CHAPTER III.. Diseases of the Synovial Membranes and of the Articulations.

DISEASES OF THE SYNOVIAL MEMBRANES AND OF THE ARTICULATIONS.

I.—SYNOVIAL MEMBRANES AND ARTICULATIONS.

SYNOVITIS.

Inflammation of the synovial membranes, or synovitis, may affect the synovial sacs either of the joints or of the tendon sheaths. It may be acute or chronic and occur either idiopathically or follow the infliction of an injury. Its two chief forms are simple, or “closed,” synovitis and suppurative, or “open,” synovitis, the essential distinction between which is that in the latter microorganisms are present, whilst in simple synovitis they are absent. In all cases the disease is characterised by distension of the sac affected.

Synovitis produced by a wound communicating with the outer air may be complicated by suppuration, and if the synovial membrane of a joint be involved the primary synovitis is almost always followed by traumatic arthritis.

The commonest forms of chronic simple synovitis are:—

INFLAMMATION OF THE PATELLAR SYNOVIAL CAPSULE.

Inflammation of the synovial membrane of the femoro-patellar joint is most commonly seen in working oxen as a consequence of strains during draught. It is also found in young animals which have injured the synovial capsule through falls, slips, or over-extension of the limb.

=Symptoms.= Development is slow and progressive, and injury may not be discovered until the lameness which follows has become fairly marked. This lesion is characterised by swelling in the region of the stifle. On palpation, fluctuation may readily be noted both on the outer and inner surfaces of the joint. The exudate is sometimes so abundant and distension so great that the straight ligaments, the neighbouring bony prominences, and the ends of the tendons are buried in the liquid swelling.

Lameness, which is at first marked, often diminishes with exercise. The length of the step is lessened.

=Diagnosis.= The diagnosis presents no difficulty, but the lesions must be distinguished from those due to tuberculosis in this region, rheumatic arthritis, and the specific arthritis seen in milch cows.

=The prognosis= is grave, for the disease renders animals useless for work.

=Treatment.= Rest, cold moist applications, and massage constitute the best treatment in the early stages. Should swelling persist, one may afterwards apply a smart blister or even tap the joint aseptically, drawing off the fluid and then applying the actual cautery. Irritant injections must be avoided.

DISTENSION OF THE SYNOVIAL CAPSULE OF THE HOCK JOINT.

Bog Spavin in the Ox.

Bog spavin is frequent in working oxen and in oxen from three to five years old. It is due to strain in draught or to strain produced in rearing up at the moment of covering. Old bulls, heavy of body, and stiff in their limbs are predisposed to it.

=Symptoms.= The symptoms usually develop gradually and without lameness, but sometimes declare themselves more rapidly with lameness, accompanied by marked sensitiveness on palpation. At first the hock shows a generalised doughy swelling, soon followed by dilatation of the articular synovial sac. Somewhat later four different swellings appear—two in front, separated by the tendons of the common extensor and flexor metatarsi, and two at the back, extending inside and outside to the flexure of the hock.

=Diagnosis.= The only precaution required in diagnosis is to avoid confusion with articular rheumatism.

=Prognosis.= The prognosis is rather grave in the case of working oxen, and even of bulls; often slaughter is preferable to treatment.

=Treatment= differs in no respect from that of distension of the stifle joint. In young bulls aseptic puncture and drainage of the joint, followed by the application of the actual cautery, probably give the best results.

DISTENSION OF TENDON SHEATHS IN THE HOCK REGION.

Like the preceding, this condition is rarely seen except in bulls and working oxen. It is characterised by dilatation of the upper portion of the tarsal sheath, one swelling appearing on the outer side, the other on the inner.

The differential =diagnosis= is based on the position of these synovial sacs, which are quite close to the insertion of the tendo-Achillis, and on the absence of any swelling in front of the joint.

=Treatment= is identical with that indicated in the last condition.

Massage and cold water applications should be employed at first, to be followed by aseptic puncture and withdrawal of fluid, supplemented if necessary by firing in points.

DISTENSION OF THE SYNOVIAL CAPSULE OF THE KNEE JOINT.

This is one of the rarest conditions now under consideration, because the synovial membranes of the knee joint are everywhere strongly supported by very powerful ligaments. The synovial capsules of the carpo-metacarpal and inter-carpal joints are incapable of forming sacs of any size. On the other hand, the radio-carpal may become moderately prominent in front, especially towards the outside above the superior carpal ligament. When weight is placed on the limb, the excess of synovia is expelled from the joint cavity towards this little sac, which then becomes greatly distended. If, on the other hand, the knee is bent, the sac shrinks or disappears.

=Treatment.= Treatment is restricted to the application of a blister or to firing in points.

DISTENSION OF THE SYNOVIAL CAPSULE OF THE FETLOCK JOINT.

The synovial capsule of the fetlock joint in the ox is strongly supported in front and at the sides, but may protrude under the anterior ligament, producing a swelling behind the metacarpus under the five branches of division of the suspensory ligament and slightly below the sesamoid bones. These distensions, like bursal swellings, are commoner in hind limbs and in old working oxen. Their development is always followed in time by a certain degree of knuckling over. At first the metacarpus and phalanges come to form a straight line, but later the fetlock joint itself is thrust forward.

=The diagnosis= necessitates careful manual examination of the region of the fetlock joint.

=The prognosis= is somewhat grave, for the disease sooner or later necessitates the destruction of certain animals.

=Treatment= is practically identical with that used in all such conditions: friction with camphorated alcohol, cold affusions and massage in the earlier stages, followed if needful by blisters or firing in points.

DISTENSION OF TENDON SHEATHS.

Distension of the synovial capsule which surrounds the superior suspensory ligament, like distension of the articular capsule of the fetlock, occurs in working animals, and most commonly affects the front limbs. It is indicated by two swellings, one situated on either side of and behind the branches of division of the suspensory ligament and in front of the flexor tendons. These two swellings extend higher than the articular swellings, which, however, they sometimes accompany. The surface of the fetlock is then swollen, doughy on pressure, and somewhat painful.

These enlargements may produce more or less marked lameness and cause knuckling.

=The diagnosis= is clear from local examination.

=The prognosis= is unfavourable, as the animals after a time become useless for work.

=Treatment.= The beginning of the disease may often be cured by baths of running water, combined with massage. At a later stage, local stimulants, blisters, or firing are necessary. The best treatment probably consists in puncturing the parts with antiseptic precautions, washing out the synovial cavity with an antiseptic, and immediately afterwards lightly firing the surface of the region in points.

DISTENSION OF TENDON SHEATHS IN THE REGION OF THE KNEE.

Any of the numerous tendon sheaths which facilitate the gliding of tendons in the neighbourhood of the knee may become inflamed and give rise to a chronic synovial swelling. The commonest of such swellings is due to distension of the sheath of the extensor metacarpi magnus, which appears as a vertical line in front of the knee, extending from the lower third of the forearm and slightly to the outer side of the central line. This synovial enlargement arises in oxen working on broken roads, in clay or marshy soils, where the animals are liable to stick fast, and are often obliged to struggle vigorously in order to extricate themselves.

=The diagnosis= is based on the position and direction of the dilated synovial sheath.

=Treatment= is identical with that of other cases of chronic synovitis.

DISTENSION OF THE BURSAL SHEATH OF THE FLEXOR TENDONS.

This condition is rare. It is announced, as in the horse, by a dilatation of semi-conical form, the apex of which is situated opposite the lower margin of the carpal sheath, the base extending as high as the infero-posterior third of the radius.

The dilatation is more marked on the inner than on the outer side of the limb.

Distension of the synovial sheath of the common extensor of the digits in the fore limb and of the extensor of the external digit is still rarer than the preceding conditions.

TRAUMATIC SYNOVITIS—“OPEN SYNOVITIS.”

When an injury in the neighbourhood of a joint penetrates deeply, it may implicate either the synovial sheath of a tendon or the synovial membrane of a joint. If the body inflicting the wound is aseptic, a condition which in accidental wounds is rare, the wound may have no grave consequences. Usually, however, the body producing the injury is infected, and the infection rapidly extends throughout the tendon sheath or synovial sac. In the first case, traumatic suppurating synovitis of a tendon sheath is the result; in the second, a suppurating articular synovitis arises, which soon becomes complicated with injury of the articular cartilages, ligaments, etc. (traumatic arthritis).

The primary lesion may only affect the periarticular region, not directly extending to the synovial membranes, and only after an interval of some days may symptoms of suppurating synovitis or suppurating arthritis appear, in consequence of progressive invasion of the parts by specially virulent microbes.

TRAUMATIC TENDINOUS SYNOVITIS.

Suppurative inflammation of the synovial bursæ of tendons in consequence of wounds most commonly affects the sesamoid sheaths of the front or hind limbs; more rarely, the tendon sheaths of the hock or knee; and, exceptionally, the small synovial sheaths of the extensors of the metacarpus and phalanges, etc.

Such inflammation follows injuries with forks, harrow teeth, or any sharp foreign body. It is characterised by the existence of a fistula or wound, indicating the course taken by the body inflicting the injury, from which at first normal synovia escapes. Later, however, the discharge becomes turbid, and after the second day gives place to a clotted, serous, or purulent fluid.

A diffuse, œdematous, warm, painful swelling very rapidly develops around the injury. The animal is more or less feverish and lame. The swelling soon extends throughout the entire length of the infected synovial sheath. The patient loses appetite, and unless treatment is promptly undertaken, complications supervene which often necessitate slaughter. The prognosis is always grave.

=Treatment.= Continuous irrigation has long been recommended. It is worthy of trial, but in the majority of cases occurring in current practice it cannot be carried out.

Moussu prefers a form of treatment which he claims has always succeeded in horses and oxen—viz., irrigation of the parts, followed by injection of sublimate glycerine solution.

He first washes out the infected synovial cavity with boiled water cooled to 100° Fahr. A counter-opening may become necessary, and the washing should be continued until the escaping water appears perfectly clear. Immediately after each such irrigation he injects from 7 to 14 drams of glycerine containing 1 part in 1,000 of corrosive sublimate. He repeats this treatment daily.

By reason of its affinity for water and for the liquids in the tissues or suppurating cavities into which it is injected, the glycerine penetrates in all directions, reaching the finest ramifications of the synovial sacs, a fact which explains its superiority over aqueous antiseptic solutions.

Suppuration is rapidly checked and repair becomes regular. The pain and lameness progressively diminish, and recovery may be complete.

It is advisable to assist this internal antiseptic treatment by external stimulants and by the use of a blister. Solutions of greater strength than 1 part of sublimate to 500 of glycerine are only required during the first few days of treatment and until suppuration diminishes. Later, they prove irritant, and interfere with healing.

TRAUMATIC ARTICULAR SYNOVITIS—TRAUMATIC ARTHRITIS—“OPEN ARTHRITIS.”

It has been described above how primary inflammation of the articular synovial membrane produced by a wound may rapidly develop into suppurating arthritis.

=Symptoms.= The pain is very marked at the moment when the accident occurs, but this pain, due to the mechanical injury inflicted, diminishes or completely disappears after some hours. Soon, however, synovial discharge sets in, announcing the onset of traumatic synovitis. At first limpid, it soon becomes turbid, then curdled, and finally grumous, purulent and greyish in colour.

Pain then returns, rapidly becomes intense, continuous and lancinating. It produces lameness, sometimes so severe that no weight whatever can be borne on the limb. A diffuse, œdematous, warm and extremely sensitive swelling then rapidly develops around the whole of the injured joint. General disturbance, with fever and loss of appetite, appears, indicating a very alarming condition.

It is sometimes a little difficult to differentiate between this condition and that due to injury of a tendon sheath, but as a rule diagnosis is easy.

=Prognosis= is very grave. Life is threatened, and wasting occurs very rapidly. Infection of the synovial membrane is soon followed by necrosis and erosion of the articular cartilages, as well as by softening and inflammatory change in the ligaments, etc.

=Treatment.= Should the patient be in reasonably good condition, but otherwise of no particular value, it should at once be slaughtered. If, on the other hand, it possess a special value, and the owner wish to preserve its life, the same antiseptic treatment should be adopted as was indicated in dealing with suppurating synovitis of tendon sheaths. The loss of the articular cartilage of the joint is followed by free granulation and union of the apposed surfaces of bone resulting in anchylosis of the joint and qualified recovery. Such results, however, are only likely to follow in relatively light animals which are capable of standing for considerable periods.

II.—STRAINS OF JOINTS.

When, in consequence of muscular contraction or external violence, the bony surfaces constituting a joint are displaced so as to stretch, lacerate, or partially tear the ligaments, synovial capsule or tendons supporting the joint, so-called sprain, or strain, or wrench results. The articular surfaces are not sufficiently displaced to cause luxation, but a series of periarticular injuries result, and are followed by the symptoms which we recognise as those of strain. Joints in which movement is restricted within narrow limits, such as the hock or fetlock, are most liable to such injuries, which also occur in very freely movable articulations like the shoulder and stifle.

STRAIN OF THE SHOULDER.

This accident is produced by the animal falling on its side, by slipping at the moment of landing, the limb being extended and in contact with the ground, by the foot slipping at the moment when it is leaving the ground and the limb is at its extreme limit of backward extension, by side slips, etc. The periarticular lesions will then be found on the front, back, or internal surface of the articulation, depending on the manner in which the accident has occurred. According to some authors, violent muscular efforts, as well as work in soft clay soil, bogs and rice swamps, are also capable of causing strain of the shoulder.

=Symptoms.= At first moving appears difficult, the patient lies down a great deal, then lameness becomes characteristic. Movement of the scapulo-humeral joint being painful, the patient endeavours as far as possible to avoid it; the limb is advanced stiffly in an abducted position and with a mowing movement. This semi-circular movement avoids the necessity of flexing the scapulo-humeral angle, but diminishes the length of the stride.

Locally, the region of the scapulo-humeral angle is swollen, doughy, and extremely sensitive on manual examination. If the practitioner endeavours to flex it by lifting the limb the animal flinches.

=Diagnosis.= The diagnosis is not very difficult, although the peculiar mowing movement is also seen in other cases, such as cracked heels and mallenders.

=Prognosis.= The prognosis is favourable, for, provided there has been only a moderate strain of the tendons or isolated injury to the muscles, recovery is almost certain.

=Treatment.= Treatment consists in resting the animal and in assisting repair.

The parts can be immobilised by the application of a vesicant or mild blister. A week or ten days later dry friction, muscular and periarticular massage are indicated, and gentle exercise should be commenced. The same treatment may be employed in strain of the elbow joint and in strains of muscles or tendons in the neighbourhood of joints. Such lesions are, however, very rare in the ox.

STRAIN OF THE KNEE.

Strain of the knee is commoner in the ox than in the horse, because of the special conformation of the knee in the ox and the mode of working under a yoke. This mode of working gives less individual liberty to the fore quarters, and sometimes interferes with the animal’s efforts when moving a load. Strains of ligaments and periarticular injuries occur as a general rule on the inner side of the limb.

=The symptoms= consist in lameness, exaggerated sensibility on pressure, pain on forced flexion of the knee, and swelling of the entire periarticular region.

=The prognosis= is somewhat serious in working oxen.

=Treatment=, when applicable, should consist of stimulant dressings, massage, and douches.

STRAIN OF THE FETLOCK.

This is one of the commonest accidents of draught oxen.

=Causation.= Working on rough, irregular, rocky ground, or on roads with deep ruts, is the commonest cause of this condition. When the animal moves on irregular surfaces the two claws do not bear an equal share of weight; sometimes the whole weight is for a moment thrown on one claw.

The phalanges, therefore, are displaced inwards or outwards, or are twisted around their vertical axis, causing the fetlock joint and its supporting ligaments to be more or less severely strained. The internal or external ligaments of the joint or the suspensory ligament or flexor tendons may even be lacerated.

The fetlock may also be strained by the animal making violent efforts to free the claws or pastern which have become fixed in a hole in the ground, in bogging, in hobbling, or in leaping a fence.

=Symptoms.= Lameness is noticeable from the beginning, but is unaccompanied by any visible lesion. On examination of the limb, the entire region from the fetlock downwards is found to be sensitive to pressure, and painful when forcibly extended or flexed from side to side. This sensitiveness is particularly marked when the phalanges are rotated on the shank. A few days later the entire fetlock becomes the seat of diffused swelling.

=Diagnosis= is facilitated by the fact that the fetlock has an entirely different appearance from that seen when tendon sheaths or the synovial capsules of joints are distended.

=Prognosis.= The prognosis varies considerably, according to the extent to which deep-seated structures are involved, and the gravity of the lesions is usually proportioned to the intensity of the symptoms.

=Treatment.= Frequent cold applications, cold foot baths for an hour or two night and morning, and even cold poultices are useful. When the pain has somewhat diminished, which usually occurs in from three to four days, vesicants may be employed, and, at a later stage, massage. Failing improvement by these methods, the injured region may be fired in points.

Strain of the hind fetlock occurs under precisely similar conditions to those above described in the case of front limbs.

STRAIN OF THE STIFLE JOINT.

Strain of the stifle joint results from over-extension of ligaments without displacement of the patella, and also (and probably more frequently) from injuries to the aponeurosis and tendons of insertion of the abductor muscles of the femur and tibia.

=Causation.= Strain of the stifle may follow violent collisions, such as occur in entering or leaving the stable, from falls on rough ground, from direct blows, from slips, etc., or even from the sudden and violent contraction of the muscles of the antero-external surface of the quarter.

=Symptoms.= Lameness follows immediately or soon after the accident, and is of a peculiar character; to avoid using the injured joint, the animal advances the hind limb with a mowing movement.

The injured region exhibits diffuse inflammatory swelling, which impedes palpation, and makes it difficult to determine the exact nature of the local lesion. The thigh at the stifle is painful.

=Diagnosis and prognosis.= Diagnosis presents no considerable difficulty. The prognosis must be based on the intensity of the symptoms, and becomes grave if the tendons or aponeurotic insertions be injured, or extensive damage have been done to ligaments.

=Treatment.= At first, continued cold applications, douches, and massage are most useful; blisters are more effective in the grave cases, and comprise not only the ordinary blisters, but the powerful mixed blister containing tartar emetic, powdered hellebore, bichromate of potash, etc. If for any special reason it is of importance to preserve the animal’s life, the parts may be fired; but for economic reasons it is usually better to fatten it for the butcher.

STRAIN OF THE HOCK JOINT.

=Causation.= Strain of the hock joint is commonest in young oxen which are being trained to work. Their hind quarters are necessarily more or less free, and the animals are apt to make side movements to avoid the goad, thus exposing the hock to irregular strain.

The internal ligaments are more frequently strained than the external, a fact due to the conformation of the hocks.

=Symptoms.= Strain is accompanied by lameness, most marked when the animals endeavour to turn, by exaggerated sensibility of the entire hock region, and, in grave cases, by subcutaneous œdema.

=Diagnosis and prognosis.= Diagnosis is simple. The prognosis is sometimes grave, because a spavin or a permanent chronic enlargement of the capsule of the true hock joint may form.

=Treatment.= It is often desirable at once to apply an extensive blister over the whole hock and to supplement this at a later stage by cold applications, or by continuous cold irrigation for half an hour or more both night and morning.

In exceptional cases the use of the actual cautery becomes necessary.

III.—LUXATION OF JOINTS.

Luxation consists of permanent displacement of the bony surfaces forming a joint, and may follow violent mechanical injury or any other cause.

Luxations have been divided into congenital, i.e., such as exist from the time of birth; spontaneous, i.e., those which result from some defect of conformation or constitution; and acquired or accidental, which occur as results of falls, wounds, accidents, etc.

From the point of view of their duration, luxations are termed temporary when they do not necessitate reduction, progressive when the tendency is towards greater and greater displacement of the surfaces, or permanent when reduction is impossible.

Those commonest in bovines are luxations of the femur, luxation of the patella, femoro-tibial luxation, and luxation of the scapulo-humeral joint.

LUXATION OF THE FEMUR.

Luxation of the head of the femur with displacement beyond the cotyloid cavity is very frequently congenital. The condition also occurs with some frequency in adults or aged animals in consequence of relaxation of the articular ligaments and the absence of the subpubic ligament (pubio-femoral ligament).

=Causation.= Luxation may be congenital, the head of the femur being displaced backwards and carried above the cotyloid cavity. This form is of no practical interest, because the animals are not usually reared. More frequently in young or adult animals it assumes the spontaneous progressive form, in consequence of degenerative changes in and relaxation of the coxo-femoral interosseous ligament. The head of the femur presses on the upper margin of the cotyloid cavity, which it injures, and eventually becomes lodged in the neighbourhood of the neck of the ilium, in the great sciatic notch.

This luxation is also found as a purely accidental occurrence in animals which have suffered from falls and from slipping of the hind limbs backwards or sidewards, as occasionally follows awkward leaping movements. The slipping outwards of the limbs, which causes this form of luxation, is comparatively easy, because of the absence of the pubio-femoral ligament. The accident may also be followed merely by subluxation, that is to say, tearing of the inner portion of the capsular ligament and rupture of some portion of the adductor muscles of the thigh without rupture of the interosseous fibres, the head of the femur not quitting the cotyloid cavity. This accident occurs in stables with smooth, slippery floors, and in railway trucks. It may affect one side or both. The latter condition is exceptional.

Finally, luxation may be either complete (in which case the capsular and interosseous ligaments are both ruptured) or incomplete. In the former case, the head of the femur becomes displaced upwards and forwards towards the great sciatic notch, more rarely backwards in the direction of the ischium, and in exceptional cases downwards and inwards below the pubis into the foramen ovale.

=Symptoms.= The symptoms vary, depending on whether the luxation is of the spontaneous, progressive order or, on the contrary, is accidental. In progressive luxation, the animals are able to rise and walk with difficulty. The affected limb swings when the animal is advancing, not as though it were paralysed, but simply as though displaced at its upper part. Pain is exhibited when weight is placed on the limb, and there is difficulty in movement. The limb appears shorter than its neighbour when the animal stands on it, and the prominence representing the trochanter is more marked. When a false joint has formed, the limb is rigid, is moved stiffly and abducted, and the stride is shortened.

In accidental luxations, either of one or both limbs, the attitude assumed by the animal is often characteristic. One of the limbs is extended at right angles to the longitudinal axis of the body, and sometimes both limbs assume this position, an attitude which would be absolutely impossible under normal conditions. The animal cannot rise. It lifts the front part of the body by rising on its knees, but the hind quarters do not follow. The ruptured adductor muscles are unable to bring and hold the limb parallel to the longitudinal axis of the body; the abductors act unopposed, and at the moment when the animal makes its greatest effort to rise the limb (or limbs) is carried outwards and the body comes to the ground on the udder or groin.

Inspection discovers a depression where the great trochanter should be. On applying the open hand over the hip joint, whilst an assistant who grasps the pastern moves the limb in different directions, one can feel and hear, in spite of the mass of muscle covering the part, a modified crepitation due to sero-sanguinolent effusion in and around the joint. This crepitation can also be detected by pushing the hand as high up as possible on the internal surface of the thigh, and thus exploring the neighbourhood of the luxation.

=Diagnosis.= The position which the animal assumes when one endeavours to make it rise is characteristic. Diagnosis of progressive luxation, however, is more difficult.

=Prognosis.= The prognosis is extremely grave; for, even though reduction can be effected, one is practically unable to ensure that the parts shall remain in position.

=Treatment.= Treatment comprises reduction of the luxation and fixation of the parts. Reduction can be effected without very much difficulty by casting the animal on the affected side, placing a block of wood, or a pail, between the thighs, and manœuvring the limb in the desired direction. As, however, subluxation is the condition most commonly seen, there is frequently no reduction to effect. Moreover, fixation of the joint after reduction is almost impossible in such heavy subjects, and luxation is very liable to recur. From an economic standpoint, slaughter is advisable or imperative.

LUXATION OF THE PATELLA.

Luxation of the patella is not uncommon in working oxen, and is occasionally seen in cows as the result of a slip when entering or leaving the byre, the reason being the peculiar anatomical arrangement of the femoro-patellar articulation.

The internal lip of the trochlea of the femur is very high, the external, on the other hand, being only slightly developed. The patella itself is smaller than that of the horse, and possesses a small cartilaginous prolongation, principally on its inner face, in marked contrast with the large cartilage found in the horse. As in the latter animal, the outward displacement of the patella is only prevented by the internal patellar ligament and the femoro-patellar aponeurosis. Under the influence of varying causes to which the joint is exposed, these supporting structures often prove insufficient to prevent the patella being displaced outwardly.

=Causation.= From an anatomical standpoint, luxation inwards seems impossible. It certainly must be very rare and be preceded by rupture of the external ligament. On the other hand, as in the horse, it seems possible that the patella may be caught on the summit of the internal lip of the trochlea, especially if the trochlea happens to present a flattening at that point.

Outward luxation may be spontaneous or accidental. It is termed spontaneous, when produced by relaxation of the ligaments of attachment or by irregular muscular action; accidental, when resulting directly from any external mechanical cause. Violent contraction of the triceps cruralis, by lifting the patella beyond its normal limit of travel, helps, or at least permits, the patella to be displaced outwardly at the moment when the muscle relaxes.

Pathological relaxation of the ligaments and muscles, by allowing the patella to descend too far on the trochlea, also renders displacement possible, hence spontaneous luxation sometimes occurs even while the animal is at rest in the stable. This luxation is certainly only of a temporary character, or perhaps only of the nature of subluxation, and is often reduced by mere muscular contraction when the animals are forced to move.

Should the hind limb slip in a backward direction the angle of the joint becomes more obtuse and the lips of the trochlea are turned downwards, thus greatly favouring lateral displacement of the patella, which under these circumstances is no longer immobilised on the trochlear pulley; displacement outwards then occurs, constituting the condition termed luxation.

Various forms of mechanical violence, like blows, collisions of the stifle with the jambs of doors, falls, etc., may also bring about this luxation.

=The symptoms= of fully-developed accidental luxation are characteristic. Immediately the accident occurs, the limb is immobilised in a state of complete extension; neither the stifle nor the hock joint can be flexed, and only the fetlock joint retains any degree of mobility.

Movement is very difficult. The hind limb appears rigid, as though formed of one bone. The pastern is directed backwards and dragged along the ground, and when weight is placed on the limb the anterior surface of the pastern may almost be in touch with the ground. The limb is advanced, but the foot cannot be placed properly on the ground.

Locally the patella is found to be outside the external lip of the trochlea, and its internal ligaments are extremely tense.

If the luxation is spontaneous and of muscular origin, or a consequence of relaxation of the tendons, it is usually noticeable immediately the animal leaves the stall. The animal cannot move without great difficulty. It grows steadily worse with the lapse of time, because the synovial membrane becomes irritated and chronic arthritis is set up.

The symptoms are identical with those of traumatic luxation, but are only temporary.

=Diagnosis.= The position of the limb and the displacement of the patella are sufficiently distinctive to render diagnosis fairly easy, and to allow of this accident being differentiated from luxation of the femoro-tibial joint or hooking of the patella in the ischio-tibial muscle.

=Prognosis.= The prognosis varies greatly. If the luxation is of traumatic origin and the accompanying symptoms are not grave, reduction may be followed by permanent recovery. On the other hand, in spontaneous luxation recurrence is almost inevitable.

=Treatment=. The indications for treatment may be comprised in a single phrase: reduction, with immobilisation of the parts for a sufficient time. To effect reduction, a strip of webbing is fixed around the pastern of the affected limb, passed over the withers, in front of the shoulder of the opposite side, and brought round in front of the neck or between the front limbs. By means of this an assistant exercises strong traction on the limb until the fetlock is raised as high as the elbow of the same side. The operator then applies strong inward pressure to the patella, which usually slips back on to the gliding surface of the trochlea at the first or second effort.

After-treatment comprises the application of a smart blister, producing œdematous infiltration of all the tissues around the joint, and thus impeding movement and recurrence of luxation. For this purpose various preparations are used—e.g., cantharides, biniodide of mercury, croton oil, etc. It is also advisable to fix the animal so that for a time it cannot lie down, and to secure the pastern to the neck by means of a side-line.

As an experiment, cases of simple fixation of the patella on the summit of the internal lip of the trochlea might be treated by Bassi’s method—i.e., subcutaneous division of the internal lateral ligament of the patella which holds the bone in its abnormal position.

Finally, in spontaneous luxation, occurring in young animals in which blisters have been ineffectually tried after reduction, Bénard’s bandage may be used, though it is not generally regarded as very practical. It consists of a piece of cloth of elongated lozenge form about four feet in length, six inches in breadth at its centre and two inches at its ends. Its centre is pierced by a transverse opening intended to surround the patella, and carries a loop for the purpose of supporting the turns of bandage. A second longitudinal opening is situated about eight inches from the centre.

Reduction being effected, the whole region of the stifle joint is covered with Burgundy or ordinary pitch and the bandage then applied. The patella projects through the central opening. The end A is passed backwards around the thigh, and through the aperture B; the two cross ends are then brought forward, crossed again at the end, the loop over the patella carried a second time backwards, again crossed, and finally fixed in front under the patella. The bandage should be firmly applied, without, however, being so tight as to interfere with circulation, and must be left in place from eight to ten days.

Van Denmoegdenberg recommends placing the patient on an inclined plane, with the hind quarters a foot higher than the front, so as to cause permanent contraction of the anterior muscles of the quarter, and thus immobilise the patella. Simple cold baths, frequently repeated, friction with camphorated alcohol or essence of turpentine, complete this original but somewhat questionable treatment, and are said to result in recovery in a fortnight.

LUXATION OF THE FEMORO-TIBIAL ARTICULATION.

This form of luxation is rare, a fact explained by the strength of the lateral ligaments of the joint, and of the cruciform interosseus ligaments. It may assume different forms, according as the head of the tibia is displaced in front of, behind, to the inside, or to the outside of the lower extremity of the femur. In all, therefore, it may appear in four different forms. The commonest is backward luxation.

=Causation.= With the sole exception of luxations or subluxations due to tuberculosis (lateral luxations, either inwardly or outwardly, occurring during tubercular arthritis, with more or less marked destruction of the condyles), these luxations are always accidental or the result of mechanical violence.

They result from leaping into hollows, falling into deep ditches or ravines, or galloping through broken or steep places. Any violent shock affecting the femur, either in front or from the outside, is capable of causing luxation backwards or inwards.

=Symptoms.= The most frequent condition is backward luxation of the upper extremity of the tibia. Movement becomes difficult, the limb is held rigidly, and all the lower part of the leg is extended. None of the joints can be flexed. The leg is dragged forward, without the animal being able to place the foot flat on the ground, and the claws are trailed over the litter or the toe grazes the soil.

On local examination the stifle is seen to be deformed. The lower extremity of the femur and the patella appear prominent. The upper part of the tibia is thrust backwards, and seems to have disappeared, leaving a depression below the femoro-patellar region. The muscles forming the back of the thigh at this level are thrust out of position, and appear to project abnormally.

Viewed from behind, the inner line of the thigh appears more or less convex when the upper extremity of the tibia is luxated inwardly. On local examination the displacement of the bones can be readily detected. In luxation forwards the prominence of the stifle is caused by the summit of the tibial crest and by the patella, whilst the lower extremity of the femur cannot be felt. In outward luxation the upper extremity of the tibia forms an abnormal prominence, above which a horizontal digital depression appears.

=Diagnosis.= Provided that the examination is made soon after the occurrence of the accident, little difficulty will be found in coming to a conclusion, but the diagnosis necessitates more care when examination is deferred for two or three days, because extensive effusion then exists. Luxations or subluxations of tuberculous origin are generally consecutive to old-standing destructive tuberculous arthritis.

=The prognosis= is grave—firstly, because reduction is difficult; and, secondly, because it is often impossible to maintain the reduction and to preserve complete immobilisation of the injured joint.

=Treatment= should not be undertaken except in young animals which have not yet attained full development.

In attempting to reduce outward or inward luxation of the tibia the animal should be cast on the side opposite to the lesion. Counterextension is practised by passing a length of webbing around the limb in the region of the groin; extension in the direction of the length of the femur by means of a loop of webbing fixed to the cannon bone: the operator uses both hands in endeavouring to replace the head of the tibia.

In forward luxation of the tibia counter-extension is effected by means of a loop of webbing passed above the hock and drawn forward. Extension is made backwards in an oblique direction, the operator again being left free to effect reduction with both hands.

Reduction of backward luxation of the tibia is still more difficult, in consequence of the contraction of the mass of muscle at the back of the thigh.

Plaster bandages are the most convenient means of immobilising the parts after reduction.

LUXATION OF THE SCAPULO-HUMERAL JOINT.

This luxation, like that of the femoro-tibial articulation, is exceptional. It may assume one of two forms, depending on whether the head of the humerus is displaced inwardly, or towards the back of the glenoid cavity; but as a rule luxation occurs inwardly. Forward luxation of the head of the humerus is almost impossible, in consequence of the resistance offered by the tendons of the flexor brachii and antea spinatus muscles. Similarly, luxation outwards is very difficult, the tendon of the postea spinatus being very powerful and offering enormous resistance.

Inwardly, on the other hand, the insertion of the subscapularis is much less powerful, and there is no real opposition to movement of the head of the humerus.

=Causation.= Violent mechanical shocks transverse to the upper third of the arm may, by sheer force, displace the head of the humerus in an inward direction, causing rupture of the internal wall of the capsular ligament and of the subscapularis muscle. Jumping from high to low ground and falling on the front limbs tend to displace the glenoid cavity in front of the head of the humerus, and often result in luxation of the bone in a backward direction, a luxation, however, which almost always assumes a postero-internal direction. The commonest causes of these luxations are the sideward falls of animals which have attempted to cover others. Whether the subject be a bull or a cow, if the stationary animal suddenly moves to one side, or if the moving animal is frightened by the appearance of a dog, one of the front limbs may be violently dragged away from the body; the resistance of the capsular ligament and internal muscles of the shoulder may be overcome and luxation produced.

=Symptoms.= Symptoms are immediately apparent: no weight can be placed on the injured limb, and the animal moves on three legs. All muscular action is avoided, the limb is slightly shortened as a consequence of the head of the humerus slipping behind the shoulder, which is held rigidly during movement; the points of the claws are dragged along the ground.

On local examination the point of the shoulder appears to be deformed and outwardly displaced, in consequence of the pressure exercised by the displaced head of the humerus. Below the glenoid cavity and coracoid process lies a depression, at the base of which the displaced humerus can be felt. This depression, however, is soon filled up by the sero-sanguinolent effusion consequent on luxation.

=Diagnosis.= Bearing in mind the conditions to which the accident is due, the diagnosis presents no great difficulty.

=Prognosis.= The prognosis is grave, for although it is relatively easy to reduce the displacement, it is very difficult to keep the joint fixed in position.

=Treatment.= To effect reduction, the animal should be cast on the sound side, and a loop of webbing passed under the arm, in order to provide for counter-extension. The limb is extended by direct traction on the cannon bone or fetlock, whilst the operator endeavours to effect reduction with one hand placed in front and one behind the joint.

In young animals of trifling weight immobilisation may be attempted, the best method being the application of pitch plasters. If, on the other hand, the subject is heavy, there is so great a chance of displacement when lying down and rising, that such cases are usually sent to the butcher, or abandoned to chance. Relative recovery, sufficient to permit of growth or fattening, may take place without professional assistance.

IV.—HYGROMAS.

Hygromas result from chronic inflammation of serous bursæ, naturally existing, or of serous bursæ which form at prominent points where the skin is exposed to repeated friction, blows, shocks, or over-extension.

They usually develop slowly, without producing marked pain or alarming symptoms, and therefore the practitioner is seldom consulted until the swelling has attained a considerable size.

The hygroma is usually characterised by its non-painful character and by regular fluctuation throughout. The walls of the serous bursæ are merely thickened, so that palpation is easy.

Should the hygroma become infected and inflamed, it assumes the same characters as an abscess: it becomes highly sensitive, is surrounded by œdematous infiltration, shows more marked fluctuation at some specialised point, and eventually breaks, discharging pus.

Long-standing hygromas often have thickened fibro-cartilaginous and extremely hard walls, which render examination more difficult.

Where the hygroma is much exposed to friction the skin covering it undergoes complete transformation, the layers of epidermis becoming converted into a substance resembling horn. The entire substance of the wall of the hygroma then undergoes change, and is often infiltrated with lime salts or encrusted with plates of bone of varying thickness.

HYGROMA OF THE KNEE.

This condition is very common in bovines, a fact explained by the manner in which these animals rise. Whilst the hind limbs are being lifted, the entire burden of the body weight is transmitted to the knees and the tissues covering them; so that, if the ground is rough, the skin may be sufficiently displaced to produce laceration of the subcutaneous connective tissue, serous effusion in the layers of connective tissue, and the immediate production of an hygroma beneath the skin and in front of the synovial sheaths of the extensor tendons.

Hygroma is principally caused by falls on the knees, roughness of the stable floor, prolonged decubitus during the course of a serious disease, or after an attack of foot-and-mouth disease.

Hygromas may be no larger than a turkey’s egg or a man’s clenched fist, but sometimes assume the dimensions of a child’s head. Calcification and ossification of the walls and cornification of the skin are commonest in old hygromas of the knee.

The sensibility and uniform fluctuation make mistakes in diagnosis difficult. The condition can only be confused with distension of the synovial sheath of the extensor metacarpi magnus; but this (synovial) swelling extends in the same direction as the tendon, i.e., vertically, attains the lower third of the radius, and is broadest above. Hygromas must also be distinguished from tumours. Moussu only mentions a single case of this kind, the tumour being very slightly bosselated and, naturally, revealing no fluctuation.

=The prognosis= is not grave, though the condition may prove troublesome, because the original injuries may be continued even during treatment and prevent recovery.

=Treatment.= Success rarely follows cold applications or blistering, which are only of value at the commencement. It is better to puncture the cavity aseptically, remove the fluid contents, and fire the growth in points. Free opening of the lowest portion of the swelling is followed by discharge of liquid, but almost inevitably by infection at a later stage, and by suppuration. Recovery certainly may occur, a slight thickening of the anterior surface of the knee remaining; but the process is often very prolonged. Some authors prefer to pass a seton or drain vertically through the swelling. The results are identical with those following free opening and drainage, suppuration being unavoidable.

If the animal be sufficiently valuable to warrant surgical intervention, the entire hygroma, together with its indurated wall, may be excised. An elliptical fragment of skin is removed from the front of the swelling, and the whole mass separated by dissecting away or tearing through the connective tissue. Considerable care is necessary to avoid injuring the synovial sheaths of the extensor tendons. This treatment, which is only applicable in valuable animals, is completed by firmly suturing the lips of the wound, and applying an antiseptic surgical dressing or a plaster bandage similar to that used in operating on broken knees in horses. The animal must be prevented from lying down until the wound has firmly united.

Footnote 1:

See Dollar’s “A Surgical Operating Table for the Horse.” (London: Gay and Bird.)

HYGROMA OF THE HAUNCH.

With the exception of hygroma of the knee, hygromas are commoner on hind than on front limbs. That of the haunch is limited to the external angle of the ilium. It follows violent falls or collisions with door posts, and results from laceration of the layers of subcutaneous connective tissue and separation of the skin from subjacent parts.

The effusion is often of a sero-sanguinolent character. It is more frequent in animals occupying narrow or irregularly shaped stalls, the hygroma being developed through repeated collision of the angle of the haunch with the wall. Finally, it may follow prolonged decubitus.

=Diagnosis= is easy, but the =prognosis= has a certain element of gravity, because, should suppuration occur, it may be succeeded by necrosis of the aponeurosis inserted into the external angle of the ilium.

=Treatment= should first be directed to removing the cause. Of the various modes of intervention, the best probably consists in disinfecting the parts, puncturing the swelling, and injecting some irritant of an antiseptic character, or simply washing out the cavity. Iodine and carbolic solutions are most commonly employed. Firing is contra-indicated.

HYGROMA OF THE TROCHANTER OF THE FEMUR.

This condition is rare, except in thin milch cows kept under bad hygienic conditions and insufficiently supplied with bedding. Continual bruising of the prominences of the quarters whilst the animal is lying is the usual cause.

This hygroma forms a hemispherical swelling covering the trochanteric prominence. Movement is interfered with, and the stride is shortened.

The condition can only be confused with the diffuse swellings due to periarthritis in the coxo-femoral region, which frequently occur in cows suffering from infectious pseudo-rheumatism.

=The prognosis= is somewhat grave, for in case of suppuration the insertions of tendons and fascia into the summit of the trochanter may become necrotic.

=Treatment.= The first point is to supply the animal with ample clean bedding. The swelling may be repeatedly blistered. If considered necessary, a puncture may be made under antiseptic precautions, the fluid drawn off, and the cavity washed out; but it is better to avoid opening the parts with a bistoury, on account of the danger of suppuration and of necrosis of the tendons and aponeurotic tissues in the neighbourhood.

HYGROMA OF THE STIFLE.

Hygroma of the stifle or of the patella appears under the skin, outside the external ligament of the femoro-tibial articulation. It usually follows repeated abrasion when lying down, especially if the paving of the stalls is rough or irregular.

The swelling varies in size from a hen’s egg up to that of a child’s head, and exhibits fluctuation throughout.

=The prognosis= is somewhat serious, for here again complications may result from necrosis of neighbouring aponeuroses.

Some authors recommend passing a seton dressed with some irritant material through the swelling. Aseptic puncture, however, seems preferable, followed by washing out of the cavity and the application of a blister.

HYGROMA OF THE POINT OF THE HOCK.

This hygroma usually results from blows with the ox-goad, which cause inflammation of the subcutaneous connective tissue and œdematous infiltration extending down the leg. Afterwards the slightest injury, or even the friction due to the animal lying down, causes liquid to collect and an hygroma to form.

This hygroma is readily infected and often suppurates; it then becomes very sensitive, producing intense lameness. More frequently, however, under the influence of prompt treatment, the liquid is absorbed, the layers of subcutaneous connective tissue become hardened, and undergo more or less extensive induration.

HYGROMA OF THE POINT OF THE STERNUM.

Hygroma of the point of the sternum is a rarity. It only occurs in thin animals in which the point of the sternum is prominent, and which are confined to stables with rough floors and provided with insufficient bedding.

The swelling should not be opened, for the tissues in front of the sternum readily become the seat of suppuration.

If treatment is desirable, the fluid may be drained off by means of an aseptic puncture.