Lameness of the Horse Part 10

Anatomy.--The carpal bones as they articulate with one another and with the radius and metacarpal bones, as cla.s.sed 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 part.i.tioning 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 const.i.tute 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.

[Ill.u.s.tration: 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.

[Ill.u.s.tration: Fig. 14--Exostosis of carpus resultant from carpitis.]

[Ill.u.s.tration: Fig. 15--Distal end of radius. Ill.u.s.trating 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 rec.u.mbency, decubital gangrene and emaciation sometimes cause death. If the subject does not soon succ.u.mb, 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 subst.i.tuted 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 const.i.tute 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 princ.i.p.al 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 quant.i.ty 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 quant.i.ty between three and ten cubic centimeters of equal parts of tincture of iodin and alcohol const.i.tutes 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 pa.s.sing, it may be said that if a perfect technic is possible in doing the last named operation, a permanent recovery is the outcome.

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.

Cla.s.sification.--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 pract.i.tioner distinctly explains to his client the various reasons which make treatment an economic impracticability, dissatisfaction is likely to follow if treatment is inst.i.tuted 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 periost.i.tis 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.

[Ill.u.s.tration: Fig. 16--Posterior view of radius (right) ill.u.s.trative 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 ma.s.sage 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 const.i.tute 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 const.i.tute cause for grave consequences; while with others an open capsule, even when infected, does not cause disturbance enough to be cla.s.sed 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.