have also come under our notice where this condition has resulted from slight injuries in the region of the insertion of the extensor pedis inflicted by the animal himself when galloping away.
Perhaps, however, the most common cause of suppurative arthritis in the foot is direct penetration of the articulation in the case of pricks. 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 constitutional 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 recumbent 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 appetite, 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 assistance.
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 constitution, 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 pyæmia. 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 pyæmia.
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 rectum, or in the case of a mare about the vulva. 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 buttocks, 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 pass 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 periostitis 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 periostitis 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 Ostitis.
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 glass 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 constitutional 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 quantity, 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 bursæ of tendons and the capsules of joints. It is also spoken of favourably by Mr. C.H. Flynn in theAmerican Veterinary Reviewfor 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 potassium 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 constitutes 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 constitutional 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 constitutional changes it occasions, and with the ever-present danger of a general septic invasion of the blood-stream, that the human surgeon under such circumstances 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 assists 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 ostitis occurring side by side with a slowly progressive caries within the bone, while outside is occurring an osteoplastic periostitis. The concurrence of these conditions leads in time to great increase in size of the parts, together with increasing anchylosis and deformity.
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, asserting 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 theinvariablestarting-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 hyperæmia, 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 quantity of synovia in the bursa. In advanced cases it is even found that the bursa isabsolutely 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).