Special Report on Diseases of Cattle Part 35

Bones may be accidentally broken in many ways and from different causes.

Fractures in general are liable to be produced by external force suddenly and violently applied, either directly to the part or at a distance, the force being transmitted through the stronger bones until it expends itself by breaking a weaker one remote from the seat of the injury. Occasionally violent contraction of muscles is sufficient to break a bone. Certain bones, those of the limbs in particular, owing to their exposed position, are more liable to fracture than others. Owing to certain predisposing causes, such as age, habit, or hereditary const.i.tutional weakness, the bones of some animals are more easily fractured than those of others. The bones of an animal advanced in years are more subject to fracture because of the preponderance of inorganic matter rendering them more brittle. They are also occasionally rendered liable to fracture by a previously existing diseased condition. Fractures are divided into four cla.s.ses--partial, simple, compound, and comminuted.

PARTIAL FRACTURES.--Partial fractures are those which are liable to occur in a young animal in which the preponderance of animal matter or the semicartilaginous condition of the bone renders it tough, so that even when considerable force is applied the bone bends, breaking on the side opposite that to which the force was applied, after the manner in which a green stick bends and breaks.

SIMPLE FRACTURES. Simple fracture is one in which the bone is severed in two parts, transversely, longitudinally, or obliquely, without serious injury to the adjoining structures.

COMPOUND FRACTURES.--Compound fracture is one in which there is an open wound permitting the air to communicate with the ends of the broken bones.

COMMINUTED FRACTURES.--Comminuted fracture is one in which the bone is shattered or divided into a number of fragments.

COMPLICATED FRACTURES.--Complicated fracture is one in which other structures surrounding the bones are injured.

GENERAL SYMPTOMS OF FRACTURE.--When a fracture of one or more of the large bones of a limb occurs, symptoms are sure to be well marked. After the accident the animal refuses to touch the foot to the ground and, if compelled to move, does so with great pain and reluctance. There is more or less shortening of the limb, with trembling of the muscles in the vicinity of the injury; deformity, and increased mobility, so that, instead of the natural joints of the limb and the natural, muscular control of their motion, a new joint, over which the animal has no control, is formed where the fracture occurred. As the leg, shortened by the ends of the bones being forced past one another from the muscular contraction which invariably takes place, hangs dependent from the body it swings in an awkward and unnatural manner, permitting the toe and foot to a.s.sume positions in their relations to other parts of the body which otherwise would be impossible.

If the fractured bone is so situated that the parts may be moved one upon another, a grating sound, known as crepitus, will be heard.

GENERAL TREATMENT OF FRACTURES.--When a fracture occurs, the advisability of attempting treatment must first be determined. If the animal is young, valuable, and of reasonably quiet temperament, and the fracture is not too great in extent, the chances of recovery are fair. On the other hand, if the animal should be of little value, irritable, advanced in years, and the fracture is a serious compound or comminuted one, the wiser course would generally be to put the creature out of its misery.

Having determined to attempt treatment, no time should be lost in restoring the parts as nearly as possible to their natural position and retaining them there. If the ends of the bones have been drawn one past the other, they should be drawn out by firm and continuous tension, until they again a.s.sume the position in which they were before the accident. All this can better be done before the swelling (which is sure to result) takes place.

If the swelling has occurred before the injury is noticed, do not attempt to treat it, but proceed at once to treat the fracture as though the swelling were not present, for no step can be taken toward recovery until the ends of the bone have been restored to their proper position. When that is done and proper appliances have been used to prevent them from being again misplaced, the swelling, which is the result of irritation, will be relieved. In selecting the appliances to be used in the treatment of fracture the judgment and ingenuity of the operator are of much importance.

Splints, made of wood shaped to fit the limb and padded with soft material where they come in contact with bony prominences, and held in position by means of bandages, are the oldest method, and with some are still most popular. The fracture pads used in human surgery, and for sale in surgical depots, are very convenient. After being dipped in water they may be molded to fit the limb and be retained by means of bandages. Heavy sole leather is also used after being soaked in warm water and molded to the shape of the limb and holes cut in it to fit over any sharp irregularities in the natural shape of the bones. Gutta-percha sheets are also used and answer well. They are prepared and used in the same way as the leather.

Another and perhaps the simplest of all methods is the application of a plaster-of-Paris bandage, which is made as follows: Strips of thin cheesecloth 3 inches wide and 8 or 9 feet long are laid flat on a board and on them is spread a layer of plaster of Paris about one-eighth of an inch thick; then, starting at one end, roll carefully so as to gather the plaster in between the layers of the bandage. It is of course important that the cloth be thin and the plaster of Paris fresh and active. After preparing four or five of such bandages the operator is ready to dress the fracture, which, after the parts have been brought into position, should be done by covering all that part of the limb to which the plaster-of-Paris bandage is to be applied with a single layer of the dry bandage, letting it extend both above and below the part to which the plaster bandage is to be applied and including under the folds of the dry bandage at each end a layer of absorbent cotton, which is intended to form a pad to prevent the ends of the plaster bandage from chafing the skin beneath. When this is done one of the plaster bandages should be placed in a vessel of water and allowed to remain till the air bubbles have ceased to rise from it, which will generally indicate that it is soaked through. Then, taking it in the hand, wind it carefully around and around the limb, unrolling the bandage as it is wound around the limb, occasionally smoothing down the plaster of Paris. Should it form roughly or in ridges the hand may be dipped in water to impart increased moisture to it. When about finished with one bandage, place another one in the water, so that the winding operation may be continued without delay. The bandages should be applied till the cast is from one-half to three-quarters of an inch thick, then gently restrain the animal for one-half or three-quarters of an hour till the plaster is hardened. Any of the appliances used should be so manipulated as to prevent absolutely any motion of the detached parts. If the fracture is near a joint, it is generally best to include the joint in the appliance. The part of the limb below the bandage should be carefully and firmly wrapped with an ordinary cotton bandage all the way from the plaster bandage down to the hoof. This last bandage will tend to prevent swelling, which is liable to occur, the result of the dependent position in which the animal is forced by nature to keep the injured limb.

When plaster-of-Paris bandages are applied to a compound fracture the injured part may be previously dressed with a small, thick pad of cotton immediately over the wound. In applying the bandage the operator may with a little care so arrange it as to keep the folds of the bandages off the cotton, or have only a thin layer over it, which may be easily cut out and the cotton removed, leaving a convenient opening through which to dress the wound without removing the bandage. The ends of the bandage or other appliance should be carefully watched to see that the skin does not become chafed, particularly at the lower end. If the bandage should become weak or broken at any part, it may be strengthened without removal by applying other bandages immediately over it. If swelling has taken place before the bandage has been applied, there is liable to be some loosening as it disappears, and even without the swelling there may be a tendency of the bandage to slide downward. This may be overcome by fastening it to a suspender attached to a surcingle or pa.s.sed over the body and attached to the opposite leg. If the looseness can not be overcome in this way, the s.p.a.ce may be filled by pouring in a thin paste of plaster of Paris. A better method, however, is to remove the bandage and apply another. Owing to the hardness of the bandage it will be removed with some difficulty. A deep groove should be cut down completely through it on the opposite sides.

This may be done with a chisel and a small hammer if the bandage is carefully held by an a.s.sistant so that the concussion of the blows is not transmitted to the injured bones. The patient should have a roomy stall, and should be tied by the head to prevent any attempts to move around. In some cases slings have been used. Ordinarily, however, they are not satisfactory in cattle practice, and if applied should be for only a few days at a time, and with a view to lessen the animal's disposition to lie down, rather than to prevent it. When they are used continuously the pressure on the abdomen may interfere with digestion and the general health of the animal.

_Modes of union._--The animal should be kept as quiet as possible and given such feed as will have a tendency to keep the bowels slightly relaxed. The success of the operation depends chiefly on the skill of the operator, but not alone in the selection and use of the appliances, for as much attention must be given to subsequent management. The patients are restless, and a single awkward motion may undo the work of weeks so far as the union of the parts of the bone is concerned. Union takes place after the same process and, if the conditions are favorable, with greater rapidity than in the human being. The injury that caused the fracture is almost sure to have extended to some of the adjacent tissues, and even though the fracture may be of the simplest type there is almost sure to be considerable hemorrhage around the ends of the broken bone. This, however, is unimportant if the skin remains intact, unless a very large vessel should be injured, or the fracture should open some of the important cavities of the body, in which case a fatal hemorrhage may result. If, on the other hand, the fracture is compound the external opening furnishes a fertile field for the lodgment of disease-producing germs.

Unless great care is taken in such cases, a suppurative process is liable to be established which will seriously interfere with, if not entirely arrest, the process of union between the bones; or it may become so serious as to endanger the general health of the animal and even be attended with fatal results. This last danger is greater if the injury has occurred to the bones of the arm or thigh. In such cases, owing to the dense covering of fascia which ensheathes the muscular covering pus is liable to be imprisoned, and, burrowing downward, saturate the whole structure, not only endangering the limb, but, by absorption, may set up blood poisoning and seriously interfere with the general health of the patient, even to causing death. In order so far as possible to prevent such an unfortunate complication, the wound should be carefully cleansed with a mild solution of carbolic acid, then dusted over with iodoform before the bandages are applied, and cleansed and dressed daily in the same way. After dressing, always cover with absorbent cotton. In the early process of union an exudation of lymph takes place, which is at first fluid, gradually becoming thicker and firmer till it forms a callus, known as the external or ensheathing callus, in the shape of a ring or ferrule surrounding the detached portions of the bone. It occasionally happens that this callus forms only at the ends of the bones, filling the s.p.a.ces that exist between them, when it is known as the intermediate callus. The process of union may be divided into five stages. In the first stage, including the first eight days, the detached portions of the bone and the sharp projections that are not sufficiently nourished are absorbed; the blood which escaped into the surrounding tissues, the result of the injury, is gradually absorbed, and the effused lymph, which is ultimately to const.i.tute the temporary cartilage, takes it place. In the second stage, from the tenth to the twentieth day, the tumor or callus is formed and fibrocartilage is developed inside and around the exposed end of the bone. In the third stage, extending from the twentieth to the fortieth or fiftieth day, according to the age and strength of the animal, the fibrocartilaginous structure undergoes a change and is gradually converted into bone, forming a ferrule on the outside and a plug on the inside, which serve to hold the part in position. In the fourth stage, extending to about the sixth month, the whole of the new structure is converted into bone. In the fifth stage, extending to the end of the first year, the callus is absorbed, being no longer necessary, and the connection between the cavities of the two bones is again established.

_Common complications._--The process of union just described is healthy and normal. Diseased conditions may at any time supervene during the treatment and render the operation unsuccessful. In the case of compound fracture, the open wound communicating with the ends of the bones, a septic condition is liable to arise which may become so serious as to endanger the animal's life and bring about conditions which in human surgery would indicate amputation. Although that operation is not a general one in veterinary practice, there is no reason why it should not be attempted as a last resort, particularly if the animal is valuable or is one whose existence is necessary in order to perpetuate some valuable strain. Even in the simplest form of fracture, if the splints or bandages are improperly applied and the fractured bone left so loosely guarded that the broken ends move one upon another, the formation of the calluses previously described is liable to be interfered with, and in place of a strong, rigid, and healthy union a formation of elastic cartilage is the result. This false structure unites the broken ends of the bones in such way that they move one upon another, depriving the bone of its stability and usefulness. When once the healthy process of union is interrupted in the manner just described, it is again established with great difficulty. It no longer does any good to continue the restraining power; in fact, the change of the temporary cartilage into bone is more liable to be reestablished if the parts move violently upon each other for a short time so as to set up and renew the process of inflammation. Then if the restraint is again applied there is some chance of union. In order so far as possible to avoid this danger, care should be taken to see that the bandage fits closely and that it is kept on till there is no longer any danger but that a perfect union has taken place. It is impossible to say at just what time the splints or bandages can safely be removed. In a young and healthy animal of quiet temperament, if the parts have been firmly held in position throughout the whole time, from 30 to 40 days may be regarded as reasonably safe. Under more unfavorable conditions as to age, vitality, and restraint, the period would better be extended to 60 days, if the general condition of the animal is such as to permit of so long a continuance. After the appliance has been removed the animal should be allowed to stand quiet for a few days, then be given very gentle exercise, gradually increased for a week or 10 days, by which time the patient will be so far recovered as to be placed in pasture. It should, however, be alone for a time, so as not to take any chance of injury from fighting or other accidents that a.s.sociation with other animals might involve.

SPECIAL FRACTURES.

FRACTURE OF THE HORNS.--Of the special fractures liable to occur, that of the horn is perhaps the most common. It is always the result of violent mechanical means, such as blows, injury occurring while fighting, or from the animal getting its head locked in some manner while feeding from a rack. When it occurs there are two ways in which the injury may affect the animal. First and most common, the h.o.r.n.y crust is liable to be stripped from the bony projection which it covers. Second, the crust and bone may both be broken or bent down, the fracture occurring in that case at the root of the horn and involving part of the bones of the head in the immediate vicinity. In the first case, if the h.o.r.n.y covering is knocked off, little attention is necessary. The animal may be relieved from suffering if the stump is smeared with pine tar and wrapped in cloth. If the core is much lacerated, perhaps it would be better to amputate. The necessity for such operation must be determined by the condition of the injury, influenced to some extent by the owner's ideas on the subject. When the operation is performed, it should be done with a sharp, fine-toothed saw, and by sawing the horn off close enough to include a little of the skin and hair around its base. The practice of dehorning has grown popular in many parts of the country. It is a simple operation, and, although attended with some immediate suffering, does not produce serious const.i.tutional disturbance. The advisability of performing the operation on all cattle is a question of expediency and must be justified by the expectation of benefit on the part of the feeder. If the horn should be broken so that the core and crust are bent out of shape without the detachment of one from the other, it may be restored to its normal position and retained there by means of a splint made to fit across the back of the head, so as to be laced to both horns, the sound horn serving to hold the broken one in position. Such a splint may be fastened on by means of either a wire or cord and allowed to remain six weeks or two months.

If both the horn and core have been broken off, bleeding is usually severe and should be checked by astringents, such as alum, or by pressure. After the hemorrhage has ceased the exposed portion of the fracture should be covered with pine tar, with or without a bandage. An imperfect growth of horn will in due time cover the exposed bone.

FRACTURES OF THE BONES OF THE FACE.--These occasionally occur, and when over the cavities of the nose produce depression, disfigurement, and impeded respiration, owing to the lessening of the caliber of the nasal pa.s.sages.

When such accident occurs, the depressed bone should be gently forced back to place by introducing the finger in the nostril, or if the fracture is too far up for this, a probe may be pa.s.sed and the parts retained by placing immediately over it a plaster of thin leather or strong canvas smeared with tar, extending out to the sound surroundings, taking care to embed the hair over the fractured portion in the tar of the plaster, so that it will be firmly held and prevented from again becoming depressed. If only one nostril is involved, the depressed portion may be held in position by packing that nostril with absorbent cotton. This practice, however, has the objection of giving the animal great discomfort and in some cases a disposition to aggravate the injury.

FRACTURE OF THE SKULL (CRANIUM).--Fractures of the bones forming the cavity in which the brain is situated are, owing to their strength, comparatively rare among cattle. Such an accident can only be the result of external violence, and it is hardly possible that it could occur without some fragment of the broken bone pressing upon the brain so as to cause coma or other severe nervous derangement, or even death.

If the animal survives the first shock, the efforts should be directed toward relieving the pressure, which may be done by making an opening in the bone (trephining), and with a hook drawing the depressed part outward.

Interference is not so liable to be attended with good results as to be warranted in all cases. The effects of a very severe shock which may not have produced a fracture, although the symptoms were alarming, will in many cases pa.s.s off, leaving the animal in a better condition than if an operation had been performed.

FRACTURE OF THE LOWER JAW.--This occasionally occurs, and is more liable to result from the kick of a horse than from any other cause. The front part of the jaw may be split or shattered in any direction in which the force may have been applied. b.l.o.o.d.y discharges from the mouth and failure to eat or ruminate are symptoms most likely to attract attention.

The treatment is simple and consists in first removing detached pieces of bone, then drawing the parts together and retaining them by means of pieces of copper wire fastened around the teeth, and feeding the animal on sloppy feed until recovery takes place. The wound should be dressed once or twice a day with a 3 per cent solution of carbolic acid, forced gently in with a syringe, so as to remove any feed which may have become impacted and interfere with the healing process.

FRACTURE OF THE VERTEBRA (SPINAL COLUMN).--This is not so common among cattle as other animals. If the fracture should be through the body of the bone, there may be pressure on or laceration of the spinal cord, causing paralysis of all parts posterior to the seat of injury. Fractures of the prominences on a vertebra occasionally occur without interfering with the ca.n.a.l in which the spinal cord is situated. Such accidents are liable to pa.s.s unnoticed, for, although the animal may suffer considerable pain, it may not be manifested in such way as to attract attention, and the deep covering of muscles serves effectually to conceal the injury. When the fracture occurs in the upper part of the neck, paralysis of the muscles used in respiration must result, and death from asphyxia very shortly ensues. The more common accident is to the loins, and when a fracture of the body of a vertebra occurs in this region so as to produce pressure on the spinal cord, paralysis of the hind legs and quarters is the result.

Diagnosis of such an accident is more difficult than in the case of any other fracture. The parts can not be moved one upon another so that crepitus is noticeable. The heavy coating of muscles conceals irregularities of shape, which otherwise may attract attention. About the only reliable symptom is paralysis or loss of use and sensation of the parts posterior to the injury. Careful examination may reveal the seat of the injury. If it was the result of a blow, there may be some abrasion of the skin. The diagnosis is only important as an aid in determining the proper course to pursue.

If paralysis is present and a depression or irregularity of the spinal column is so apparent as to leave no doubt of the existence of a fracture, the only alternative is to destroy the animal, for of recovery there can be no hope. If, on the other hand, the paralysis is incomplete and there is no depression or irregularity of the spinal column or other evidence of fracture, the patient should be made as comfortable as possible by being placed in a well-bedded box stall and a few days permitted to elapse before the case is abandoned. The symptoms last described may possibly be the result of a severe strain of the muscles of the loins, in which case an improvement will soon be noticeable.

FRACTURES OF THE PELVIS.--The pelvis, or bony framework which gives shape to the posterior part of the body, is liable to fracture in many ways. A common one is by a separation of the two bones which const.i.tute the whole pelvis along the bottom and center line (symphysis pubis). In early life the two bones are separate and distinct. The union between them, which is at first cartilaginous, undergoes a change and is converted into bone, so that in adult life the whole pelvis is practically one bone. The point on which the two bones are united is weaker than the adjoining parts of the bone. When an animal slips violently, spreading the legs wide apart, the weaker materials give way and the bones are divided. If the accident is noticed when it occurs, it is likely to throw light on the nature of the injury. The animal will immediately go stiff behind, the legs being spread apart. Further examination may be made by introducing the hand, previously carefully oiled, into the r.e.c.t.u.m or v.a.g.i.n.a and pressing down along the central line, which will cause the patient to evince acute pain. In this case no appliance can be used to advantage. The animal should be tied in a stall until the parts become reunited and the lameness disappears.

Fracture of the posterior parts of the bone (ischium), which forms the point of the b.u.t.tocks occasionally occurs. The b.u.t.tock on the injured side will be less prominent than the other. Careful manipulation will generally move the parts so that crepitus may be recognized. If the fracture is through the posterior part of the bone, it is unimportant and deserving of no more attention than placing the animal in such position as to insure it against subsequent injury until the bones are united. Some distortion may result, but not sufficient to warrant interference.

Fracture through the body of the bone on a line with the hip joint (acetabulum) occasionally, though rarely, occurs, and is nearly always a.s.sociated with dislocation of the hip joint and the forcing of the head of the upper bone of the leg (femur) upward, far out of its place. The violent contraction of the powerful muscles of the hip renders it impossible to reduce the dislocation, and even if it were possible the fractured pelvis could not be held in position, so that the case becomes at once hopeless.

It may be recognized by the animal's standing on three legs, the leg on the injured side seeming shorter than its fellow and hanging pendulous, the muscles of the hip violently contracted and hard to the touch. The animal evinces great pain when the limb is moved. There is liable to be some apparent distortion in the relations between the point of the hip and the point of the b.u.t.tock. This will be more readily noticed by comparing the injured side with the other. The parts may be moved so as to produce crepitus. The examination may be completed by introducing the oiled hand into the v.a.g.i.n.a or r.e.c.t.u.m, when the two sides of the pelvis will reveal well-marked differences.

FRACTURE OF THE POINT OF THE HIP.--The anterior and external part of the pelvis (ilium), commonly known as the point of the hip, is liable to fracture, which stock owners describe as "hipping," or being "hipped," or having the hip "knocked down." This accident may be the result of crowding while pa.s.sing through a narrow door, of falling violently on the point of the hip, or from a violent blow directed downward and forward against it.

The lesion generally extends across the flat surface of the bone from its outer and posterior edge forward and inward. Distortion is liable to be the only noticeable symptom. The detached portion varies in size in different cases and with it the resulting deformity. The animal is noticed to be slightly lame, but this symptom soon disappears. The detached portion of the bone is drawn downward and away from the main part by the action of the muscles below, which are so powerful as to render return impossible. The bones therefore remain permanently separated, union taking place by fibrous callus. The animal suffers very little inconvenience, and for practical use may be as serviceable as before the accident, though the distorted appearance depreciates its value.

FRACTURE OF THE RIBS.--Such an occurrence can take place only as the result of a direct injury, as from blows or crowding. The posterior ribs, being more exposed, are more liable to fracture. Pain in moving, slight swelling over the seat of injury, and difficult breathing are obvious symptoms. If the fracture is complete, crepitation may be occasionally noticed by placing the hand flat over the injured part, carefully observing the motion as the chest contracts and expands during respiration. This symptom is more noticeable when the animal coughs. Unless the point of the broken bone penetrates the cavity of the chest the fracture is usually unimportant and calls for no treatment other than quiet. If the breathing is very labored and attended with much pain, motion may be limited by applying a wide bandage firmly around the chest. The animal should be restricted in the amount of feed and water for a few days, the stomach being kept as nearly empty as possible. Sloppy feed should be given to encourage, as much as possible, free action of the diaphragm in breathing.

FRACTURE OF BONES OF THE LIMBS.--On this subject much has been said in the preceding remarks on general fractures. As a rule, fracture through one of the large bones of the shoulder (scapula) or thigh (femur) is very difficult to manage. The powerful contraction of the muscles and the changing shape of the limb resulting from their action renders it impossible to retain the detached parts of the bone in proper position.

Therefore, though the union should take place, there is almost sure to be considerable deformity and more or less lameness. Fracture of the arm (humerus) or leg (tibia) is likely to be attended with better results. The muscular covering is not so thick, the sheath in which they are held is more tense, and the change in the shape of the limb from muscular action not so noticeable, the muscular force not so great, all of which facilitate replacing the dislodged ends and retaining them.

FRACTURE OF THE KNEE (CARPUS) AND HOCK (TARSUS).--This seldom occurs unless it is the result of a very violent injury, and is generally a.s.sociated with other injury and serious complications. Displacement does not generally occur to any considerable extent. The treatment, of course, consists in holding the limb perfectly quiet in a natural position, which may be done by the application of long, wooden splints retained by bandages, or a plaster-of-Paris bandage.

FRACTURES BELOW THE KNEE.--Fracture of the long bone below the knee (metacarpus) and hock (metatarsus) is more common. In young animals of quiet temperament the treatment of simple fractures here is likely to be attended with good results. On the other hand, a compound fracture in this region becomes a serious matter. The structures which surround the bones are so thin that a very small degree of sloughing will expose parts of the bones and be liable to lead to serious complications and probably fatal results.

FRACTURES OF BONES BELOW THE FETLOCK.--These fractures are comparatively unimportant unless a.s.sociated with other serious injury. The parts can generally be held in position without much difficulty, and union generally takes place quite rapidly.

APPLIANCES.--Of the appliances used in the treatment of the fracture of limbs above the knee, splints made of wood or iron strips and bandages are likely to serve best. Below the knee plaster-of-Paris bandages are preferable. The writer is well aware that many of the standard authors deprecate the use of the latter, but an extensive experience leads me to believe that they have many advantages over any of the other appliances when used alone, and in many ways they may be used with advantage in combination with others.

DISLOCATIONS.

Luxation, or displacement without fracture of the bones forming a joint, is comparatively rare among cattle. It most frequently occurs in the stifle joint, where dislocation of the kneepan (patella) takes place. A glance at the skeleton (Pl. XXV) will show the relations better than they can be described. It will be observed that the small, irregularly shaped bone (patella) plays on the anterior rounded part of the lower edge of the thigh bone (femur) and between it and the upper end of the shank bone (tibia).

The outer ridge on the lower end of the thigh bone is less prominent than the inner one, so that displacement, when it does take place, is by slipping outward. Such an accident may occur from direct injury or external force, as a blow, or from slipping. When it does occur the symptoms produced are somewhat alarming. The animal is unable to draw the leg forward, and either stands with it thrown back with the toe pointing downward, or, if it should succeed in getting its weight upon it, holds it firmly on the ground, fearing to move it. Examination of the outside of the joint will disclose the situation of the patella outside its proper place.

If the operator is not familiar with the normal appearance of the joint, it is well to make a comparison between the injured and the sound one. If compelled to move, the animal does so with great difficulty, jerking the leg which it is unable to bring forward, hopping with the other, and partially dragging the injured one.

[Ill.u.s.tration: PLATE XXV. SKELETON OF THE COW.]

_Treatment._--The treatment is simple. A rope 20 feet long should be applied around the fetlock of the affected leg, pa.s.sed forward between the front legs and up over the opposite side of the neck, back over the withers, and wrapped once behind the elbow around that portion of the rope which pa.s.ses between the front legs. The leg is then drawn away from the body and forcibly pushed forward by an a.s.sistant, while another person tightens up the slack in the rope until the affected leg is off the ground in front of the supporting leg. The rope is then drawn taut and the a.s.sistant grasps the tail and pulls the cow toward the affected side. The animal makes a lurch to keep from falling, contracts the muscles, and the patella slips into place with a sharp click, and the animal walks off as if nothing had happened. If the animal resists this method of handling, it may suffice to manipulate the dislocated kneepan by shoving it inward and forward with the heel of the hand while the affected leg is drawn well forward. Unless some precaution is taken the accident is liable to recur, as the ligaments have been stretched by the dislocation till they no longer hold the bone with that firmness necessary to retain it. The animal should be tied and the foot fastened forward, so that the patient can just stand on it comfortably, by means of a rope or strap around the fetlock carried forward between the front legs, around the neck, and tied on the breast.

Should this accident occur more than once it is a good practice to apply a blister around the joint, as in the formula recommended for sprain of shoulder, and observe the precautions as to restraint and subsequent treatment there recommended. With this one exception dislocations in the ox occurring independently of other complications are rare.

Dislocation with fracture may occur in any of the joints, and if one is suspected or discovered, examination should always be made for the other before treatment is applied. When a fracture occurs near a joint the force sufficient to rend the bone is liable to be partly exerted on the immediate tissues, and when the bone gives way the structures of the joints may be seriously injured. It occasionally happens that the injury to the joint becomes the most important complication in the treatment of a fracture. In order clearly to understand the reason for this a few words are necessary in relation to the structure of joints.

The different pieces const.i.tuting the skeleton of the animal body are united in such manner as to admit of more or less motion one upon another.

In some of the more simple joints the bones fitting one into another are held together by the dense structures around them, admitting of very little or no movement at all, as the bones of the head. In other joints the bones are bound together by dense, cartilaginous structures, admitting of only limited motion, such as the union of the small bones at the back part of the knee and hock (metacarpal and metatarsal). In the more nearly perfect form of joint the power of motion becomes complete and the structures are more complex. The substance of the bone on its articular surface is not covered with periosteum, but is sheathed in a dense, thin layer of cartilage, shaped to fit the other surfaces with which it comes in contact (articular). This layer is thickest toward its center when covering bony eminences, and is elastic, of a pearly whiteness, and resisting, though soft enough to be easily cut. The bones forming an articulation are bound together by numerous ligaments attached to bony prominences. The whole joint is sealed in by a band or ribbonlike ligament (capsular ligament) extending around the joint and attached at the outer edge of the articular surface, uniting the bones and hermetically sealing the cavities of the articulation. This structure and the articular surface of the bone is covered by a thin, delicate membrane, known as the "synovial membrane,"

which secretes the joint oil (synovia). This fluid is viscid and colorless, or slightly yellow, and although it does not possess a large quant.i.ty of fat, its character somewhat resembles oil, and it serves the same purpose in lubricating the joints that oil does to the friction surface of an engine. Although the tissues of the joint when used in a natural way are able to withstand the effect of great exertion, when unnaturally used, as they are very delicate and complex, they are liable to inflammatory and other changes of a very serious nature. The synovial membrane, and in fact the whole structure of the joint, is susceptible to injury and serious inflammatory derangement, and the capsular ligament is liable to be distended from excessive secretion of synovia. The latter process may be almost noninflammatory, and attended with little inconvenience or importance other than a blemish to the animal, which in cattle is not serious. It may occur on the back part of the leg above the fetlock or on the inner and fore part of the hock, corresponding in its location to windgalls and bog spavin of the horse. Continuous support by bandages will generally force reabsorption, and as the limb is not subjected to violent action, as in the case of the horse, the affection is not so liable to recur.