The subject should be cared for as has been previously suggested in arthritis proper provisions for comfort being made. Good nursing is always essential to a successful issue. However, the author cannot view cases of open stifle joint with the same optimism concerning their course and outcome that is expressed by a number of writers on this subject. It is a grave condition wherein the prognosis should be given advisedly.

Etiology and Occurrence.—Because of its exposed position to kicks, and its lack of protection by heavy musculature (especially on its inner surface), there is afforded ample opportunity for frequent injury to the tibia. Fractures are complete and varying as to nature, or incomplete. The heavy tibial fascia affords sufficient protection so that fissures without entire solution of continuity of the bone may occur from violence to which this part is often subjected. Möller classes tibial fracture as ranking second in frequency—pelvic fracture being more often met with in horses. This does not apply in our country as phalangeal and metacarpal and even metatarsal fractures are observed in more instances than are such injuries to the tibia. The tibia is occasionally broken at its middle and lower thirds, but malleolar fractures are not common.

A careful examination of parts of the tibia, i.e., noting the amount and painfulness of swellings, exploration with the probe, and observations of the course taken in any given case, will determine the exact nature of injuries. Such examination needs to extend over a period of a week or in some instances two or three weeks may pass before the true state of affairs is apparent. In the meanwhile, cases are to be handled as though tibial fracture certainly existed.

In a foal the author has in one instance succeeded in obtaining complete recovery in a simple fracture of the lower third of the tibia where the only support given the broken bone was a four-inch plaster-of-paris bandage which was adjusted above the hock. Below the tarsus a cotton and gauze bandage was applied to prevent swelling of the extremity. In this instance (an emergency case in which materials that are not to be recommended were necessarily employed) recovery took place within thirty days.

As has been mentioned in the consideration of radial fractures, heavy leather is better suited for immobilization of these parts than a cast or other rigid splint materials. Mature animals may be expected to resist the immobilization of the hind legs because of the normal manner of flexion of the tarsal and stifle joints in unison. Therefore, the application of rigid splints to the leg and including the hock is productive of disastrous results in some cases.

The application of cotton and bandages to pad the member and the adjusting of heavy leather splints on either side of the leg, and retaining them in position with four-inch gauze bandages will prove more nearly satisfactory than some other methods employed. Prognosis is unfavorable, however, in most cases of compound fracture and recovery is improbable when the upper portion of the tibia is broken.

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. Möller 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 fashion that division of the tendon results.

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.

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, classification does not lend any particular assistance 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 practitioner as yet be reasonably certain of effecting permanent relief in any case. Treatment is, therefore, entirely empirical.

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 constitute 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.

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.

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.

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 passed.

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 horsemen 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.

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.

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.

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

Because of the quality of their temperaments, nervous animals possessing no particular congenital structural defects of the hock and having no history of spavined progenitors, are subject to spavin when kept at work likely to produce tarsal sprain. Spavin usually develops early in such subjects and examples of this kind may be frequently observed in agricultural sections of the country. Where spavin develops in unshod colts at three and four years of age, shoeing is not an influencing agency when animals are not worked on pavements.

Symptomatology.—Where a visible exostosis exists, the presence of spavin is easily detected, yet exostoses that extend over large areas may constitute cause for serious trouble and still be difficult of detection. By observing the internal surface of the hock from various suitable angles, such as from between the forelegs or directly behind the subject, one may note the presence of any ordinary exostosis.

The position assumed by the spavined horse is often characteristic. More or less knuckling is usually present (Liautard, McDonald). There is abduction of the stifle in some cases, or the toe may be worn in unshod horses so that it presents a straight line at the surface. This is manifested to a great degree in some animals and in others the foot is not dragged and there is no wearing of the hoof at the toe.

The "spavin test" is of value as a diagnostic measure when it is employed with other means of examination, though reaction to this test is seen in some cases in old "crampy" horses that have experienced hard service. The test consists in flexing the affected leg (elevating the foot from the ground twelve to twenty-four inches) and holding the member in this position for a minute, whereupon the animal is made to step away immediately at a trot. During the first few steps taken directly thereafter, the subject shows pronounced lameness and this constitutes a reaction to the spavin test.

Where no exostosis is present it becomes necessary to exclude other causes for lameness but the characteristic spavin lameness is to be relied upon to a greater extent in such cases than are other means of examination. Such cases are known as occult spavin and may be present for months before any external changes in structure are observable. In some instances no extoses form even during the course of years. The spavin test is of aid in establishing a diagnosis here but the marked "warming out" peculiar to spavin is not so pronounced in such cases.

Treatment.—Many incipient cases of spavin yield to vesication and a protracted period of rest. Results depend primarily upon the nature of the affection. However, in every instance if there is involvement of the tibial tarsal (astragalus) bone, complete recovery is highly improbable. When the disease is confined to the lower tarsal bones, lameness subsides as soon as the degenerative changes are checked and ankylosis occurs.

After cauterization the subject should be kept quiet in a comfortable stall for three weeks; thereafter, if the animal is not too playful, the run of a paddock may be allowed for about ten days and a protracted rest of a month or more at pasture is best. It is unwise in the average case to put an animal in service earlier than two months after having been "fired."

Where cases progress favorably, lameness subsides in about three weeks after cauterization and little if any recurrence of the impediment is manifested thereafter. However, because of violent exercise taken in some instances when subjects are put out after being confined in the stall, a return of lameness occurs and it may remain for several days or in some cases become permanent. No good comes from the use of blistering ointments immediately after cauterization. The actual cautery is a means of producing all necessary inflammation and it should be so employed that sufficient reactionary inflammation succeeds such firing. The use of a vesicating ointment subsequent to cauterization invites infection because of the dust that is retained in contact with the wound. The employment of irritating chemicals in a liquid form following firing is needless and cruel.

Cunean tenotomy has been advocated and practiced by Abildgaard, Lafosse, Peters, Herring, Zuill and others and good results have followed in many cases so treated.

Considering results, the employment of chemicals of various kinds for the purpose of relieving spavin lameness does not compare favorably with firing. Moreover, so many animals have been tortured and needlessly blemished in the attempted cure of spavin that agents which are not of known value, the use of which are likely to result in extensive injury to the tissues, are only to be condemned.

When spavin is bilateral and lameness is likewise affecting both members, prognosis is at once unfavorable. Such cases are often benefited by cauterization but only one leg at a time should be treated.

Bossi's double tarsal neurectomy (division of the anterior and posterior tibial nerves) has undoubtedly been of decided benefit in many cases, but is not at present a popular method of treatment in this country. This operation has its indications, however, and may be recommended in chronic lameness where no extensive exostosis exists which may mechanically interfere with function.

Distension of the capsular ligament of the tibial tarsal (tibioastragular) joint with synovia is commonly known as bog spavin. This condition is separate and distinct from that of distension of the sheath of the deep flexor tendon (perforans) though not infrequently the two affections coexist.

Treatment.—The most practical method of handling bog spavin consists in aspiration of synovia and injection of tincture of iodin. Discretion should be employed in selecting subjects for treatment, regardless of the manner in which such cases are to be handled. Where there exists chronic distension of the joint capsule of several years' standing in old or weak subjects, needless to say, recovery is not likely to result. When animals are vigorous and two or three months' time is available, treatment may be begun with reasonable hope for success.

Following the injection, the subject is kept in a stall or in a suitable paddock, so that conditions may be observed for four or five days. The object sought by the introduction of iodin is not only for a local effect upon the synovial membranes in checking secretions, but the production of an active inflammation and great swelling, which will remain from four weeks to three months subsequent to the injection. This periarticular swelling should produce and maintain a constant pressure over the entire affected parts for a sufficient length of time until normal tone is re-established.

In some cases, swelling does not develop as the result of a single injection of iodin. When marked swelling has not taken place within five days, none will occur and a repetition of the injection may be made within ten days after the first treatment has been given. One may safely increase the amount of iodin at the second injection in such cases by one-fourth to one-third.

In Europe this method of treating bog spavin has been employed by Leblanc, Abadie, Dupont and others according to Cadiot; but Bouley, Rey, Lafosse and Varrier used it with bad results. Where a perfect technic is executed (and no other is excusable in this operation), no infection will occur if a reasonable amount of iodin is injected. The dilution of iodin with an equal amount of alcohol has been practised by the author in many cases, but later this was found unnecessary.

Line firing over the distended capsule is a practical method of treatment. This is attended with good results in young animals in many cases, but considerable blemish is caused when sufficient irritation is produced to stimulate resolution.

Vesication also is successfully employed in some instances. However, only cases of recent origin in young animals—colts of two years or younger—yield to blistering, and in some affected colts no doubt recovery would have been spontaneous had no treatment been instituted.

Ligation of the saphenous vein at two points, one above and the other below the distended ligamentous capsule, is an old operation, which has undoubtedly given good results in some cases, although it does not seem to be a rational procedure.

After-Care.—After swelling has fully developed—which occurs within a week—the subject is turned to pasture and no attention is necessary thereafter. A gradual subsidence of the swelling occurs and in the average instance, this completely resolves within six or eight weeks.

Complete recovery succeeds the aspiration-and-injection-treatment in about seventy-five per cent of cases as the result of one operation, and subjects may be gradually and carefully returned to work in about sixty days after treatment has been given.

The terms "thoroughpin" or "throughpin" are translations from the French vessignon chevillé and have the same significance. They are so named because of the diametrically opposed distensions of the sheath of the deep flexor tendon in such manner that the distensions appear to be due to a supporting peg.

During the acute inflammatory stage there is marked lameness present but this soon subsides when local antiphlogistic agents are applied to the parts. In fact, spontaneous relief from lameness usually results in the course of ten days' time following the appearance of thoroughpin. No lameness marks the advent of this affection when it develops as the result of continuous strain and concussion occasioned by hard service, and local changes tend to remain in status quo.

The application of blistering agents is of no value in stimulating resorption of an excessive amount of synovia in chronic cases and the actual cautery when employed without perforation of the synovial structure, is of little benefit. Trusses or mechanical appliances for the purpose of maintaining pressure upon the distended parts are of no practical value because of the great difficulty of keeping such contrivances in position. They usually cause so much discomfort to the subject that they are not tolerated.

Where good facilities for executing a careful technic in every detail are at hand, incision of the tarsal sheath, evacuation of its contents and uniting its walls again by means of sutures and providing for drainage with a suitable drainage tube, may be practiced. This manner of treatment has been satisfactory in the hands of a number of surgeons.

Enlargements which occur upon the summit of the os calcis, whether hypertrophy of the skin and subcuticular fascia, the result of injury or repeated vesication, distension of the subcutaneous bursa or injury to the superficial flexor tendon (perforatus) or its sheath, are generally known as capped hock. However, the term should be restricted to use in reference to distensions of synovial structures of that region.

Etiology and Occurrence.—Usually there occurs a hygromatous involvement of the subcutaneous bursa due to contusion. As in bog spavin, following certain infectious diseases (influenza, purpura hemorrhagica, etc.) there remains a distended condition of the subcutaneous bursa, after swelling of the member has subsided. In feeding pens where numbers of young mules are kept in crowded quarters many cases may be observed. In some instances where violent contusions result from kicking cross-bars of wagon shafts (by nymphomaniacs or in habitual kickers where there is opportunity for doing such injury) the superficial flexor tendon and its synovial apparatus are injured and a more serious condition may result.

Symptomatology.—In acute and extensive inflammation of the parts, lameness is present, but in the average case no inconvenience to the subject results. The prominent site of the affection is cause for an unsightly blemish. This is undesirable, particularly in light-harness or saddle horses. These affections are characterized by a fluctuating mass which has a thin wall and in all cases of long standing the condition is painless.

By careful palpation one may readily distinguish between a hygromatous condition of the superficial bursa and involvement of the underlying structures. Affection of the expanded portion of the flexor tendon and contiguous structures makes for an organized mass of tissue which is somewhat dense and in some instances painful to the subject when manipulated. This is particularly noticeable in cases where the parts are regularly and repeatedly injured as in habitual kickers.

The surgical wound heals in two or three weeks and inflammation gradually subsides. Bandages are retained one or two weeks, as the case may require, and subsequently a good wound lotion may be employed several times daily. A good lotion for such cases as well as in many others has long been employed with success by Dr. A. Trickett of Kansas City. It consists of approximately equal parts of glycerin, alcohol and distilled extract of witch hazel, to which is added liquor cresolis compositus, two percent, and coloring matter q.s.

Complete resolution does not occur in the average case. There remains some hyperplastic tissue and even where the enlargement is slight, the prominent situation of the affection precludes its being unnoticed.

In disease of the flexor tendon and its bursa where contiguous inflammation of tissue is present, the parts are blistered or fired. Line firing is beneficial in such instances but in all cases the cause is to be removed if possible.

Rupture of this tendon may occur during work on rough and uneven roads, particularly in range horses that are ridden over ground that is burrowed by gophers or prairie dogs; in such cases, horses are apt to suddenly and violently turn the foot in position of volar flexion, thereby causing undue strain to the digital extensor and its rupture sometimes follows. In foals of one or two days of age, this tendon is sometimes found parted or ruptured and the condition may be bilateral.

As the result of accidents, the digital extensor may be divided and when the wound becomes contaminated, as it does because of the marked volar flexion (knuckling) which occurs during the course of this affection, regeneration of tissue is checked and recovery is tardy.

Symptomatology.—There is no interference with ability to sustain weight in such cases, when the foot is placed in normal position; but immediately upon attempting to walk, the toe is dragged, and if weight is borne with the affected member, it comes upon the anterior face of the fetlock. The flexors are not antagonized and if there be an open wound the parts soon become contaminated; or, in rupture, if animals travel about very much, there soon occurs necrosis of the tissues of the anterior fetlock region and the condition is rendered incurable. Cases are reported of animals that have suffered rupture of the long digital extensor and the subjects learned to throw the member forward during extension, substituting for the extensor tendon the pendulum-like momentum which the foot affords when so employed; and a walking and even a trotting pace was possible without doing injury to the fetlock region.

Where a subcutaneous division exists as in rupture, the divided ends of the tendon may be definitely recognized by palpation.

Open wounds are treated along general surgical lines, dressed as frequently as occasion demands, and recovery will be complete in a few months' time unless much of the tendon has been destroyed. In one instance, the author had occasion to observe such a condition, which, because of the extensive destruction of tendon and lack of facilities for giving proper attention to the subject, results were so unfavorable that it was deemed necessary to destroy the animal.

When, during locomotion, injury is inflicted upon the mesial side of an extremity by the swinging foot of the other member, the condition is termed interfering.

Etiology and Occurrence.—Faulty conformation, bad shoeing and over-work are the principal causes of interfering. Horses that are "base narrow" or that have crooked legs are quite apt to interfere. Shoes that are put on a foot that is not level or applied in a twisted position, or shoes wide at the heel will often cause interfering and injury. Animals that are driven at fast work until they become nearly exhausted may be expected to interfere. Such cases are frequently observed in young horses that are driven over rough roads, particularly when so nearly exhausted or weakened from disease or inanition that the feet are dragged forward rather than picked up and advanced in the normal manner.

When only an abrasion is caused, little if any lameness occurs, but where interfering is continued and nerves are involved or subfascial infection and extensive inflammation succeed such abrasions, marked lameness and evidence of great pain are manifested. Frequently, in chronic cases affecting the hind leg, the fetlock assumes large proportions, and at times during the course of every drive the subject strikes the inflamed part, immediately flexing and abducting the injured member, and the victim hops on the other leg until pain has somewhat subsided.

Interfering is much more serious in animals that are used at fast work than in draft horses. In light-harness or saddle horses, it may render the subject practically valueless or unserviceable if the condition cannot be corrected.

Treatment.—Wherever possible, cause is to be removed and if animals are properly used, ordinary interfering wounds will yield to treatment. If the shoeing is faulty, this should be corrected, the foot properly prepared and leveled before being shod and suitable shoes applied. In young animals that become "leg-weary" from constant overwork, rest and recuperation are necessary to enhance recovery. In such cases it will be found that very light shoes, frequently reset, will tend to prevent injury to the fetlock region such as characterizes these injuries of hind legs.

Palliative measures of various kinds are employed where cause is not to be removed and a degree of success attends such effort. In draft horses or animals that are used at a slow pace, shields of various kinds are strapped to the extremity and protection is thus afforded. Or, large encircling pads of leather, variously constructed, serve to cause the subject to walk with the extremities apart.