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Development of an Approach to Lameness Examination in Cattle
Symposium on Bovine Lameness and Orthopedics
Development of an Approach to Lameness Examination in Cattle P.R. Greenough, F.R.C.VS. *
Contemporary literature contains a wealth of information regarding the etiology and pathogenesis of conditions affecting the limbs and particularly the digital region of cattle. The analytical process by which a diagnosis is reached is rather vague, however. Nevertheless, a subjective or "anecdotal" approach is an anathema to the scientific mind,. Despite this, it is with the "art" of diagnosis that this article will be concerned. Why is it that when the young, inexperienced veterinarian is presented with a cow that is lame but demonstrates no obvious lesion, he or she experiences a sense of panic and lack of direction? An experienced clinician presented with the same case will instinctively explore several possibilities. This instinctive reaction is a subconscious process through which complex variables are analyzed. In the pages that follow, this analytical process will be examined in order to develop protocols and to approach the diagnosis of the causes of lameness with objectivity. There is no secret formula for diagnosing the causes of lameness. The lesions most likely to be encountered will vary depending on the climate, environment, nutrition, age, breed, and sex of the animal.
OBSERVATION AND HISTORY In the writer's opinion, the method in which one initiates the examination of a lame animal may be summarized in the following words: "Observe the observable and then confirm that which you think that you have observed as being a correct observation."
Observation is a quiet process in which an attempt is made to "palpate the limbs with the eyes." All of the limbs should be visually examined from every angle. Although the owner may indicate the affected limb, there may *Professor, Department of Veterinary Anesthesiology, Radiology, and Surgery, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
Veterinary Clinics of North America: Food Animal Practice-Vol. 1, No. 1, March 1985
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be clinical signs in all the limbs (laminitis, for example) that may suggest a common underlying cause. Similarly, a lesion might be found in the digital region of one limb that could be associated with the etiology of a different lesion in the lame limb (interdigital dermatitis, for example). The objective of observation is to gain information on the most probable "seat of lameness." The "seat" is a region or zone in which the lesion causing the lameness is located. Observation must never preclude a thorough physical examination however obvious the lesion may be. In the author's opinion, inadequate evaluation of the "obvious" cases of foot rot is a major factor in the development of many serious complicated conditions of the digital region. The period of observation provides an opportunity for the clinician to take the animal's history. Because the clinician is busily examining the animal with his eyes, a confrontational interrogation of the owner is avoided. As a result, the history-taking process becomes more productive. It is often quite crucial to obtain very accurate information regarding the duration of the lameness and the rate of increase in the severity of the clinical signs. Therefore, it would be useful to combine the two procedures-that is, remark on your observations and invite the owner to comment from his knowledge and perspective of the history of the animal. Observations may be grouped in some of the following categories: 1. Conformation. Conformation, for the purpose of this discussion, is the shape of the animal that is dictated by inherited characteristics of the skeleton or hooves. Acquired changes in shape resulting from disease, environmental conditions, or nutritional extremes should be considered as separate entities rather than as part of conformation. In some cases, the influences that bring about "acquired changes" in the animal's shape may be associated with changes in posture or stance. As a general rule, unless the acquired changes have been present for a significant period of time, they are usually reversible. Straight limbs (the dorsal angle of the tarsus exceeds 150°) is the most frequently encountered conformational abnormalities. Arthritis of the hip and stifle and damage to one or other of the menisci of the femorotibial articulation or their associated ligaments are commonly encountered in cattle with straight hind limbs. 1· 4 Generally speaking, the older the animal the greater the probability of joint pathology. Excessive fatness in young animals with straight limbs can suggest several possibilities. In the clinic at the Western College ofVeterinary Medicine, partial or total avulsion of the hoof has been seen in a number of young bulls of the exotic breeds. This possibility seems greater in animals with small hooves. If the ani1nal is overweight, it will also suggest the possibility of a high level of concentrate feeding; therefore, in a later examination of the hooves, hemorrhages of the wall and sole may indicate the presence of subclinical laminitis. 2. Engorgement of the Superficial Veins of the Limb. The following vessels are of particular significance: the cranial tributary of the lateral saphenous vein, the dorsal common digital vein, and the lateral digital vein. These veins appear extremely prominent and, when palpated, feel very turgid in cattle that are affected with acute laminitis. 2
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3. Muscular Atrophy. Atrophy of the muscles can occur in any region in which physical activity has been restricted, usually because movement is painful. Atrophic muscle groups tnu~t be viewed from several angles, and comparisons should be made with similar structures on the contralateral limb. Palpation of the musculature can also be useful in making comparisons. As muscles atrophy, certain bony prominences become more obvious; it is important not to be misled into thinking that bony changes have occurred if this is not the case. A good example is the prominence of the great trochanter when atrophy of the gluteobiceps has occurred. A prominence of the trochanter does not indicate any abnormality in that particular structure; in some instances, however, the disuse of this muscle group may be associated with pain in the hip. 4. Stance and Posture. The manner in which an animal holds its limb must not be confused with conformational abnormality. For example, cattle that are affected with acute laminitis adopt a stance comparable to that seen in similarly affected horses. Cattle affected with pododermatitis circumscripta will invariably stand "camped back." An animal that is showing tarsal supination (cow-hocked stance) is likely to have a build-up of horn beneath the heels of the lateral claws. 3 Holding digits extended may indicate a lesion in the toe of the hoof and may be confused with flexion associated with nerve paralysis (peroneal or tibial). If the animal holds his extremity in such a way that it is touching the ground lightly, there is a strong possibility that pus might be present between the distal phalanx and hoof wall or that the distal phalanx may be fractured. 5. The Hoof Animals of less than 2 years of age should have normally shaped hooves and well-developed bulbs. The periople should be clearly visible. Hooves of this type are likely to be resistant to the chronic degenerative conditions more commonly observed in older animals; therefore, when lameness is encountered in cattle with good hooves, the condition is likely to be associated with trauma. If the pain is severe, the presence of a penetrating foreign body may be considered. On the other hand, if the hoof appears low at the heel and the animal has been confined on concrete, bruising of the sole is a possible etiology. Older animals-particularly those in a milking herd on concrete or housed under unhygienic conditions-are likely to have hooves of soft texture. The hooves may be flattened, the dorsal surface may be concave, the perioplic sheen may be diminished, and ridges may be present in the texture of the hoof. In such animals, heel erosions, avulsion of the white line, and related conditions can be suspected. 6. Swellings. Although usually obvious, swellings can be misleading. Hematomas over soft-tissue areas tnay be unsightly but are not necessarily the cause of lameness. Swellings may be an indicator of cellulitis and not necessarily the primary cause of the lameness. Swellings in the digital region are usually indicators of pathology that can be misinterpreted. A bilateral swelling of the region with separation of the digits is the most commonly encountered lesion that can immediately suggest interdigital necrobacillosis (foot rot). However, this is a condition that probably will have been treated by the owner. If the animal has been treated correctly for even a few days and such a lesion persists, it is likely that the lesion is associated not with foot rot but a serious complication of
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that condition. A painful erythetnatous swelling of the coronary band in the dorsal region may indicate a septic vertical fissure or an early septic invasion of the distal interphalangeal joint. A similar swelling of the abaxial coronary band may be associated with a lesion originating in the white line and would require careful exploration to eliminate a diagnosis involving the bursa of the distal sesamoid (navicular bursa). A unilateral swelling of one heel is a sure indication of a retroarticular abscess. If one toe is extended in respect to the other, in all probability the deep flexor has avulsed from the distal phalanx. If the coronary band is generally swollen but erythema and pain are minimal, it is likely that infection has been present and that the joint is ankylosing owing to the presence of periarticular exostoses. None of the preceding observations, in themselves, are necessarily diagnostic. Nevertheless, they are all observable at some distance from the animal and serve as a basis on which the animal should be examined. Of course, there are a host of other observable features such as those associated with bone fractures, tendon ruptures, or skin laceration. One is sornetimes misled into believing that because 80 per cent of the cases of lameness are located in the digital region, a high rate of success can be obtained by an immediate examination of the hoof. A protocol for systematic observation will assist the clinician in making an accurate diagnosis.
LAMENESS: THE CLINICAL SIGN Pathokinesthetic alterations in movements are those that are associated with disease and provide us with the clinical sign that we refer to as lameness. The term "lameness" signifies some alteration in the quality of movement during progression but must be extended to include the quali.ty of stance. The qualities of lameness are evaluated subjectively by the clinician on the basis of his or her experience rather than on any predetermined system. Historically, the terms "swinging" and "supporting" leg lameness have crept into the literature. These terms relate to pain during movement and pain during weight-bearing, respectively, but they are of very little help to the bovine clinician who must appreciate the significance of alterations in the quality of locomotion. For diagnostic purposes, it may be useful to suggest that lameness can be categorized in one or more of the following groups: 1. 2. 3. 4.
Aberrations of stride Pain-dominated lameness Specific lameness Characteristic stance
Aberrations of Stride A stride is a full cycle of limb motion that begins with weight-bearing (the stance phase), is followed by propulsion (posterior swing phase), and is continued into an anterior swing phase before there is a return to the stance phase. Each of the phases (stance and anterior and posterior swing phases) can be objectively measured in respect to duration; the swing phases can also be measured in respect to length. Restriction of either swing phase is
DEVELOPMENT OF AN APPROACH TO LAMENESS EXAMINATION IN CATTLE
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likely to indicate functional deficiency in the systems involving movement of the proximal limb. A component of pain is usually involved in aberrations of stride; therefore, the more intense the pain the shorter the stride is likely to be. This evaluation of stride is carried out from the side of the animal as it passes the observer. This is a subjective evaluation that is of most practical value after the digital region has been definitely eliminated as the seat of lameness. In practice, it is useful to make an evaluation of movement before and after the detailed examination of the digital region, because any examination of the digital region will involve either tranquilization of the animal or manipulative procedures that might alter the patterns of the stride. For example, the initial examination of the stride might suggest that there is a shorter anterior phase; after manipulation, however, the whole stride might be shortened. The procedure for evaluating the stride cannot be developed as a diagnostic recipe. With experience, however, it may be possible to develop a logical procedure for analyzing the signs observed, which will enable the clinician to make a more critical examination of a particular region of the proximal limb.
Pain-Dominated Lameness In all probability, more than 90 per cent of lameness will be associated with pain rather than with a functional disorder. The degree of pain experienced will be variable; as the pain increases in intensity, the animal will attempt to modify weight-bearing in order to minimize its suffering. The pain will cause the animal to shorten its stride and to place the hooves very carefully on the bearing surface and then remove the limb from the weightbearing position as soon as possible. This will give the appearance that the animal is snatching its limb from the ground. In the most intense form of painful lameness, the animal will "nurse" the limb. There may be an associated state of anxiety, loss of milk, inappetence, and muscular wastage. The term "pain-dominated lameness," therefore, is an arbitrary one, but it is nevertheless useful because pain that is intense enough to cause the animal to make a conscious effort to seek relief provides the observer with useful indications of the most likely seat of lameness. The most intense pain is associated with fractures or, more commonly, with fluid that is exerting pressure on the sensitive laminae or the corium of the sole. The presence of pus between the hoof wall and distal phalanx is extremely painful, and the pain will usually increase in intensity over a period of hours or days; the onset of lameness caused by a fracture or trauma would be extremely rapid, however.
Specific Lameness A specific lameness is one that produces a highly characteristic alteration in the quality of progression, and the diagnosis is based mainly on observations. However, because a possibility for error does exist, it is recommended that confirmation be made wherever possible by supplementary tests and the elimination of other causes of lamenesses, particularly those that may be associated with the hoof. Spastic paresis produces a "specific" lameness. However, some animals
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with very straight hindlimbs may have a comparable stride. In straightlegged cattle, changes in the joints may occur as the animal gets older; therefore, difficulty in locomotion may become progressive. Upward luxation of the hip will cause the hock to be rotated medially on the affected limb, which the animal will tend to drag. Manipulation of the limb would confirm this diagnosis. Specific nerve paralyses will cause muscular weakness in certain muscle groups that produce characteristic signs of peripheral nerve paralysis, although a definitive diagnosis may be impossible without careful neurologic testing. Luxation of the patella produces another specific lameness that may require manipulative examination in order to confirm the true nature of the condition. Characteristic Stance A characteristic stance is an aid to diagnosis rather than a specific diagnostic sign. For example, a dropped hock will probably be associated with damage to the tendon or muscle of gastrocnemius. However, nerve paralysis can produce the same general effect. Sometimes a characteristic stance will indicate the probable seat of lameness. For example a crossed-legged stance has been observed in some animals with fractured distal phalanx and in others with laminitis. Cattle with very acute laminitis will adopt the various stances characteristic of laminitis in horses. Cattle that stand with both limbs well back quite frequently have painful lesions in the posterior aspect of the sole. Sole ulceration quite often will produce this stance. As has been mentioned earlier, a cow standing with both hocks turned inwards would suggest an abnormal growth of horn beneath the lateral claws. Although not characteristic of any particular pain-producing lesion, it is likely that there are some inflammatory changes in the corium of the sole.
PHYSICAL EXAMINATION OF THE DIGITAL REGION Pain Reflex Cattle are relatively more reactive to manipulation and pressure on the hoof than are horses. Unless the operator is extremely careful, a response may be elicited that is not significant from the diagnostic point of view. Digital pressure around the entire coronary band is a mandatory procedure. Hoof testers may be applied, but one must take care to ensure that the distal interphalangeal joint is not subjected to excessive movement and that so-called sensitivity is specific to one claw rather than reflecting .. discomfort." Manipulation of the distal interphalangeal joint can be painful when this joint is associated with some disease process; unfortunately, this form of manipulation often will be resented by an animal even in the absence of pain.
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EXAMINATION OF THE SOLE A hoof that has good conformation but has a Hat sole will have been subjected to excessive wear and will be associated with the animal having borne its weight on the entire sole rather than on the abaxial wall. Usually, the sole will show traumatic blemishes, most of which are of no significance at all. Each blemish must be examined individually, however, because in the case of the Hat sole some form of trauma to the sole is the most likely cause of lameness. It is counterproductive to pare the entire sole, because this procedure will weaken the mechanical characteristics of an already worn structure. The Hat sole indicates that the hoof is at high risk for traumatic injury. However, such hooves are likely to be more healthy than those that are irregular, rough, and flattened. Rough and irregular soles will require evaluation on the basis that several different related or unrelated lesions are likely to be present. Paring the sole to remove superfluous horn should be the first stage in this examination. The following factors would need to be evaluated: 1. The status of the white line at the junction of the sole and heel. Avulsion of the white line is a progressive lesion that can be associated with a retroarticular abscess, navicular bursitis, or abscessation at the coronet. 2. Erosion of the heels may be associated with interdigital dermatitis, in which case an evaluation of the herd status in respect to this condition might be appropriate. This would be particularly appropriate if the incidence of lameness is generally higher than would be expected. 3. Pododermatitis circumscripta may be present. The majority of sole ulcers will be mature and will have penetrated the entire sole. However, some of the lesions encountered in their early stages will be discovered lying beneath the level of intact sole horn. 4. Subclinical laminitis may be present. It may be suggested by a yellowish coloration of the horn, hemorrhages in the horn, or avulsion of the horn at the apex of the sole. Again, this is likely to have implications for herd care.
NERVE BLOCKS Regional nerve blocks are just as valuable in the cow as they are in the horse. Usually, however, the seat of lameness is located much more easily in cattle than it is horses. For this reason, nerve blocks are used less often in the diagnosis of bovine lameness. Most workers seem to experience difficulty in providing an adequate degree of desensitization of the forelimb using a regional nerve block and resort to regional intravenous perfusion for surgical procedures. Regional intravenous perfusion is an inappropriate procedure for the diagnosis of lameness. A ring nerve block of the entire digital region is the only reliable method by which the extremity can be completely desensitized. In the hindlimb, regional nerve blocking is much more specific. The technique can proceed in three stages.
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The Lateral Block A subcutaneous track of local anesthetic should be laid horizontal with the bearing surface on the abaxial surface of the limb at the level of the "dew claws." The needle would be inserted 2 em dorsal (anterior) to the dew claw and should penetrate 8 to 9 em dorsally (anteriorly). As the needle is withdrawn, a track of up to 5 ml of 2 per cent lidocaine would be injected. This block will desensitize most of the abaxial region of the digit. The Axial Block Two injections should be given. The first should be given in the midline of the dorsal surface and the other in the midline on the plantar surface. The point on the dorsal surface will be in the midline immediately below the metatarsophalangeal joint. The injection on the plantar surface will be immediately below the tough plantar ligament, which occurs at the level of the dew claws. Each injection should be to a depth of approximately 5 em, and up to 5 ml of anesthetic should be deposited in each site as the needle is withdrawn. The axial nerve block will desensitize the cleft and a very significant portion of each digit. The Medial Block This block is placed in exactly the same 1nanner as the lateral block and, if used in conjunction with the axial and lateral block, will completely anesthetize the entire digital region. The animal may be evaluated for changes in the quantity of lameness after each block has been given and before one proceeds to the next stage of blocking.
SUMMARY In the preceding pages, the various components of an examination have been described. Each clinician will formulate his own method of utilizing these components. The following are suggested steps in a practical approach to the diagnosis of lameness. 1. Evaluate the conditions under which restraint of the animal is possible (corral, free stall, stanchion barn). Assess the temperament, physical strength, and general amenability of the animal to be examined. If the animal is at liberty, its movements can be studied. If it is standing quietly observe it. If the animal is tied up and it seems feasible to examine the animal while it is walking, observe the animal and take its history while it is still tied up. Aggressive and wild animals should be observed, but little beneficial information will be gained from a regional approach to evaluating movement at this stage. 2. Even if the seat oflameness seems to be in the proximal limb, it is mandatory in every case to examine the hooves and interdigital space at some stage during the evaluation. However, if the probability of proximal lameness is high, the clinician may proceed to make a complete evaluation, which would include studying the quality of movement before checking that the distal extremity is normal in every way. 3. If the clinician decides to proceed with an examination of the digital region and is unable to locate a causative lesion in the extremity, he would then evaluate
DEVELOPMENT OF AN APPROACH TO LAMENESS EXAMINATION IN CATTLE
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movement and manipulate and palpate the proximal limb. If no cause of the lameness becomes apparent, the nerve supply to the extremity would then be blocked. It should then be apparent that the lameness is seated in the proximal or distal limb. Radiographic and/or arthroscopic examinations may be used if these techniques appear appropriate and are available.
REFERENCES 1. Bartels, J. E.: Femoral-tibial osteoarthrosis in the bull. I. Clinical survey and radiologic interpretation. J. Am. Vet. Radial. Soc., 16:151, 1975. 2. Nilsson, S.A.: Clinical, morphological and experimental studies oflaminitis in cattle. Acta Scand., 4[Suppl. 1]: 1963. 3. Toussaint-Raven, E.: Some reflections after three symposia on bovine digital disorders. In Proceedings of the Fourth International Symposium on Disorders of the Ruminant Digit, 1982. Department of Veterinary Anesthesiology, Radiology, and Surgery Western College of Veterinary Medicine University of Saskatchewan Saskatoon, Saskatchewan Canada S7N OWO
Development of an Approach to Lameness Examination in Cattle P.R. Greenough, F.R.C.VS. *
Contemporary literature contains a wealth of information regarding the etiology and pathogenesis of conditions affecting the limbs and particularly the digital region of cattle. The analytical process by which a diagnosis is reached is rather vague, however. Nevertheless, a subjective or "anecdotal" approach is an anathema to the scientific mind,. Despite this, it is with the "art" of diagnosis that this article will be concerned. Why is it that when the young, inexperienced veterinarian is presented with a cow that is lame but demonstrates no obvious lesion, he or she experiences a sense of panic and lack of direction? An experienced clinician presented with the same case will instinctively explore several possibilities. This instinctive reaction is a subconscious process through which complex variables are analyzed. In the pages that follow, this analytical process will be examined in order to develop protocols and to approach the diagnosis of the causes of lameness with objectivity. There is no secret formula for diagnosing the causes of lameness. The lesions most likely to be encountered will vary depending on the climate, environment, nutrition, age, breed, and sex of the animal.
OBSERVATION AND HISTORY In the writer's opinion, the method in which one initiates the examination of a lame animal may be summarized in the following words: "Observe the observable and then confirm that which you think that you have observed as being a correct observation."
Observation is a quiet process in which an attempt is made to "palpate the limbs with the eyes." All of the limbs should be visually examined from every angle. Although the owner may indicate the affected limb, there may *Professor, Department of Veterinary Anesthesiology, Radiology, and Surgery, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
Veterinary Clinics of North America: Food Animal Practice-Vol. 1, No. 1, March 1985
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be clinical signs in all the limbs (laminitis, for example) that may suggest a common underlying cause. Similarly, a lesion might be found in the digital region of one limb that could be associated with the etiology of a different lesion in the lame limb (interdigital dermatitis, for example). The objective of observation is to gain information on the most probable "seat of lameness." The "seat" is a region or zone in which the lesion causing the lameness is located. Observation must never preclude a thorough physical examination however obvious the lesion may be. In the author's opinion, inadequate evaluation of the "obvious" cases of foot rot is a major factor in the development of many serious complicated conditions of the digital region. The period of observation provides an opportunity for the clinician to take the animal's history. Because the clinician is busily examining the animal with his eyes, a confrontational interrogation of the owner is avoided. As a result, the history-taking process becomes more productive. It is often quite crucial to obtain very accurate information regarding the duration of the lameness and the rate of increase in the severity of the clinical signs. Therefore, it would be useful to combine the two procedures-that is, remark on your observations and invite the owner to comment from his knowledge and perspective of the history of the animal. Observations may be grouped in some of the following categories: 1. Conformation. Conformation, for the purpose of this discussion, is the shape of the animal that is dictated by inherited characteristics of the skeleton or hooves. Acquired changes in shape resulting from disease, environmental conditions, or nutritional extremes should be considered as separate entities rather than as part of conformation. In some cases, the influences that bring about "acquired changes" in the animal's shape may be associated with changes in posture or stance. As a general rule, unless the acquired changes have been present for a significant period of time, they are usually reversible. Straight limbs (the dorsal angle of the tarsus exceeds 150°) is the most frequently encountered conformational abnormalities. Arthritis of the hip and stifle and damage to one or other of the menisci of the femorotibial articulation or their associated ligaments are commonly encountered in cattle with straight hind limbs. 1· 4 Generally speaking, the older the animal the greater the probability of joint pathology. Excessive fatness in young animals with straight limbs can suggest several possibilities. In the clinic at the Western College ofVeterinary Medicine, partial or total avulsion of the hoof has been seen in a number of young bulls of the exotic breeds. This possibility seems greater in animals with small hooves. If the ani1nal is overweight, it will also suggest the possibility of a high level of concentrate feeding; therefore, in a later examination of the hooves, hemorrhages of the wall and sole may indicate the presence of subclinical laminitis. 2. Engorgement of the Superficial Veins of the Limb. The following vessels are of particular significance: the cranial tributary of the lateral saphenous vein, the dorsal common digital vein, and the lateral digital vein. These veins appear extremely prominent and, when palpated, feel very turgid in cattle that are affected with acute laminitis. 2
DEVELOPMENT OF AN APPROACH TO LAMENESS EXAMINATION IN CATTLE
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3. Muscular Atrophy. Atrophy of the muscles can occur in any region in which physical activity has been restricted, usually because movement is painful. Atrophic muscle groups tnu~t be viewed from several angles, and comparisons should be made with similar structures on the contralateral limb. Palpation of the musculature can also be useful in making comparisons. As muscles atrophy, certain bony prominences become more obvious; it is important not to be misled into thinking that bony changes have occurred if this is not the case. A good example is the prominence of the great trochanter when atrophy of the gluteobiceps has occurred. A prominence of the trochanter does not indicate any abnormality in that particular structure; in some instances, however, the disuse of this muscle group may be associated with pain in the hip. 4. Stance and Posture. The manner in which an animal holds its limb must not be confused with conformational abnormality. For example, cattle that are affected with acute laminitis adopt a stance comparable to that seen in similarly affected horses. Cattle affected with pododermatitis circumscripta will invariably stand "camped back." An animal that is showing tarsal supination (cow-hocked stance) is likely to have a build-up of horn beneath the heels of the lateral claws. 3 Holding digits extended may indicate a lesion in the toe of the hoof and may be confused with flexion associated with nerve paralysis (peroneal or tibial). If the animal holds his extremity in such a way that it is touching the ground lightly, there is a strong possibility that pus might be present between the distal phalanx and hoof wall or that the distal phalanx may be fractured. 5. The Hoof Animals of less than 2 years of age should have normally shaped hooves and well-developed bulbs. The periople should be clearly visible. Hooves of this type are likely to be resistant to the chronic degenerative conditions more commonly observed in older animals; therefore, when lameness is encountered in cattle with good hooves, the condition is likely to be associated with trauma. If the pain is severe, the presence of a penetrating foreign body may be considered. On the other hand, if the hoof appears low at the heel and the animal has been confined on concrete, bruising of the sole is a possible etiology. Older animals-particularly those in a milking herd on concrete or housed under unhygienic conditions-are likely to have hooves of soft texture. The hooves may be flattened, the dorsal surface may be concave, the perioplic sheen may be diminished, and ridges may be present in the texture of the hoof. In such animals, heel erosions, avulsion of the white line, and related conditions can be suspected. 6. Swellings. Although usually obvious, swellings can be misleading. Hematomas over soft-tissue areas tnay be unsightly but are not necessarily the cause of lameness. Swellings may be an indicator of cellulitis and not necessarily the primary cause of the lameness. Swellings in the digital region are usually indicators of pathology that can be misinterpreted. A bilateral swelling of the region with separation of the digits is the most commonly encountered lesion that can immediately suggest interdigital necrobacillosis (foot rot). However, this is a condition that probably will have been treated by the owner. If the animal has been treated correctly for even a few days and such a lesion persists, it is likely that the lesion is associated not with foot rot but a serious complication of
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that condition. A painful erythetnatous swelling of the coronary band in the dorsal region may indicate a septic vertical fissure or an early septic invasion of the distal interphalangeal joint. A similar swelling of the abaxial coronary band may be associated with a lesion originating in the white line and would require careful exploration to eliminate a diagnosis involving the bursa of the distal sesamoid (navicular bursa). A unilateral swelling of one heel is a sure indication of a retroarticular abscess. If one toe is extended in respect to the other, in all probability the deep flexor has avulsed from the distal phalanx. If the coronary band is generally swollen but erythema and pain are minimal, it is likely that infection has been present and that the joint is ankylosing owing to the presence of periarticular exostoses. None of the preceding observations, in themselves, are necessarily diagnostic. Nevertheless, they are all observable at some distance from the animal and serve as a basis on which the animal should be examined. Of course, there are a host of other observable features such as those associated with bone fractures, tendon ruptures, or skin laceration. One is sornetimes misled into believing that because 80 per cent of the cases of lameness are located in the digital region, a high rate of success can be obtained by an immediate examination of the hoof. A protocol for systematic observation will assist the clinician in making an accurate diagnosis.
LAMENESS: THE CLINICAL SIGN Pathokinesthetic alterations in movements are those that are associated with disease and provide us with the clinical sign that we refer to as lameness. The term "lameness" signifies some alteration in the quality of movement during progression but must be extended to include the quali.ty of stance. The qualities of lameness are evaluated subjectively by the clinician on the basis of his or her experience rather than on any predetermined system. Historically, the terms "swinging" and "supporting" leg lameness have crept into the literature. These terms relate to pain during movement and pain during weight-bearing, respectively, but they are of very little help to the bovine clinician who must appreciate the significance of alterations in the quality of locomotion. For diagnostic purposes, it may be useful to suggest that lameness can be categorized in one or more of the following groups: 1. 2. 3. 4.
Aberrations of stride Pain-dominated lameness Specific lameness Characteristic stance
Aberrations of Stride A stride is a full cycle of limb motion that begins with weight-bearing (the stance phase), is followed by propulsion (posterior swing phase), and is continued into an anterior swing phase before there is a return to the stance phase. Each of the phases (stance and anterior and posterior swing phases) can be objectively measured in respect to duration; the swing phases can also be measured in respect to length. Restriction of either swing phase is
DEVELOPMENT OF AN APPROACH TO LAMENESS EXAMINATION IN CATTLE
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likely to indicate functional deficiency in the systems involving movement of the proximal limb. A component of pain is usually involved in aberrations of stride; therefore, the more intense the pain the shorter the stride is likely to be. This evaluation of stride is carried out from the side of the animal as it passes the observer. This is a subjective evaluation that is of most practical value after the digital region has been definitely eliminated as the seat of lameness. In practice, it is useful to make an evaluation of movement before and after the detailed examination of the digital region, because any examination of the digital region will involve either tranquilization of the animal or manipulative procedures that might alter the patterns of the stride. For example, the initial examination of the stride might suggest that there is a shorter anterior phase; after manipulation, however, the whole stride might be shortened. The procedure for evaluating the stride cannot be developed as a diagnostic recipe. With experience, however, it may be possible to develop a logical procedure for analyzing the signs observed, which will enable the clinician to make a more critical examination of a particular region of the proximal limb.
Pain-Dominated Lameness In all probability, more than 90 per cent of lameness will be associated with pain rather than with a functional disorder. The degree of pain experienced will be variable; as the pain increases in intensity, the animal will attempt to modify weight-bearing in order to minimize its suffering. The pain will cause the animal to shorten its stride and to place the hooves very carefully on the bearing surface and then remove the limb from the weightbearing position as soon as possible. This will give the appearance that the animal is snatching its limb from the ground. In the most intense form of painful lameness, the animal will "nurse" the limb. There may be an associated state of anxiety, loss of milk, inappetence, and muscular wastage. The term "pain-dominated lameness," therefore, is an arbitrary one, but it is nevertheless useful because pain that is intense enough to cause the animal to make a conscious effort to seek relief provides the observer with useful indications of the most likely seat of lameness. The most intense pain is associated with fractures or, more commonly, with fluid that is exerting pressure on the sensitive laminae or the corium of the sole. The presence of pus between the hoof wall and distal phalanx is extremely painful, and the pain will usually increase in intensity over a period of hours or days; the onset of lameness caused by a fracture or trauma would be extremely rapid, however.
Specific Lameness A specific lameness is one that produces a highly characteristic alteration in the quality of progression, and the diagnosis is based mainly on observations. However, because a possibility for error does exist, it is recommended that confirmation be made wherever possible by supplementary tests and the elimination of other causes of lamenesses, particularly those that may be associated with the hoof. Spastic paresis produces a "specific" lameness. However, some animals
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with very straight hindlimbs may have a comparable stride. In straightlegged cattle, changes in the joints may occur as the animal gets older; therefore, difficulty in locomotion may become progressive. Upward luxation of the hip will cause the hock to be rotated medially on the affected limb, which the animal will tend to drag. Manipulation of the limb would confirm this diagnosis. Specific nerve paralyses will cause muscular weakness in certain muscle groups that produce characteristic signs of peripheral nerve paralysis, although a definitive diagnosis may be impossible without careful neurologic testing. Luxation of the patella produces another specific lameness that may require manipulative examination in order to confirm the true nature of the condition. Characteristic Stance A characteristic stance is an aid to diagnosis rather than a specific diagnostic sign. For example, a dropped hock will probably be associated with damage to the tendon or muscle of gastrocnemius. However, nerve paralysis can produce the same general effect. Sometimes a characteristic stance will indicate the probable seat of lameness. For example a crossed-legged stance has been observed in some animals with fractured distal phalanx and in others with laminitis. Cattle with very acute laminitis will adopt the various stances characteristic of laminitis in horses. Cattle that stand with both limbs well back quite frequently have painful lesions in the posterior aspect of the sole. Sole ulceration quite often will produce this stance. As has been mentioned earlier, a cow standing with both hocks turned inwards would suggest an abnormal growth of horn beneath the lateral claws. Although not characteristic of any particular pain-producing lesion, it is likely that there are some inflammatory changes in the corium of the sole.
PHYSICAL EXAMINATION OF THE DIGITAL REGION Pain Reflex Cattle are relatively more reactive to manipulation and pressure on the hoof than are horses. Unless the operator is extremely careful, a response may be elicited that is not significant from the diagnostic point of view. Digital pressure around the entire coronary band is a mandatory procedure. Hoof testers may be applied, but one must take care to ensure that the distal interphalangeal joint is not subjected to excessive movement and that so-called sensitivity is specific to one claw rather than reflecting .. discomfort." Manipulation of the distal interphalangeal joint can be painful when this joint is associated with some disease process; unfortunately, this form of manipulation often will be resented by an animal even in the absence of pain.
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EXAMINATION OF THE SOLE A hoof that has good conformation but has a Hat sole will have been subjected to excessive wear and will be associated with the animal having borne its weight on the entire sole rather than on the abaxial wall. Usually, the sole will show traumatic blemishes, most of which are of no significance at all. Each blemish must be examined individually, however, because in the case of the Hat sole some form of trauma to the sole is the most likely cause of lameness. It is counterproductive to pare the entire sole, because this procedure will weaken the mechanical characteristics of an already worn structure. The Hat sole indicates that the hoof is at high risk for traumatic injury. However, such hooves are likely to be more healthy than those that are irregular, rough, and flattened. Rough and irregular soles will require evaluation on the basis that several different related or unrelated lesions are likely to be present. Paring the sole to remove superfluous horn should be the first stage in this examination. The following factors would need to be evaluated: 1. The status of the white line at the junction of the sole and heel. Avulsion of the white line is a progressive lesion that can be associated with a retroarticular abscess, navicular bursitis, or abscessation at the coronet. 2. Erosion of the heels may be associated with interdigital dermatitis, in which case an evaluation of the herd status in respect to this condition might be appropriate. This would be particularly appropriate if the incidence of lameness is generally higher than would be expected. 3. Pododermatitis circumscripta may be present. The majority of sole ulcers will be mature and will have penetrated the entire sole. However, some of the lesions encountered in their early stages will be discovered lying beneath the level of intact sole horn. 4. Subclinical laminitis may be present. It may be suggested by a yellowish coloration of the horn, hemorrhages in the horn, or avulsion of the horn at the apex of the sole. Again, this is likely to have implications for herd care.
NERVE BLOCKS Regional nerve blocks are just as valuable in the cow as they are in the horse. Usually, however, the seat of lameness is located much more easily in cattle than it is horses. For this reason, nerve blocks are used less often in the diagnosis of bovine lameness. Most workers seem to experience difficulty in providing an adequate degree of desensitization of the forelimb using a regional nerve block and resort to regional intravenous perfusion for surgical procedures. Regional intravenous perfusion is an inappropriate procedure for the diagnosis of lameness. A ring nerve block of the entire digital region is the only reliable method by which the extremity can be completely desensitized. In the hindlimb, regional nerve blocking is much more specific. The technique can proceed in three stages.
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The Lateral Block A subcutaneous track of local anesthetic should be laid horizontal with the bearing surface on the abaxial surface of the limb at the level of the "dew claws." The needle would be inserted 2 em dorsal (anterior) to the dew claw and should penetrate 8 to 9 em dorsally (anteriorly). As the needle is withdrawn, a track of up to 5 ml of 2 per cent lidocaine would be injected. This block will desensitize most of the abaxial region of the digit. The Axial Block Two injections should be given. The first should be given in the midline of the dorsal surface and the other in the midline on the plantar surface. The point on the dorsal surface will be in the midline immediately below the metatarsophalangeal joint. The injection on the plantar surface will be immediately below the tough plantar ligament, which occurs at the level of the dew claws. Each injection should be to a depth of approximately 5 em, and up to 5 ml of anesthetic should be deposited in each site as the needle is withdrawn. The axial nerve block will desensitize the cleft and a very significant portion of each digit. The Medial Block This block is placed in exactly the same 1nanner as the lateral block and, if used in conjunction with the axial and lateral block, will completely anesthetize the entire digital region. The animal may be evaluated for changes in the quantity of lameness after each block has been given and before one proceeds to the next stage of blocking.
SUMMARY In the preceding pages, the various components of an examination have been described. Each clinician will formulate his own method of utilizing these components. The following are suggested steps in a practical approach to the diagnosis of lameness. 1. Evaluate the conditions under which restraint of the animal is possible (corral, free stall, stanchion barn). Assess the temperament, physical strength, and general amenability of the animal to be examined. If the animal is at liberty, its movements can be studied. If it is standing quietly observe it. If the animal is tied up and it seems feasible to examine the animal while it is walking, observe the animal and take its history while it is still tied up. Aggressive and wild animals should be observed, but little beneficial information will be gained from a regional approach to evaluating movement at this stage. 2. Even if the seat oflameness seems to be in the proximal limb, it is mandatory in every case to examine the hooves and interdigital space at some stage during the evaluation. However, if the probability of proximal lameness is high, the clinician may proceed to make a complete evaluation, which would include studying the quality of movement before checking that the distal extremity is normal in every way. 3. If the clinician decides to proceed with an examination of the digital region and is unable to locate a causative lesion in the extremity, he would then evaluate
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movement and manipulate and palpate the proximal limb. If no cause of the lameness becomes apparent, the nerve supply to the extremity would then be blocked. It should then be apparent that the lameness is seated in the proximal or distal limb. Radiographic and/or arthroscopic examinations may be used if these techniques appear appropriate and are available.
REFERENCES 1. Bartels, J. E.: Femoral-tibial osteoarthrosis in the bull. I. Clinical survey and radiologic interpretation. J. Am. Vet. Radial. Soc., 16:151, 1975. 2. Nilsson, S.A.: Clinical, morphological and experimental studies oflaminitis in cattle. Acta Scand., 4[Suppl. 1]: 1963. 3. Toussaint-Raven, E.: Some reflections after three symposia on bovine digital disorders. In Proceedings of the Fourth International Symposium on Disorders of the Ruminant Digit, 1982. Department of Veterinary Anesthesiology, Radiology, and Surgery Western College of Veterinary Medicine University of Saskatchewan Saskatoon, Saskatchewan Canada S7N OWO