Lameness of the Horse Part 9

If suppuration occurs, it is necessary to provide for drainage as soon as it is possible to distinguish the presence of pus. Due regard is given the manner of establis.h.i.+ng drainage because of the usual existence of sub-fascial fistulae. In these cases, one avoids injecting solutions of aqueous antiseptics. By gently compressing the parts, pus is caused to drain out and in enforcing a moderate amount of exercise at a walk, when lameness is not intense, drainage is maintained. Cotton packs, moistened with hot antiseptic solutions, and kept around the forearm for several hours daily, are helpful because drainage is facilitated, and resolution is stimulated by the increase of blood thus attracted to the parts, and pain materially diminishes.

In lacerated wounds of the anterior brachial region, after having controlled hemorrhage, an area around the wound margin is freed of hair by clipping or shaving. The wound is carefully examined, and the best site for drainage is selected and a suitable opening for wound discharge is provided for. Where the extensor carpiradialis (metacarpi magnus) with other structures, is divided and the distal portion is torn downward, as frequently is the case in barbed wire cuts, it is necessary to make careful provision for drainage. The wound is thoroughly cleansed by means of ablutions if necessary; but preferably by swabbing with pledgets of cotton or gauze which are moistened in antiseptic solutions. All shreds of macerated tissue are clipped with scissors and finally the whole wound surface is painted with tincture of iodin.

If drainage is made by cutting through the tissues in the median portion of the structures that have been displaced, the opening should be packed with gauze so that it may remain patent after swelling has occurred.

Such packing is left _in situ_ for twenty-four hours.

The pendant muscular portions of tissues are sutured up by means of tapes and, while perfect apposition is not ordinarily possible, it is very essential to train the pendant tissues in their normal position even if they require resuturing within a week. This minimizes granulation of tissue, and there results less scar if the detached portions are kept near, even if not in contact with the proximal wound margins. The skin together with subcutaneous fascia is sutured on either side unless drainage is to be provided for on one side, and the lowermost part of that side is left unsutured.

After-care.--Where extensive suturing of tissues has been necessary, subjects must be kept quiet. They are best confined in box stalls and not taken out for several weeks. Particularly is this true where transverse division of extensors has taken place. Sutures are removed at the end of from ten days to three weeks as cases permit. Drainage of wound secretions, which usually become infected, is necessary, because with obstructed drainage in an infected wound of this kind, there will result an early destruction of tissue at some point sutured. Daily irrigation done in a manner that practical asepsis is carried out, is necessary for about a week. All irrigation is done by way of the drainage opening, and this with warm aqueous solutions of suitable antiseptics. After a week or ten days' time, the wound should not be dressed more frequently than twice weekly.

If it is necessary to leave a portion of the wound uncovered, as in cases where skin is destroyed, the frequent (three or four daily) application of a suitable antiseptic powder is necessary to check exuberant granulation. This may be directly effected by the use of an astringent or desiccant preparation, and such dressing serves as a mechanical protection as well.

When such wounds are kept clean, where drainage is properly maintained, and the subject kept quiet, no particular attention other than the local application of an astringent lotion (such as the zinc and lead lotion) is necessary after the first three or four weeks. Usually, if the animal gnaws at the parts or otherwise manifests evidence of discomfort, it is an indication that new areas of infection are being established because of obstructed drainage or retained eschars. A thorough cleansing of the wound with a two per cent solution of Liquor Cresolis Compositus and this followed by moistening every part of the wound with tincture of iodin, will check all such disturbance if done promptly.

Where practically all of the anterior surface of the radius has been denuded, recovery is tardy and there is in some cases imperfect extension of the leg for months after the wound has healed. But in such instances, animals gradually regain complete use of the affected member and in the course of a year function is fully restored.

Inflammation and Contraction of the Carpal Flexors.

Anatomy.--The structures which are usually considered as true flexors of the carpus are a group of three muscles, which have separate heads of origin and different points of tendinous insertion.

The _flexor carpiradialis_ (flexor metacarpi internus) originates from the medial epicondyle of the humerus. It is inserted to the proximal end of the medial metacarpal (inner metacarpal or splint) bone. This muscle is the smaller of the three and is not usually divided in doing carpal tenotomy.

The _flexor carpiulnaris_ (flexor metacarpi medius) has two heads of origin; one, the larger, originates from the epicondyle of the humerus and the other from the posterior surface of the olecranon. The two heads unite at the upper third of the radius and the muscle, becoming tendinous, as is the case with the other carpal flexors, is attached by one point of insertion to the accessory carpal bone (trapezum). The other blends with the posterior annular ligament of the carpus.

The _ulnaris lateralis_ (flexor metacarpi externus) has its origin from the lateral epicondyle of the humerus and inserts to the proximal extremity of the fourth metacarpal (outer splint) bone and by another attachment to the accessory carpal bone (trapezium) with the tendon of the flexor carpiulnaris (flexor metacarpi medius).

Acting together, these muscles flex the carpus or extend the elbow and this action is antagonized by the biceps brachii (flexor brachii) and extensors of the carpus and phalanges.

Etiology and Occurrence.--Inflammation of the muscular or tendinous parts of the carpal flexors, does not occur as frequently as does inflammation of the flexors of the extremity. They are subject to injury such as is occasioned by hard work and concussion and contract as a result; but, more frequently a congenital malformation of the leg is responsible for undue strain upon these parts. Horses that are "knee sprung" or that have a congenital condition where in the anterior line, 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 hors.e.m.e.n 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.

[Ill.u.s.tration: 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 pract.i.tioner'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 establis.h.i.+ng 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 inst.i.tuted, 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 circ.u.mduction 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.

[Ill.u.s.tration: 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 appet.i.te and some elevation of temperature.

Chronic cases do not occasion serious pain or const.i.tutional 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.

[Ill.u.s.tration: Fig. 12--Hygromatous condition of the right carpus, also distension of sheaths of extensor tendons of both fore legs.]

Open Carpal Joint.