LAMENESS IN HORSES Definitions are proverbially difficult to frame, and the most careful definition of lameness admits of exception and qualification. For tunately every one knows what is meant by the word, and therefore failure to express in a verbal formula what is or what is not lameness is practically unimportant. To say that lame ness is"a movement of the horse's limb accompanied by a halt, or some defect in action"is hardly accurate, and it is too wide, because the action under observation 'may be the natural gait of the horse. A distinction is sometimes attempted between lameness and stiffness, but it is not easy to differentiate between the two. A condition affecting one limb may make a horse lame, whereas the same condition affecting two opposite limbs would so balance his move ments as to suggest stiffness. Old horses, like old men, are often stiff in their movements, not in one limb but in all, and also in the muscles of the body.
Lameness is a sign of disease or injury. It varies according to the nature and extent of the pathological alterations in the limb, and is modified by the temperament of the horse. Some horses exhibit pain, and therefore lame ness, from causes which in another horse would induce little sign of discomfort. Percivall's definition slightly altered is comprehensive and practical:"Lameness is the manifestation in the act of progression, by one or more limbs, of pain, disease, weakness, deformity, or impedi ment." Lameness arising from weakness may be seen in old horses, in those suffering from debility or fatigue, in influenza and other systemic diseases, and in horses with worn joints. Lameness due to deformity or- impediment may be seen in cases of luxation, anchylosis, mechanical lame ness, and rupture of the tendinous flexor meta tarsi. Lameness arising from pain only, or from pain with inability, is shown in cases of muscular cramp, strain, certain wounds, bruises, and frac tures. Sometimes lameness appears from disease or injury of other than locomotory organs, as in cases of pleurisy, hernia, and scirrhous tumour of the testicular cord, when the movement of a limb causes pain in the affected part and consequently lameness. All lameness is not due to pain, although much the larger part is, and, as a rule, the intensity of pain is pro portionate to the degree of lameness. As the result of disease of a joint, sprain of a tendon, or fracture of a bone, pain arises, and any move ment of the injured part increases the pain. Lameness is probably the first indication of injury to a limb shown by the horse, and often the only clear and definite symptom. Pain, as shown by lameness, may be acute though temporary, as when a horse hits his fetlock with the opposite foot. Pain due to some joint affections may be very acute when movement of the limb follows a rest, but disappears en tirely, so far as is indicated by lameness, when motion has been maintained a little time. Pain due to inflammation, with infection or pus formation, increases until the pus escapes. The gradual increase of lameness generally denotes progressive pathological changes in the injured limb. When lameness is plainly due to pain, rest is required. If the degree of lameness is proportionate to the pain caused by movement, then the quality of the lameness should enable the observer to judge whether or not the horse may continue at work. In the majority of cases of severe lameness there can be no justifica tion for working the animal, because work is then accompanied by constant pain. There are certain conditions of lameness in which motion is beneficial, as in cases of congestion of the sensitive laminae of the foot, and in some cases of swollen legs. There are cases of thick leg resulting from lymphangitis, or from"grease,"in which horses are permanently lame but in which the lameness is so slight and so much owing to stiffness of the limb that work may be considered justifiable.
Continuous acute pain in horses very soon produces constitutional disturbance, inappetence, and wasting of the body. The fact that horses work for years with such lamenesses as have just been referred to, and maintain their appetite and condition, is evidence that the degree of pain caused by work is not such as can be regarded as inhumane.
Probably 90 per cent of lameness in horses is due to pain, though mechanical impediment too is an occasional cause. Contracted tendons may result from a condition which was, but has ceased to be, painful. Bent knees and deformed fetlocks may cause lameness without the exist ence of pain, so also may fibrous anchylosis of a joint. Of course, these conditions may be accompanied by chronic inflammation, and often there is great difficulty in being sure that pain is absent. Disputes have frequently arisen regarding the existence of pain in mechanical lameness, and, as we are unable to elicit the subjective evidence in horses, the question is likely to remain undetermined. Analogous con ditions may be seen in human beings, who confess that while they suffer more or less inconvenience they are free from pain.
Lameness may be due to suspension or loss of nerve power, as in the various local or partial paralyses. Great lameness is seen as a result of injury to the radial or the suprascapular nerve, but it depends upon inability of muscles to per form their functions. Following an ,attack of hmmoglobinuria extensive atrophy of the ex tensor muscles of the stifle or elbow-joint may occur: lameness is excessive but it is not due to pain, it results from inability of the leg to sus tain weight owing to the inert muscles failing to hold the joint extended.
Causes of Lameness.The causes of lameness are direct or exciting, and indirect, predisposing, or contributing.
The exciting causes are those which directly produce the lesions giving rise to lameness, as blows, wounds, bruises, strains, burns, scalds, electric shocks, and other injuries contracted by the horse in slipping, falling, hall-falling, colli sions, or from over-exertion. Inflammation, however induced, may be a cause, as in arthritis, myositis, strain of tendon or ligament, laminitis, and other diseases of the foot, in cracked heels,"grease"or verrucose dermatitis, and eczema of the limbs. Other exciting causes of lameness are: neuritis, nerve injury or derangement, as in shivering, stringhalt, cramp, and partial or local paralysis; arterial obstruction causing intermittent lameness, as in aortic, iliac, or axillary thrombosis; tumour formation on a limb; hernia, orchitis, hydrocele, scirrhous tumour of the testicular cord, when interfering with the movement of a hind limb; partial luxation or wrenching of a joint; ostitis of fatigue resulting from special effort or prolonged hard work; systemic disease, as purpura hmmorrhagica, influenza, lymphangitis, farcy, malignant oedema, etc., causing symptomatic lameness.
External violence is the most common and obvious cause, though serious injury often results from the movements of the horse plus his own weight unequally distributed. A horse at play may fracture a pastern by bringing a foot suddenly to the ground when the muscles of the limb, having momentarily lost their usual control, permit the bones of the pastern to assume an abnormal relation to each other. A horse may sprain a tendon by a false step, or even fracture a hip by a sharp sudden turn, as at polo, when weight is thrust upon a part un supported by muscular action. In effect the injury resulting from a misdirected or uncon trolled action of the horse is similar to that produced by external violence.
Sprains of tendons or ligaments seldom occur as a result of excessive muscular contraction, though sometimes they are sustained towards the close of great muscular effort, as in racing, when the tiring muscles become exhausted. Usually strain is caused by weight being sud denly thrown upon the tendon or ligament when unassisted by the normal action of the muscles. So long as the extensors and flexors of the limb act together weight is supported by the elastic muscles, but when the muscles fail—it may be only momentarily—to act in concord, then weight is thrown entirely upon the unyielding tendon or ligament, with the result of either sprain or rupture. A simple example of this is the sprained ankle of man, caused by a mis step, or the"curb"which a horse springs when jumping a bank that gives way as his foot touches it. In neither instance is injury caused by excessive muscular contraction, but by the sudden lurch and failure of the muscles to regulate the movement.
Among causes of lameness the part played by bacteria should not be overlooked. The limbs of horses are very liable to injury, but the process of repair is active and the most formid able-looking wounds heal well so long as no infective complications arise. Bacterial infec tion is the direct cause of the unfavourable termination of many wounds and bruises, and it constitutes the chief danger in wounds of joints, tendon sheaths, and other synovial cavities.
An exciting cause may be of sufficient force to produce lameness in the best formed limb, but there are many lesions giving rise to lame ness which would not occur without the co operation of a predisposing cause. Disease may alter the strength or resistance of tissues and so render them liable to suffer from apparently trivial injuries, and other influences favour the origin of lameness when an exciting cause comes into action, though of themselves they would not give rise to it. These influences have very decided effect on the duration and termination of lameness, and they merit further considera tion. They are sometimes in evidence at the purchase of a horse as well as during its working career.
Conformation.By selection and breeding, man has obtained classes of horses specially suitable for different uses: for strength and for speed; some for walking and drawing heavy loads, some for trotting, and others for gallop ing. For each class a certain conformation is best, and the experienced eye recognizes at a glance the typical hunter, vanner, hack, or cart-horse. To put a horse of one class to do the work of another is to invite trouble. Cer tain peculiarities of conformation or structure predispose to lameness in any class of horse. Amongst the more important of these are bones which are relatively weak, soft in texture, not flinty, and round rather than flat, because they have a tendency to suffer in wear from inflam mation and bony outgrowths; small, narrow joints, as small knees or narrow hocks, in which the effects of concussion are insufficiently or unequally distributed, and defective feet, as brittle hoof, thin wall or sole, shelly hoof, flat sole, weak or thin heels, feet too much spread, and club foot. A flat foot is more liable to injury than an arched one, and a thin or low heel is easily bruised. Brittle hoofs readily break and thus interfere with effective shoeing. A short, upright pastern is more exposed to jarring and to joint disease than one longer and more sloping. Pasterns which are very long, excessively sloped, or have too much play, pre dispose to strain of the ligaments or tendons. The out-turned-toed horse is more likely to hit his knee in the trot than the animal with a properly placed foot."Sickle-shaped"hocks are supposed to be specially liable to curb. Long or weak forearms predispose to the early advent of bent knees. Bent knees and sprung fetlocks, by interfering with the rhythm or symmetry of movement, lessen power and hinder precision in locomotion. The horse whose tendons below the knee are small or"tied-in"is more liable to sprains than one with promi nent tendons and stronger formation of limb. Horses which naturally lack muscle take short steps. Short steps increase work and retard speed. The flat-sided horse with a light middle can seldom be kept in robust health or good condition.
Age and immaturity have considerable in fluence on the inception of lameness. In very young animals the tissues of the body are tender and immature and easily damaged. This is partly compensated by the rapid repair of the injured tissue. Old horses, on the contrary, have firm and mature tissues which, though not so easily injured, are less rapidly repaired. Horses four years old or under that age cannot withstand hard work, a fact known to all large owners of working-horses, but not yet appar ently fully recognized by military authorities. Some lamenesses are specially influenced by age. Thus splints seldom cause lameness in old horses, whilst navicular disease rarely appears before the age of six. The racehorse put to work at two years old is often a cripple at an age when other classes of horse show no sign of lameness because they have been allowed to mature before being worked. Pre mature work, before complete development of the bones, ligaments, tendons, and muscles, is responsible for the early appearance of splint, ringbone, bony enlargements, swollen joints, windgalls, and knuckling at the fetlocks.
Temperament.Horses vary as much as men in courage and energy, and these two charac teristics influence the wear of the horse quite as much as conformation. The best made horse without courage is an undesirable animal and infinitely inferior to a plain one that possesses this quality. As a rule a"slug"passes through life with less damage to his limbs than do other horses because he will make no excessive efforts. A horse may have too much energy, and some forms of lameness are seldom seen except in the tear-away animal.
Work.The horse that has done no work should be sound in his limbs. Very few working horses, six years old and upwards, have clean legs, free from blemish. Work is necessary to bring the horse to the highest state of useful ness. Without work the best muscular condi tion is never reached, and it is only when the muscles are in the highest state of tone and strength that work is most economically per formed. Work not only hardens the muscles of the limbs, it increases the activity of all the organs of the body. Circulation, respiration, and digestion are, equally with locomotion, brought to the highest pitch of functional per fection. An inferior horse in hard condition will do more work with less fatigue than a better animal in lax condition. Half the sprains that cause lameness occur in tired horses or in those which are lacking in healthy, bodily vigour or that state of physical fitness called condition. When a horse is tired and leg-weary his muscles have to some extent lost their tone and energy and he more easily slips and stumbles. The better the horse's condition the greater the effort he can make and the longer he can stay. Over work shows its effects upon even the strongest and best - conditioned horses, by causing them to tire, to sweat excessively, to fail in their appetite, and to lose weight. When overwork takes the form of too long a journey, too heavy a load, or excessive pace, it may cause serious injury to limbs or to lungs and other internal organs. If such effects are escaped, a rest for a day or two will enable a healthy horse to recuperate. When overwork is not quite so excessive as to produce the results just men tioned but is continued for weeks, horses gradually become debilitated and recuperation is slow even when complete rest is allowed. There is no economy in overworking horses. Lameness is sure to appear in some and enforced idleness is then inevitable. Should influenza or other infectious disease obtain entrance to an overworked stud, its ravages are ten times more severe than in one of fairly worked horses.
The ill-effects of overwork may be greatly added to by the driver. Some men will do the same amount of work as others and keep every horse they have in good condition. Some men injure every horse they have. Irregular changes of drivers, even if all are excellent, upset horses and detract from their working usefulness.
Shoeing.Bad shoeing may be a direct or exciting cause of lameness. Injuries from badly driven nails and improperly fitted shoes produce some of the most serious forms of lame ness, but these are soon detected and traced to their cause. Defective shoeing is also a pre disposing cause of lameness and often it escapes immediate attention. By retaining the shoes too long upon the feet the hoofs become over grown and out of proportion. A strain is thus put upon the ligaments of the joints above, and they are predisposed to further injury from comparatively slight exciting causes. By failing to have worn-out shoes replaced by new ones at the proper time, a shoe may be cast at work, and even when the hoof is not broken it is usually worn so thin that bruising of the sole is almost a constant result of the accident. By leaving the heels too high or the toe too long a disproportionate hoof is formed; this alters the normal relation of the foot to the leg and exposes the structures above the hoof to strain. A common error in shoeing is to leave one side of the wall higher than the other, causing irregular lateral pressure to be thrown upon the lower side. When this fault is allowed to continue for a few months a permanent twist of the hoof or foot is evident at the coronet. It is rare now to see a hoof so pared as to yield to light pressure, but in times gone by the practice of excessive paring was common, and the pedal bone frequently showed atrophy and flatten ing as a result of unnatural pressure. Certainly the art of horse-shoeing has improved, but it is still not uncommon to see a shoe so fitted on the foot surface that no level bearing is provided. The shoe is bevelled out from the external border to the internal like a saucer and on this sloping surface the hoof has to rest. No worse fault could be committed, as the effect on the hoof is to maintain a constant pressure on the wall, forcing it inwards and predisposing to lameness even when direct injury is not inflicted.
Roadways.As is well known, stiff and lame horses no longer fit for use in towns may work satisfactorily for years in the country. Work on the land or on country roads is attended with more friction, but the foothold is better and there is less jarring than on paved streets. Roads and streets paved with stone setts and cobbles, and, during rain, snow, and frost, those laid with macadam, concrete, asphalt, or wood, contribute to the production of lameness by causing the horse to slip, fall, or half-fall. In this way sprains of ligaments and tendons, wounds and bruises are contracted, joints are wrenched and bones broken. Horses working regularly at a fast pace on paved streets sooner or later suffer from tho effects of concussion. They lose action, acquire rounded joints and bony enlargements, and eventually, in too many instances, navicular disease. Horses doing slow draught work where the foothold is insecure, by slipping or half-falling when starting, holding, or setting back a load frequently contract bruises, strains, or limited fractures.
Heredity.In horses various peculiarities of conformation, action, and temperament are inherited. Although heredity as a cause of lameness has not been proved, the transmission of a tendency to certain defects or diseases of the limb bones can hardly be disputed. There is no doubt that some forms of lameness, as spavin, ringbone, and navicular disease, are commonly seen in the offspring of horses affected with these diseases. The foal is not born with spavin, but it may have inherited from its sire or dam a peculiar weakness of structure or tissue which predisposes the bones of the hock to spavin disease. Frequently it has been observed that a very large percentage of the foals got by an unsound horse sooner or later develop the special unsoundness of their sire. The mare also transmits her unsoundness, and a very significant fact is that if sire and dam suffer from a similar unsoundness hardly a foal escapes the development of this defect. The recog nized hereditary diseases associated with lame ness are ringbone, sidebone, bone spavin, navicular disease, grease, stringhalt, shivering, and unsound feet.
Symptoms of Lameness.Symptoms of lame ness are the signs by which disease or injury of the limbs is detected and located. Some symptoms are noticeable when the horse is standing at rest, some when the limbs are in motion, and others only on close inspection and manipulation of the lame limb. A lame horse may stand as square on his feet as a sound one, but usually he gives evidence of pain or dis comfort in a limb by"resting"it. The foot may be slightly advanced, or the fetlock joint may be half flexed and the heel of the foot raised from the ground. This position is assumed because the tension of muscles and tendons necessary to keep the leg extended causes suffering when a painful lesion exists in any part of the leg. Relaxation of tension affords ease and permits the bending of joints. The degree of bending is not in exact propor tion to the quality of pain and is influenced by the nature and position of the injury. In many instances acute foot lameness is accompanied by notable resting of the foot, whereas a horse may be very lame from splint and not rest the foot at all. Bending the knee generally coexists with flexion of the fetlock, and is very evident in cases of severe sprain or injury to the tendons at the back of the leg.
As a rule, partial flexion of the joints of a limb is simply due to voluntary relaxation of muscular tension, but there are cases in which flexion is due to paralysis. These are dis tinguishable by presenting complete flexion of a joint which does not resume its normal position when the horse is forcibly moved.
"Pointing"is the term employed to describe a position of a foreleg in which the foot is placed on the ground in advance of the opposite foot while the knee is bent only very slightly or held extended. Although pointing is indicative of chronic foot -lameness, particularly navicular disease, it is also seen in other lamenesses, and occasionally it has been noticed in horses that are quite sound in action. Trembling and knuckling of the forelegs are noticeable in horses that are unsound in both fore-feet. They fre quently accompany bent knees and straight fetlocks, conditions which indicate the effects of wear or premature work.
A horse is said to"nurse"his leg when he holds it up with the foot off the ground. This is often a sign of acute pain, and suggests that the foot is probably the part affected. In injuries to the foot complicated by pus forma tion, holding the foot raised from the ground is a prominent symptom. It is seen in cases of pricked foot, suppurating corn, complicated sand-crack, fractured navicular bone, open-joint, rheumatism, and very painful conditions of the hock and stifle.
The relative position of fore and hind feet is instructive, as when great pain affects both fore, the hind feet are placed well forward under the body so as to carry an extra share of the weight of the animal and thus relieve pressure on the fore-feet. Abnormal fixation of a limb is a rather striking sign of lameness. One joint or the whole limb may be fixed. A remarkable example of this is seen in outward luxation of the patella in which the limb is projected backwards resting on the toe-wall. Abnormal mobility is indicative of some important struc ture having given way, as in rupture of tendon or fracture of bone.
The action of the lame leg during locomotion, save in a few instances, is not diagnostic, but it is suggestive and it often discloses symptoms which are necessary or helpful to the formation of a correct opinion. If the observer knows how a horse moves the fore and hind legs when sound, he will quickly recognize the irregular way in which movement takes place when the horse is lame. At first he may not notice every devia tion from the normal, but as his experience increases he will be unlikely to overlook any indication of lameness; and if his attention is directed to it he cannot well be mistaken, although he may not understand its nature or see its significance.
Nearly every lame horse takes a shorter step with the lame leg than with the sound one. Movement of an injured leg or sustaining weight upon it causes pain, and therefore a short step is adopted to lessen pain. There are a few lamenesses in which the lame leg takes the longer step; for example, acute arthritis of the knee or stifle, wrenched hock, and suppurating toe sand-crack of the hind foot.
Adduction of a limb takes place when it is drawn unnaturally inwards during progres sion. Muscles on the inner and outer sides of the limb act together and the leg is brought forward in a more or less straight line. If from pain or incapacity one set of muscles ceases to act or the other set overacts, the limb is drawn away from its proper line by the stronger group. When the leg is adducted it is because the outer muscles are inactive or acting with less energy than the inner.
Abduction is applied to a movement in which the leg is drawn away from the body and the foot in passing forward is thrown outward. Both adduction and abduction are movements over which the horse has no control when they are due to incapacity or paralysis of the muscles. But either movement may be voluntary and resorted to by the horse to overcome a difficulty or to prevent or modify pain. If a horse suffers from a painful condition of the sternum, or a wound of the axilla, he may adduct the limb because any movement outwards causes pain. Abduction is seen in bruised hip, obturator paralysis, tumour of the groin, abscess forma tion in the upper region of either fore or hind limb, and in acute disease of the knee or hock which is stiff and very painful when flexed. Abduction of both hind limbs or a straddling gait is seen in orchitis, large scirrhous cord, acute hydrocele, mammitis, and fracture of the pelvic floor.
The movements of the foot during progres sion are important as symptoms of lameness. The manner in which the foot is brought to, laid on, and taken off the ground should be noted. When the heel of the foot is conspicuously brought first to the ground, usually a painful condition exists at the front of the foot. When the toe is brought to the ground and the heel is kept raised, it may be that the hinder part of the foot is the seat of pain, as in bruised heel. But a horse goes on his toe in many lamenesses not affecting the foot, as in active spavin disease and open knee-joint. He does so because the flexor muscles are employed to hold the limb steady and rigid and thus prevent pain from full extension of the affected joints higher up the leg. Thus the heel may be raised from the ground simply as a coincidence accompanying action adopted for a purpose quite independent of the foot. In very painful lameness, irre spective of the position of the diseased or injured part of the limb, the foot is placed on the ground gently and with hesitation because the jar of contact or the effort required to sustain weight is felt throughout the limb. When the bones or joints are the seat of acute pain, supporting weight upon the foot produces perhaps its worst effect, and in such cases, as soon as the foot reaches the ground, the limb slightly yields and the foot is as rapidly as possible raised again. In some cases, notably in complicated sand crack, the foot is absolutely snatched off the ground, and in other cases the limb is carried, the foot not reaching the ground.
Certain veterinarians attempt a distinction in the symptoms of lameness by the terms"swing ing leg lameness"and"supporting leg lame ness."Whilst allowing that it may be possible in a few instances to note a difference between the signs of difficulty shown by the horse in moving the leg and his manifestation of objec tion or fear to bear weight upon the foot, the distinction has very little practical value either as helping description or diagnosis. Dragging the toe is a symptom seen both in fore and hind leg lameness. In the fore, usually it is due to inability of the shoulder muscles to raise the leg sufficiently for the foot to clear the ground. In the hind, it is mostly seen as the result of insufficient flexion of the hock or stifle. In the chronic case when the horse continues at work the toe of the shoe shows excessive wear, and thus another sign is given which assists diagnosis.
It is always important to note any abnormal motion of joints in a lame limb. A joint may be fixed, overextended, or overflexed. The two opposite feet should be raised at each step to the same height. When weight is placed upon the feet the same angle should be formed at the joint of one leg as at the corresponding joint of the opposite leg. In the hind limb the hock and stifle joints move together. They are so anatomically bound to each other that only when the connection is impaired or is broken can the one act out of unison with the other. Pain in the stifle gives rise to limitation of move ment in the hock and vice versa. It is very difficult to say from action alone whether the pain is in the stifle or hock. In the absence of obvious or discoverable local alteration of either joint, and as stifle lameness is comparatively rare while hock lameness is common, want of free flexion of the hind limb may in many cases be safely attributed to pain in the hock.
Lame horses may exhibit peculiarities of action which are strongly irregular and very often quite diagnostic. In injury to the shoulder resulting in paralysis of certain muscles on the outer surface of the scapula, the point of the shoulder bulges outwardly at each step just when weight is placed upon the foot. In some ruptures of tendons such abnormal motion of a joint is per mitted that the lesion causing it may be named without manipulation of the limb. Paralysis of muscles may also allow such definite alteration in the form or movement of a limb as to point directly to the lesion. In disease or injury of the spinal cord and brain the movements of the horse direct attention to the nature of the lame ness. Sometimes the movements are convul sive, but more often irregular and indicative of loss of control. They usually affect the whole limb and often all the limbs, but the hind limbs are most likely to show plainly the effects of cerebro-spinal lesions.
The symptoms of lameness so far referred to are those which can readily be seen when the horse is standing or slowly moving. There are others which require close' examination for their detection and which are of much im portance because they generally indicate the position of the lesion causing lameness.
Swelling of a limb is common. It results from (=edema, injury, or disease, and varies con siderably in its pathology. Probably the most common swelling is that which accompanies inflammation. It is firm and painful when pressed, and as a rule it does not extend far from the seat of injury. Swelling due to effusion of blood arises with great rapidity, as in speedy cut, and is the result of laceration of small blood-vessels. In fractures, the sharp edges of the broken bone may cut arteries or veins, causing extravasation of blood and very extensive swelling. In lymphangitis the whole limb is swollen to an enormous extent, and so it may be in farcy and in purpura hmmo rrhagica. Swelling extending upwards from the heel and coronet is met with as a result of wound infection or"blood poisoning."It is remark able for the intense pain accompanying it and the rapid formation of many necrotic abscesses in the affected tissues. Diffuse swelling of the legs below the knee and hock arises from many different causes. It is seen as one of the earliest signs of some forms of influenza. It may indicate rheumatism of the flexor tendon sheaths, or it may be connected with suppura tion within the hoof. It is often produced by rubbing irritants into a lame leg, and then is a nuisance, because it covers and disguises lesions which otherwise might indicate the seat of lame ness. The veterinary surgeon, arriving after the amateur has"used a little embrocation,"has often to wait days for this swelling to subside before he can be sure of diagnosing the nature and cause of the lameness.
(Edematous swelling of the legs also results from debility and from disease or functional derangement of the heart, liver, or kidneys. Sometimes it is constitutional and associated with a lymphatic temperament. Frequently it is temporary and arising from indigestion. Swelling due to cedema or serous effusion pits on pressure and the impression made by the finger remains for some time. (Edema may coexist with inflammatory swelling in a lame limb, as in bruised knee with oedematous swell ing of the shank—the cedema extending beyond ,the painful part.
Limited or well-defined swellings, compress ible when recent, firm and resistant when old, may be seen at the fetlocks, knees, and hocks. They are due to distension of natural synovial cavities and are known as windgalls, bog spavins, and thoroughpins. They only cause lameness when injured or when the distension is so large as to interfere with the play of the tendons or the movements of the joint.
Outgrowth or enlargement of bone is common and as a rule is attended by lameness during the process of formation or while the bone is inflamed. Exostosis may gradually arise with out lameness and may remain, when fully formed, without pain. Splints, spavins, and ringhones are examples of bony enlargements which nearly always cause lameness during their formation.
Pain may be the only indication of a lesion causing lameness. Pain may sometimes be discovered by movement of a suspected part. A joint may be flexed or extended and may thus give clear evidence of pain. An injured bone may sometimes be detected by gently moving it with the hands, but it should be re membered that some horses object to the most simple handling of their limbs. The tempera ture of a part may indicate the seat of injury. The foot, joint, or any part of a limb in which acute inflammation exists is usually warmer than the adjoining parts. Heat and cold are comparative terms and the hand that detects them is not always accurate in its estimate. In those rare cases of intermittent lameness due to obstruction of the blood supply, exercise, whilst maintaining or increasing the surface tempera ture of the sound limbs, leaves the unsound one remarkably cold below the obstruction.
Discoloration is not easily seen on the hair covered legs of horses. In white-legged animals changes of colour may be noticeable, as in cases of cracked heels, when congestion or inflamma tory redness of the skin is evident. In injuries of the foot discoloration is visible on the white horn. On the ground surface of the hoof changes in colour indicate two frequent causes of lame ness—at the heels, corns, and round the toe, bruise from the shoe or a picked-up stone, or even moss-litter firmly caked under the shoe.
Deformities of limbs may be temporary or permanent. As the result of injury with swell ing a joint may be so altered externally as to equal a deformity. Fractures produce deform ities, some permanent. Fracture of the outer angle of the haunch is an instance. Fractures of the longer bones of the limbs of horses are seldom surgically treated. When they are, there are few that escape more or less permanent deformity. Ruptures of muscles or tendons may be attended by deformity, as in cases of"complete breakdown"in racehorses. Con traction of tendons, with or without adventi tious adhesions, also causes deformity, as when the knees are badly bent, the fetlocks overshot, or the heel permanently raised from the ground. Dislocation of the joints of the limbs is rare in horses. When it occurs it gives rise to marked deformity which may be aggravated by co existent fracture.
Crepitation is the crackling or grating noise which may be heard when the opposed surfaces of a broken bone rub against each other. It is quite diagnostic when present, but there are some cases in which care is necessary to distin guish it from sounds emitted by joints. A bone may be completely fractured and yet give no crepitus, because either displacement has not occurred, or blood-clot, muscle, or other tissue has found its way between the surfaces of the fracture.
Twitching of muscles is often noticeable in the region of a fractured bone. In fracture of flat bones (scapula, pelvis) covered by muscles, twitching is a useful guide in the first few hours following the accident. In comminuted and compound fractures of long bones, twitching is often continuous while the horse is standing. Spasm of muscles is seen in its most exaggerated form in acute tetanus. Muscular spasm may accompany abscess formation, rheumatism, acute arthritis, and laminitis of all four feet. In 'lameness connected with the shoulder (fracture, dislocation) the levator humeri muscle is spas modically affected. When the horse is moved this muscle becomes rigid and is rendered very prominent. Cramp is uncommon in horses, but it has been observed affecting the extensors of the shoulder and the extensor (crural) muscles of the stifle. Rigidity of the muscles of the haunch, sometimes of the elbow, is seen in hmmo-albuminuria and in rheumatism of the neck and loins. A very curious spasmodic con dition is shown in stringhalt. At rest the muscles seem normal, but on movement of the affected limb the foot is jerked up. In cases of intermittent stringhalt, movement is quite regular in the intervals between the abnormal contractions which appear to be excessive and hurried. In shivering affecting the hind limb the spasms last longer than in stringhalt. The limb is raised, abducted, and held quivering for -a few seconds, then the foot falls quickly to the ground. Frequently in both stringhalt and shivering the symptoms are not conspicuous and only appear at long intervals.
General systemic disturbance very often accompanies the graver and more painful lame nesses. The symptoms usually are sweating and blowing, and later a rise of temperature, increased rapidity of pulse, and emaciation. Loss of appetite is a serious symptom when arising from lameness. As a result of wound infection fever is rapidly set up, and in some cases of severe injury to the leg or foot often brings about a fatal termination.
Diagnosis of Lameness. Diagnosis is the art of recognizing symptoms and correctly esti mating their meaning and value. The dia gnosis of lameness in horses is made solely from the objective symptoms. Subjective symptoms which are so helpful to the human surgeon are not available to the veterinarian. There was a time not long past when the belief prevailed that some men possessed an intuitive talent for diagnosing lameness, and there were even occa sional veterinary surgeons who modestly claimed to possess this mysterious gift. In a few cases the experienced practitioner may exercise his snapshot diagnosis with great precision, but in the majority care and time and the most minute examination are necessary. When one has de tected every symptom exhibited by the lame horse, then comes the time to weigh and balance them all, to put aside those which are accidental, to value those which are essential, and to draw an inference. Every case of lameness is a logical problem the solution of which requires technical knowledge and sound natural judg ment. Experience, of course, assists men in diagnosing, but length of practice is not the measure of experience: two cases. properly ob served, studied, and understood afford more experience than twenty casually noticed and never mastered. Along experience includes many failures, and mistakes leave on the mind a deeper impression than successes. Few men make the same mistake a second time, and thus practice inculcates caution. Diagnosis of lameness may be easy or very difficult according to the nature of the case. Lameness varies greatly in degree. The defect in action may be intermittent, trivial, or so slight that doubt may exist as to which leg is lame. Often the lame leg is quite obvious. Sometimes the action of the horse suggests that it is lame on more than one leg, and this is not uncommon. All cases of lameness, and par ticularly those which are obscure, should be examined methodically. Method simplifies pro cedure. It ensures accuracy, imparts confidence, and saves time.
In diagnosing lameness the examiner should first ascertain which is the lame leg, then he should find the seat of the exciting cause of the lameness, and having found it he should make an effort to form a just estimate of the nature of the injury or lesion, its curability, and of the treatment required. Lameness arising from wounds and bruises of muscles usually offers less difficulty in diagnosis than that due to disease or injury of bones, tendons, or joints. A lame leg that is clean and apparently free from blemish often gives rise to misgiving in dia gnosis.
Detection of the Lame Leg.Movement of the horse, walking or trotting, is necessary in most cases. A slow trot with a loose rein is the best pace for disclosing lameness. The road should be paved or hard, with an even surface and a slight gradient. Trotting a slightly lame horse on grass or other yielding surface may mislead the observer. The animal should be led out quietly and slowly trotted for about thirty yards straight, turned, and trotted back to the observer. The distance of thirty yards is, of course, merely approximate, but a shorter distance may not clearly show slight lameness, whilst a run of sixty yards may temporarily remove the symptoms of a chronic case.
Front-leg lameness is best seen when the horse is coming towards the observer, and its indi cation is a nodding movement of the horse's head—the head rising when the foot of the lame leg is on the ground and falling with the sound one. Hind-leg lameness is best seen as the horse trots from the observer, and it is shown by a sinking of the quarter on the sound side at each step. The head may rise and fall in hind leg lameness, but the head rises when the lame leg comes to the ground. In many lamenesses of the hind limbs there is no"nodding"of the head.
It is not always easy to distinguish the lame leg. A horse may be lame on one, two, three, or even all four legs, though few horses are lame on more than two at the same time. Only a novice can be doubtful in deciding between a left and right front, or a left and right hind limbs, but an experienced observer may be puzzled to decide between the diagonal limbs— between a near-fore and an off-hind, or a near hind and an off-fore—of"cross lameness,"in which a horse lame on only one limb gives the impression of being lame on two. Still more puzzling is the horse that is really lame on both diagonal limbs. Lameness affecting the fore and hind limbs of one side may cause the observer to hesitate, especially if the degree of lameness in front and behind is nearly equal. A horse lame on three legs—as one fore and both hind—may lead to error in diagnosis. The inexperienced observer may know the symptoms of lameness, but until he has had considerable practice in watching lame horses he will continue more or less uncertain of the lame leg. Mistakes in detecting the lame leg are frequently made by horsemen and others who ought to be familiar with lameness. A groom's diagnosis of the lame leg is often wrong, and it should not be accepted without verification.
In making an attempt to distinguish the lame leg, the observer should watch the horse's head in front lameness and the quarters in hind lameness. He should not attempt to watch both ends of the horse at the same time. Neither should he try to distinguish the lame front limb while the horse is moving from him, nor the lame hind limb while the horse is coming to him. That the expert may do, though seldom that alone. He should pay special attention to the movements of the limbs when the horse is turning, and in some cases he should take a side view of action while the horse is trotting past him.
The beginner in directing his eyes to the head may have an inclination to look at the horse's feet. This should not be encouraged, at least not at first, or until he has acquired sufficient ability to detect the lame leg at a glance. Next he should endeavour to enlarge his view, and with a little practice and by training his eyes to see more and more at each attempt, he should soon be able without effort to cover in one view the head, shoulder, knee, shank, pastern, and foot in front lameness, or the quarters and limb downwards to the foot in hind lameness. He should bear in mind that while the head falls with the sound limb in well-marked front lame ness, it may fall very little when the lameness is slight, and in trivial or doubtful front lameness the head may not yield at all. He should not forget that in hind lameness the quarter of the sound limb gives, sinks, or falls when the foot of the lame leg comes to the ground, and that in some cases the head rises at the same time. To reach a positive conclusion in diagonal or"cross lameness"the safest way for the observer is to have the horse trotted at short intervals until he is quite certain of the lame limb or limbs, watching, always separately, the move ments of the fore and hind extremities. In some foot diseases both fore-feet are equally affected, and when the defect is slight it is not easy to decide whether the horse is lame or stiff, or merely possessed of low or bad action. It is seldom that lameness equally affects both hind limbs. It may, however, occur from lesions of the feet or hocks, and in either case the horse's action suggests injury to the back or spine.
Stiffness of both hind limbs renders the motion of each similar and causes a movement which may be described as crouching. In those cases, where both fore or both hind limbs appear more or less lame, the horse should be exercised and, in doubtful hind lameness, with weight on his back. Twenty minutes' trotting exercise fol lowed by a rest of half an hour and another run out in hand will in most instances settle the point by increasing the lameness or by leaving the action of the limbs unaltered.
There are intermittent lamenesses which, when the veterinary surgeon examines the horse, may not be visible. Under such circumstances a trial should be given under the same conditions as existed when the horse showed the lameness complained of. It may be that a trial in harness or in the saddle is necessary to bring out the symptoms, and such trial should last a little longer than the time which elapsed when the defect was shown.
Detection of the Seat of Lameness.Having ascertained which leg is lame, the next step in diagnosis is to locate the seat of the exciting cause. This may be quite obvious or it may have been discovered while the horse was trot ting. Often, however, the seat is not evident, and a careful examination of the whole limb is necessary. While the horse is trotting close attention should be given to the action of the lame limb. By watching the way the foot is brought to and placed upon the ground, the movement of the fetlock and pastern, the flexion of the knee or hock, the play of the shoulder or stifle, and the carriage of the quarters, symptoms may be seen inviting attention to one or another part of the lame limb. For example, in shoulder lameness there is restricted movement of the scapula, the step is short or swinging, or the point of the shoulder appears to have too much play. In carpitis, knee - splint, and acute thoroughpin the knee is stiff, extended with care, and only partially flexed. In acute flexor strain, the knee, not fully extended, tends to lean forward, and the heel of the foot rests lightly on the ground. In fetlock injuries the joint is fixed or carried stiffly. In hind lameness, a"bobbing"movement of the quarter on the lame side suggests disease of the hock. When the quarter is carried high with abduction of the limb the seat of lameness usually is in the hip (fracture, bursitis, etc.), and when the quarter is carried high without abduction most often the fetlock is at fault. A peculiar hitching movement of the hind limb in the trot is char acteristic of stifle injury which is nearly always accompanied by deformity of the front of the joint. In flexor metatarsi lameness the carriage of the hock and relaxation of the Achilles tendon are quite diagnostic.
Assuming that observation of the movements of the limb has failed to discover the seat of lameness, examination with careful palpation or manipulation of joints, tendons, and ligaments should be practised, beginning always with the foot. Frequently the foot has been examined by the farrier, but this should not hinder its further examination by the veterinary surgeon, who is responsible for the diagnosis and treatment of the lameness.
In all cases, fore or hind, the foot should be examined, for although an obvious or sufficient cause of lameness exist higher up the leg, often the foot is also the seat of injury or disease. The foot is tested by compression and percussion, then the shoe is removed, and after clearing loose horn from the sole, frog, and heels, and lightly paring the sole where necessary, the ground surface of the hoof—nail-holes, quarters, heels, and toe—are carefully searched. Failing dis covery of any sign of pain, injury, or disease, the shoe may be replaced and the horse run out again. Then the pastern, fetlock, and shank should be manipulated, giving special attention to the sesamoid region and the flexor tendons. If the lameness is in front and the horse is under six years old the cannon should be searched for splint. Next the knee or hock should be palpated, and so on until the limb from the coronet upwards has been carefully examined. As a rule the seat of lameness can be discovered by this method of examination. The first attempt may fail, and in that event, which happens occasionally in slight lameness, the examiner may either prescribe complete rest for the horse and suspend judgment of the case for a day or two, or at once have the horse severely exercised, lunged, or ridden, then rested for half an hour, and repeat the examination. Sometimes difficulty in detecting the seat of lameness may be diminished by resorting to negative diagnosis, that is, by examining and excluding one part after another of the lame leg. This method by limiting the field of discovery is helpful, though it does not tend to confident opinion. Occasionally where some part, though free of evident injury or disease, is peculiarly sensitive to manipulation, a local anaesthetic injected into or immediately above the region may afford useful information by temporarily suspending sensation in and below the area of injection and perhaps removing the lameness. The seat hi front lameness is oftenestin the foot or near it, and in hind lameness in the hock. There are rare cases of lameness in which the exciting cause is indefinite, hidden, or beyond reach, but the examiner with patience, assiduity, and well-considered effort should very seldom fail in finding its seat. First views and hasty opinions of lame horses are often erroneous and fraught with danger to the reputation of the practitioner, who should not often accept a con spicuous defect as the actual or only cause of lameness without further examination of the limb. In this connection may be recalled the old, yet useful, warning to the examiner: that swelling over the flexor tendons may coexist with pus formation within the hoof.
The nature of the exciting cause of lameness may have been ascertained in the effort to fmd its seat. The immediate effects of punctured foot, gathered nail, and other injuries to the sensitive foot are easily recognized, though frequently the extent of the damage cannot be discovered. Pastern and fetlock cases usually require careful palpation, with comparison of the suspected part with the corresponding part of the opposite limb. Tendons and ligaments give less trouble, but sometimes, owing to swelling masking the lesion, diagnosis may have to be deferred. Joints may have to be examined repeatedly before the nature of the lameness can be determined, and the anxious owner of the horse may suggest resort to the X-rays. In lameness affecting the upper region of the fore or hind limb, discovery of the nature and extent of the injury or disease may be very difficult because of the thick muscular covering of the part. Often only a tentative diagnosis can be reached after prolonged examination. In fracture and other injuries of the pelvis rectal exploration should not be neglected.
In this work of arriving at a positive opinion of the nature of the lesion, an intimate know ledge of the normal anatomy of the limbs is extremely useful to the practitioner. He should be familiar with the disposition and relations of the tendons, ligaments, synovial sheaths and burs, the bony prominences, the form and mechaniina of the joints; the muscles, and their actions in effecting the various movements of the limbs.
Lameness according to the Region affected. lameness,"as commonly employed, is necessarily a comprehensive term, because many of its examples are indefinite as to nature and causation. Wounds, bruises, and other injuries associated with deformity of the shoulder can hardly be mistaken, but cases in which there is no evident surface alteration of the part very rarely admit of positive diagnosis. Atrophy of the shoulder muscles may result from inaction of the limb, and the lesion inducing lameness may be in the foot, fetlock, or at some distance from the shoulder. Fortunately, shoulder lame ness is not very common, although frequently lameness of a fore limb is wrongly attributed to this region. The fore limb, unlike the hind one, has no bony connection with the spine, and this to some extent explains the infrequency of shoulder lameness.
The shoulder-joint, formed by the scapula and humerus, has only one ligament, a capsular one, which is well supported by muscles or their tendons. It is a ball and socket joint. The movements of extension and flexion are extensive, but those of abduction, adduction, and rotation are much restricted by muscular attachments. The head of the humerus is furnished with three synovial burs which are of importance in con nection with shoulder lameness. One of these bursae facilitates the play of the biceps tendon over the bicipital groove; another is placed between the external tuberosity and the infra spinatus tendon, and the third lies on the inner side between the humerus and the tendon of the subscapularis muscle.
Shoulder lameness may be due to cutaneous wounds, galls, or acne pustules, wounds or bruises of muscles, abscess formation, tumours, myositis, or rheumatism, muscular rupture, atrophy, and cramp; bursitis, fracture (humerus or scapula), wrenched joint, dislocation, open or closed arthritis, ostitis, arterial obstruction, paralysis, and occasionally fistulous withers. In most instances shoulder lameness is shown by restricted movement of the scapula, which appears held to the trunk, the step is shortened, the joint is insufficiently raised, and the foot— apt to catch the ground—is swung outwards or dragged, or it may be carried. Certain forms of shoulder lameness present additional symptoms which may be characteristic and of considerable assistance in diagnosis. In supra - scapular paralysis, and owing to loss of power in certain muscles which support the joint, the point of the shoulder appears to roll or bulge outwards when the foot comes to the ground, and within a few days of the inception of lameness the extensor muscles become plainly atrophied, producing noticeable deformity of the shoulder. In arthritis and in fracture implicating the articular surface of scapula or humerus, the joint, in locomotion, is fixed, the limb is carried, and the patient strongly resents manipulation of the shoulder, which sooner or later becomes enlarged over the joint. Rheumatic shoulder lameness is often intermittent. Under exercise, or while the horse is warm, the action of the limb may gradu ally improve and lameness may even disappear; but after a rest lameness recurs and it may be aggravated. In walking or trotting, a horse affected with rheumatic myositis may be unable to move forward in a straight line, as happens sometimes in cases involving the mastoido humeralis muscle. In myositis of the pectoral
muscles arising from fatigue, as after a hard day's hunting, the horse is unwilling or unable to trot, and when forced he straddles, flounders, or threatens to fall. Inflammation of the bursa of the biceps tendon (bursitis intertubercularis) is marked, in walking, by inability to advance the foot, though in standing the limb may be used to support weight, and in backing it can be moved without much difficulty. In trotting, the scapula is held forward on the trunk, the shoulder-joint is lowered and fixed, and the foot is dragged. Manipulation of the biceps tendon with passive flexion or extension of the joint appears to cause great pain. This lameness when arising from collision or street accident may be temporarily masked by bruising or painful swelling of the shoulder. Dislocation of the shoulder-joint, which may be complicated by partial fracture of scapula or humerus, or by rupture of ligament or muscle, is distinguished by conspicuous deformity and immobility of the shoulder, and by shortening of the limb which is trailed or carried. The head of the humerus rides on the scapula, and the muscles around the joint are tense or spasmodically contracted. The horse is uneasy, blowing, and sweating.
Shoulder abscess varies considerably in its early manifestation. When the abscess forms in the substance of the levator humeri, beneath it, or in connection with the prepectoral lym phatic glands, the first indication may be stiff ness or lameness with diffused swelling of the shoulder extending to the breast and base of the neck. The position of the abscess may be uncertain, but as the abscess matures careful palpation usually discovers a small, very tender area, which when deeply punctured yields pus. Lameness of the arm is met with occasionally. Diagnosis is very difficult except in cases of wounding, or of fracture of the humerus.
Elbow lameness is often remarkable for the excessive nodding or falling of the horse's head. Even when the exciting cause is superficial or trivial this feature may be observed. It has been attributed to limited extension of the joint, which is probably true of some cases of elbow lameness. The elbow is a hinge joint, and its ligaments are two lateral and one anterior or capsular. The joint is closed behind by the synovial membrane, and protected by a portion of the ulna (olecranon), by the extensor muscles of the elbow and the tendons of the five flexors of the knee and foot. Its movements are ex tension and flexion. Extension is limited by the tension of the lateral ligaments and by the beak of the olecranon, which may be fractured in forced extension of the elbow, an accident which sometimes happens in the recumbent position when a fore foot is secured to a hind limb for operation.
The principal causes of elbow lameness are wounds and bruises, paralysis, fracture, arthritis, and occasionally dislocation and capped elbow. Radial paralysis affects the extensor muscles of the elbow, and the symptoms point to loss of power. The elbow droops, the knee and fetlock are half-flexed, and extension of the elbow and the joints below it cannot be maintained by the horse, though the limb can be thrown forward from the shoulder. In backing the limb is dragged. Radial paralysis is not always a primary affection; it may be symptomatic of haemoglobinuria. Wounds and bruises of this region frequently lead to open elbow-joint. The wound may not directly penetrate the articulation, in fact it may be an inch or more below it. Small or trivial wounds of the outer side of the elbow may eventually assume a serious aspect by communicating with the joint cavity. Open arthritis of the elbow is attended with few special signs apart from lameness and escape of synovia. The joint may be held slightly flexed, or it may be extended and apparently bearing weight while under treat ment. Except in cases due to bruising there is little swelling and seldom systemic disturbance, even when the wound is suppurating. Closed arthritis, which is a slowly progressive disease, is almost confined to very old horses which have done much work. Sometimes both elbow-joints arc affected. In trotting, the horse is stiff or lame, the step is shortened and the foot only slightly raised. The front action is crouching, and the lame limb attracts attention by showing a peculiar yielding or leaning movement—the knee not fully extended—when the foot comes to the ground. Dislocation of the elbow is nearly always complicated by rupture of the internal lateral ligament and the chief symptoms are deformity, swelling, and immobility.
Lameness of the forearm is most frequently due to wounding or bruising. Muscular strain is a possible cause, though few cases have been recorded. Punctured and contused wounds of the skin, fasciae, muscles or, near the knee, their tendon sheaths constitute the bulk of the cases of lameness of this region. The usual symptoms are stiffness or lameness, painful swelling extend ing beyond the wound or seat of injury, and, in infected cases, fever, loss of appetite, and other signs of constitutional disturbance. Horizontal wounds though shallow are often troublesome to heal. They tend to gape, and sutures seldom retain their position long enough to ensure closure of the wound without pus formation. Punctured wounds, especially in hunting horses, are always dangerous because frequently they lodge a foreign body, a thorn, bit of wire, or wood splinter, etc. Suppuration with extension of infection beneath the fasciae of the forearm is almost a constant complication. Counter openings for discharge of pus and disinfection are often necessary, and though generally recovery ensues, sometimes the limb is per manently disfigured. Lacerated and other wounds may heal enclosing a foreign body, unsuspected or overlooked, which leads to recurrent abscess formation and lameness. Such cases are sometimes attributed to fresh injury, the horse having worked since the first wound healed, but repeated suppuration within or close to the area of a cicatrized wound is nearly always due to retention of a foreign body. Contused tendon sheaths, though re maining closed throughout, are apt to assume a chronic character, prolonging lameness and producing permanent distension, which, though unsightly, is unlikely to hinder work.
Lameness of the Knee. The horse's knee corresponds to the wrist of man. It comprises three transverse joints and a number of vertical articulations. The two principal joints are the racliocarpal, formed between the radius and the upper range of small bones, and the intercarpal, formed between the upper and lower rows of carpal bones. These are hinge joints. The third transverse articulation formed between the lower range of carpal bones and the meta carpus is a simple gliding joint. The bones of the knee are held together by twenty-six liga ments, of which four—two lateral, the posterior and anterior capsular—are common to the whole carpus. The movements of the knee are almost confined to flexion and extension. In flexion very slight abduction, adduction, or even cir cumduction may be effected, but in extension these movements are prevented by the tension of the lateral ligaments. During flexion the posterior ligament is relaxed, the lateral liga ments are less rigid, and the anterior ligament is quite tense. The stretched condition of the anterior ligament in extreme flexion explains the frequency of open-joint as a complication of broken knee, the ligament being ruptured when the horse falls. Knee lameness may be due to contusion, wounding, wrenching, knee-splint, speedy cut, open or closed arthritis, fracture, ostitis, and thoroughpin. Wounds and bruises of the knee give little difficulty in diagnosis. Wrenched knee is always associated with painful swelling of the joint. Fracture of one of the small bones may not be discovered during life. Knee-splint may be confounded with arthritis or Cherry's disease. Thoroughpin which affects the synovial sheath of the carpal arch, through which run the flexor tendons, is easily recognized. In most painful conditions of the knee, flexion of the joint is restricted and the knee is raised very little. In acute carpitis the foot, in trotting, is thrown outwards, and the knee is very slightly bent. The step of the lame limb is lengthened, and the shoe is worn at the heels. Flexion of the knee is exceedingly painful in thoroughpin, in which the leg may be abducted and carried in forward movement. Knee lameness not due to visible injury may be diagnosed by watching the action of the limb and by careful palpation of the joint. Carpitis or synovitis of young horses is often associated with swelling and palpably increased heat of the affected knee."Capped knee,"which is a familiar example of contusion, varies greatly in degree. This injury may be contracted in the stable by the horse striking the knee against the manger, or on the street through the horse falling. Swelling, due to serous effusion, and sometimes blood extravasa tion, forms in front of the knee, and, depending on the severity of injury, the limb above and below the joint may be oedematous. In some cases the effusion accumulates beneath the skin, but often it lies between the fasciae and the annular ligament. At first the swelling fluctu ates, but later, owing to partial absorption of the fluid and to changes in the skin and fascim, it is firmer and more resistant. The knee is stiff, painful to manipulation, and lameness may be insignificant or prominent. Capped knee, though seldom interfering with the horse's usefulness, is unsightly and liable to result in permanent deformity of the front of the joint.
"Broken knee"is the term applied to wound ing of the front of the knee. It may be a simple abrasion of the skin, or a contused, lacerated, or other wound penetrating the skin and fascial layers, a tendon sheath, or even one of the carpal joints. Usually the injury is contracted by the horse coming down on his knees, but occasionally it may result from his failure in jumping to clear a wall or fence. At the first examination of a case the practitioner may have difficulty in forming an accurate estimate of the extent of injury. Wounds small at the surface may communicate with a joint, and large wounds exposing some of the small bones, though very alarming, may be far less serious. Synovia may escape from a tendon-sheath or a joint, but its source is of minor importance. Infection is the chief danger of broken knee. Superficial and contused wounds, even when complicated by sloughing or loss of tissue, usually heal more or less satisfactorily, though frequently they leave scars, indurated skin, and other blemishes which depreciate the market value of the horse. Deep or penetrating wounds often result in permanent stiffness of the knee, and a horse with a stiff knee is seldom workable. Open knee-joint or tendon-sheath is hopeful so long as the discharge is free of pus, and even the infected case, though less promising, is not always hopeless. Per sistent suppurative arthritis usually terminates in anchylosis of one of the principal joints of the knee, but frequently long before this result has been reached, and in consequence of emaciation, weakness, or exhaustion of the patient, slaughter is advisable.
Lameness of the Cannon.Splints, sore shins, strains of the flexor tendons, subcarpal and sus pensory ligaments, wounds, bruises, and frac tures are the chief causes of lameness of this region. The action of the lame limb, except in a few cases of splint, flexor strain, and fracture, affords little or no assistance in diagnosing the seat of lameness. Strain of the perforatus is accompanied by deformity of the posterior border of the shank, but in strain of the per forans, subcarpal and suspensory ligaments, though swelling may be seen, diagnosis can only be made by careful palpation of the tendon or ligament. In severe perforans or subcarpal strain the horse may"go on his toe"with the heel raised, but in many instances of moderate strain the tread of the foot is unaltered. In some cases of splint lameness the action of the limb is stilty and suggestive of severe injury or fracture.
Fetlock Lameness. The fetlock joint is formed by the large metacarpal or cannon, the long pastern, and sesamoid bones. It has ten ligaments arranged in two sets: four attaching the cannon to the pastern and sesamoids, and six binding the sesamoids to the pastern. The single synovial membrane is protected in front and at the sides by the anterior capsular and lateral ligaments, but behind it is free, forming a prolongation, which lies in front of the divisions of the suspensory ligament, and which when dilated constitutes articular windgall. The fet lock is supported in front by the extensor tendons of the foot and-pastern, behind by the flexor tendons which play over the sesamoid pulley, and the whole joint is surrounded by an aponeurosis which serves as a strong fibrous brace to the flexor tendons and sesamoids. The movements of the joint are flexion and exten sion, with very limited lateral motion during flexion. The flexibility of the fetlock is in fluenced by breeding and by the conformation of the limb. In horses with long, sloping pasterns, full extension is very similar to flexion, and in action the play of the joint is spring-like and pliant. The resiliency of the fetlock probably accounts for its comparative freedom from the effects of strain and concussion to which by its position it is much exposed.
Fetlock lameness may be due to strain of tendon, suspensory or other ligament, sesamoid itis, fracture, rupture, arthritis, bursitis, wounds and bruises (striking, cutting, or brushing). In most instances swelling or other surface altera tion attracts attention to the joint, and in cases of rupture, severe strain, or fracture the carriage of the fetlock in progression is suggestive if not diagnostic of the seat of lameness. Frequently the nature of the exciting cause can only be ascertained by palpation, and by resorting to passive movement of the joint. Knuckling is apt to mislead the examiner, for often this deformity has no immediate connection with the fetlock. Sinking of the fetlock may be due to rupture of the flexor tendons, the suspensory or the subcarpal ligament, or the above-men tioned aponeurosis. Rupture of the perforans below the point where it is joined by the sub carpal ligament is followed at once by more or less sinking of the fetlock and elevation of the toe. In rupture of either the suspensory or perforatus alone the fetlock sinks very little and the toe is not elevated, and in perforatus rupture the fetlock may be slightly overshot. When the fetlock rests on the ground both flexors and the suspensory have given way, and sometimes this rupture is complicated by fracture of the sesa moid bones. Obvious yielding of the fetlock accompanies rupture of the aponeurosis even when the flexors and suspensory are not im plicated.
Intermittent lameness with varying local surface heat is characteristic of inflamed sesa moid sheath, a condition which may be con founded with navicular disease. Ostitis of the sesamoid is nearly always associated with palpable enlargement of one or both bones and persistent slight lameness. Fetlock lameness increasing in degree from day to day is usually due to abscess formation or infected puncture of the joint. Painful (or painless) swelling in front of the fore fetlock is most often due to injury or chronic distension of the s vnovial bursa of the extensor pedis tendon. The bursa of the extensor suffraginis tendon is seldom affected. Windgalls, articular or tendinous, cause lame ness when bruised and also when their distension is large enough to hinder free movement of the joint. Tendinous windgall of the hind fetlock, in consequence of injury producing chronic inflammation, thickening and induration of the sheath, may cause permanent lameness with obstinate knuckling, the horse"going on the toe"as in acute bone-spavin disease.
Lameness of the Pastern and Foot.The pastern or coronary joint is formed by the os suffraginis and os corona, or the long and short pastern bones. These are held in position by three ligaments: two lateral, one on each side, and a posterior, which is represented by the glenoid fibro-cartilage and its attaching bands. Each lateral ligament after its attachment to the os corona is prolonged downwards to the corresponding extremity of the navicular bone to form the posterior lateral ligament of the coffin joint. The glenoid fibro-cartilage, which extends the articular surface of the os corona posteriorly, is attached to the os suffraginis by six short, fibrous bands. Its posterior surface is polished to facilitate the gliding of the per forans tendon, for which the fibro-cartilage serves as a fixed sesamoid. In front, the coronary joint is protected by the extensor pedis tendon, which is expanded and continuous by its borders with the lateral ligaments, and behind, it is supported by the' perforans. The perforatus tendon, be tween its attachment to the radial ligament at the knee and its fixed insertion on the os corona, plays the part of a suspensory or supporting ligament to the coronary joint. The joint is hinge-like, and its movements are flexion and extension, with slight lateral motion during flexion. The whole joint is enclosed by a single synovial membrane which forms on the posterior surface of the os suffraginis, a prolongation which occasionally is distended in racehorses.
The pedal or coffin joint, which is completely concealed by the hoof, is formed by the os corona or short pastern, os pedis or coffin bone, and the navicular. It is a hinge joint of very limited mobility. The bones are held together by five ligaments: four lateral, two on each side, and an interosseous, which binds the navi cular to the os pedis. This joint is strengthened by the extensor pedis and flexor pedis perforans tendons, which expand as they descend to their fixed insertions on the coffin bone, and by the lateral cartilages with their attachments to the bones. The posterior-lateral ligaments at their insertion on the navicular bone concur in forming a fibrous cushion which extends the gliding surface of the sesamoid for the perforans tendon. The single synovial membrane which encloses the joint forms between the lateral ligaments a small dilatation which is sometimes accidentally opened in the operation for necrosis of the lateral cartilage.
Lameness of the Pastern and Foot.While pastern lameness is almost confined to ringbone, fractures, wounds, bruises, and cracked heels, foot lameness arises from many different causes, of which the more common are corn, quittor, bruised coronet, sand-crack, seedy-toe, laminitis, navicular disease, canker, horn tumour, gathered nail, injuries contracted in shoeing, and defects of the hoof.
Pastern lameness, save in a few instances, is not easily distinguished from lameness of the foot. When the pastern presents a wound, bruise, or other obvious injury, lameness may be attributed provisionally to the visible lesion, though frequently another and more important cause may exist elsewhere in the same limb. Fissured or split pastern may be suspected from the history of the case, but until swelling and other local symptoms appear diagnosis may be uncertain. Lameness arising from ringbone may not be particularly different from lameness caused by a lesion existing immediately above or below the pastern. In chronic articular ring bone the gait of the affected limb is modified, the coronary joint is enlarged and fixed, and the shoe appears excessively worn at either its toe or heels. Cab-horse disease, a variety of ring bone, is always accompanied by enlargement of the inner head of the long pastern bone. Pyra midal disease or ringbone of the os pedis pro duces deformity of the hoof, the toe-wall presenting a ridge or convexity moulded on the outgrowth of the coffin bone, and in the trot the action of the foot resembles that of chronic laminitis, with which pyramidal disease may be confounded. In the hind foot, pyramidal disease may easily be mistaken for"buttress foot,"a condition resulting from fracture of the os pedis. Lameness of both fore feet due to corns may be mistaken for chronic navicular disease; but in the former, exercise induces no marked improvement in the horse's action, while in the latter, exercise either diminishes or tem porarily removes the lameness. When corns and navicular disease coexist, exercise has little or no influence on the horse's action, and more or less lameness persists in spite of successful treatment of the bruised heels. Chronic navi cular disease of both fore feet may sometimes be confidently diagnosed by watching the horse moving at different paces. In intermittent slight front lameness incipient navicular disease may be suspected, but diagnosis is always attended with difficulty, and frequently doubt remains after the use of a local anaesthetic has reduced the area of the exciting cause of lame ness to the foot. In all cases of obscure front lameness the form of the foot should be care fully considered and compared with that of the sound one. The fore feet may be odd or unequal in size, and though frequently the smaller foot is the seat of disease, the examiner should remember that the inequality may be congenital, or possibly the result of accident during foal hood temporarily preventing full use of the limb. Commencing seedy-toe can only be discovered after removal of the shoe. Extensive seedy-toe produces deformity of the hoof and alters the tread of the foot. The toe may be tilted at each step, a symptom which is also shown in painful toe sand-crack and horn tumour of the wall of the hoof. Lameness arising from un complicated quarter sand-crack has no peculiar feature, but in open or overlapping sand-crack with infection of the exposed laminae the tread of the foot is eased on the painful side. Acute laminitis of the fore feet can hardly be mistaken for any other cause of lameness, though dia gnosis may be hesitating at the onset of the attack. Chronic laminitis is usually associated with deformity of the hoof, particularly of the toe-wall and sole. This lameness may some times be diagnosed at a distance from the horse"going on his heels,"but as a rule close inspec tion of the feet is desirable. Canker may be discovered by its offensive smell. The advent of lameness or its aggravation in canker is often coincident with the beginning of curative treat ment. In many acutely painful conditions of the foot (suppurating toe sand- crack, abscess formation, fracture, bruised coronet, etc.) the limb is carried or very carefully used in pro gression. A horse may"go on the toe"in painful toe sand - crack of a hind foot. The degree of lameness arising from gathered nail depends on the position and depth of puncture or the structures penetrated. Infection of the wound always aggravates the lameness. Frac tured navicular bone, even when unaccompanied by external lesion, produces great lameness, and often the patient refuses to use the foot in standing or walking. A foreign body - splinter, wire, or thorn—which has entered the coffin joint from the coronet may give no external indi cation of its presence other than persistent severe lameness. In this and similar cases resort may be had with advantage to the X-rays, though it must be said that skiag,raphs of fractures without displacement and of inflamed joints are not very helpful in diagnosis.
Lameness of the or Hip.At the croup the pelvis on each side articulates with the spine, forming the sacroiliac joint, which has very limited movement, though probably its slight mobility assists in diminishing the effects of concussion. The hip-joint, formed by the pelvis and femur, is similar to the shoulder joint, but it has three ligaments and the globular head of the femur is closely embraced by the cup-like articular cavity of the pelvic bone. It is a ball-and-socket joint, and its movements are flexion and extension with abduction, adduc tion, and circumduction.
Lameness of the haunch or croup may result from casting a horse for operation or from the horse struggling when down in a stall or loose box. In draught horses it is often due to a heavy weight (scaffold pole, truss of hay, iron pipe or beam) falling from a height on the croup. The symptoms vary from stiffness of the hind-quarters to severe lameness with drooping of the pelvis and a straddling gait. There may be little or no swelling in the region of the sacroiliac joint, but usually the horse evinces great pain on palpation of the croup, which sinks under very light pressure. The action of one or both hind limbs may resemble that shown in partial motor paralysis and in fracture of the iliac brim. In five or six days after the accident atrophy of the muscles of the croup, extending to the loins, will be evident. Cases uncomplicated by fracture eventually recover, though difficulty in backing a load may remain for many months and the atrophied muscles may never regain their normal volume.
Hip lameness when not due to fracture of the pelvis is oftenest caused by bruising or wounding and only occasionally by strain, wrenching, or arthritis. Dislocation of the hip joint and lameness involving the teres ligament are extremely rare, but in towns, and mainly owing to horses falling on the streets, inflam mation of the bursa of the middle tendon of the gluteus maximus is not uncommon, and sometimes this lesion is associated with ostitis of the trochanter major of the femur. Rheu matic myositis of the gluteal or other muscles of the quarter may be met with at long intervals, but gluteal paralysis is seldom a primary cause of lameness.
Lameness of the hip, like that of the shoulder, is easily recognized, though frequently, and mainly owing to the thick muscular covering of this region, the nature of the exciting cause cannot be discovered. An acute observer may be baffled in diagnosing the seat of slight hip lameness. Fortunately, cases of slight hip lame ness often recover rapidly and sometimes before treatment has been applied. In severe hip lameness rectal exploration is generally advis able: it removes doubt when it does not confirm suspicion. Some authorities state that hip lameness may be distinguished by"a hop and a catch"in the movement of the lame limb, but this or a like peculiarity of action is more often connected with superficial injury to the stifle. In most cases of hip lameness the quarter on the lame side is carried high, the step is shortened, and the limb, more or less dragged, may be adducted or abducted, or even swung outwards. Movement of the hip in walking, trotting, and turning is notably restricted. In teres or hip-joint lameness the horse moves diagonally or away from the lame side, the limb is adducted, and in harness work the shaft next the sound side shows the effects of con stant contact with the limb. In bursitis the limb is abducted, the quarter elevated, and painful swelling may exist over the convexity of the trochanter major of the femur. Abduc tion of the limb is a feature of obturator para lysis, which, when arising from fracture, may be diagnosed by rectal exploration. Certain pelvic fractures with impaction or displacement of the fractured parts and consequent noticeable deformity of the quarter (angle of the haunch, tuber ischii, iliac and ischial shafts) may be located at the first inspection of the case, while others require careful examination of the pelvis internally as well as externally before the position and extent of the injury can be dis covered.
Lameness of the thigh is often referred to the quarter for the reason that the seat of the lesion may be very difficult to find. In some cases, however, the cause is obvious. Thigh lameness with marked abduction of the limb may be due to tumour formation, abscess, large scirrhous cord, acute hydrocele, orchitis or mammitis, and inflamed scrotal hernia. Other causes are paralysis, fractured femur, wounds and bruises of the muscles of the thigh. Crural paralysis may he a primary affection or it may be symp tomatic of hmo - albuminuria, and however arising, its principal symptom is loss of power in the extensor muscles of the stifle, which sinks at every attempt at extension in the same way as the elbow in radial paralysis. When connected with hmmo-albuminuria, crural para lysis always leads to atrophy of the affected muscles. Drooping of the thigh and stifle is also seen in fractured patella and external popliteal paralysis, conditions which hinder flexion of the hock while they favour flexion of the fetlock and dragging of the toe.
Stifle Lameness.The horse's stifle, which corresponds to the human knee, comprises two joints: one formed by the patella or knee-pan with the femoral trochlea, the other by the head of the tibia with the condyles of the femur. The first is a gliding joint, and in action the patella moves on the femoral trochlea, or with equal accuracy it may be said that the trochlea moves on the patella, which plays the part of a sesamoid bone. The patella, suspended by the extensor muscles of the stifle, is attached to the tibia by three strong fibrous cords and to the upper and lateral borders of the trochlea by the capsular ligament, which is strengthened laterally by two fibrous bands. It is also held in place by the tensor of the fascia of the thigh and by certain other muscular connections. The second, or femoro-tibial, is a hinge joint. It is peculiar in having interposed between the articular surfaces two crescent - shaped fibro cartilages which participate in its movements— flexion, extension, and rotation. This joint has a capsular and two strong lateral ligaments with two fibrous bands (interosseous ligaments) con necting the bones within the articulation, and it is furnished with two synovial membranes, which sometimes communicate with the single synovial membrane of the femoro-patellar joint —a fact of some importance in connection with the treatment of hydrops and of penetrating wounds of the stifle. The existence of a mucous bursa which lies on the upper half of the anterior surface of the patella should also be remembered in the diagnosis and treatment of stifle injuries.
Stifle lameness may be recognized by watching the horse's gait. The quarter on the lame side is carried nearly level or very slightly elevated when the foot comes to the ground. The step is shortened, and usually there is evident deformity of the front of the stifle. In frac tured patella the stifle droops, extension is defective, the fetlock is flexed, and the toe scrapes the ground. Wounds and bruises of the stifle nearly always implicate the patellar bursa, which when distended constitutes capped stifle — a very similar condition to ordinary capped hock. A blow without skin abrasion over the patella is often followed by severe lameness, and frequently in cases of trivial wounding or mild contusion, the degree of lame ness exhibited by the horse is much greater than the character of the injury would appear to justify. Deforming arthritis may affect -either joint of the stifle. In femoro-tibial disease the horse at first shows only slight intermittent lameness, with a tendency at every opportunity to ease the leg by semiflexing the stifle, hock, and fetlock, the foot resting on the toe with the heel raised. Later, lameness is continuous, and when standing the horse holds the foot raised from the ground, flexing the stifle, hock, and fetlock. The surface depression normally existing below the patella at the front of the joint is now effaced, the stifle appears' broader and more prominent, yet manipulation usually fails to discover enlargement or exos tosis of the femoral condyles or the tibial facets. In femoro-patellar disease, from the beginning lameness is constant and much more noticeable than in that just mentioned. At rest the horse' uses the limb to support weight, the extended stifle appears deformed, while enlargement of the borders of the trochlea and patella may be discovered by manipulation. Dropsy of the stifle usually affects the femoro-patellar joint of one or both limbs. Lameness may be slight, but in most cases the limb is dragged. Deformity of the patellar region produced by distension of the joint capsule attracts attention to the stifle. Luxation of the patella may be outwards or upwards on the femur. In upward luxation the limb is held extended with the stifle and hock rigid, and in movement the toe is elevated, with the heel in contact with the ground. In outward luxation the stifle is fixed, the limb projected backwards with the foot resting on the toe-wall. Horses with straight stifles and weak extensor muscles are particularly liable to recurrent out ward luxation of the patella, but in these the backward projection of the limb is limited and reduction of luxation is often spontaneouAly effected. In subluxation or momentary arrest of the patella on the femoral trochlea, flexion of the stifle, hock, and fetlock is suddenly interrupted, the limb is extended and slightly abducted, and in the effort following the pause, which seldom lasts many seconds, the patella moves, the hock is sharply flexed, the foot rising as in stringhalt. Subluxation has been called"straw-cramp."It frequently affects horses— often ponies—standing in loose-boxes, and the movement suggests muscular spasm. The same or a very closely allied condition may be seen in debilitated animals, worm-infested colts and fillies after a run on poor pasture, and in horses approaching convalescence from influenza and acute respiratory disease.
Lameness of the lower thigh or leg, excepting paralysis and so-called rupture of the tendinous flexor metatarsi, presents no peculiarity of action that is of much service in diagnosis. Wounds and bruises causing lameness are easily seen, and fracture of the tibia may be suspected when the wound or bruise is on the inner side of the lower third of the leg. In fracture, fre quently the wound appears trivial, with slight cedema extending above and below the point of injury. Displacement of the fractured parts does not take place for some time, and in many instances not at all. Lameness varies from stiffness or slight lameness to carrying the leg. The fracture may split the bone in two or three directions from the point of injury, or it may be limited to fissuring of its inner wall. Often the horse is kept at work until the leg gives way, a result which may be avoided by resting the horse—tied up or in slings—for three weeks after the accident. It has been supposed that the fascia which closely invests the bone hinders separation of the fractured parts, though more probably the true explanation of the delay may be found by assuming that the immediate effect of the blow or kick is a"star fracture"—that is, a centre corresponding to the point of im pact with fissures of varying length and depth radiating from it—and that when the horse is rested sufficiently to permit of union neither extension of the fracture nor its separation takes place.
The carriage of the limb in flexor metatarsi lameness is strongly suggestive of loss of power in the flexor of the hock. In progression the limb from the stifle downwards is lifted and advanced without hock flexion, and the un apposed tendo Achillis is lax enough to appear flaccid. External popliteal paralysis interferes with the action of the stifle, hock, and fetlock, and the tread of the foot. In forward move ment the limb is dragged, the front of the pastern and foot grazing the ground, but in backing the horse, the foot is used to support weight, the heels resting on the ground. Passive flexion of the hock is very difficult if not im possible.
Lameness of the Hock and Shank.Many lamenesses are connected with the horse's hock, which corresponds to the ankle in man. The bones are arranged in two rows: the upper of two (astragalus and os calcis), the lower of four bones (cuboid, scaphoid, and two cuneiform). They form with one another, and with the tibia above and metatarsus below, five articulations, of which the principal and most important in movement is that formed by the tibia and astragalus. It is a hinge joint; its movements are flexion and extension, and the two bones are held together by seven ligaments—three internal and two external lateral, with two capsular which close the joint in front and behind. The synovial membrane communicates with that of the joint immediately below the astragalus, and its distension constitutes the condition called bog spavin. The other or subsidiary joints of the hock have extremely limited motion, but the articulations of the lower bones with one another and with the metatarsus are important, because they are often implicated in bone spavin disease.
The common causes of hock lameness are bone spavin, sprained or wrenched hock, curb, synovitis, arthritis, wounds and bruises. Frac tures or dislocations of the bones and luxation of the perforatus tendon are extremely rare. The term spavin is often misunderstood. It has an evil reputation which horse-owners not infrequently apply to many different forms of hock disease. Bone spavin is an ostitis with a bony outgrowth ("jack or spavin") at the seat of disease. Occult spavin is an ostitis and ulcerative arthritis, terminating in fusion of the affected bones but producing no appreciable enlargement or bony outgrowth ("jack or spavin"). Chronic bog spavin is a painless distension of the anterior capsule of the true hock joint, and blood spavin—a harmless con dition—is a dilated or prominent vein which crosses the hock close to the seat of bone spavin.
Bog spavin and thoroughpin seldom cause lameness except when the distension is excessive or has been bruised. Very large bog spavin by hindering free movement of the hock joint may induce stiffness or even lameness, but in such case the cause is evident. In active bone spavin disease with enlargement the horse in trotting carries the quarter low on the lame side; at each step the hip appears to sink moment arily when the foot comes to the ground, the stride is shortened, the toe dragged, and there is restricted flexion of the hock. Lameness is most conspicuous when the horse leaves the stable after a rest. Usually while the horse is at exercise lameness diminishes or temporarily disappears, recurring after a brief rest. But in occult spavin and other forms of tarsal arthritis there is no remission of lameness, which on the contrary may be aggravated by exercising the horse. In bone-spavin lameness restricted hock flexion is not due to disease or implication of the principal joint, but to the painful effects of free movement and compression or concussion on the inflamed or spavined bones.
Sprained or wrenched hock is always accom panied by painful swelling or distension of the true hock joint, which is not flexed even in slow movement of the horse, and in trotting the limb is carried.
Curb is a prominence or limited thickening, arising from strain, of the calcaneo-metatarsal ligament, which binds the os calcis to the cuboid and external metatarsal bones. The lesion is visible, firm and fairly well defined in most cases, forming a bulge on the otherwise straight, posterior line of the hock. Small curb, and even large curb, frequently exists without lameness, though slight lameness may be noticeable for a day or two immediately after the accident. Diffused or extensive curb arising from severe or repeated strain may be attended with per sistent lameness which cannot be easily removed. The action of the lame limb has no distinguishing peculiarity, although in trotting the horse may go"on the toe"and in standing elevate the heel. Curb may be confused with"false curb"and with"curby hock."In some horses with well-formed limbs the head of the external metatarsal or splint bone is exceptionally large or prominent, the increase in size produc ing a nodular enlargement or"false curb." Similar enlargement of the head of both small metatarsal bones may be seen in"curby hock,"which can be readily recognized by observing the position of the head of the os calcis, which instead of being upright is inclined forwards, and by the unbroken curvature of the posterior border of the limb. Hind limbs of faulty conformation, and particularly sickle-shaped hocks, are said to be predisposed to curb, but in wear such limbs may never show this lesion, while straight hocks and those of excellent formation are often affected. The tendency to curb is favoured not only by conformation of limb but also by the work, age, and temperament of the horse. Nervous or excitable young animals and those of high courage or playful ness are the chief subjects of curb.
The lamenesses of the hind limb below the hock are similar to those of the fore limb below the knee, but of the many diseases which affect the fore cannon, pastern, and foot only a few are met with in the hind limb. Strain of the flexor perforans tendon or of its check ligament is common in draught horses. Lameness of the hind shank in aged horses is often due to splint which forms on the outer side of the upper third of the bone. In neither case is the action of the limb peculiar or of much assistance in dia gnosis. Injuries to the fetlock and foot are more common in the hind than in the fore limb, but navicular disease, sidebone, and corn are rarely found in the hind feet.
Defective action or lameness of one or both hind limbs, including paralysis, shivering, and stringhalt, arising from spinal lesions, nerve derangement, or vascular obstruction, will be described later (see pp. 725-35).
General Treatment of Lameness. The exciting causes of lameness vary greatly in nature and severity, and although each case should be treated according to its particular requirements, there are certain curative measures which can be applied more or less satisfactorily in all cases. Wounds and bruises causing lameness may be dealt with by the methods detailed under"Accidental Wounds and their Treatment"(pp.
559-95). After healing of a wound or bruise lameness may continue, owing to the effects of the injury (formation of adventitious fibrous tissue, or bony outgrowth) interfering with function, as the movement of a joint, the play of a tendon or ligament, or with muscular action. Acute or chronic inflammation, however arising, of bone, ligament, tendon, muscle, joint, nerve, or synovial membrane, is the predominant cause of lameness, and in most cases treatment must be directed to arresting or modifying the inflam matory process. The age of the patient, dura tion of lameness, the position and nature of the ' lesion or exciting cause, should be considered before treatment is commenced.
In all cases attention should be given to the horse's feet and shoes. Removal of one or all four shoes may be desirable, and in some cases the shoe must be removed to facilitate examina tion and treatment of the lame foot. But removal of shoes is not advisable in every case, even when the feet are sound, for in standing without shoes the hoofs are soon broken and the sensitive foot may be bruised. Weak, flat feet with thin heels should not be left unprotected for many days, and if the horse must rest for several weeks he should be re-shod with light, plain shoes of fair breadth of web, or with bar shoes. Lameness caused by corn, seedy-toe, or sand-crack usually requires immediate altera tion of the shoe. Lameness due to acute strain of perforans tendon or subcarpal ligament, spavin disease, curb, or wrenched fetlock. with constant elevation of the heel, is benefited by a thick-heeled, calkined, or even a patten-shoe. Raising the heels of the shoe affords relief by supporting the hinder part of the foot and easing tension of the flexor tendons. In perforatus strain a high-heeled shoe is not advisable, as it tends to induce knuckling at the fetlock. (See also"Surgical Shoeing,"pp. 1099-1106.) Rest is one of the most valuable aids to the successful treatment of lame horses. For many it is imperative, for the majority it is beneficial, and for all it is desirable though not always advisable. Lameness in foals, yearlings, and young stock generally, and especially when the nature of the cause is obscure, is often removed by rest alone. For lameness in growing animals, rest, prolonged rest in loose-box, straw-yard, or paddock, is often preferable to lotions, lini ments, or blisters, which frequently only irritate the wrong place and, even when correctly applied, have only a superficial and transient effect, while further applications may be hindered or prevented by the condition of the skin or by some unexpected accident or com plication. Impartially considered, this sort of treatment is without advantage, for apart from the period of skin irritation the patient has been actually resting. Older horses, animals which are amenable to handling and the necessary restraint, and which have reached maturity of structural development, may be given assistance when lame, but even those animals frequently regain soundness of action within a reasonable time under rest and without interference by treatment of the lame part. Further restric tion of movement in lameness can be obtained by slinging the horse, a practice that is less popular now than formerly even in the treat ment of fractures. Slinging a patient affected with severely painful lameness, as acute laminitis, cannot be commended, because it is more likely to aggravate than mitigate the animal's suffering. In certain lamenesses local rest can be obtained by resorting to splints, plaster or starch band ages, a charge, or a pitch plaster.
Warm fomentations are often beneficial in painful lameness, and in any case they are seldom harmful, but the employment of hot water in a satisfactory mariner is frequently attended with inconvenience. To succeed, warm fomentations should be frequently re peated at short intervals or continued for several hours, and afterwards the injured part should be swathed in flannel, blanket, spongio-piline, or other compress—wrung out of hot water— and covered with rubber sheeting to prevent evaporation and too rapid loss of heat. Hot fomentations, by dilating the vessels at the periphery of the injured part, relax the tissues, ease pain, and promote rest. They are specially indicated in cases of wrenched joint, severe contusion, and muscular sprain. When infec tion of the part is doubtful, a non-irritating antiseptic should be added to the water.
Poultices of bran and linseed meal, spent hops, oatmeal, pulped roots or other materials, though contra - indicated as applications to wounds, are still useful in diseases of the feet to cleanse and soften the horn prior to explora tion of the foot. Poultices, medicated or mixed with disinfectants or deodorants, may be em ployed in the early treatment of thrush and canker. Immersing the foot for a time in hot water is an excellent substitute for a poultice, but at best an inconvenient one. Compresses of flannel, layers of cotton-wool, or calico folded several times and thoroughly saturated with hot water may be used in lieu of poultices for some cases. When it is necessary, prior to further treatment, to soften and remove crusts or scurf and cleanse a part, as in some cases of cracked heels, a medicated compress or an oatmeal poultice will be found very effective. Anti septic compresses, hot or cold, are sometimes desirable after operations to limit consecutive cedema and to support the sutured wound.
Lotions and liniments are often employed in the early stages of lameness. Caution is re quired in applying liniments to inflamed parts, for often they are used at the wrong time when they aggravate the mischief they are intended to repress. Slight temporary lameness is often prolonged by the erroneous application of some domestic or vaunted"cure-all"liniment, which frequently by its irritant effects disguises the nature of the primary injury and retards pro gress towards recovery. But when employed intelligently liniments often render considerable service in the treatment of temporary lameness. Stimulating embrocations of turpentine, solu tion of ammonia and oil, of soap liniment, or of compound camphor liniment may be applied to the unbroken skin in certain cases of lame ness arising from slight bruising or strain of muscle, but care is necessary in applying oil of turpentine to the horse's skin, which appears to be especially susceptible to its action; the surface of application should not be extensive, or the horse may become very restless or un manageable.
Cold in the form of douching, spraying, or continuous irrigation with cold water, ice poul tice, or evaporating lotion is often valuable in the initial stage of inflamed tendon, joint, or muscle. After blistering, firing, or other severe treatment, douching the part with cold water for fifteen minutes two or three times a day removes congestion and swelling, contracts the skin vessels, braces the tissues and promotes recovery. Recent sprains are much benefited and readily prepared for more active measures by refrigerant lotions of methylated spirit and water, solution of ammonium chloride, lead acetate, or Epsom salt, or by shot compresses, or Leiter's tubes through which ice-cold water continuously runs.
Massage, kneading, or hand-rubbing, when properly carried out, is very useful after sub sidence of the more acute or painful local symptoms of tendon sprains. Hand-rubbing is often practised in limb cases and generally in a downward direction, but a better result would follow rubbing or kneading the injured part upwards or in the direction of the venous blood stream. Usually it is desirable, in order to induce effort in the masseur, to prescribe a bland oil to be well rubbed into the swollen joint or tendon. By this method it has been said that the effects of recent sprains of tendons have been completely removed and the lame horses made sound.
Pressure bandages have a very limited appli cation in the treatment of lameness. Carefully applied within a few hours of the occurrence of tendon sprain, they restrict swelling and exuda tion and promote resorption of extravasated blood. Pressure bandages consist of a thick layer of cotton-wool disposed evenly over the injured tendon and secured in position by a linen or, preferably, a rubber bandage. They should not be removed for several days unless they become displaced, in which event they should be immediately adjusted or reapplied. After ten to fifteen days they may be dis continued and replaced by bandages saturated with cold water or astringent lotion preparatory to further treatment of the part by blistering or firing.
Scarification or local bleeding is sometimes advantageous in the treatment of bruised coronet and other parts of the fore or hind limb. Many cases of bruising, particularly of joints, indicate early scarification as a useful remedy, but owing to the risk of infection of the punc tures discrimination is required in resorting to this method of relieving pain. In some cases a full dose of purgative medicine, acting as a derivative, may with advantage take the place of local bleeding.
Counter-irritation by blistering, setoning, or firing the skin over the injured part is often employed after the more acute local symptoms have disappeared. Although the mode of action of counter-irritants has not been satis factorily explained, experience of their effects tends to show that they are frequently indis pensable to the successful treatment of lame ness. By rest alone a lame horse may be restored to soundness of action, and he may continue sound or he may fall lame again on resuming work. In most cases of lameness the result is uncertain, and in order to secure if possible a useful recovery some form of counter irritation is generally necessary or advisable. But too much should not be expected from either blistering or firing; neither is a certain cure for every lameness, but conjoined they constitute the most effectual remedy for many cases of chronic lameness due to disease of bones or joints. Nothing can be gained by firing a sidebone or an established ringbone; the ossified lateral cartilage is beyond repair, and firing has no influence for good on the joint already fixed by anchylosis. Firing a splint, a spavin, or a ringbone in process of formation may and often does effect improvement by arresting the process, hastening its completion, or by consolidating the new growth already formed and diminishing its prominence. Blis tering alone, even when repeated at short intervals, is less effective than firing followed by blistering, though it does not blemish the skin as firing in lines is sure to do. Firing in points, the cautery penetrating the lesion, is more serviceable than line firing, which, while the inflammation continues, is said to have a bracing influence on the skin.
Setons, properly employed, maintain their irritant effects much longer than firing, and in certain cases they are preferable to other forms of counter-irritation, though they are often objected to on account of the pus-formation which attends their use.
Neurectomy, which has been described as the last resort of the baffled practitioner, is often quite useful in the treatment of chronic lame ness of the lower parts of the fore or hind limb after counter-irritation has failed as a remedy. Chronic lameness arising from navicular disease, ringbone, or exostosis of the fetlock can be removed by resection of nerves, and in suitable cases this operation should be performed with out hesitation or delay. As a rule, lameness which indicates the advisability of neurectomy is not removable by any other means. Although neurectomy is not free from risk of accident (sloughing of hoof, tendon rupture, fracture, etc.) as a consequence of the operation, the failures seldom exceed five per hundred, a pro portion which hardly amounts to a deterrent.
Tenotomy is a useful operation in selected cases of chronic knuckling at the fetlock, spavin disease, and continuous stringhalt, but the result cannot be foretold. Flexor tenotomy is only advisable when the horse-owner is willing to rest the animal long enough to permit of complete consolidation of the replacing fibrous tissue at the seat of section—a period of from six to nine months. Cunean tenotomy is a doubtful remedy for spavin lameness, though sometimes the result is fairly satisfactory. Peroneal tenotomy is always worth trying for the relief of well-marked stringhalt, and if it fail to remove the defect it is otherwise a harm less operation.
Lame horses should be suitably fed and clothed, and walking exercise should be pre scribed when desirable. Their diet should be simple and laxative. Lame horses should be allowed freedom to lie down so long as they can rise without assistance. J. M.