Lameness of the Horse Part 23

Rupture and Wounds of the Tendo Achillis.

Etiology and Occurrence.--Cases are recorded by Uhlrich in which rupture has followed degenerative changes affecting the tendo Achillis.

Not infrequently, the result of a trauma, division of the tendo Achillis occurs. Moller states that rupture of this tendon may be due to jumping, in riding horses and in draught horses, in their efforts to avoid slipping. In runaways, it sometimes occurs where sharp-edged implements are bounced against the legs in such fas.h.i.+on that division of the tendon results.

Symptomatology.--With division of the tendo Achillis or of the musculature of the gastroenemii and the superficial flexor (perforatus), there remains nothing to inhibit tarsal flexion except the deep flexor tendon (perforans) and this does not support the leg. When attempt is made to sustain weight with the affected member, abnormal flexion of the tarsus takes place and the hock sinks almost to the ground. The symptoms are so characteristic that recognition is always easy even in case no wound of the skin exists.

Prognosis.--Spontaneous recoveries occur and such cases are reported by Bouley who is quoted by Cadiot as having observed division of the tendo Achillis due to a sword wound wherein at the end of four months recovery was complete. Division of this tendon in brood mares has been practiced by the early settlers of parts of the United States for the purpose of preventing their straying too far from home. In such instances one leg only was so mutilated and in most instances, it is reported that spontaneous recovery took place.

In unilateral involvement without complications, the prognosis is not unfavorable if provisions for giving necessary attention are available.

Treatment.--The subject is to be confined in a sling and the member bandaged and supported by means of leather splints. Immobilization as for fracture is not necessary but, nevertheless, movement is to be restricted as much as possible. In case of open wounds, the exposed tissues are cared for along general surgical lines. Where the divided parts of the tendon are maintained in fairly close and constant relation, granulation of tissue, sufficient to sustain weight takes place in from six weeks to three months.

Spring-Halt. (String-Halt.)

Occurrence.--This condition is a myoclonic affection of the hind leg which is discussed in works on theory and practice under the head of neuroses, but the cause or causes have not been established. Theories that heredity is responsible have their supporters and advocates of hypotheses attributing it to disease of the sciatic nerve, patellar subluxation, fascial contraction of various muscles, "dry spavin"

(tarsal arthritis), iliac exostoses, disease of the foot and contraction of the hoof, are on record in veterinary literature. This ailment affects old horses more frequently than it does young and is seen in all breeds of animals including mules.

[Ill.u.s.tration: Fig. 52--Spring-halt.]

Symptomatology.--This disease develops slowly, and progressively increases in severity as a rule, but does not ordinarily const.i.tute cause for rendering an animal unserviceable. While the affection is sometimes bilateral (occasionally affections of the forelegs are reported) and the extreme flexion of the legs in the spasmodic manner which characterizes spring-halt, cause great waste of energy during locomotion, yet such cases are rare. Usually the ailment is markedly evinced when subjects are first taken from the stable, but as they are exercised the manifestation diminishes, and in many instances it completely subsides. The condition is generally more noticeable when the subject is made to step backward. In some animals there is marked abduction at the time flexion occurs and in singular instances the spasmodic contraction is so violent that the subject falls to the ground as a result of the peculiar flexion of the leg.

In severe cases of "scratches" or chemical irritation of the extremity, the legs are abnormally flexed in a manner which simulates spring-halt, but because of the evident injury of the parts this is not likely to confuse. Since all facts concerning etiological agencies are surrounded with so much obscurity, cla.s.sification does not lend any particular a.s.sistance in the consideration of this ailment.

Prognosis.--One cannot intelligently give a prognosis in these cases if forecast is expected to state the exact course following treatment.

However, in a general way, cases of recent affection are thought more favorable than are those of long standing or in old animals where myositis and other muscular and fascial affections exist owing to years of hard service.

Treatment.--No known line of medicinal treatment is of service, nor is any particular surgical operation to be considered dependable for obtaining relief. Operations of almost every conceivable nature have been tried with the hope of securing recovery in spring-halt but under no condition can the pract.i.tioner as yet be reasonably certain of effecting permanent relief in any case. Treatment is, therefore, entirely empirical.

Neurectomies have been performed and recoveries following were attributed thereto; fascial divisions in the crural region have been done with good results and this manner of treatment has its favorers.

Advocates of tenotomies, likewise, are to be found. Consequently, one may summarize thus: Spring-halt is a disease of unknown origin--the exact cause has not been determined; therefore, all treatment is, in a way, experimental. The recommendation of any given procedure in handling cases must then be a matter of opinion based either upon practical experience or knowledge of the experiences of others. Divisions of the lateral digital extensor (peroneus) below the tarsus near its point of insertion to the extensor of the digit is recommended here because it is followed by a percentage of recoveries that is as large as in any other method of treatment and the operation is not difficult to perform nor is its performance fraught with any dangerous complications. In selected subjects about fifty per cent of cases recover in from two to six weeks following this operation.

[Ill.u.s.tration: Fig. 53--Lateral (external) view of tarsus showing effects of generalized tarsitis.]

Open Tarsal Joint.

Like the tibia the hock is exposed to frequent injuries and in some cases wounds perforate the joint capsule. When due to calk wounds where horses are kicked, the injury is often on the side of the tarsus (medial or lateral) and such wounds not infrequently result in infectious arthritis. Horses sometimes jump over wire fences and wounds are inflicted which const.i.tute extensive laceration of the joint capsule. In firing for bone spavin, where a deep puncture is made very near the tibial tarsal (tibioastragular) joint if infection gains entrance, serious and generalized infection of the open joint cavity supervenes in some cases.

Symptomatology.--There is no marked difference in the const.i.tutional disturbances which are occasioned in this condition and those encountered in other cases of septic arthritis (previously considered herein) except that there is a difference in the degree of resultant derangement and local tissue changes. Chiefly, because of the difficulty encountered in keeping the hock joint in an aseptic condition or securely bandaged, open tarsal joint const.i.tutes a more serious condition than a similar affection of the fetlock. Otherwise, a very similar condition obtains and the same diagnostic principles serve here that have been described on page 110 in considering open fetlock joint.

Treatment.--The same plan that is described in detail for treatment of similar conditions affecting the fetlock joint is indicated in this affection. Exceeding care must be exercised in bandaging the hock, however, lest the animal be so irritated that in the extreme flexion of the tarsus which is often caused by bandaging, the wound dressings may be completely deranged. A wide gauze bandage material is most satisfactory; cotton of long fiber is separated in thin layers and wound about the hock, extending from the site of injury to a point about six inches proximal to the summit of the os calcis. By using an abundance of cotton in this way, it will not be found necessary to apply the bandages very snugly; with a four-inch gauze bandage material, which is supported above the cap of the hock and brought across the anterior face of the tarsus in a diagonal manner, a comfortable and very serviceable protective dressing is provided for. Animals so treated will not ordinarily resist because of pressure from the bandages. Pressure is unavoidable in the use of adhesive dressings or where careful attention is not given the manner of applying cotton to the parts. Such methods are sure to result disastrously. But if subjects are kept quiet after the parts have been properly bandaged, no difficulty is encountered in maintaining asepsis in an uninfected wound. Recovery takes place in favorable cases in from three weeks to three months, depending on the nature and extent of injuries inflicted.

Fracture of the Fibular Tarsal Bone (Calcaneum.)

Etiology and Occurrence.--This condition though rarely met with in the horse, is the result of violent strain upon the os calcis by the gastrocnemius and superficial flexor tendons in efforts put forth by animals in attempts to regain a footing when the hind feet slip forward under the body, or in jumping and in falls or direct contusion by heavy bodies. h.o.a.re[50] reports a case of a mare that had produced fracture in jumping.

Fracture of the other tarsal bones are very seldom observed but may be occasioned by contusions wherein multiple or comminuted fractures are produced, such as are to be seen in small animals. Fracture of the tibial tarsal bone (astragalus) is to be observed as a complication in luxations of the tarsal joint and, according to Cadiot, the other tarsal bones may likewise suffer fracture in luxations of the hock.

Symptomatology.--Great pain attends this accident according to the observations given in recorded cases. In the case cited by h.o.a.re the animal evinced great pain and uneasiness; the hock was unduly flexed; the calcaneum was displaced forward; and marked crepitation was present.

A portion of the body of the calcaneum was protruding through the perforated skin. The animal was destroyed and the bone was found broken in three pieces.

[Ill.u.s.tration: Fig. 54--Right hock joint. Viewed from the front and slightly laterally after removal of joint capsule and long collateral ligaments. T.t., Tibial tarsal bone (distal tuberosity). T.c., central tarsal bone. T.3. Ridge of third tarsal bone. T.f. Fibular tarsal bone (distal end). T.4. Fourth tarsal bone. Mt. III, Mt. IV. Metatarsal bones. Arrow points to vascular ca.n.a.l. (From Sisson's "Anatomy of the Domestic Animals.")]

Since the support for the tendo Achillis is removed in such fracture and no leverage on the metatarsus obtains, it naturally follows that any attempt to sustain weight must result in extreme flexion of the hock and descent of this part in a manner similar to cases of rupture or division of the Achilles' tendon. The two conditions should not be confused, however, as the parts may be definitely outlined by palpation and the slack condition of the tendon and displaced summit of the calcaneum, which characterize fracture of the fibular tarsal bone, are easily recognized.

Treatment.--Prognosis is unfavorable in the majority of cases, but should attempts at treatment be undertaken in young and quiet mares which might prove valuable for breeding purposes in case of imperfect recovery, they should be put in slings and the member is to be immobilized as in tibial fracture. Authorities are agreed that prognosis is entirely unfavorable in mature animals, when the case is viewed from an economic standpoint.

Tarsal Sprains.

Etiology and Occurrence.--The hock joint is often subjected to great strain because of the structural nature of this part and its relation to the hip as well as the manner in which the tarsus functionates during locomotion. That ligamentous injuries owing to sprain frequently occur and attendant periarticular inflammations with subsequent hypertrophic changes follow, is a logical inference. Fibrillary fracture of the collateral ligaments may take place in falls or when animals make violent efforts to maintain their footing on slippery streets. In expressing opinions concerning the frequency with which the hock is found to be the seat of trouble in lameness of the pelvic members, different writers place the percentage of hock lameness at from seventy-five to ninety per cent. And when one considers the possibility that a goodly proportion of cases of tarsal exostis are the outcome of sprains, the occurrence of tarsal sprains may be more generally admitted.

Symptomatology.--A mixed type of lameness is present and the nature of the impediment varies, depending upon the location of the injury.

Sprains of the mesial tarsal ligaments cause lameness somewhat similar to that of spavin. However, in establis.h.i.+ng a diagnosis, local evidence in these cases is of greater significance than the manner of locomotion.

During the acute stage of inflammation there is to be detected local hyperthermia, some hyperesthesia and a little swelling. Later, when resolution is not prompt, considerable swelling (or perhaps correctly speaking, an indurated enlargement) variable in size is developed. In some cases the entire tarsal region becomes greatly enlarged and this swelling is very slowly absorbed in part or completely. Such sub-acute cases are observed during the winter season and particularly where subjects are kept in tie stalls without exercise for weeks at a time.

Treatment.--Attention should be directed toward relief for the animal in all acute inflammations. Local applications of heat are helpful and, of course, rest is essential. Towels that are wrung out of hot water and held in position by means of a few turns of a loose bandage and this covered with an impervious rubber sheet, will serve as a practical means of application of hydrotherapy. Following this when conditions improve, as in the handling of all similar cases, counterirritation is indicated.

When proper care is given at the onset and where injury does not involve too much ligamentous tissue, recovery takes place in a few weeks but in some cases which occur during the winter season in farm horses, complete recovery does not result until several months have pa.s.sed.

Curb.

The hock is said to be curbed when the normal appearance, viewed from the side, is that of bulging posteriorly at any point between the summit of the calcaneum and the upper third of the metatarsus. Among some hors.e.m.e.n a hock is said to be "curby" whenever there exists an enlargement of any kind on the posterior face of the tarsus whether it be due to sprain, exostosis or proliferation of tissue as a result of contusion.

French veterinarians consider under the t.i.tle of "courbe," an exostosis situated on the mesial side of the distal end of the tibia. Cadiot and Almy state that this condition (courbe) is of rare occurrence. Percivall defines curb as "a prominence upon the back of the hind leg, a little below the hock, of a curvilinear shape, running in a direct line downwards and consisting of infusion into, or thickening of, the sheath of the flexor tendons." Moller's version of true curb is a thickening of the plantar ligament (calcaneocuboid or calcaneometatarsal). Hughes and Merillat consider curb as a synovitis having for its seat the synovial bursa which is situated between the superficial flexor tendon (perforatus) and the plantar ligament.

Occurrence.--Certain predisposing factors seem to favor the occurrence of curb. A malformation of the inferior part of the tarsus so that its antero-posterior diameter is considerably less than normal is a contributing cause. Such hocks are known as "tied-in." Another fault in conformation is the existence of a weak hock that is set low down on a crooked leg, especially when such a member is heavily muscled at the hip. Given such conformation in an excitable horse, and curb is usually produced before the subject is old enough for service. It is certain that in cases where conformation is bad, greater strain is put upon the plantar ligament. This structure serves to bind the tibial tarsal (calcis) bone to the metatarsus; traction exerted upon its summit by the tendo Achillis is great when animals run, jump or rear and also at heavy pulling. In animals having curby hocks, sprain is likely to result and curb supervenes.

Symptomatology.--The characteristic swelling which marks curb may develop quickly and lameness occur suddenly or the enlargement comes on gradually and slowly, causing little lameness. Lameness is not proportionate to the size of the swelling and in all cases whether subacute or chronic, the condition improves with rest, but lameness is again manifested upon exertion. A horse which "throws a curb" will go lame until the acute inflammatory condition subsides and depending upon treatment received and conformation of the hock, this requires from three days to two or three weeks.

The character of the swelling varies; in some cases it is not large but rather dense and lacking in evidence of heat and hyperesthesia; in other cases there is considerable swelling, which is hot and doughy, somewhat painful to the touch but not necessarily productive of much lameness. In any event, whether the swelling or enlargement is big or little, its location makes it conspicuous when viewed in profile.

In most cases after the acute inflammatory period has pa.s.sed, lameness is slight, if at all present, and in time no interference with the subject's usefulness is occasioned because of the curb, but the animals often remain blemished--complete resorption of inflammatory products being unusual when much disturbance has existed.

Treatment.--The handling of curb during the acute inflammatory stage is along the same lines as in sprain--local applications of cold and heat. Subjects must be kept quiet until all inflammation has subsided, for there are no cases wherein a little brisk exercise is more likely to cause a recurrence of lameness before recovery is complete than in curb.

Vesication is in order in a week or ten days after the affection has set in; in old stubborn cases that have resisted ordinary treatment for a few months, the use of the actual cautery (line firing) is to be recommended.

[Ill.u.s.tration: Fig. 55--Spavin.]

Spavin. (Bone Spavin.)

This term is applied to an affection of the tarsus which is usually characterized by the existence of an exostosis on the mesial and inferior portion of the hock. There is also included under this name, articular inflammation wherein no external evidence is shown. Spavin lameness has long been recognized and much has been written upon this subject. Since authorities are agreed that most cases of lameness in the hind leg are due to hock affection, and because the majority of cases of lameness which have the tarsal region as the seat of trouble are instances of spavin lameness, this disease merits all the attention it has received.

Etiology and Occurrence.--Causes may well be cla.s.sified as predisposing and exciting, for there are many etiologic factors to be reckoned with in spavin, some of which are widely different in nature.