LAMENESS OF THE HORSE VETERINARY PRACTITIONERS' SERIES, NO. 1 TEXT

proportion of tissue that is composed of lymph vessels and glands, it is then obvious that inflammation of these structures should cause a painful affection of members, when so affected, and that marked lameness and, in some instances, general constitutional disturbance such as anorexia, hyperthermia and general circulatory disorder are to follow. Lymphangitis is most frequently occasioned by the introduction of septic material into the tissues; consequently, infectious lymphangitis is more frequently observed than the non-infectious type. Specific infectious forms of lymphangitis are seen in glanders and in strangles; infectious types of this disturbance are found in many instances where, initially, a localized or circumscribed infection has occurred--the contagium having been introduced by way of an injury. An example of this kind is to be seen in a wound perforating the tibial fascia, where the injury is inflicted by means of a horse being kicked by another animal shod with sharp shoe-calks. Cases of this kind invariably result in a septic lymphangitis, and frequently lymphadenitis also occurs, for the inguinal lymph glands are so situated that their becoming contaminated is almost certain. The trite phrase that "the tissues are bathed in lymph" should make clear the reason for the frequent occurrence of infectious lymphangitis and lymphadenitis. Foreign substances, bacteria and their products, inorganic material and in fact, anything that is introduced into the tissues, if soluble or miscible, will be taken up and conveyed by the afferent lymph vessels and disseminated throughout the system--hence the constitutional disturbances so frequently thus caused. A non-infectious type of lymphangitis is frequently seen in the heavy draft breeds of horses and in such cases one or both hind legs are involved--it is very seldom that the thoracic limbs become so affected. Law[3] refers to this ailment as "Acute Lymphangitis of Plethora in Horse." When one takes into consideration that these cases so frequently occur in heavy draft animals that are not worked regularly, that the pelvic limbs are the ones involved, and that the disorder often runs a short course (recovery often taking place within two or three days, with no treatment given other than a purge, circulatory stimulants and walking exercise) it is plausible to ascribe the condition to idiopathic factors. Admitting the frequency of non-infectious lymphangitis, the practitioner must not confuse this type with similar lymphatic inflammation occasioned by nail punctures of the foot. It is very embarrassing indeed to make a diagnosis of lymphangitis--expecting that the disturbance will terminate favorably and uneventually--and later to discover a sub-solar abscess caused by a nail prick in the region of the heel. Recurrent attacks of this disturbance cause hypertrophy of the lymph vessels and in some cases lymphangiectasis. In old subjects used for dissection or surgical purposes, it is very evident that in the ones which have suffered from chronic lymphangitis there exists an excessive amount of sub-facial connective tissue, making subcutaneous neurectomies quite difficult in some instances. A sequel of chronic lymphangitis is a condition known as elephantiasis. In such cases there occurs a hyperplasia of the skin and subcutaneous tissues, resulting in some instances, in the affected member attaining an enormous size. Sporadic cases of this kind are to be seen occasionally, and are apparently caused by repeated attacks of lymphangitis. The affection is not benefited by treatment, and while a horse's leg may become so heavy and cumbersome as to mechanically impede its gait, as well as to fatigue the subject when made to do service even at a slow pace, elephantiasis causes no constitutional derangement. The hind legs, in elephantiasis, are affected and a unilateral involvement is more often seen than a bilateral one. The legs may be enlarged from the extremity to the body, but ordinarily the affection does not extend higher than the hock or the mid-tibial region. A chronic, progressive, hyperplastic-degeneration exists in some cases and the subjects are in time rendered unserviceable because of the burden of getting about encumbered by the affected extremity. In other animals hyperplasia progresses for a time--until the parts become greatly enlarged and conditions apparently attain an immutable state. Nevertheless animals so affected may continue in service for years without being distressed. AFFECTIONS OF THE FEET. Lameness is very often due to affections of the feet, and in all foot diseases probably the most constant cause is injury inflicted in some manner. Resultant from injury, there frequently develops complications and the one most often seen is infection. Because of the fact that the feet are constantly exposed to germ-laden soil and filth, if not actually bathed in such infectious materials, it naturally follows that septic infection of some part of the feet must be of frequent occurrence. Subsequent to being obliged to stand in mud and other damp or wet media, exposure to desiccating influences such as stabling upon dry floors, or at service on hot and dry road surfaces causes the insensitive parts of the feet to become dry, hard and brittle. This favors "checking" of the protecting structures and it frequently results in the formation of large fissures which expose the underlying sensitive parts of the feet and lameness is the inevitable outcome. The function of the feet--bearing the weight of the animal at all times when the subject is not recumbent, and in addition to this, the increased strain put upon them at heavy draft work, together with the concussion and buffeting occasioned by locomotion, make the feet susceptible to frequent affections of various kinds. Being almost completely encased by a somewhat inexpansible and insensitive wall and sole, renders the foot subject to pathologic changes peculiar to itself. The very nature of the structure of the foot together with the function of the sensitive lamina is sufficient cause for an affection unlike that seen involving other tissues--laminitis. An exhaustive consideration of foot affections is a study in itself and one that comes within the realm of pathologic shoeing; nevertheless, a practical knowledge of diseases of the foot is indispensable in the diagnosis of lameness wherein the foot may be at fault. The peculiar nature of foot affections renders them difficult of classification on any sort of basis that is helpful in the consideration of this subject. Injuries are the most constant cause of foot lameness, yet one must admit that there results complications because of infection in most instances; and that in some cases the injury is slight--just enough to permit the introduction of vulnerant organisms into the tissues. Therefore, one might well classify affections of the feet as infectious and non-infectious. There can be grouped in the class of infectious affections such conditions as nail pricks, calk wounds and canker. In the class of non-infectious affections one may consider conditions such as laminitis, strain and fractures. FOOTNOTES: [Footnote 1: A System of Veterinary Medicine by E. Wallis Hoare, F.R.C.V.S., Vol. I, page 519.] [Footnote 2: Ibid, page 807.] [Footnote 3: Vol. I, page 534, Veterinary Medicine, by James Law, F.R.C.V.S.] SECTION II. DIAGNOSTIC PRINCIPLES. _To observe attentively is to remember distinctly._--_Poe_. Before treatment is administered in constitutional disturbances resulting in disease, _cause_ is logically sought; so, in order to handle effectively any case of lameness, it is necessary first to discover the source of the trouble and contributing conditions affecting the structures. Hence, diagnostic ability is the prime requisite; and a thorough knowledge of pathologic anatomy or of surgical technic is of little value if this knowledge is not applied with the insight of the trained diagnostician. The cruel and unnecessary methods employed by those untrained for diagnostics, cannot be too vigorously condemned. For instance, the application of an active and depilating vesicant upon a large area on the gluteal or crural region, in a case where the practitioner "guesses" the condition to be one of "hip lameness," constitutes an exposition of gross ignorance, and at once stamps the perpetrator as a crude bungler without scientific insight whose works are no credit to his profession. How much better it would be, if the practitioner does not see fit to call in a competent consultant, to prescribe a suitable agent to be given internally, and to recommend complete rest for the subject. In establishing a diagnosis in such cases, the student or practitioner seldom has recourse to laboratory assistance, and his work is done by means of physical examination; therefore, a thorough knowledge and a clear conception of the physiology of locomotion are essential. Memorizing nosological facts without an understanding of underlying principles is of no more practical benefit for qualification as a diagnostician in cases of lameness, than is the employment of similar methods in the study of theory and practice. A knowledge of the dosage of drugs does not in itself qualify one as being competent to administer such therapeutic agents to a proper effect. How much is a practitioner benefited by the knowledge that a high temperature is usually present in septic intoxication, if he is not possessed of a scientific understanding of anatomy, physiology, bacteriology and pathology, as well as the principles of clinical diagnosis? In order to determine the reasons for certain symptoms manifested by the subject, an analysis of these symptoms is the proper method of procedure, insofar as this is possible. If one may reason that an animal assumes a certain position while at rest to allow relaxation of an inflamed tendon or ligament, such a fact enables the diagnostician to recall that this is indicative of some specific ailment. In acute tendinitis, the subject while at rest, maintains the affected member in volar flexion because this position permits relaxation of the inhibitory apparatus, including the inflamed tendon. Likewise, the various abnormal positions assumed,--adduction, abduction, undue flexion or pointing--have their own significance and are taken into account by the trained diagnostician in the course of an examination. In the examination of lame subjects, where the cause is not obvious, a systematic method of diagnosis is pursued even by the most expert practitioners. In all obscure cases of lameness a methodical and thoroughly practical examination of the animal according to an established procedure is necessary to determine the nature and source of the affliction. Anamnesis. The first thing to be given consideration in diagnosis is the fact that related history of the case is not always dependable, because of lack of accurate observation or wilful deceit on the part of the owner or attendant. The successful veterinarian soon acquires the faculty of obtaining information in a manner best adapted to his client,--either by direct interrogation or by subtle means of suggestion, and in this way he draws out evaded facts essential to his diagnosis. In time he learns to make allowance for misstatements made to shield the owner or driver and to hide the facts of apparent neglect or abuse that the subject may have experienced. A suppurating cartilaginous quittor, complicated by the presence of a large amount of hyperplastic tissue, cannot be successfully represented to be an acute and recently developed affection, where a trained practitioner is left to judge the validity of the statement. In complicated conditions, where there is evident a chronic disturbance which could not be conceived as sufficient cause for a marked manifestation of lameness, accurate history of the case may be of great aid in arriving at a diagnosis. An aged animal, having recently become very lame, showing a small exostosis on the first phalanx, and with the history given that the osseous deposit was of long standing, should at once lead the veterinarian to seek the source of trouble elsewhere. Visual Examination. As in all diagnostic work, a careful visual examination of the subject should be made before it is approached. The novice is given to hasty examination by palpation, not realizing how much may be revealed by a careful scrutiny of the subject. In this way he is led to erroneous conclusions which the skilled diagnostician has learned from experience to avoid. _Too much emphasis cannot be placed on the importance of making a thoughtful visual examination in every instance before the subject is approached._ In this examination, type, conformation and temperament are taken into account at once, for each of these qualities is in itself, a determining factor in predisposing a subject to certain ailments or inherent attributes, which may exert a favorable or unfavorable influence upon existing conditions and thus make recovery probable or otherwise. Draft animals are less likely to be permanently incapacitated as a result of tendinitis, than are thoroughbreds. Likewise, one would not expect to find this affection present in heavy harness horses as frequently as in light harness animals. Mal-formation of a part, or an asymmetrical development of the body as a whole, may render an animal susceptible to certain affections which cause lameness. A "tied in" hock predisposes the subject to curb, and an animal having powerful and well-developed hips and imperfectly formed hocks, will, if subjected to heavy work, be a favorable subject for bone spavin. The matter of temperament cannot be disregarded in diagnosis, for in some instances, it is the chief determining factor which materially influences the outcome of the case. A nervous, excitable animal, that is kept at hard work, may, under some conditions, be expected to experience disturbances which more lethargic subjects escape. Nervous subjects, it is known, are more prone to azoturia than are those of lymphatic temperament. Furthermore, the lymphatic subject often recovers from certain bone fractures which are successfully treated only when the animal is sufficiently resigned by nature to remain confined in a sling for weeks without resistance. The physiognomy of a subject is often indicative of the gravity of its condition. The facial expression of an animal suffering the throes of tetanus, azoturia, or acute synovitis, is readily recognized by the experienced eye, and upon physiognomy alone, in many instances, may the opinions regarding prognosis be based. Particularly is this true where death is a matter of minutes, or at most is only a few hours distant. Due allowance should be made for restiveness manifested by some more nervous animals when the surroundings are strange and unusual. In such instances, even pathognomic symptoms may be masked to the extent that little, if any, sign of pain or malaise is evinced. In these cases the subject should be given sufficient time to adjust itself to the new environment, or it should be removed to a more suitable place for examination. Animals quickly detect the note of friendly reassurance in the human voice and can very often be calmed by being spoken to. By visual examination one may detect the presence of various swellings or enlargements, such as characterize bruises and strains of tendons where inflammation is acute. Inflammation of the plantar (calcaneocuboid) ligament in curb is readily detected when the affected member is viewed in profile. Spavin, ringbone, splints, quittor and many other anomalous conditions may all be observed from certain proper angles. The fact that the skins of most animals are pigmented and covered with hair, precludes the easy detection of erythema by visual examination, consequently this indicator of possible inflammation is not often made use of in the examination of equine subjects. Attitude of the Subject. The position assumed while the subject is in repose, is often characteristic of certain affections and this, of course, is noted at once. The manner in which the weight is borne by the animal at rest, should attract the attention of the diagnostician and if the attitude of the subject is abnormal or peculiar, the examiner tries to determine the reason for it. If weight-bearing causes symptoms of pain, the affected member will invariably be favored and held in some one of a number of positions. The foot may contact the ground squarely and yet the leg may remain relaxed and free from pressure; volar flexion, in such cases, is indicative of inflammation of a part of the flexor apparatus. If the condition be very painful, position of the afflicted member is frequently shifted, but in all cases where the pain is not so keenly felt, the inflamed member is held in a state of relaxation. There is need then, for a knowledge of anatomy and certain principles in physics to enable the observer to determine just which structures are purposely eased in this manner. Where palpation of parts is possible, one does not need to depend on visual examination alone, and it is always wise to take into consideration every factor that may influence conditions. Manipulation or palpation of the structures thought to be involved, should not be resorted to until a careful and thorough observation of the subject has revealed all that it can reveal to the diagnostician. In all conditions where extreme pain is manifested by the constant desire of the animal to keep its foot in motion off the ground, examination should be made for local cause. This is seen in certain septic inflammations of the feet such as those caused by nail punctures invading the navicular joint, or in newly made wounds where nerves have been divided and the proximal end of such a nerve is exposed to pressure or irritation. "Pointing" affords a comfortable position in some cases of navicular disease, and in a unilateral affection, one may observe the subject bearing weight with one sound member, while the affected foot is planted well ahead of the sound one. In a bilateral involvement of this kind, weight may be frequently shifted from one foot to the other, or in chronic cases, where no marked pain is experienced, the subject stands squarely upon both front feet and no peculiar shifting of weight or pointing is evident. In some cases of hip or shoulder involvement, complete relaxation of all parts of the affected member may be noticed. In brachial paralysis, the pectoral member is held limply; if the patient is made to move, it is evident there is lack of innervation to the afflicted part. In some cases where contusion has caused acute inflammation of the member, the subject instinctively tries to keep it inactive to relieve the pain which movement occasions. Where there is an active and painful inflammation of the prescapular lymph glands and contiguous structures, in some cases of "levator-humeri abscess," the scapulohumeral joint is extended. This is brought about by flexion of the elbow and carpal joints. There are some cases of bi-lateral affections which occasion such pain during weight-bearing that the subject shifts its weight from one affected leg to the other; an example of this condition may be observed in any acute case of gonitis which affects both patellar regions, making it equally painful to bear the weight on either member. A peculiar characteristic position is assumed in acute laminitis of the fore feet. In such instances, the hind feet are brought forward under the body sufficiently to relieve the front feet of the weight, insofar as is possible by the abnormal position taken in cases of acute laminitis. So in each position that is abnormal to any degree, assumed by a suffering animal, there may be deduced, the fact that the subject is