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Lameness Arising from Diseases of Bones and Joints

LAMENESS ARISING FROM DISEASES OF BONES AND JOINTS Inflammation of the Shoulder-joint. This is a rare condition, as the joint is well protected from injury by its muscular covering. Injury to the capsular ligament, however, may arise from excessive abduction, adduction or rotation. Rheumatism may be responsible in a few cases. Chronic cases of arthritis in this joint are usually accompanied by considerable exostosis. Joint ill in the foal may affect the shoulder.

The symptoms are those of shoulder lameness, and diagnosis is difficult in the early stages, particularly as the bursa of the biceps may be involved simultaneously. When exostosis occurs the enlargement is usually quite visible, but it may be more easily detected by pushing the biceps slightly to one side. Anchylosis of the joint usually results after a very prolonged lameness often extending into years.

We have observed a case of rheumatic arthritis in a two-year-old cart colt in which distension of the synovial capsule of the shoulder-joint was evident. After blistering, the symptoms abated but the opposite shoulder-joint became affected. For six months the condition changed from one shoulder to the other repeatedly, and then suddenly disappeared.

Treatment. Rheumatic arthritis may be im proved by local blistering and the internal administration of pot. iodid., sod. salicylas, colchicine, alkalies, laxatives, etc.

Chronic arthritis seldom improves under any form of treatment. Firing and blistering may be tried, but as soon as bony exostoses make their appearance slaughter is most economical.

Luxation of the This is a rare condition, and usually occurs whilst landing from a jump or when the foot is fixed and cannot be freed.

We have observed the condition on several occasions in a steeplechaser. Whilst landing from a jump, luxation occurred and the animal fell. Attempts to get the horse on his feet brought about reduction, but lameness was intense for several days afterwards. This horse on several different occasions met with the same accident but reduction was always auto matic.

As a rule reduction is difficult, and is effected by forced traction by a block and pulley attached to the affected limb whilst the operator stands on the shoulder-joint. Blistering subsequently produces sufficient pain and swelling in most cases to maintain the position of the bones. Some prefer a pitch charge. Rest in slings is always advisable.

Fracture of the deltoid tubercle of the humerus is by no means uncommon, either as a result of muscular action or from direct injury, as from a blow received whilst passing through a gate way or stable doorway. A kick from another horse may be responsible. When fractured the deltoid tubercle can be moved about with the fingers.

The symptoms resemble a mild form of radial paralysis. The knee and fetlock are flexed, the toe is dragged, and the animal has difficulty in advancing the limb. When the foot is placed in position the horse is able to stand his weight upon it. There has not been any appearance of"dropped elbow"in the cases we have observed. Occasionally the symptoms are less severe and only amount to slight difficulty in advancing the limb, with more or less flexion of the phalanges.

The cause may be loss of action of the deltoid and possibly of the postea-spinatus muscles, but this would hardly account for the severity of the symptoms often shown and the apparent loss of power in the lower extensor muscles. We are inclined to believe that the local inflam mation set up by the fracture extends to the musculo-spiral nerve.

As a rule the deltoid tubercle forms a fibrous union with the humerus and restores the action of the deltoid muscle. Lameness usually dis appears in six or eight weeks.

Treatment consists in securing rest and the application of a blister which contributes to that end by rendering the parts painful upon movement.

Chronic Inflammation of the We are of opinion that chronic inflammation of the elbow-joint with resulting disease of the arti cular cartilage is more common than is generally believed. Post-mortem examination of several cases of supposed shoulder lameness has re vealed chronic arthritis with ulceration of the articular surfaces of both the radius and humerus. The cause is unknown. Possibly kicks or small wounds of the sheath of the flexor metacarpi externus may infect the joint in some instances, but there was no evidence of this having occurred in the cases above mentioned.

The symptoms are similar to those of shoulder lameness. There is difficulty in advancing the limb and the animal assumes a three-cornered gait, the affected side being carried to the rear, whilst progression is mainly accomplished by the other limb. Swelling of the shoulder as the result of previous blistering is apt to deceive one into imagining that the shoulder is the seat of lameness, and in most cases there is indeed but little to distinguish elbow-lameness from shoulder-lameness. There is seldom any indica tion of pain upon pressure, nor is heat or swelling observable.

Treatment is useless, and in the event of a certain diagnosis being arrived at, slaughter is the most economical treatment.

Luxation of the This accident is rare in the larger animals owing to the great strength of the lateral ligaments of the joint. Several cases have been reported in horses as the result of rupture of these ligaments from falls.

In dogs and cats luxation is sometimes observed, the radius slipping outwards.

An Airedale terrier was run over by a light rubber-tyred buggy. The wheel passed over the shoulder, producing complete external luxa tion of the radius. Reduction was effected under chloroform and the joint encased in a plaster bandage. This was removed after a week, when the animal was found quite sound.

In the dog the ulna may ecome displaced upon the radius with inabilit to extend the elbow. Flexion is but little interfered with. If not dealt with early, acute arthritis may result with swelling of the whole joint region and distension of the tendon sheaths at the back of the articulation. This condition is exceedingly painful.

Lameness.Fractures of the small bones and chronic arthritis of the knee-joint may be met with.

Fractures are not common, as the small com pact bones are well protected from concussion, but such cases occasionally occur as the result of falls particularly upon stones, or by contact with sharp bodies. Fracture of the pisiform bone has frequently been observed in racehorses and steeplechasers, from excessive contraction of the middle and external flexors of the knee. The intercarpal ligament uniting the pisiform to the external splint bone and the uniform is usually ruptured simultaneously.

Syniptoms. Fracture of the small bones of either row is difficult to diagnose with certainty. There is swelling and a painful condition of the joint, with severe lameness both in advancing and placing weight upon the limb.

Fracture of the pisiform gives rise to symp toms much resembling those of radial paralysis. The fractured portion usually becomes more or less displaced according to the amount of damage caused to the ligaments. Crepitation and increased mobility make diagnosis certain.

Prognosis. Fracture of the small bones is usually comminuted and often compound. When union does occur, the resulting callus formation hinders or prevents movement of the other bones of the knee. The pisiform usually unites by means of a fibrous adhesion, and its function may be thus partly restored, but horses are of no further use for racing or jumping."Bent-knee"is often a sequel. Recovery usually requires several months. It is not un common for laminitis to develop in the other foot through bearing excessive weight for so long a period.

Treatment. The animal should be placed in slings, and the knee secured by means of a well padded splint. Subsequently blistering and walking exercise on soft ground are beneficial and lessen the risk of anchylosis.

Compound fractures require strict antisepsis. Continuous irrigation of the knee which is kept at rest by a splint placed at the back will give the best results. Anchylosis is almost certain, and cases are seldom worth treatment except in breeding stock.

Chronic Arthritis of the Knee,

sometimes re ferred to as"knee spavin,"in causation, symptoms and treatment much resembles the corresponding condition occurring in the hock joint. Prognosis is, however, less favourable as anchylosis is more serious in the former position than in the latter, where the large joint between the tibia and astragalus provides most of the movement. Ponies seem to form the class of animal most frequently affected, though cart horses and racehorses alike may develop the condition.

When the disease is confined to the lower part of the joint, movement may be only slightly interfered with. Lameness may be therefore hardly noticeable or severe, and is always, in the early stages at least, accompanied by marked swelling of the knee and the formation of a considerable amount of fibrous thickening. Later, this in great part disappears, and a hard bony swelling remains. Very often the knee is more or less bent and incapable of being fully extended or flexed owing to adhesions between the ulcerated articular cartilages and the forma tion of peripheral exostosis.

Inability fully to advance the limb causes the action to resemble that seen in shoulder lame ness. Koller mentions three distinguishing characteristics of"knee-spavin."lameness: (i.) The circular sweep of the limb when moved forward.

(ii.) The horse brings the quarter of the hoof to the ground first.

Pain is produced when the joint is forcibly flexed.

Treatment must be confined to firing and blistering and median neurectomy when these measures fail to remove the lameness.

Rupture of the Interosseous Ligaments of the Knee. This is a rare condition, but has been observed as the result of a fall whilst At rest the knees nearly touched and were curved backwards. At the walk they were normally flexed, but the horse went on his heels as in laminitis. The knees were tender on pressure, and there was an increased amount of synovia present. Some amount of lateral movement was possible.

On post-mortem only the anterior ligaments were affected, and only those of the radio carpal articulation.

Splints. — A splint is a bony enlargement developed upon the large or small metacarpal (or metatarsal) bones or upon both of these as the result of a localized osteo-periostitis. The inner side of the limb is more commonly affected although many cases occur upon the outside, and in fact both sides may be, and frequently are, affected simultan eously. Splint is most frequently observed in young horses doing fast work on hard surfaces. It is commonest at the age before complete natural bony union has occurred between the large and small meta carpals, that is to say, in horses up to five or six years of age. It does, however, some times occur in older horses.

Causes. The actual cause of splint is osteo periostitis, involving the large or small meta 1 A. J. Williams, Vet. Lieut. A.V.D., V et. Record, Nov. 16, 1901.

carpal bones. The exciting influence is con cussion, which by throwing excessive weight upon the small splint bone causes tension of the interosseous ligament and inflammation of the adjacent periosteum. Dieckerhoff considered that the pull of the fascia of the forearm was responsible.

The predisposing conditions which favour the production of splints are small bone with diminished joint surface, and therefore greater concussion, employing young horses at fast work on hard roads, high action, faulty conform ation and defective shoeing. When an ex cessive amount of bear ing is given to the outer wall of the foot at the expense of the inner, as when the shoe is not quite true, increased strain is thrust upon the inner splint bone at each step.

Traumatic injury may also cause exostosis in this region, hence horses with turned-in or turned out feet and those with high action may strike the inside of the splint bone many times during a single journey.

The Nature of Splint. A splint is an exostosis occurring at the junction of the large and small metacarpal or occasionally of the metatarsal bones. In slight cases the periosteum covering the larger bone appears to be the origin of the enlargement, but in severe forms both large and small bones are involved and the latter are frequently affected with diffuse bony growths. The commonest situation of a splint is the upper or middle third of the small splint bone, but cases may occur in which enlargement even of the button is present, or it may extend the whole length of the bone. Several different terms have been applied to splints according to their situation. A simple splint is a small, well defined enlargement usually at the front of the small metacarpal bone. Pegged splints occur on either side of the small splint bone, and are connected by a bony communicating bar. Knee splints involve the head of the splint bone, and may interfere with the action of the knee-joint, or may cause ostitis with arthritis as a sequel. Chain splints occur as a number of pea-like growths running nearly the length of the splint bone.

Splints of considerable size may also develop on the inner aspect of the small bones, and extend on to the posterior surface of the meta carpal bones, causing injury to, and displace ment of, the suspensory ligament, and sometimes interfering with the play of the flexor tendons.

Symptoms. — Many horses exhibit well - de veloped splints without any history of previous lameness. It must be remembered that the large and small metacarpal bones are connected in the horse up to middle age by the interosseous ligament. Later, this becomes replaced by bone, excepting about two inches at the lower extremity, though in well-bred horses the large and small bones may remain distinct throughout life.

It is possible that many splints which develop without the production of inflammatory symp toms are the result of a premature but natural deposit of bone, stimulated by some local weak ness of the bone tissue.

Lameness, however, may appear several weeks before any enlargement is noticeable, and one may be led to ascribe the symptoms to other causes.

The lameness nearly always increases with exercise, and is more noticeable on hard ground where concussion is increased than on soft ground where it is diminished. The horse may appear quite sound whilst walking, but may be very lame in the trot. The nodding of the head, the stilty gait, and general lameness are then quite out of proportion to that shown whilst walking. After a few minutes' rest the horse usually trots sound for the first dozen steps, after which lameness becomes evident. Pressure upon the affected spot causes pain, and is evidenced by lifting of the leg in a forward direction and resistance to further attempts at manipulation. The swelling is at first soft and doughy, later it becomes hard and bony.

When the splint involves the knee-joint, marked abduction is usually observed. Some times the knee cannot be properly flexed, and is carried stiffly in consequence.

Enlargement, due to striking with the opposite foot, is usually observable at the commencement of the lameness in contrast to splint lameness which usually precedes the formation of the exostosis. There is also more superficial injury, and frequently the skin is damaged over the affected part. Although bony enlargement may occur from this cause, in the majority of cases the greater part of the thickening is fibrous in nature. When a considerable enlargement is present the tendency to strike the spot is in creased. Carefully noting the action from the front of the animal at various paces should lead one to a correct diagnosis.

Prognosis. This is always satisfactory ex cepting in those cases in which there is inter ference with the action of the knee or flexor tendons, and when the splint is of sufficient size and in such a position that it may be struck with the opposite foot. Occasionally, upon resuming work inflammation may again arise with the production of fresh exostosis either as an extension of the pre-existing enlargement or in another situation.

The majority of young horses, however, after recovering from splint lameness do not show any reappearance of the symptoms in the same limb, though it is not uncommon for the opposite limb to become affected, especially in light horses deficient in bone.

Heavy horses doing slow work do not so frequently exhibit splint lameness. Enlarge ment of the head of the small metacarpal bone usually interferes with the action of the knee either mechanically or by causing changes in the articular surfaces of the opposed bone or bones. Chronic lameness is a frequent sequel, and although after a prolonged rest the action may be apparently restored, yet lameness usually reappears upon working the animal. Large splints on the postero-internal surface of the small bones may cause distortion of the sus pensory ligament and bulging of the flexor tendons and more or less chronic lameness from a double cause, viz. interference with these soft structures and pressure of the same upon the splint.

Striking with the opposite foot causes inter mittent lameness which in most cases can be benefited by special shoeing. Long"spongy"splints occurring throughout the length of the splint bones are frequently bilateral and indi cate weakness of bone. Lameness usually disappears after a period sometimes extending to months.

Very rarely splint formation is attended by suppuration as a result of external injury during the inflammatory process. We have observed a case of this sort with an abscess cavity extend ing the whole length of the cannon and attended by exfoliation of bone.

Splints on the hind legs seldom cause lame ness. When present they are usually found on the outer side of the metatarsal bone.

Treatment. In mild cases cold fomentation, cold water bandages and the application of a cooling lotion, with rest or slow work may be sufficient to remove the lameness. In more severe cases this treatment should certainly be adopted until the acute inflammatory stage subsides somewhat. After about a week or a fortnight a biniodide of mercury blister may be applied and the animal, with the shoes removed, given a run at grass. Should lameness con tinue, puncture-firing, preferably deep acupunc ture, gives the best results.

Acute cases attended with marked heat and pain and with a well-defined rather soft swelling are usually afforded early relief by subcutaneous periosteotomy. A short transverse incision is made below the seat of the splint, a strong periosteotomy knife is inserted flatwise under the skin. The cutting edge is then turned towards the'bone and as the knife is withdrawn sufficient pressure is brought to bear upon it to sever the fascia and periosteum and to cause it to cut into the swelling. Aseptic precautions are advisable. The operator must avoid in juring the metacarpal vessels and nerve, though, as these lie usually well behind the splint, there should be no danger if reasonable care be taken.

Large enlargements which are struck by the opposite foot should be protected by a leather legging and blistered with biniodide of mercury. The offending foot should be carefully shod with a feather-edged shoe worn well beneath the inside wall, the edge of which may be rasped away. Sometimes a three-quarter shoe is useful whilst an ordinary shoe filed away at the ground surface of the inner branch, with a piece of leather the inside edge of which projects slightly beyond the foot, may prevent the animal striking with the shoe. Knee-splint can only be treated by point-firing and blistering. Neurectomy may be necessary to remove the lameness.

Careful attention must always be paid to shoeing, and it is especially important that the coronet should lie parallel with the ground surface so as to ensure even bearing and a minimum of concussion.

Chronic cases may be shod with leathers, rubber pads or tips with the same object in view.

Extirpation of splints by means of mallet and gouge or by bone forceps was formerly much practised, but is only admissible when a promi nent enlargement forms a mechanical obstacle to movement of the tendons or when it is con stantly being injured by the opposite foot and cannot be reduced by other means.

Sore Shins.This is a common condition among young racehorses in training, particularly in two-year-olds.

The cause is usually periostitis of the meta carpal, or less frequently of the metatarsal bones resulting from concussion. In horses over four years of age the condition is rarely seen, as the bones then contain more mineral and less animal matter, are less vascular, and therefore more able to withstand impact.

The symptoms usually first make their appearance after a gallop. One or both legs may be affected, when only one at a time it is usually the leg the animal leads off with. The leg is rested or when both are affected the animal shifts his weight from one leg to the other re peatedly. The action is shuffling and restrained. Swelling of the front of the metacarpal region appears within the first few days. A sub periosteal exudate is thrown out and imparts to the enlargement a characteristic elastic, tense feeling. Later the overlying skin and sub cutaneous tissues become oedematous and in very severe cases pus formation (purulent peri ostitis) may occur. This is not a common sequel. If the sub-periosteal exudate is very great necrosis of the surface of the bone may occur as a result of separation from the periosteum, or the exudate may be replaced by bone in the form of a casing around the old bone. Lame ness then usually disappears. Mild cases, that is to say, those in which the condition is recog nized early and immediately treated, usually recover without complication.

Treatment. Daring the inflammatory stage cold irrigation by means of the hose pipe several times daily for half an hour, followed by the ap plication of warm flannel bandages over a thick layer of cotton wool, may give relief and diminish the amount of exudation. When the latter is very great, puncture with a fine trochar or sub cutaneous periosteotomy carried out under strict asepsis followed by an antiseptic dressing and a bandage is to be recommended, as it prevents further separation of the periosteum. After one or two days a biniodide blister should be applied.

Complete rest is at all times essential. When suppuration occurs, an opening should be made as low as possible for exit of the pus and anti septic leg baths employed at frequent intervals.

Fracture of the Sesamoid Bones. Causes. In most cases the actual cause of fracture is the opposing pull of the suspensory and inferior sesamoid ligaments at the moment that the greatest weight is being placed on the fetlock joint. Galloping on soft ground or on sand or slipping forward on the heel of the shoe on muddy ground whilst galloping may be the cause of the injury. Fracture appears more likely to occur after the animal has been con fined to the stable for some time previously to being taken out.

The direction of the fracture may be either horizontal or longitudinal. The former is the more common, as will be understood when one considers the cause of the injury. Comminuted fracture also occurs and the bone may be broken into four or five separate portions.

Symptoms. In horizontal fractures displace ment of the fragments results in loss of function of the suspensory ligament. The fetlock there fore sinks towards the ground but does not actually come into contact with it so long as the flexor tendons remain uninjured. The hoof retains its normal position and there is no tilting upwards of the toe as is seen in rupture of the flexor perforans tendon.

Swelling, heat, and pain may be detected in the sesamoid region and occasionally crepitation may be felt upon manipulation, but in most cases this symptom is masked by the amount of swelling. More often a gap can be felt be tween the fractured portions immediately after the occurrence of the accident.

In longitudinal fracture dropping of the fetlock may not be observable.

Very severe lameness accompanies all forms of sesamoidean fracture.

Prognosis. Cases of longitudinal fracture have been successfully treated, but horizontal fissures result in displacement, and bony union seldom, if ever, occurs. Fibrous union may take place, but this does not usually restore the animal's usefulness. Comminuted fractures are hopeless.

Treatment. Rest in slings is imperative. The limb may be fixed in such a position that the fetlock joint is slightly flexed, by means of a patten shoe. To the toe of this a piece of light iron about 1 inch wide, A- of an inch in thick ness and about a foot in length should be welded and then bent to follow the shape of the limb. The back of the sesamoid region is padded with several layers of cotton wool and then sur rounded by a strong plaster bandage applied over the metal splint.

If union does eventually occur the heel of the shoe must be gradually lowered until a shoe with thin heels can be worn, and this should be continued for some time to avoid contraction of the suspensory ligament or flexor tendons. Blistering and a run at grass will then be advisable.

Inflammation of the Sesamoid Bones.

This condition is often associated with chronic in flammation and distension of the metacarpo phalangeal sheath, the synovial membrane of which lubricates the pulley-like surface formed by the sesamoid bones and the intersesamoid ligament, and is reflected on to the flexor tendons. Both the anterior and'posterior sur faces of one or both sesamoid bones may be affected. Ostitis occurs in the bones them selves and extends to the articular cartilages, which become ulcerated. These changes may also occur in the articular surfaces at the back of the metacarpus and eventually bony union may occur between the sesamoids and this surface. In long - standing cases the disease may extend to the fetlock joint with resulting exostosis and anchylosis.

The condition may occur in either hind or fore limb but more commonly in the latter.

Symptoms. Lameness is usually constant but may not be severe. The fetlock is flexed whilst the limb is at rest. Upon starting off lameness is the more noticeable, the toe is dug into the ground for the first few steps and but little weight is placed on the heel of the shoe.

The sesamoid bones are enlarged and painful upon pressure. The flexor tendons are usually thickened where they glide over the roughened intersesamoid ligament, and there is in most cases an increased amount of synovia in the metacarpo-phalangeal sheath with corresponding distension. In the later stages contraction of the flexor tendons causes chronic knuckling at the fetlock joint, and anchylosis may exist between the sesamoids and metacarpal or metatarsal bones and sometimes between the latter and the suffraginis in addition.

Treatment. In acute cases cold fomentation, cold water bandages, or bandaging over a thick layer of kaolin paste may be beneficial. Astrin gent, cooling lotions applied on cotton wool and covered by a flannel bandage assist in com bating inflammation. A lotion of plumbi acet. and alum as 1 oz. in one and a half pints of water makes a useful application in the early stages.

In chronic cases treatment is of little use. Firing and blistering may be tried sometimes with temporary success, but the lameness usually recurs upon severe exertion.

Median neurectomy is recommended, but may be followed by fracture of the diseased bones or rupture of the suspensory ligament or of the abraded flexor tendons.

Ringbone.The term"ringbone"is generally used amongst horse-owners to describe any bony enlargement of the phalanges. Amongst veterin arians the expressions"true"and"false"ringbone are commonly employed. As these two conditions are pathologically and clinically unrelated much confusion has arisen from this description and in addition endless litigation, which in great part might have been avoided if only an agreement had at some time been arrived at amongst members of the profession as to what constitutes a ringbone.

Ringbone existing as an arthritis with slight exostosis is a very different matter from the point of view of a buyer or owner as compared with a large exostosis which is in no way con nected with an articular surface. The former renders the horse more or less permanently lame and greatly decreases his value, the latter, though it may cause temporary lameness, is of far less importance, and may indeed never interfere with the animal's usefulness.

"High ringbone"denotes the condition when the articulation involved is that occurring be tween the suffraginis and the os coroner;"low ringbone"that occurring between the os coronw and the os pedis.

Both these forms undoubtedly commence as an ostitis with extension to the articular sur faces and the subsequent or coincident produc tion of exostosis around the margin of the joint.

The condition spoken of as"false ringbone"is neither more nor less than periostitis, an inflamed and over-active condition of the periosteum covering the shaft of the suffraginis or os coronae without marked changes in either the bone tissue or the articular surfaces.

Causes. The actual cause of ringbone is similar to that of spavin and many other chronic joint diseases, viz. concussion acting upon bone tissue which is from some cause lacking in its power of resistance. Heredity is generally recognized as playing an important part in the production of ringbone, either through trans mission of certain conformation or of defective bone tissue. Probably the latter is more often the case, as we see very many horses with con formation conducive to concussion of the bone which develop no trace of ringbone in spite of years of hard work. On the other hand, statistics prove that when both parents are affected with ringbone, the offspring invariably develop the disease, and when affected animals are bred from for several generations ringbone occurs at an earlier age in each.

Strain of ligaments, which was at one time and is now by some observers considered a causal factor, seldom or never produces arti cular disease.

Both strain and concussion may produce periostitis and the formation of large exostoses, but these are purely surface disorders provided that the hereditary predisposition to ostitis is lacking. Strain of the ligaments of the phal angeal region is frequently the result of bad shoeing, unequal distribution of weight upon the wall of the foot through neglect in obtaining a level bearing, wearing the shoes too long a time and working on rough or irregular surfaces. Periostitis may also be caused by traumatic influences, from blows, kicks from the attendant upon the coronet, deep wounds involving the periosteum and from incomplete fracture. We have reason to believe that the latter condition is much more common than is generally imagined. Great pain is usually manifested quite suddenly, and this alone causes the animal to rest the limb sufficiently to secure union of the undisplaced portions of bone with the resulting formation of a callus which is usually diagnosed as"ringbone."" Chip"fractures are the most common type, then next in order come"splits"of varying length. These are usually the result of jumping, prancing, gallop ing or rearing and landing upon the foot with the pastern held too straight or in such a position that co-ordination of muscular pull is lacking.

Lesions. As before stated, ringbone is purely a bone disease with extension to the articular surfaces. Inflammation of bone tissue runs a course very similar to that of the softer tissues with certain special characteristics. The first stage is purely a vascular derangement. On section of an inflamed bone, undue softness is usually observed and change in colour from the normal either as an increased redness or a peculiar dark-blue coloration. This is observ able through the semi-transparent articular cartilage. In due course inflammatory changes extend in the direction of the long axis in the case of the pastern bones until the perichon drium is reached. It must be remembered that articular cartilage itself possesses no nerves, blood-vessels, or lymphatics but is surrounded by this very vascular layer which apparently stands in a similar relation to cartilage as does the periosteum to bone. As a result of con gestion in the parachondrium with resulting effusion the articular cartilage in certain areas becomes, so to speak, cut off from its origin and isolated. This occurs more readily in the cup-shaped articulation, the central portion of which lies nearest the inflammatory condition present in the centre of the bone tissue. It will almost invariably be found in the case of a bone such as the os corona, possessing one concave and one convex extremity, that the concave end is first affected. Hence, in"high upper articulation of the os coronae is usually the seat of disease, and in"low ringbone"the concave articulation of the pedal bone. Con tinuous movement of the joint soon causes ulceration of the articular cartilage when the parachondrium becomes congested and the vessels of the latter being exposed to irritation and friction commence to bud and form granu lations on the surface of the joint. The carti lage covering the opposing articulation may become removed by friction set up 'ay the diseased surface of the opposing bone, but we believe that this is due more to mechanical causes than to disease. Two granulating sur faces are thus opposed to one another, and given sufficiently long rest and freedom from move ment adhesion is the natural result. Effusion from the bone itself occurs simultaneously with these changes or from the internal surface of the periosteum surrounding the edges of the joint. This presently becomes more or less organised and appears partially cartilaginous. Lime salts then become deposited in this newly developed tissue and so the joint becomes surrounded by a layer of new bone, the exostosis, which com pletes the anchylosis of the joint.

If inflammation ceases at an early stage through removal of the exciting cause, such as concussion, recovery may occur and lameness may cease, but if the vascular changes have been sufficiently severe or prolonged to i cause exten sive effusion complete recovery s practically impossible. Bone elements have not the same capability of getting rid of inflammatory pro ducts as have the softer tissues, and their continued presence acts as would a foreign body, causing more or less continuous inflammation, especially after periods of increased concussion, and the production of fresh exostosis at intervals.

The so-called false ringbone is, on the other hand, in no way connected with inflammatory changes in the bone tissue, but is due to localized inflammation of the periosteum, principally at those areas which give insertion to ligaments or tendons. Concussion may play a part and the pull of the ligaments may increase the in flammation. Continuous slight strain acts as detrimentally as severe sudden strain. The former is in fact the cause of large exostoses surrounding the bones of the coronet, whilst the latter more frequently causes a small local exostosis which may never grow larger unless the strain be repeated. The deposit of fresh bone is developed from the inner surface of the periosteum, and the new growths, at least when of moderate extent, are covered by this mem brane.

Progno8i8. Complete recovery in cases of ringbone is practically unknown, and when it has been assumed to have occurred there has been in all probability an error in diagnosis. Ulceration of the joint surface can never be remedied, and the most favourable termination that we can hope for is complete anchylosis of the joint, which will of course leave permanent stiffness.

Whether a horse can work without pain with an anchylosed joint is a matter which has caused endless dispute. In most cases anchylosis is not complete in the sense that the joint is quite immobile. This, of course, depends upon the fusion of exostosis and the union of the arti cular surfaces themselves. In the majority of instances this does not occur throughout, but the new growths on the opposed bones are in many places merely in contact, and although they prevent extension and flexion of the joint on the part of the animal, yet some movement still remains and pain is aggravated by their re peated contact and by the strain placed upon the completely anchylosed areas. New growths of bone are almost always more or less spongy and yielding, and if post-mortem specimens of the bones of affected coronets be examined, in very few will complete rigid fusion be discovered. Apart from this, the fixation of the joint, often with the bones in an almost straight line with each other, directly increases the concussion, and although the animal saves the limb as well as he may be able, yet if forced to do fast work on hard ground, pain must occur from both the exostosis and the inflamed articular surfaces. The only reliable method of determining the existence of pain when peripheral exostosis exists is injection of cocaine over the plantar nerves just below the centre of the cannon. This operation when properly performed gives definite information, as although it cannot give freedom to the joint, yet apparent diminution of the lameness when subsequently trotted on a hard road indicates that the condition is a painful one. Care must be taken to test the skin covering the affected region before coming to a conclusion in order to ensure that local anaesthesia has been definitely established.

Periosteal exostosis is not nearly such a serious condition as ringbone. Young horses frequently exhibit prominences at each side of the lower end of the suth.aginis, which are termed by horsemen"anklets."In many cases these are not abnormal but are due to natural prominence of the bone.

Periostitis resulting from sprain is seldom or never associated with disease of the articular surfaces excepting in those cases in which true ringbone develops independently. There is no reason why a horse should not from conforma tion or lack of attention to level shoeing develop exostoses at the insertion of the lateral ligaments and yet subsequently develop ostitis and ring bone as the result of concussion, if bred from unsound stock.

Nevertheless lameness from periostitis un complicated by ringbone is a matter of frequent occurrence, and when there is no reason to suspect any hereditary tendency to ostitis there is in the majority of cases reason to believe that with due care in treatment and with removal of the exciting cause which in the majority of cases is neglect on the part of the farrier or owner, recovery may occur and the animal may remain, for some time at least, workably sound. Exostoses cannot be removed and any attempt at treatment with this object in view is useless. New growths of bone are always larger upon first being formed and diminish somewhat in size upon subsequent consolidation, but beyond this stage they cannot be lessened. Swelling of the tissues overlying the enlargement usually lessens when inflammation beneath the latter ceases.

Bony anchylosis of the joint may occasionally occur as a result of periostitis arising from strain of the ligaments or contusion, through extension of the inflammatory changes round the joint or by the formation of a mass of bone in a parti cular part which may be an obstacle to complete flexion or extension. But in these cases the articular surface of the joint is not involved anc upon the abatement of inflammation we se( true mechanical lameness, not necessarily asso ciated with pain. Fibrous anchylosis may airs( occur and cause similar stiffness without pain.

When the conditions which have caused the periostitis are not or cannot be removed, Cher lameness persists and may be continuous o] intermittent. The ever-present irritation of the periosteum results in the formation of a gradu ally enlarging exostosis and the animal ma3 become ultimately useless for work.

Ringbone may occur in either fore or hinc limbs but more frequently in the former, prob ably owing to the increased concussion borne b3 them. It is more common to get ringbone than periostitis in the hind pasterns, hence bony exos tosis in this situation is more commonly con nected with arthritis and so permanent lameness more often results.

The form of low ringbone affecting the coron ary-pedal joint is often followed by exostosis of the pyramidal process (pyramidal disease), and as the parts are encased within the hoof constant pain results.

Symptoms. The external appearances of ring bone may vary considerably from a large bony exostosis easily visible to very slight enlargement only distinguishable upon very careful palpa tion. Occasionally large outgrowths of bone may develop at the back of the joint under the flexor tendon and may interfere with its action.

In the so-called"pyramidal disease"the exostosis on the front of the pedal bone causes a marked bulging of the front of the hoof which grows down as a distinct ridge. Sometimes the foot appears almost triangular, with the apex in front.

Periostitis arising independently of ringbone isually commences on one or other side and 3xtends towards the front of the bone. Some Ames diffuse exostosis occurs around the whole the bone. The suffraginis may be included n the process.

The main difference in the two types of 3X0StOSiS is that in ringbone the enlargement is thiefly to be felt around the edges of the arti 3ulations, in periostitis the enlargement is lawny at about the centre of the shaft of the bone or at the point of insertion of the liga nents. As may be expected, periosteal enlarge ments may occur in the neighbourhood of the articular surfaces which cannot during life be distinguished from ringbone except by the symptoms exhibited. In these, unless anchy losis of the joint occurs, lameness usually sub sides after rest or treatment or may even never occur, whilst in true ringbone formation in the neighbourhood of a joint lameness never ceases altogether.

Frequently ringbone is complicated by side bone. Ringbone formation is ushered in by gradually appearing lameness without any signs of heat and frequently without any evidence of pain upon palpation. The action of the horse usually suggests foot lameness, that is to say, the animal yields when the affected foot comes to the ground, at the moment when concussion is greatest. At rest the fetlock and coronet are carried somewhat straighter than usual. If the animal be rested at this stage, the symptoms may subside, but in most instances recur upon again working upon hard roads. It will be observed that lameness is noticeable before any bony enlargement appears. The appearance of the exostosis is gradual, and some months may elapse before it attains any great size.

Periosteal exostosis may occur gradually with out lameness or it may be accompanied by lameness similar to that just described. If the animal be kept at work the degree of lameness will be found to vary from time to time, becoming worse or better in proportion to the nature of the work and the degree of concussion.

In ligamentous strain increased lameness is shown when the animal is turned towards the diseased side and when lateral movements of the foot are forcibly made.

Treatment —No lasting benefit results from the treatment of ringbone when once the disease has become established.

If the disease be recognized in the early stages prolonged daily irrigations with the hose-pipe and rest, with the shoes off, in a paddock is the best treatment. Hot fomentation increases the amount of exudation and the degree of subse quent exostosis. If rest in a stable is given the animal should be kept on a soft bed of peat.

Shoeing must be attended to early, the foot must be kept level so that undue strain falls on no part of the joint. A leather under the shoe when at work lessens the amount of concussion. After a week or ten days of cold irrigation blistering or line firing may be tried, or point firing may be tried if exostosis is developing. Should lameness abate after this treatment, no work should be performed for at least six weeks, and if possible the animal should be employed only on soft ground such as in farm work.

When ringbone is actually existent, relief may be obtained from double plantar neurectomy. The animal may thus continue at work for years, or fracture of the pastern or another sequel to the operation may occur very shortly.

Neurectomy is of more value in horses doing work on the land than on the roads.

The treatment of periosteal exostosis is more hopeful. In the early stages careful attention to the foot is essential, both sides of the foot must be made perfectly level so that the animal secures an even balance on the foot without undue strain on either side. This is more im portant than any other treatment. Cold irri gation followed by a blister and a run at grass may suffice in mild cases, but when large exos toses cause lameness, deep point-firing followed by blistering gives the best results.

Cases of suspected partial fracture should be rested and either encased in a pitch or plaster bandage or well blistered with cantharides. The resulting soreness will induce the animal to rest the limb and union may then occur.

Cab-horse disease is a name given to a peculiar form of lameness observed in horses working in buses, cabs, and vans, principally in the streets of large towns. In reality it is a type of high ringbone, but it is characterized by its position, viz. the inside and lower front of the fetlock joint.

Cab-horse disease may be defined as an ostitis of the suffraginis associated with changes in its upper articular surface.

The cause is in all probability an ostitis de pendent upon concussion and possibly hereditary influence. Paved streets seem conducive to the condition, which is only occasionally met with in the country. Traumatic influences have also been blamed, such as brushing with the opposite foot, but the situation of the enlargement renders this unlikely and there is usually no external sign of injury. Moreover, striking with the other foot would not account for lesions in the joint itself, though it might be responsible for external thickening.

Symptoms. This is mainly a disease of horses over middle-age. In the early stages the horse falls lame whilst upon a journey. After being brought home and rested he may again become sound in action until again worked. After a time lameness becomes more or less constant. On handling the part nothing can be detected; there is no indication of heat, swelling, or pain.

This may continue for several weeks, the horse gradually becoming more and more lame. A bony swelling will then commence to appear on the inside of the fetlock joint; very rarely indeed is the outside affected. This exostosis very gradually increases in size.

The lesions observable on post-mortem are congestion and softening of the os suffraginis in recent cases, an increased whiteness and hard ness in old-standing ones. Periostitis exists with exostosis of the head of the suffraginis, whilst the lower end of the metacarpal bone almost invari ably remains intact. The articular cartilage is always affected with ulceration, and in some cases there is loss of tissue in the articular surface of the bone itself, particularly on the inner portion of the joint.

In some cases the condition is complicated by disease of the sesamoid bones which may become fused on to the back of the pastern bone.

Prognosis is always unfavourable, and cases seldom become sufficiently sound for town work, though if of sufficient size they may work on soft ground at farm work. The condition is, however, usually seen in light harness horses, which are unsuitable for anything but moderate draught.

Treatment is of little service. Attention to the bearing of the feet and puncture firing usually alleviate the condition but cannot cure it. Neurectomy of the internal or both plantar nerves or preferably of the median nerve may render the animal useful for a time. The internal plantar nerve should be divided im mediately below the oblique branch which is given off from the external plantar and joins the internal an inch above the button of the splint bone.

Lameness. — Inflammation of the hip-joint is rare in horses but occasionally seen in cattle. The causes are forced abduction, as may occur in falling with the hind limbs straddled and bruising, which is not commonly seen; the bursa of the gluteus medius tendon is more frequently injured through this cause than is the joint.

In cattle we have on several occasions observed arthritis of the hip-joint with marked enlarge ment and exostoses on the rim of the aceta bulum and head of the femur. These symptoms produce marked wasting of the whole body and continuous severe lameness. Possibly these were cases of articular rheumatism.

Symptoms. In both horses and cattle the limb is advanced with a circular swinging motion at slow paces. In the horse whilst at the trot the quarter on the lame side is elevated with as little movement of the hip as possible and appears to come up with a jerk."Three cornered"action is usually noticeable; the affected limb is abducted, and the animal appears to move away from the lame limb.

At rest the foot may rest on the toe, with flexion of all the joints below the hip. When the lameness is severe the animal may only be moved with difficulty. The foot is held con stantly off the ground whilst at rest, mainly by the action of the muscles below the hip region, allowing the gluteals to remain in a state of relaxation. Atrophy soon follows from inaction of these muscles.

Treatment. Calkins on the heels of the shoes help to rest the hip-joint. In acute cases of strain or bruising cold fomentations may be employed, followed by blistering or firing and blistering.

Bruising of the hip-joint usually recovers in from a fortnight to a month, but arthritis and rupture of the ligamentum teres seldom respond to treatment, although post-mortem examina tions have on several occasions revealed old standing rupture of the ligamentum teres with out any history of lameness.

Fracture of the acetabulum, of the head of the femur, or of the trochanter is occasionally met with.

Fracture of the acetabulum is characterized by loss of control over the limb, that is to say, abduction and adduction occur independently of the animal's will. In one step the limb may be adducted, in the next abducted. Crepita tion is very distinct in the interval between fracture and the appearance of swelling, and can be heard every time the hand presses upon the muscles of the hip region.

Fracture may occur either in the head or at the neck of the femur. Marked abduction is usual, and lameness is apparent in all positions of the limb. Union by fibrous adhesion some times occurs.

The great trochanter or the third trochanter of the femur may be fractured by direct violence.

Union often occurs after several months' rest, but the connection is usually fibrous and not bony. In one horse used for dissection pur poses at the Royal Veterinary College the third trochanter was attached by fibrous tissue but no lameness was apparent before slaughter. In another horse we observed fibrous union of the great trochanter and disappearance of lame ness after three months' rest. The most visible

symptom at the time of the fracture was shorten ing of the forward stride.

Luxation of the Femur. This is an exceed ingly rare condition in the horse, owing to the strength of the ligamentum teres and the cup like shape of the acetabulum. In oxen this part of the articulation is not so deep, and cases of luxation are more commonly met with. Cases also occur in dogs occasionally.

Rupture of the ligamentum teres is necessary before complete luxation can take place, and in the horse fracture of the head of the femur is more likely to accompany or precede luxation.

In cattle, falling with the hind limbs"straddled"after leaping or service may result in rupture of the teres ligament and luxation of one femur or of both. The hind limbs are extended at right angles to the long axis of the body, and the animal is unable to rise. Often the adductor muscles on the inside of the thigh are ruptured and adduction becomes impossible. The animal lies upon the pubis or udder.

Treatment. — Reposition may usually be effected by placing a stout plank or log of wood between the hind legs and levering the head of the femur into position. It is, however, a matter of difficulty to secure it in the aceta bulum. Rest in slings in the case of horses and a thick pitch charge applied over the joint may assist, but in cattle at all fit for the butcher slaughter is advisable.

Stifle - joint Lameness.The con sists of two separate articulations, the femoro tibial and the femoro-patellar. Each joint is provided with its own synovial membrane, and in the majority of cases the two communicate by means of one or more small openings. This, however, is not always the case.

The lesions of closed arthritis may involve either or both of these articulations.

Dropsy of the stifle-joint, chronic serous arthritis, may exist, and must be distinguished from dropsy of the prepatellar bursa, which is present in most cases on the anterior surface of the patella and at times may be very well developed.

Fracture of the patella is rare. Cases of rupture of the straight ligaments and of the lateral ligaments are sometimes met with, whilst luxation of the patella, either partial or complete, is fairly common.

Chronic Inflammation of the Gonitis Chronica.In most instances the femoro tibial articulation is involved, together with the interarticular discs of fibro-cartilage. The changes in the joint consist in ulceration of the articular surfaces of the head of the tibia, particularly in the neighbourhood of the tibial spine, and corresponding changes on the con dyles of the femur. The interarticular cartilages become degenerated and shredded, whilst osteo phytes may appear upon the surface of the joint. The inner division of the joint is the more often affected; sometimes the external division shows no lesions whatever. The internal condyle becomes enlarged in advanced cases, and this may be appreciated upon pal pation in the live subject. The synovial mem brane is thickened and vascular, and may present a granulating surface with long villous projections.

Arthritis of the femoro-patellar joint is not nearly so common. Hunting and Porch, F.R.C.V.S., writing in the Veterinary Record of November 2, 1907, described two cases of stifle-joint lameness in which the lesions were confined to this joint. In both,"on the trochlea of the femur the cartilage covering the inner lip was thin and roughened; it was not ulcerated and it retained its translucent quality, so that through it could be seen a reddened and roughened surface of bone for nearly the whole length of the inner lip of the trochlea. The patella was unaltered, except that the articular cartilage corresponding to the diseased part of the femur was thin." Apparently in neither of these cases was there any excess of synovia.

We have ourselves observed a case of chronic arthritis with very great distension of the femoro-patellar capsule and continuous pain and lameness which was followed by apparent recovery. Lameness ceased though slight enlargement remained, and the animal returned to work on the land. A week later the symp toms were as severe as before. Aseptic' punc ture, followed by a biniodide blister, again brought about apparent recovery, and a little later the animal was returned, but not being required for work was turned out to graze. In a fortnight he was brought back in a float in the same condition as previously. Destruc tion was decided upon, and a post-mortem examination carried out. The synovial capsule of the femoro-patellar joint was very much thickened, the synovial membrane was red and vascular-looking in parts, in others quite black and apparently necrotic. The joint cavity was distended with a clear watery fluid containing numerous flakes of fibrin. No change whatever could be detected in the articular surfaces of either femur or patella. In spite of the fact that the synovial capsules of the femoro-tibial and femoro-patellar joints are supposed to com municate, the former contained a normal amount of healthy synovia without clots and the synovial membrane appeared sound.

Prognosis. Chronic arthritis of the stifle joint with structural changes in the cartilages or articular surfaces is incurable.

The symptoms are usually developed gradu ally, and are apt to be wrongly diagnosed in the early stages before swelling appears. Occasion ally several months or years elapse before the horse becomes useless.

Symptoms. In disease of the femoro-tibial joint, whilst the animal is at rest the limb is held in such a position that the inflamed joint surfaces are kept as far apart as possible. To facilitate this the thigh is flexed upon the pelvis and the leg upon the thigh, whilst the fetlock is also flexed. In place of this attitude the horse may extend the hip and stifle and stand with the fetlock so far flexed that the front of the foot and the coronet rest upon the ground. Later, the limb may be held"in the air"with the foot clear of the ground and with all the joints flexed. When induced to work the animal shows pain, upon advancing the limb, and the stride is always shortened. During movement the stifle-joint is usually fixed in a position of moderate or marked extension, and this accounts for the difficulty in bringing the leg forward.

Trotting is usually difficult or impossible. The limb is carried"in one piece"and the toe constantly strikes the ground.

On moving over in the stable, the horse frequently carries the lame limb and occasion ally jerks it up, in a manner simulating string halt. This is evidently the result of sudden, severe pain.

Distension of the synovial capsule produces a swelling at the front of the stifle. Very often the external straight ligament seems to divide this swelling, and an enlargement is then visible a little to the outside and another immediately in front of the stifle. The tendon sheath of the extensor pedis may also be involved. This usually communicates with the joint capsule. The lameness may precede the appearance of the enlargement by some months, and is often intermittent in the early stages.

The symptoms of femoro-patellar joint lame ness vary somewhat from those just described. They are well described in Hunting and Porch's article before mentioned, from which we will quote in brief: "At the commencement of lameness the symptoms were not well marked—little more than stiffness of the hind limbs. Later the extensor muscles of the thigh showed excessive rigidity when the animal was moved. When made to walk, the hind legs were carried forward stiff and straight as though jointless, and the muscles in front of the femur were spasmodic ally contracted. Both hind legs were affected, but the near hind showed rather the more aggravated symptoms.

In another case the lameness was"at first, not well marked, chiefly stillness. Then came the ' wooden ' position of the hind limbs, for both were affected—the difficulty of movement when made to walk and the striking rigidity of the extensor muscles of the thigh, especially of the vastus externus and the tensor vaginae femoris." Treatment. There is no beneficial treatment for chronic gonitis when once the diagnosis is certain. With care some cases may work on for years, but slaughter is usually necessary sooner or later.

Dropsy of the may appear soon after birth. In some respects it resembles bog-spavin in that it results from weakness of the joint, which may be hereditary.

Sometimes the condition is confined to one limb, frequently both are affected simultane ously.

As a rule lameness is not marked, unless the distension is sufficient to produce mechanical interference with movement of the joint. In this case there will be shortening of the stride and slight abduction or circular movement of the limb. The limb whilst at rest is frequently held with the stifle and hock semiflexed and the front of the foot and coronet resting upon the ground.

Treatment. This is seldom required or even advisable excepting in horses used for exhibi tion purposes. Blistering is seldom successful; in working horses line-firing and blistering may give better results.

Aspiration and subsequent injection of hydrarg. perchlorid. solution 1 in 1000 or a 1 per cent solution of potass. iodid. has been recom mended. Successful results have been recorded, but great care as regards asepsis and technique are called for. Sometimes in young horses the condition disappears spontaneously.

Fracture of the Patella.This is a very rare condition in animals. The cause may be traumatic, such as from falls, kicks, or blows, or the patella may be broken by muscular action (into-ordination). In the former case the fracture may be comminuted or vertical and is frequently compound, whilst in the latter it is usually transverse.

Symptoms. Weight cannot be borne upon the limb, and movement causes great pain.

There is inability to extend the stifle. Swelling of the tissues covering the front of the joint appears rapidly and disguises crepitation.

Prognosis. Many cases of simple fracture unite by fibrous adhesion if given rest and time, and so the action of the extensor muscles becomes re-established. On the other hand, in fractious patients recovery may never occur ,owing to inability to keep the limb at rest.

Andrien reported recovery of a compound fracture, attended by escape of synovia, in two months, though such success is exceptional.

Treatment. Rest in slings with the stifle extended gives the best chance of success. As it is difficult to effect this in horses one may try fixing the hock-joint in a position of moderate flexion, which will often produce extension of the stifle. Small animals may be bandaged.

In the horse, blistering may hasten union and lessen movement. Large callus formation need not be feared as the patella is practically devoid of periosteal covering and the blood supply is scanty. In vertical and some com minuted fractures the fibrous covering of the bone assists in keeping the pieces together.

Luxation of the Patella.In the ,horse the groove of the trochlea is nearly vertical in direction and the inner lip is much the more prominent of the two. In the ox the upper extremity of this lip is somewhat flatter than the remaining portion, that is to say, if the rim of the trochlea be regarded as the segment of a circle drawn around a given centre, the upper portion of the rim would be nearer to that centre.

In the horse, the inner lip of the trochlea is also the more prominent but its upper edge is even less rounded than in the ox, and in many instances appears slightly concave.

In the dog the lips of the trochlea are of equal height.

Luxation of the patella may be (a) Upwards, or (b) Lateral: Upward Luxation of the Patella.This may be complete or partial. By partial or moment ary luxation we refer to that condition in which the patella becomes temporarily fixed during motion.

The causes of upward luxation may be slack ness of the straight ligaments, spasmodic con traction of the rectus and vasti muscles, or defective shape of the trochlea. It is certain that the joint must be fully extended before upward luxation can occur. The patella then rides upon the trochlea to its highest point, which, as before mentioned, is flatter than the lower portion, and there becomes arrested. The internal lateral ligament may become fixed upon the bone, or the extension may be sufficient to allow the bottom edge of the patella to rest upon the inner trochlea.

The symptoms are characteristic. The con dition may be only momentary and recurrent, or the patella may become upwardly luxated so that the animal cannot effect reduction un aided. Momentary or recurrent luxation is more often seen in slack-jointed colts and young horses out of condition, though it may occur in older animals. Lameness may vary according to the extent of luxation. At the trot, the foot appears to rest for a moment just as it leaves the ground, or in more severe cases the animal may be trotting quite naturally when suddenly the hind limb becomes abnormally straight, i.e. extended, and is carried behind the other like a wooden leg. After one or two steps the symptoms may disappear and normal action may be resumed, or the condition may exist for several seconds or minutes.

Complete upward luxation is more common in older horses. It may occur as the result of undue extension, as from falls with the hind limb extended backwards, from kicking, failing to clear a jump, or from slipping the limb back wards whilst pulling hard.

In recurrent luxation we must suppose that the patella becomes fixed above the normal height by the tension of the lateral ligaments which hold the bone tightly against the less curved portion of the trochlea. This may be facilitated by slackness of the straight liga ments. In complete upward luxation, however, the base of the patella actually rests on the flattened or concave area at the upper extremity of the condyle.

Whilst the bone is in this position the stifle remains extended to its utmost, and, as all the other joints of the hind limb must follow suit, the limb is stretched out behind the animal and cannot be flexed even with external assist ance, unless the patella be first restored to its normal position.

Prognosis.Even in colts the prognosis of recurrent luxation is by no means favourable. Occasionally cases recover, and these may be due to slackening of the straight ligaments through ill-health. Congenital luxation is seldom curable in our experience in spite of treatment, and by the time that the foal has become old enough to carry a surgical shoe, the trochlea will have become roughened and diseased from constant displacement of the bone. Cases of complete luxation may recover under treatment so that in three or four days lameness may be absent, but there is always a predisposition to a repetition of the luxation under similar circumstances.

Treatment. Recurrent luxation requires rest and attention to the general health of the patient. Thin, anaemic colts require tonics and nourish ing food. Blistering the stifle appears to be beneficial, probably because it thickens the skin overlying the patella and provides a natural bandage.

To avoid luxation whilst at rest or at pasture, a rope may be attached from the hind leg, just above the hock, to a collar or neck-rope, or a strap with a D attached may be fastened above the hock and connected to a neck-strap by means of a stout elastic band. A shoe with a "toe-prong"attached answers a similar pur pose, as also does a temporary shoe fitted with a thick toe-piece and calkins, which enforces moderate flexion of the limb by raising the foot from the ground. For running at pasture a"patten-shoe"with a toe-piece is preferable as calkins sink into the soft earth.

For work, a shoe with a thickened toe is usually efficient.

Complete or"stationary"upward luxation is reduced by one or other of the following methods: (1) By drawing the foot forward by means of a rope applied around the hind fetlock and passed through a collar or neck-rope, and then backing the animal whilst downward and out ward pressure is exerted upon the patella. This method is usually successful.

(2) By sudden backing or turning move ments, accompanied by an unexpected blow from a whip. This causes contraction of the extensor muscles, which may free the patella.

(3) By manipulation of the patella whilst the animal is under the influence of chloroform.

Section of the internal straight ligament has been recommended by many Continental veterinary surgeons for the relief of recurrent luxation. The division should be effected at its insertion into the tibia to avoid injury to the synovial capsule.

Lateral Luxation of the Patella.In the horse and in cattle the patella usually becomes dis placed outwardly, but in the dog inward luxa tion is more common.

The

cause is usually stretching or rupture of one of the lateral ligaments of the joint. The symptoms differ from those of upward luxation, as the lever action of the patella is lost and the extensors of the stifle-joint are rendered power less to straighten the limb.

Continuous flexion of all the joints is there fore seen, and the symptoms very much resemble those of crural paralysis. The rectus and vasti muscles are still capable of advancing the limb, which is carried forward under the body but is incapable of bearing weight, so that the quarter of the affected side sinks when the foot comes to the ground. The patella, in its altered position, appears as an enlargement on the antero-external aspect of the stifle and is clearly visible.

Treatment.Reposition in horses and cattle is usually difficult, but in dogs it is easy, though in all animals the greatest difficulty will be found in keeping the bone in position sub sequently.

Forced extension of the limb by means of a rope attached to the fetlock and carried through a neck-rope or collar may assist reduction, which is effected by lateral pressure. Con siderable ingenuity will be required to maintain the patella in position. In horses slings and a pitch charge or a blister may be successful. In dogs pitch bandages are best.

Luxation of the Femoro Joint.This condition has sometimes been observed in cattle as the result of external violence, usually from falls over banks or into ditches. The direction of the luxation may be backward, forward, or to either side.

Backward luxation is more common.

Symptoms.The leg is extended backwards, rigid and immobile. When the animal is made to walk the claws are dragged and the sole of the foot cannot be brought to the ground. There is always deformity of the stifle region, varying according to the direction of luxation. After a short time local swelling appears and may give rise to some difficulty in diagnosis.

Treatment.Reposition may be attempted by passing a length of webbing or a rope around the thigh or cannon, and applying traction by means of a block and pulley. Simultaneous pressure upon the head of the tibia in the required direction may be successful. As luxa tion of this joint is accompanied in most in stances by extensive rupture or stretching of ligaments, luxation is liable to recur, and in any but valuable animals slaughter for food is to be advised when other circumstances permit.

Rupture of the Straight Ligaments of the Patella. Rupture of the external straight ligament may result from direct violence or sudden strain. The condition is very rare.

The symptoms are supporting leg lameness, pain upon pressure, and the existence of a hollow where the external ligament normally exists. The patella does not become displaced and the limb is capable of being extended and flexed.

Treatment is merely a matter of complete rest. Recovery usually occurs in one or two months.

Tibial Lameness.Under this heading we refer to those cases of lameness due to injury to the tibia without apparent fracture.

The causes of such injury may be kicks from other horses, particularly where animals are tied on"lines"or where bails are used, getting the hind leg over a"bail,"or becoming"hung up"in a gate or fence whilst jumping. The seat of the lameness is usually the inner side of the tibia, where it is most exposed and covered only by the tibial fascia and the skin.

The lesions produced vary according to the nature and degree of the injury. The peri osteum may be alone involved and periostitis may result, occasionally with the occurrence of suppuration under the tibial fascia and some times with the formation of a bony growth which may extend the length of the bone.

More violent injury usually produces fracture, which may be of several different types. The bone may be dented and"starred,"that is to say, from a central point fissures radiate involv ing only the superficial layer of the bone. Later these splinters may become displaced and set up suppuration, extending throughout the in side of the tibial fascia with necrosis of this tissue.

As a result of the injury the bone may be deeply fissured and yet, being tightly bound by the peniosteum and tibial fascia, displace ment may never occur, or it may be produced even weeks later by a violent muscular effort overcoming the resistance of the surrounding tissues.

Symptoms.Tibial lameness is usually of a more or less severe character, although many cases of fracture occurring suddenly whilst at slow work must be attributed to previous injury (deferred fracture) which has caused an un displaced fracture unattended by lameness.

There is usually both supporting and swing ing leg lameness, though the former is usually the more marked. The horse frequently comes out of the stable exhibiting symptoms greatly resembling acute foot lameness. In more severe cases the leg is carried and movement is accom panied by groaning. Palpation of the inner tibial region reveals pain, and frequently the overlying skin is oedematous or a tense elastic swelling can be felt along the course of the bone (subperiosteal effusion). Later, exostosis is frequently observable.

Pressure upon the sensitive parts causes lifting and abduction of the limb, and in severe cases the animal may almost fall.

Treatment.With the possibility of fracture always borne in mind, we must at first insist upon rest in the stable, and on some occasions slinging may be necessary. Periostitis may be treated by warm fomentations, or a narrow bag of sacking fastened above the hock and of sufficient length to reach to the stifle may be packed several times daily with hay steeped in hot water. This retains its heat for some hours.

Hot poultices made by mixing powdered kaolin with hot water and a little treacle to produce a hygroscopic action, kept in position by stitching sacking around the limb after applying the material thickly on cotton-wool, retain their warmth and moisture for at least twelve hours and are very effectual in relieving local inflammation.

If subperiosteal exudation is excessive, as is evidenced by the presence of a tense elastic swelling, cold applications are best and should be followed by a mild biniodide of mercury blister.

Suppuration and fracture must be treated on surgical lines.

Spavin.It is a very difficult matter to pro vide a definition of spavin which will cover the condition in all its aspects. The generally accepted description is a bony enlargement on the lower and inner aspect of the hock. This is hardly sufficiently definite, as many cases of disease involving the articular surfaces of the bones are attended by little or no apparent bony enlargement. Moreover, commencing ()s tabs may be accompanied by lameness with out visible change in the appearance of the hock, which may persist for some considerable length of time, and yet the condition must be considered as spavin from the commencement.

Occasionally the external surface of the hock may be the seat of enlargement, and in a number of such cases the lesions are identical with those seen on the internal surface in a typical case of spavin.

The Nature of Spavin. Spavin pro bably originates as an ostitis. Many ob servers have regarded it as primarily a diseased or strained condition of the liga ments, and there is evidence to prove that cases of exos tosis on the inner lower aspect of the hock may indeed arise from this cause. But, when these enlarge ments are examined post mortem true bony anchylosis and lesions of the joint surface are invariably absent. Fibrous anchylosis may exist in a few, but the appearance is easily distinguishable from true spavin.

It is evident that the majority of cases of spavin commence as a rarefying ostitis attack ing, as a rule, the head of the metatarsal bone first and then extending to the cuneiform and scaphoid bones. Sometimes only the large cuneiform and scaphoid are affected. The cuboid is but seldom involved.

The changes first occur in the deeper portions of the bone and then extend peripherally towards the edges, or upwards or downwards to the articular surfaces, or in both directions. Breaking down of the bony tissue results in the production of small cavities which become filled with granulation tissue. Later condens ing ostitis or osteo-sclerosis follows and results in anchylosis and exostosis.

Sometimes the ostitis extends peripherally only, resulting in peripheral anchylosis without changes occurring . in the articular surfaces; sometimes the latter are affected with ulceration of the cartilages and subsequent anchylosis without the production of exostosis on the edges of the bone. This condition is spoken of as"occult spavin." A few veterinarians consider that spavin arises as an inflammation of the bursa of the branch of the tendon of the flexor metatarsi which is inserted into the cuneiform parvum.

This bursa is frequently involved in the process of spavin formation, as the cunean tendon crosses the seat of spavin. When the exostosis is large and in a painful condition the tendon no doubt causes pressure and exagger ates the pain, but there is no evidence to sup port the view that the changes which occur originate in the bursa itself. Section of the cunean tendon has been practised for a long time for the relief of spavin lameness, but it is probable that the good results which have often been observed have been due more to the irritation and inflammation caused by the process than by lessening the pressure.

Cau.sea. One of the most commonly accepted theories explaining the prevalence of spavin is hereditary influence. Exactly what is trans mitted from parent to offspring is not stated; by some it is regarded as weakness arising from defective conformation, by others as being due to the character of the bone-tissue itself. Con formation of the hock has apparently very little to do with spavin formation. Turned-out hocks, cow-hocks, sickle-shaped and"tied-in"hocks have all been blamed, but the fact remains that we see hocks of every description un affected with spavin as well as we see perfectly shaped hocks with spavin enlargement. Con formation of the body or the limb as a whole apparently does exert some influence according to the degree of concussion which is transmitted to the bones of the hock. Thus straight pasterns and heavy quarters may play their part in the production of spavin. Nevertheless, the con dition does not appear to occur more in one class of animal than another. Horses working on soft ground, riding horses carrying heavy weights on hard roads, harness horses, ponies used for fast or slow and comparatively heavy work may all or none develop spavin, but there appears to be no particular tendency to do so in one more than in another. Working horses at too early an age is also frequently blamed, but on the other hand we often see young horses which have done no work with well-developed spavin. Also, too, we fre quently observe the early stages of the disease in old horses which have never exhibited hock lameness in earlier life. We can only conclude that the tendency to ostitis is handed down only as regards the bone-tissue itself and that it exists in a varying degree, i.e. it may be sufficiently pronounced to occur in an un worked two-year-old or the tendency may be so slight as to resist years of hard work. Pos sibly the process is only an attempt on the part of nature to strengthen that portion of the limb least adapted to fulfil its function.

Apart from concussion or compression a local inflammatory condition of the tissues surround ing the hock may produce exostosis on the seat of spavin. Sprain of the ligaments during the act of jumping or through slipping or external violence may produce bony enlargement following a period of acute lameness. From a veterinary legal point of view this too must be considered as spavin, although in a stallion or brood mare the tendency to transmit spavin need not necessarily be present. As before stated, artic ular anchylosis is in this case rarely present, and true peripheral anchylosis does not always exist although the bones may be considerably enlarged.

Peters considered that spavin resulted from strain of the ligaments due to rotary movements of the lower bones of the joint. As the joint between the tibia and the astragalus is a ging lymoid one and its axis lies obliquely to the body, and as the two tibiae converge from above downwards, whilst the two metatarsal bones are practically parallel, he concludes that when weight is placed on the limb the muscles rotate the joint as well as extend it. The weaker lateral ligaments of the small bones have there fore to take the most strain, and this he con sidered set up inflammatory changes in the periosteum.

Symptoms. Lameness may be apparent be fore enlargement occurs. In occult spavin the latter is entirely absent whilst the lameness is usually very marked. In some cases, how ever, horses develop considerable bony enlarge ments without exhibiting any lameness at all, or in any case not sufficient to attract the driver's or owner's attention.

The diagnosis of a spavin is not always by any means an easy matter when the animal does not exhibit lameness. When well developed, it is patent to the trained eye and touch, though in some cases one hock may vary considerably in profile from the other and yet be perfectly sound. A brief consideration of the surface anatomy of the inner aspect of the hock is necessary before proceeding further. The prominent blunt tuberosity on the lower and inner surface of the astragalus is easily felt. The lower edge of this marks the line of articula tion of the latter bone with the scaphoid, the more or less prominent rim of which can be traced by the finger. Slightly lower will be felt a groove running inwards, then backwards and upwards. This represents the junction of the scaphoid with the large and small cuneiform bones, the edges of which may then be palpated. A groove running from above downwards may be detected which joins the horizontal groove described above. This is the separation be tween the large and small cuneiform bones. Below the prominent ridge of these latter is yet another horizontal groove representing their articulation with the metatarsal bone. In a thin-skinned horse the cunean tendon of the flexor metatarsi may be felt running inwards and downwards from the front of the hock into the cuneiform bone in line with the chest nut. The head of the small splint-bone, above which lies the cuboid, must be carefully felt. Enlargement of the head of this bone may be confused with true spavin.

The ridges on the scaphoid and cuneiform bones vary in size in different horses, and frequently even in the two hocks of the same animal. Excessive prominence of these gives a feeling of roughness and a prominent appearance, to which the term"coarse hocks"has been applied."Odd hocks"signifies the condition when the ridges are developed more on the one hock than on the other. Without careful palpa tion one may be deceived into thinking that a spavin exists when as a matter of fact the hocks are sound.

When the animal is lame from spavin there may be recognized certain symptoms which are more or less characteristic. In the first place, lameness is most marked when the animal starts to move, and it tends to diminish or even dis appear with exercise. This is, however, not the case in"occult"spavin lameness, which does not improve as the horse goes farther. Lame ness is continuous in this form. In mild cases of spavin, lameness may only be evident after the horse has rested after violent exercise. In marked cases of lameness the toe is dragged slightly along the ground for the first few steps; when in harness with a heavy load, stumbling with the affected leg may sometimes be noticed upon starting. The toe of the shoe always shows wear in advance of the heel. As the animal progresses the heel comes more and more to the ground, and after trotting a mile the heel may be brought down and lameness may disappear until such time as the animal is rested, after which the symptoms will reappear.

The affected hock is not flexed to the same extent as the sound one. This may be observed either when the horse is trotted past or when viewed from behind, when it will be noticed that the point of the spavined hock is not lifted as high as its neighbour. The limb appears to be carried"in one piece,"the extension of the limb being mainly conducted from the hip and stifle whilst the fetlock is moderately flexed. The reason of this lack of flexion of the hock is usually ascribed to rigidity resulting from anchylosis, but when we consider that practi cally all extension and flexion movements of the hock occur in the joint between the tibia and astragalus, this hardly sounds feasible. The real explanation probably is that the limb is carried in the position which causes the least pain. Probably Peters's theory of rotation may explain this. When the limb is extended and the foot takes the weight of the body, a certain amount of rotation occurs between the small bones of the hock and the metatarsal bones. By flexing the hock and lessening the weight on the limb, by bringing the toe first to the ground with the fetlock slightly flexed, this rotary movement with its accompanying pain is avoided.

Another symptom observable in long-stand ing cases is atrophy of the gluteal muscles. There is also a peculiar dropping of the affected quarter at each forward stride, which may best be observed from behind the animal.

Atrophy of the gluteal muscles appears to occur whilst the animal is kept at work, but disappears if rested in the stable for some weeks.

The late Mr. Hunting explained this fact in this way. So long as the horse works the pain ful condition of the hock remains, and in the stable is aggravated. He therefore rests the limb and the gluteal muscles are in disuse between journeys. In other words, during twenty out of twenty-four hours of the day the muscles are out of use. When work ceases altogether, pain in the hock grows less and so the gluteal muscles gradually come into use and atrophy abates.

Old-standing cases of spavin are often com plicated by chronic contraction of the flexor tendons resulting from constantly flexing the fetlock whilst at work and at rest.

In the stable this constant flexion of the lower part of the limb is very noticeable. When turned from side to side lameness is more evident when moving away from the lame leg.

The lameness is often of a more or loss inter mittent character, and it is not uncommon in the early stages to find the horse sound one week and lame the next, and vice versa.

The so-called"spavin test"is conducted by holding the limb with the hock fully flexed for half a minute. Upon subsequent movement lameness is greatly increased. This test is not at all a safe guide, as many other conditions may cause the same increased lameness after forced flexion, and in old horses it is not at all a reliable test.

Prognosis. In the majority of cases marked lameness only accompanies the acute inflam matory symptoms, that is, the period of acute ostitis. The development of large exostosis with complete fusion of the small bones in volved usually brings about improvement and the animal may even trot sound and remain so. A really large spavin is usually less likely to cause future lameness than is a small one. In the latter case, when ostitis has been confined to one or two bones or has terminated in only a moderate degree of anchylosis, relapse is more liable to occur either as the result of imperfect fusion or from the development of ostitis in other parts of the hock. Spavin in young horses which have done little or no work is usually more serious than in older animals. Some animals never recover their soundness of action, constantly wearing the toe and imper fectly flexing the hock. In these cases atrophy of the gluteal muscles is usually persistent, and this is often regarded as an indication that the animal is suffering pain to a greater or less degree whilst at work. It is probable, however, that carrying the limb for a considerable time in this position results in contraction of the tendons and adaptation of the ligaments to such an extent that the leg becomes more or less fixed in that position. In those cases in which lameness continues after anchylosis is complete, soreness in the bones themselves, in creased by concussion, is probably the cause. The ostitis may possibly be subacute or chronic.

Cases which recover under treatment usually require resting for at least six weeks. Twelve weeks is to be preferred when the animal can be spared sufficiently long. The prognosis in cases of"occult"spavin is always unfavour able, and after six months' to twelve months' rest and treatment lameness may be as severe as before.

Treatment. In order to secure union of the granulating areas of bone, rest is essential. Recovery seldom, if ever, occurs whilst the animal remains at work. The general rule is to turn the horse out in a flat field when weather permits, though certain practitioners insist upon complete rest in a stall, and some even forbid the animal to be taken out of the stable for as long as two months whilst other remedial measures are being carried out. This method of treatment certainly produces excellent results and appears quite rational.

The surgical treatment of spavin has made no great advance for over a century. Firing, blistering, and other forms of counter-irritation are still employed and apparently aid in bring ing about recovery, either by hastening the pro duction of the inflammatory deposit or by in creasing the local pain and securing voluntary limitation of movement of the affected joint.

The actual cautery is far preferable to mere blistering. Line - firing, pyro -puncture, needle puncture are all in vogue. Probably the best method is line-firing with the addition of one or two applications of the pyriform iron at the most prominent points of the enlargement. If this situation is selected there is practically no risk of opening the joint. The internal meta tarsal vein must be guarded against accidental puncture.

The operation of firing may be followed by the application of a blister. Biniodide of mercury ointment mixed with cantharides oint ment is the most useful for this purpose. Some practitioners recommend aseptic firing. The skin is first disinfected and the lines or points are subsequently dressed with iodoform or bathed frequently with an antiseptic.

Subcutaneous firing as recommended by some Continental veterinarians has no obvious advan tage. Cunean tenotomy often gives good results, but the operation in cases where exos tosis is marked usually resolves itself into sub cutaneous scarification of the enlargement in which the cunean tendon is practically buried. Hunting reported about 80 per cent of recoveries following the operation. He considered that section of the tendon relieved the parts beneath of much pressure, and that when healing occurred there would be adhesion throughout the whole of the bursa and the pull would be on the part most anteriorly attached. In other words, the pressure would be less on the spavin afterwards than it was before, even if one only divided the tendon.

Cunean tenotomy may be performed with the patient in the recumbent position, and under anaesthesia. The upper hind limb is secured forward. The inner surface of the affected hock having been prepared for operation, an incision is made at the point shown in Fig. 154, exposing the cunean tendon, which is then divided. A portion of the tendon may be excised and the surface of the spavin scarified. The wound of the skin is then sutured and protected by an antiseptic adhesive.

A variation of this process is the insertion of a plug of gauze or tow, saturated with an irritant fluid, such as a spirituous solution of perchloride of mercury subcutaneously over the seat of the spavin. This is left in position for twenty-four or forty-eight hours and is followed by swelling and suppuration. It is in reality a modified seton and a form of counter-irritation.

Setons are occasionally employed, but possess no advantages and many disadvantages.

Neurectomy of the anterior tibial nerve followed by section of the posterior nerve, when improvement does not follow the first operation, has been recommended. This is usually un successful, and in some cases paralysis of the extensor pedis results with knuckling of the fetlock, and occasionally the horse may walk on the front of the fetlock-joint.

Shoeing with raised heels and shortening the toe often improves the action and is useful in chronic cases. In recent acute cases it is liable to increase the tendency to contraction of the tendons and to bring about permanent flexion of the hock.

Bony enlargements of the outer surface of the hock more usually result from periostitis than from true ostitis, though cases of true external spavin associated with articular disease are occasionally seen. In most cases lameness is only coincident with the inflammatory period. Exostosis is chiefly confined to the head of the small metatarsal bone, though sometimes the cuboid is involved. In some instances lame ness is not noticeable. When treatment is necessary point-firing followed by blistering and a run at grass gives the best result.

Chronic Synovitis of the True Hock - joint. Bog-spavin. The a chronic distension of the synovial capsule of the true hock-joint.

Causes.Without doubt defective conforma tion of the hock plays the most important part in the production of bog-spavin. The type most commonly affected is the upright hock in which there is a considerably increased area of the anterior capsular ligament unprotected, as compared with that in the case of a well-formed hock. Working animals of this sort at an early age is almost certain to produce the disorder.

Probably strain as in covering or overwork may produce bog-spavin, even in old horses, though in most cases weakness of structure is primarily responsible.

Possibly the excessive secretion of synovia is a provision of nature to protect the articular surfaces of badly formed joints. At any rate it is quite usual for hocks affected in this way to remain workably sound as long as the majority of better-looking ones. Lameness is not at all a common symptom. When it does occur it is usually the result of excessive distension of the synovial capsule, which mechanically prevents full flexion of the hock-joint, or else it arises from acute synovitis, which will presently be described and is quite distinct from bog-spavin.

The distended synovial capsule causes a tense fluctuating swelling on the antero-internal aspect of the hock, and when the tension is very great or when pressure is put upon the enlargement two smaller dilatations on the lateral surfaces of the hock may also be seen to be filled. These are termed"articular thoroughpins." Treatment. Unless lameness is present, little benefit will be derived from treatment. The excessive secretion of synovia is probably advan tageous in a badly formed joint, as it not only ensures thorough lubrication but acts as a buffer, warding off the effects of concussion. Moreover, hocks thus affected usually remain sound (from the view of utility) for many years. When lameness is present from over-distension. line-firing and blistering may cause a reduction by contracting the skin and exerting pressure upon the swelling. Spring trusses are of little practical value, as the reduction in size is usually only temporary.

Aseptic aspiration of the contents and sub sequent injection of a 1 per cent solution of iodine dissolved by the aid of iodide of potash, or a 1 in 1000 solution of hydrarg. perchlorid., has often given good results. Occasionally the synovia may be turbid and flaky and it may be impossible for it to flow through the needle. The site of the puncture should be closed with iodoform collodion and a biniodide blister im mediately applied, or a pressure bandage main tained in position by pitch or glue may be substituted.

Another method is acupuncture performed by puncturing the bog-spavin with four or five needles pushed through a cork so that their pointed ends protrude about three-quarters of an inch. The operation is repeated in a week and the parts are well rubbed with iodine oint ment and covered by a pressure bandage.

Acute Synovitis of the This con dition may be caused by severe wrenching of the joint, as a result of infection from without, or from the navel in foals or after strangles, or it may arise from acute rheumatic changes.

Symptoms. The limb is carried and the foot swung clear of the ground in a forward direction.

The hock is much swollen, particularly over the antero-internal surface, hot to the touch and very painful. Pressure upon the distended capsular ligament causes acute pain with rapid abduction and lifting of the limb; the animal may almost fall in the process.

In severe cases laminitis may ensue in the opposite foot. There is often constitutional dis turbance, fever, loss of appetite, and rapid wasting.

Prognosis. As changes usually occur some what rapidly in the articular cartilage of the astragalus and tibia, in the form of deep grooves with thickening and even calcification of the synovial membrane and increased secretion of synovia, which becomes turbid and occasionally purulent, the condition is always a grave one. Sometimes the joint ruptures under the ex cessive distension of its capsule. Occasionally resolution occurs and the animal may work sound or almost so for some months, when lame ness will again appear. Old-standing cases are hopeless owing to the joint lesions developed.

Treatment. In the early stages rest in a level field or in slings and warm fomentation followed by friction with a mild liniment are beneficial. The hock should subsequently be wrapped in warm flannel.

Later line-firing followed by a mixed bin iodide and cantharides blister and a prolonged run at grass may improve matters. Occasion ally shoeing with calkins may diminish the lameness.

Fracture of the Os Calcis.Causes.Direct injury by blows or kicks, by the horse lashing out, or by sudden slipping, as during rising or falling with the hock flexed. Fracture is then caused by the pull of the tendo Achillis. In young animals fracture may occur at the summit of the bone before complete ossification has occurred.

Symptoms resemble those of rupture of the tendo Achillis, but there is usually apparent flattening of the point of the hock. No weight can be borne on the limb, which collapses at each step. In walking, all the joints are flexed and the lower portion of the limb may jerk up wards and forwards (excessive flexion of the hock-joint), or they may rest on the ground through dropping of the hock, owing to lack of support.

Prognosis. Recovery may occur in two to three months when the fragments can be kept in contact. Compound fractures are seldom curable. In most cases of complete fracture it is impossible to maintain the bones in contact, as every movement of the gastrocnemius and perforatus causes displacement. Laminitis is a frequent sequel.

Treatment. A high-heeled shoe should be applied and the horse placed in slings. Tightly rolled wedges of tow should then be applied at the sides and back of the calcis after reposition has been effected, and the whole surrounded by a series of pitch bandages. The hock should be kept extended as far as possible.

Fracture of the other bones may often be suspected, but exact diagnosis is difficult. Fracture of the astragalus is scarcely distinguish able from acute arthritis of the astragalo-tibial joint.

Treatment when carried out must aim at anchylosis .

bone, joint, usually, limb and animal