LAMENESS OF THE HORSE VETERINARY PRACTITIONERS' SERIES, NO. 1 TEXT

as formed by the radius, carpal and metacarpal bones, is bent forward at the carpus, are subject to inflammation and contraction of the carpal flexors. When these flexors are contracted, the condition is commonly known among horsemen as "buck knee." In itself, inflammation of the carpal flexors is not a condition which is likely to prove troublesome, but because of carpal involvement (which is often present) the cause of the trouble remains, and inflammation of the carpal flexors recurs or becomes chronic and contraction of tendons results. Symptomatology.--Inflammation of the carpal flexors, when acute and uncomplicated, is characterized by a painfully swollen condition of the affected tendons. No weight is borne upon the affected leg and the carpal joint is flexed. Mixed lameness is present. There is no difficulty encountered in arriving at a diagnosis because of the very noticeably inflamed parts. Many fully developed cases of contraction of the tendons of the carpal flexors are observed where the condition has become established gradually and no lameness has resulted from tendinitis or carpitis. In some of these cases, subjects are stumblers and when they are carelessly handled or kept at fast work over irregular or hard roads, chronic carpitis with hyperplasia of the structures of the anterior carpal region results, owing to frequent bruising from falls. [Illustration: Fig. 10--Contraction of carpal flexors, "knee sprung."] Where inflammation is caused by a puncture wound and subfascial infection occurs, there is evident manifestation of pain. No weight is supported by the affected member and because of the pressure, occasioned by the swollen muscles confined within the non-yielding brachial fascia, there exists marked supersensitiveness of the affected parts. Flexion of the elbow is avoided because contraction of the biceps brachii (flexor brachii) or the extensors, which are antagonists of the flexors of the carpus, tenses the carpal flexors and pain is thereby increased. However, in most instances, the practitioner's attention is not directed to typical and uncomplicated cases, but to subacute or chronic inflammations which are often attended with contraction of the tendinous parts of the carpal flexors, and in such cases carpitis is present. Animals so affected have lost the rigidity which characterizes the normal carpal joint when the leg is a weight bearing member, and because of its sprung condition, the leg trembles when supporting weight. Treatment.--Acute inflammation is treated by means of local application of cold or hot packs until the pain and acute stage of inflammation has subsided and later stimulating liniments are indicated. Absolute quiet must be enforced. Especially where the carpus is involved must the subject be kept quiet until all evidence of inflammation has subsided. The application of vesicants or line-firing is beneficial in subacute inflammation of the tendons of the carpal flexors. Where contraction of tendons exists and no osseous or ligamentous change prevents correction of the condition, tenotomy is necessary. The reader is referred to Merillat's "Veterinary Surgery"[17] for a good description of the technic of this operation. In all serious cases of inflammation of the carpal flexors, whether tenotomy has been performed or not, the subject needs a long period of rest subsequent to treatment. In fact, three or four months at pasture is necessary to permit of recovery and this where no congenital deformity has predisposed the subject to such affection of the flexors. Return to work must be gradual and the character of the work such as to enable the animal to become inured to service without a recurrence of the trouble if possible. It follows then, that tenotomy, here as in other cases, is not practical from an economic viewpoint, unless the animal be of sufficient value to justify the long period of rest for recovery. Tenotomy is not of practical benefit unless ample time is allowed for regeneration of divided tendinous tissue. Fracture and Luxation of the Carpal Bones. Etiology and Occurrence.--Fracture of the carpal bones is of infrequent occurrence in horses and, when it does occur, it is usually due to injuries, and because of their nature (resulting as they generally do from heavy falls or in being run over by street cars or wagons), a comminuted fracture of one or more bones exists. The accessory carpal bone (trapezium) is said to be fractured at times without being subjected to blows or like injuries, but this is exceptional. Luxations of the carpal joint are of rare occurrence, and very few cases of this kind are on record. Walters[18] reports a case of carpometacarpal luxation in a pony wherein reduction was spontaneous and an uneventful recovery followed. His reason for reporting the case, as he states, is its rarity. Symptomatology.--Fractures of the carpal bones as they usually take place are diagnosed without difficulty. Because of their usually being comminuted, abnormal movement of the joint is possible. Such movement is not restricted and flexion of the leg at the carpus in any direction is possible. Crepitation is readily detected and frequently these fractures are of the compound-comminuted variety. In fracture of the accessory carpal bone (trapezium) or in fracture of any other single bone when such exists, there is no increase in the movement of the joint. The accessory carpal bone may be readily manipulated and when fractured, its parts are more or less displaced. Recognition of fracture of any other single carpal bone must be done by detecting crepitation unless it be a compound fracture, whereupon probing is of aid in establishing a diagnosis. Carpal luxation when present is to be recognized by finding the apposing carpal bones joined in an abnormal manner--that is, out of position. There is restricted or suspended function of the joint, and in the cases recorded, no difficulty has been experienced in making a diagnosis. The carpometacarpal portion of the articulation is the part which is usually affected. Prognosis and Treatment.--There is no chance for complete recovery in the usual case of carpal fracture because of the fact that there results sufficient arthritis to destroy articular cartilage beyond repair. In the average instance, because of arthritis which persists for a considerable length of time, more or less ankylosis results. At best, one can only hope for partial recovery, that is to say, the member may regain its usefulness as a weight-supporting part, but because of restricted or abolished joint function, locomotion is more or less difficult. Exostoses, articular and periarticular, occur and the carpus usually becomes a large immobile articulation. There is danger of infection resulting in simple carpal fractures and, needless to say, in a compound-comminuted fracture of the carpus, infection usually occurs and a fatal outcome is probable. When treatment is instituted, antiseptic precautions are taken in handling the compound fractures, and in any case immobilization of the parts is sought. Here, as has been previously pointed out, it is best to employ leather splints, so that a maximum degree of rigidity with a minimum of distress and inconvenience to the patient will result. The leg must be bandaged from the hoof upward, making use of a sufficient amount of cotton to ensure against pressure-necrosis. The leather splints are placed mesially and laterally and, of course, need to extend as high as the proximal end of the radius. Subjects must be kept in slings until union of bones has become established, and as a rule there will then exist marked ankylosis. There is no particular difference in the handling of carpal luxation and dislocation of other bones. Where ligaments have not been destroyed to the extent that reduction is of no practical use, the parts are kept immobilized, if thought necessary. Later, vesication of the whole pericarpal region is done and the subject allowed exercise at will. Carpitis. Etiology and Occurrence.--Inflammation of the carpus is caused by contusions, such as are occasioned in falling, by kicks by striking the carpus against objects in jumping and sometimes by striking it against the manger in pawing. The condition is of rather frequent occurrence. Symptomatology.--Evident symptoms of inflammation in carpitis are always present--hyperthermia, supersensitiveness and swelling. Also, there exists lameness which is characterized by an apparent inability to flex the leg, and there is circumduction of the leg as it is advanced because in this way little if any flexion of the carpus (which increases pain) is necessary. Depending upon the nature of the cause, there occurs a marked difference in the character and amount of swelling. [Illustration: Fig. 11--Pericarpal inflammation and enlargement due to injury.] Naturally, when much extravasation of serum and blood takes place, there is occasioned a fluctuating swelling which is usually less painful to the subject upon manipulation than is a dense inflammatory change without marked extravasation. In acute carpitis, there is present, then, a very painful condition which involves the articulation, causing marked lameness, disturbance of appetite and some elevation of temperature. Chronic cases do not occasion serious pain or constitutional disturbances, but do interfere with locomotion in direct proportion to the existing articular inflammation and periarticular hypertrophy of ligamentous and tendinous structures. Treatment.--If possible, keep the subject absolutely quiet, employing the sling if necessary. During the first stages of inflammation, the application of ice packs to the affected parts, is of marked benefit. At the end of forty-eight hours, hot applications may be used and this treatment continued throughout several days. Anodyne liniments are of service and should be employed throughout the acute stage of inflammation during intervals between the hydrotherapeutic treatments. As inflammation subsides, a counterirritating application such as a suitable liniment and later blistering or line-firing is helpful in stimulating resolution. [Illustration: Fig. 12--Hygromatous condition of the right carpus, also distension of sheaths of extensor tendons of both fore legs.] Open Carpal Joint. Anatomy.--The carpal bones as they articulate with one another and with the radius and metacarpal bones, as classed by anatomists, form three distinct articular parts of the joint as a whole and are known as radiocarpal, intercarpal and carpometacarpal. These three pairs of articulating surfaces are all enclosed within one capsular ligament. On the anterior face of the bones, the capsular ligament is attached to the carpal bones in such manner that an imperfect partitioning of the three joint compartments is formed. Posteriorly, the capsule is very heavy and forms a sort of padding over the irregular surfaces of the bones, and also its reflexions constitute the sheaths of the flexor tendons. The anterior portion of the capsular ligament forms sheaths for the extensor tendons, and both portions of the joint have an attachment around the distal end of the radius and another at the proximal end of the metacarpal bones. [Illustration: Fig. 13--Carpal exostosis in aged horse.] Etiology and Occurrence.--Puncture wounds of any kind may serve to perforate the joint capsule and such traumatisms are occasioned by falls, kicks and in various ways in runaway accidents, and open carpal joint may follow. Symptomatology.--The pathognomonic symptoms of the existence of an open joint is the exposure to view of articular surfaces of bones or noting the escape of synovia from the joint capsule. As has been previously referred to, there always exists a peculiar suspension of carpal flexion in all cases of carpitis. Non-infective wounds which may cause open joint are not necessarily productive of an active carpitis--a synovitis may be the extent of the disturbance. Unlike synovitis, which may characterize a non-infectious penetrative wound of the capsular ligament, septic arthritis which may supervene is a very painful inflammatory disturbance. It is characterized by all of the symptoms which attend the case of open joint and synovitis plus the obvious manifestation of great pain. There is an elevation of temperature of from two to five degrees above normal; circulation is accelerated; the pulse is bounding; respiration is hurried; there is an expression of pain as indicated by the physiognomy; and because of rapid erosive changes of cartilages which take place, there is soon so much of the articulation destroyed that death is inevitable. Death is usually due to generalization of the arthritic infection. [Illustration: Fig. 14--Exostosis of carpus resultant from carpitis.] [Illustration: Fig. 15--Distal end of radius. Illustrating the effects of chronic carpitis.] In the meanwhile, if the character of the infectious material is not so virulent, the disease will take on a slower course and the subject may experience laminitis from supporting weight upon the sound member, or because of continued recumbency, decubital gangrene and emaciation sometimes cause death. If the subject does not soon succumb, it is compelled to undergo days or even weeks of unnecessary suffering, and too often in such cases, it is later deemed advisable to destroy the animal because of the cost of continuing treatment until the horse is serviceable. Therefore, it is evident that when such joints as the carpus or tarsus are open and infection exists, if they are not promptly treated and the infectious process checked, it is neither humane nor practical to prolong treatment. Distinction must be made between the different joints when infected as the condition is much more serious in some cases than in others. All things considered, perhaps open joints rank, with respect to being serious cases as follows: elbow, navicular, stifle, tarsus, carpus, fetlock and pastern. This, of course, is restricted to articulations of the locomotory apparatus. Treatment.--Preliminary care in the treatment of an open carpal joint, is the same as has been described in this condition as it affects the scapulohumeral articulation described on page 65. Likewise the further treatment of such cases is along the same lines except that where it is possible, the parts are kept covered with cotton and bandages. However, in some cases, animals have been successfully treated without bandaging and by keeping the patient in a standing position and on pillar reins until recovery resulted. Such cases were of the non-infectious type and recovery was possible within three or four weeks. Further, the condition is not sufficiently painful in such instances as to prevent the subjects bearing weight with the affected member; hence, no danger of resulting laminitis is incurred. And finally, where bandages are not employed, the frequent use of antiseptic dusting powders is substituted for cotton as a protector. When bandaged, such wounds need dressing more or less frequently, as individual instances demand. The purulent infective inflammation of a carpal joint will require daily dressing; whereas, in other cases (non-infective), semi-weekly change of bandages is sufficient. Equal parts of boric acid and exsiccated alum constitute a suitable combination for the treatment of these cases, and this powder should be liberally employed. Tincture of iodin may be injected into the joint capsule where there is provision for its ready evacuation, as conditions seem to require. Daily injections for three, four or five days, are not harmful and will control infection in many instances. Thecitis and Bursitis. Etiology and Occurrence.--The thecae and bursae of the leg are several in number. In the carpal region, the flexors of the phalanges are contained together in the carpal sheath, and this is the principal theca in the carpal region. Each of the tendons is provided with synovial sheaths which are subject to inflammation and occasionally synovitis and distension of these synovial sheaths occur. Because of faulty conformation, some animals are subject to inflammation of these sheaths, and all forms of strenuous work which taxes the tendons greatly is apt to result in synovitis. Direct injury such as blows may be the cause of synovial distension of thecae and the affection is to be seen in all horses that have done much fast work on hard road surfaces or pavements. The usual case as it occurs in practice is a non-infective synovitis, but where puncture wounds cause the trouble, an infectious inflammation obtains. Symptomatology.--No trouble is experienced in diagnosing distension of tendon sheaths, for the affection is very palpable. During acute inflammatory stages of this affection, some lameness is present--in infectious inflammation lameness is intense. Local heat and pain upon manipulation are readily discernible in all acute cases. And finally, where there is reason for doubt, an aseptic exploratory puncture of the wall of the fluctuating enlargement may be made with a suitable trocar, and the discharging synovia will be proof of the existence of synovial distension. After the affection becomes subacute or chronic, no lameness or inconvenience is manifested, and the condition is undesirable only because of its being a blemish. Treatment.--Acute non-infectious synovial distension of tendon sheaths is treated by aspirating as much synovia as possible from the affected theca (this is, of course, done under strict asepsis) and by means of bandages, a uniform degree of pressure is kept over the parts for ten days or two weeks. The patient is kept quiet and in the course of two weeks an active blistering agent is employed over the region affected. Usually, at the end of a month's time, complete recovery has taken place and the subject may be gradually returned to work. When synovial distensions are of long standing, it is necessary to take special precautions to check excessive secretion of synovial fluid, and, also because of the atonic condition of the tissues affected, resolution is tardy. In addition to aspirating synovia, the introduction of equal parts of alcohol and tincture of iodin into the theca is necessary. The quantity of this combination injected, depends upon the size of the sheath affected and the amount of synovia retained at the time injection is made. Experience is necessary to judge as to this part of the work, but one may consider that a quantity between three and ten cubic centimeters of equal parts of tincture of iodin and alcohol constitutes the proper amount to employ. Where much synovia is contained within the sheath at the time of injection, there occurs great dilution of the agent injected and consequently less irritation results. The object of such injections is to check synovial secretion, and this is sought by the local effect of iodin in contact with the secreting cells together with the reactionary swelling which occasions pressure. An increase in the local blood supply also follows. In all cases where it is possible to employ suitable bandages, this should be done. The ordinary derby bandages serve well and if their use is continued for a sufficient length of time, good results follow. There are other methods of treating these affections, and each has its advantages and disadvantages. Line-firing, instead of the vesicant is made use of by some, but the object desired is the same and results obtained are similar. Sheaths may be opened surgically by means of a knife, and the removal of a portion of the wall of distended and atonic tendon sheaths is possible. These operations belong to the realm of surgery and are not properly a part of this treatise. However, in passing, it may be said that if a perfect technic is possible in doing the last named operation, a permanent recovery is the outcome.