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

Fracture of the Metacarpus. Etiology and Occurrence.--As the result of all sorts of violence, such as falls and injuries in accidents of various kinds wherein the metacarpals are subjected to contusions, fractures may result. In the horse it is unusual for fracture of one of the small metacarpal bones to take place without there being at the same time a fracture of the third (large) metacarpal bone. Classification.--Fractures of the metacarpal bones as they occur, are as likely to be compound as simple, and the multiple and comminuted varieties are occasionally observed. The manner in which the third (large) metacarpus is fractured, largely determines the outcome in any given case. Symptomatology.--Abnormal mobility of the broken parts of bone and crepitation mark fracture of the metacarpus, and the condition is easily diagnosed. In many instances, when compound fracture exists, broken ends of bone are protruding through the skin. No weight is borne upon the fractured member ordinarily, although during the excitement occasioned by runaways, horses are sometimes seen to support weight with a broken leg even when the protruding bone is sunk into the ground in so doing. Prognosis.--Generally speaking, fractures other than the simple-transverse in young animals, are considered unfavorable cases. With the metacarpus, however, there are instances where compound fracture occurs in colts that justify treatment. But in all cases of compound fracture, the element of infection in addition to the increased difficulty in maintaining immobility of the broken bone, creates almost insuperable difficulties in the average instance. And unless the practitioner distinctly explains to his client the various reasons which make treatment an economic impracticability, dissatisfaction is likely to follow if treatment is instituted without such an understanding. Treatment.--Perfect apposition of the broken ends of bone is easily effected and less difficulty is encountered in maintaining such relations in metacarpal fractures than in fractures of the radius. However, reduction and immobilization of this as in all fractures, must be done without delay. In simple fracture, the metacarpus is covered with enough cotton to pad the parts, and this is retained in position by bandages. Splints of heavy leather or of thin pieces of tough flexible wood are placed on each side of the leg and firmly held in position with bandages. Bandages may be put on in layers and a coating of glue applied over each layer if this is thought necessary. The advantage gained in using glue or other adhesive materials is that the cast thus formed is more rigid than where such material is not employed. On the other hand, all elasticity is lost as soon as the cast adapts itself to the contour of the extremity, and because of this rigidity, it is doubtful if anything is gained by the incorporation of glue, except in the way of added strength of the cast. Since the animal does not walk upon the broken leg, it is possible to employ splints of suitable materials which are retained in position without glue and frequent readjustment of a part of the immobilizing apparatus is possible. This is impossible with casts. In compound fractures, provision ought to be made for dressing the wound of the soft structures. This entails adjusting the splints in such manner that one splint may be retained and others removed for dressing the wound and readjusted as often as wound dressing is necessary. Splints. By this term is meant a condition where there exists an exostosis which involves usually the second (inner small) and third (large) metacarpal bones. While an exostosis involving any one of the splint bones, even when directly caused by an injury, is called a "splint," the term is employed here, in reference to exostoses not due to direct injury such as in contusions. Etiology and Occurrence.--This condition is one wherein there is osseous formation following a periostitis and the region of the upper portion of the second (inner small) metacarpal bone is the usual site of the exostosis. There is incited an inflammation of the periosteum at the site of the interosseous ligament which attaches the small to the large metacarpal bone. This ligament is involved in the inflammatory process, and according to Havemann, whose view is supported by Moller, this inflammation is the origin of the trouble. Various theories attempting an explanation of the frequent affection of this one certain part so regularly involved have been offered, but no proof of the correctness of any exists. It follows, however, that splints occur in young animals; that the affection seldom starts in subjects that are ten years of age or older, and that when the exostosis has formed, lameness usually subsides. Anything which will cause undue strain or irritation of the metacarpal bones in young animals, is quite apt to result in a splint being formed. Concussion such as is caused by fast work on hard roads, or work on rough or irregular road surfaces which cause unequal distribution of weight, will cause splint lameness and exostosis follows. [Illustration: Fig. 16--Posterior view of radius (right) illustrative of effects of splint. Note the extent of exostosis.] Course.--Because of the peculiar manner in which the second and third metacarpal bones articulate in young animals, until the bones become ossified and permanently joined, the inflammation which attends the acute stage of this affection, causes lameness. Later, unless an unusually large exostosis is formed, which may cause a constant irritation due to its size and juxtaposition to the carpus, lameness is discontinued. Symptomatology.--Lameness is usually the first manifestation of this disorder, and the thing which characterizes splint lameness is its peculiar intermittence. There is a mixed form of lameness which may not be in evidence when an affected animal is started on a drive, but which is marked after the subject has gone some distance. The animal may, however, go lame throughout the whole of a drive and continue to be lame for several days or weeks in some cases. It is noticeable that lameness is augmented or produced when the subject travels on rough road surfaces and that little or no difficulty is encountered when roads are smooth. The heavy brachial fascia is inserted in part to the head of the second metacarpal (inner small) bone together with the oblique digital extensor (extensor metacarpi obliquus) and this explains the reason for pain being manifested during extension of the member. Before there is a visible exostosis, supersensitiveness is readily recognized upon palpation of the parts, if careful comparison is made between the sound and unsound members. However, frequently splints occur on both forelegs at the same time and in some instances exostoses are several in number upon each member affected. In some instances, the affection involves the outer splint bone and no evident involvement of the inner one exists. Treatment.--At the onset complete rest should be provided and the local application of some good cataplasm is in order. A stimulating liniment is beneficial when employed several times daily and massage is also quite helpful. Later, the application of a blistering ointment is good treatment. The use of the actual cautery stimulates prompt resolution, but there is seldom any resorption of products of inflammation following firing. Whereas, in cases where other treatment is begun early, there usually follows considerable diminution in the size of the exostosis. A rest of four or five weeks is necessary and very young animals should not be put to work too soon, if the character of the work is such as to induce a recurrence of the trouble. Many cases are treated successfully in draft types of animals (where the subjects are not kept at work that occasions serious irritation to the affected parts) by blistering the exostosis repeatedly and allowing the animals to continue in service. In such cases, it is unreasonable to expect to check the size of the exostosis and, of course, such methods are not employed where lameness causes distress to the subject. Firing usually causes prompt recovery from lameness and is a dependable manner of treating such cases but there remains more blemish following cauterization than where vesication is done. OPEN FETLOCK JOINT. This condition, because of the frequency with which it occurs may be taken as typal, from the standpoint of treatment and results obtained therefrom. While it serves to constitute a basis from which other joints, when open, are to be considered, due allowance must be made for the fact that, as has been previously mentioned, some articulations when open constitute cause for grave consequences; while with others an open capsule, even when infected, does not cause disturbance enough to be classed as difficult to handle. Moreover, the fetlock joint is admirably suited, anatomically, to bandaging; and when wounded, is easily kept protected by means of surgical dressings. This fact is of great importance in influencing the course and termination in any given case of open fetlock joint and should not be forgotten. There is no logical reason for comparing the pedal joint with the pastern on the basis that it may also be completely and securely bandaged. Open navicular joint does not occur, as a rule, except by way of the solar surface of the foot, and the introduction of active and virulent contagium is certain to happen; consequently, an acute synovitis quickly resulting in an intensely septic and progressively destructive arthritis soon follows in perforation of the capsule of the distal interphalangeal articulation. Etiology and Occurrence.--Wounds of the fetlock region resulting in perforation or destruction of a part of the capsular ligament are caused by all sorts of accidents, such as wire cuts, incised wounds occasioned by plowshares, disc harrows, stalk cutters and other farming implements. In runaways the joint capsule is sometimes punctured by sharp pieces of wood or other objects. In horses driven on unpaved country roads the fetlock is occasionally wounded by being struck against the sharp end of some object, the other end of which is firmly embedded in the ground. In one instance the author treated a case wherein the fetlock joint was perforated by the sickle-guard of a self-binder. In this case there occurred complete perforation causing two openings through the _cul-de-sac_ of the joint. Such wounds are produced by implements which are, to say the least, non-sterile, and this perforation of the uncleansed skin conveys infectious material into the joint capsule. Yet in many instances, especially in country practice, no infectious arthritis results where cases are promptly cared for. Symptomatology.--A difference in the character of symptoms is evidenced when dissimilar causes exist. Small penetrant wounds which infect the synovial membranes cause infectious arthritis in some cases, whereas a wound of sufficient size to produce evacuation of all synovia will, in many instances, cause no serious distress to the subject, even when not treated for several days. If it is not evident that an open joint exists and the articular cavity is not exposed to view a positive diagnosis may be early established by carefully probing the wound. In some cases where a small wound has perforated the joint capsule, swelling and slight change of relation of the overlying tissues may preclude all successful exploratory probing. In such instances it is necessary to await development of symptoms. Twenty-four hours after injury has been inflicted, there is noticeable discharge of synovia which coagulates about the margin of the orifice, where synovial discharge is possible. Particularly evident is this accumulation of coagulated synovia where wounds have been bandaged--there is no mistaking the characteristic straw-colored coagulum which, in such cases, is somewhat tenacious. No difference exists between other symptoms in infectious arthritis caused by punctures, and non-infectious arthritis, excepting the intensity of the pain occasioned, the rise in temperature, circulatory disturbances, etc.; all of which have been previously mentioned. Treatment.--Just as has been stated in discussions on the subject of open joint, probing or other instrumentation is to be avoided until the exterior of the wound and a liberal area surrounding has been thoroughly cleansed--too much importance can not be placed on this preliminary measure. In cases of open joint where ragged wound margins exist and the interior of the joint capsule is contaminated, much time is required to thoroughly cleanse all soiled parts. In some instances an hour's time is required for this cleansing process after the subject has been restrained and prepared. In order to thoroughly cleanse these delicate structures without doing them serious injury, one ought to be skillful and careful in all manipulations of the exposed parts of the joint capsule. The general plan of treatment, after preliminary cleansing has been accomplished, has been outlined on page 66 in the consideration of scapulohumeral joint affections. The injection of undiluted tincture of iodin in ounce quantities, it must be remembered, is not to be done unless there is provision for its free exit. Where good drainage from the joint cavity exists all infected wounds should be thus treated, and this treatment may be repeated as conditions seem to require--until infection is checked. If daily injections are necessary, dilution of the tincture of iodin with an equal amount of alcohol is advisable in order to avoid doing irreparable damage to the articular cartilages and synovial membranes. An antiseptic powder composed of equal parts of boric acid and exsiccated alum is employed to protect the wound surfaces and the margins, and the parts are then bandaged. In bandaging wounds of this kind a liberal amount of cotton should be employed, and after a large surface surrounding the wound has been thoroughly cleansed, it must be so kept thereafter. This is impossible, if one uses a small amount of cotton, particularly if such meager quantity of dressing material is carelessly wrapped in position with an insufficient amount of bandage material. Mention, without description of the elemental problem of applying cotton and bandages to a wound, would be sufficient, were it not that this is a very important part of the handling of such cases, and many practitioners are not only thoughtless in this part of their work, but also apparently careless. What does it profit to prepare a part and cleanse a wound with painstaking care and then neglect to take every possible precaution to prevent its subsequent contamination? In the handling of open joint capsules where the perforation of the capsular ligament is small and discharge of synovia does not immediately follow, there is presented a problem which is difficult to decide upon and that is the manner in which such wounds are to be handled. One hesitates to enlarge such openings to drain or irrigate the capsule when there is no proof that serious trouble will follow because of infectious material which has probably been introduced at the time the wound was inflicted. It is especially difficult to decide upon the manner of handling such cases where the tarsal joint is wounded, although one hesitates to invade any joint to the extent of incising its capsule, unless there is urgent need of so doing. Frost[19] offers the following suggestion in such instances: The treatment recommended by us for open joints, in which we wish to prevent ankylosis, is, first, to shave all hair from the area surrounding the wound, following with a thorough cleansing of the skin and disinfection of the wound, and then to inject a twenty per cent Lugol's solution in glycerin into the wound. This should be repeated two or three times a day, each time enough of the solution being injected to fill the joint capsule, thereby securing the flushing effect. As this solution does not cause irritation to the tissue and yet is a strong antiseptic, it serves to shorten the period of congestion and inflammation and to overcome the infection without causing a destruction of the secreting membrane until the external wound has had time to heal. The injection of this solution seems to retard the excessive secretion of synovia. The larger the joint capsule and the smaller the external wound, the longer our antiseptic will remain in contact with the inflamed tissues as the glycerin, being thick, does not flow through a small opening. After-care.--Following the initial cleansing and treatment of open joint, subsequent dressing is necessary as frequently as conditions demand. If the parts are badly infected and profuse discharge of pus exists a daily change of dressings is necessary. In the average instance, however, semi-weekly treatments are sufficient. And in many instances where one is obliged to travel a considerable distance to handle the affected animal one weekly dressing of the wound will suffice after the second treatment. The same general plan of treatment concerning the subject's comfort that has been previously mentioned in arthritis, is carried out here. A further and detailed consideration of the subject of handling of open joints follows.[20] * * * Such wounds may be classified in two general groups as follows: First, wounds in which the trauma has exposed the articulation to view, and second, those the result of punctures, in which the external wound is small and free drainage is lacking. Wounds in which the articulation is exposed to view have drainage either all ready provided for, or it is established without hesitancy surgically. With free drainage thus established there is little or no chance for the adjacent tissues to become infiltrated with infected wound discharge. This prevents an extension of the injury and the establishment of a good field for the growth of anaerobic bacteria. Open joints caused by punctures, unless the puncture is aseptic, produce a swelling which is more painful than is the open wound which exposes the joint to view. Especially is this true if the puncture is of small diameter, allowing the tissues to partially close the opening immediately after the wound has been made. Where drainage is lacking there follows an exudation which congests the tissues surrounding the injury and all factors favoring germ growth are present. It is perhaps advisable to establish good drainage in such cases as soon as a diagnosis is made. It is not always an easy matter to recognize an open-joint, when first made, but twelve to twenty-four hours later there is no cause for doubt. The condition is then a very painful one; lameness is excessive; there is rise in temperature; acceleration of the pulse and manipulation or palpation of the region affected, occasions great pain. The treatment of open joints must be varied to suit the disposition of the animal, the nature and location of the injury, the length of time intervening between the infliction of the wound and the first attention given, and the surroundings in which the patient is kept. In each and every case in which there exists an open wound the surface surrounding the wound is cleansed thoroughly, the hair is shaved if possible, and the margin of the wound is curretted and cleansed thoroughly with antiseptic solutions. If there is evidence that the articulation contains infective material, it is washed out with copious quantities of peroxide of hydrogen--usually as much as six or eight ounces. This is followed