With the patient standing, one should observe for weakness, limb trembling, asymmetry of regions of the limbs indicative of muscle atrophy, asymmetry of the head and neck, limb position, and conformation (Figure 10-1). It is common for standing animals to bear less weight on a limb afflicted with lameness. In this situation, the animal may not have the entire foot in contact with the floor. One method to assess the relative amount of weight placed on each limb is for the examiner to place the front feet or the rear feet on the palm of each hand and allow the animal to bear weight on the observer’s hands rather than on the floor. This is a semiquantitative method of assessing weight bearing. Another method to assess weight bearing is to use bathroom scales, or more sophisticated devices described in Chapter 13, under each foot to determine the amount of weight placed on each limb at a stance. In many lamenesses there is also marked muscle atrophy of the affected leg. In some chronic lamenesses there may be abnormal foot pad wear and unequal weight bearing that may be noticeable.

Figure 10-1 The dog should be observed from (A) the front and (B) the rear while standing for evidence of reduced weight bearing on an affected limb, turning the toes out, and not bearing weight symmetrically in comparison with the contralateral limb. Note the reduced weight bearing on the left rear limb indicated by less contact of the metatarsal pad with the ground and the more lateral position of the foot as compared with the other rear limb.

Gait

Gait evaluation is generally performed after observing the dog rising and at a stance. The patient’s gait is best observed in a large, enclosed exercise area from a distance. In addition, it is beneficial to have an area in which observations may be made with the dog off leash. Gaiting begins with the handler moving the patient first at a walk, then at a trot. The patient should be evaluated while moving directly away from, and then toward the examiner (Figure 10-2). The patient should then be evaluated from the side at a distance (Figure 10-2C). Evaluation at a lope or gallop may be performed if the patient is able, but this gait is less useful for evaluation of most lameness because of the speed of limb motion and the fact that these gaits are asymmetric. It may be helpful to capture the gait with a video camera and then evaluate the gait in slow motion. The degree of lameness may be subjectively evaluated using a lameness scoring system to allow comparison of the lameness over time (Box 10-1).

Box 10-1 Lameness Score (Applied Separately at a Walk and a Trot)

0: Normal

1: Slight, intermittent lameness

2: Obvious weight-bearing lameness

3: Severe weight-bearing lameness

4: Intermittent non–weight-bearing lameness

5: Continuous non–weight-bearing lameness

Observation of the patient while it is walking is beneficial for those patients with severe lameness that may be unwilling to trot. Because the walk is a slow four-beat gait, each limb may be separately evaluated. This is particularly beneficial to help differentiate a lameness seen at a trot, in which a diagonal forelimb and hindlimb strike the ground at the same time. Observing at a walk with separate limb strikes helps to determine which diagonal limb is affected in cases of subtle lameness. In many cases, the head will nod up and down if a lameness is present. In general the head will nod up when the affected leg is placed on the ground if a forelimb lameness is present, and the head will nod down when the affected limb is placed on the ground if a hindlimb lameness is present. The reason for this is to reduce weight bearing and force on the lame limb by using the head and neck as a lever arm to shift weight from the painful limb to the opposite end of the body.

The patient should also be evaluated at a trot, which is a symmetric two-beat diagonal gait. Subtle lameness is generally easier to see at a trot because greater forces placed on the lame limb accentuate the lameness. Although moderate forelimb and hindlimb lameness may be differentiated at a walk because the pattern of footfalls is separated, differentiation of forelimb and hindlimb lameness is more challenging at a trot. The reason for this is that diagonal forelimbs and hindlimbs strike the ground at the same time. As an example, consider a head that nods up when the left forelimb strikes the ground. This may indicate a left forelimb lameness. However, it may also be indicative of a left hindlimb lameness, because as the left hindlimb strikes the ground, the head will nod down; as the right hindlimb and left forelimb strike the ground immediately after, the head will nod back up. Careful observation of other features of gait may help distinguish between forelimb and hindlimb lameness at a trot, in conjunction with other features of the physical examination. It may also be helpful to place each major joint through a full range of motion, and then reassess the lameness. Stresses placed on joints as they are flexed and extended may accentuate a subtle lameness.

In addition, other factors such as stride length, limb carriage, joint motion, and side bending of the spinal column are useful in evaluating lameness. The affected limb may have a shortened stride length and reduced flexion and extension of the affected joints. Most dogs will walk with the normal limb centered under the body during the weight-bearing phase of gait on that limb, whereas a lame limb may be carried further eccentrically during weight bearing. The affected limb may also circumduct during gait. Animals with hip or stifle conditions may have increased lateral flexion of the spinal column toward the affected side in an attempt to advance the limb by using the back, especially if the stride is shortened on that side. In all cases, symmetry of movement should be evaluated. Abnormal proprioception, dragging of the nails, knuckling over on the dorsum of the paw, and hypermetria indicate neurologic disease.

When possible, the patient should be walked and trotted in a large circle in both directions. In many cases, lameness of the inside limb will be accentuated. Stairs and steps may also be helpful in observing lameness and subtle neurologic problems. Dogs may skip up or down steps with the affected limb rather than pushing off the limb to ascend or descend a flight of stairs, or may knuckle over on the dorsum of the paw of a limb afflicted with a neurologic condition.

General Palpation for Symmetry and Atrophy

Following observation of the patient for lameness during ambulation, a brief examination is performed while the dog is still standing to assess symmetry and to assess relative muscle mass and the presence of muscle atrophy. Simultaneous palpation of both forelimbs and then both rear limbs will allow the examiner to detect subtle differences between limbs that are normally symmetric (Figure 10-3). Fractures and neoplasia of the musculoskeletal system are usually obvious. Individual regions are evaluated for swelling, abnormal shape, heat, and sensitivity and pain.

Figure 10-3 Simultaneous palpation of both hindlimbs for evidence of muscle atrophy and asymmetry.

Beginning with the forelimb, the dorsal border of the scapula is palpated to be certain that one side is not higher than the other. The spine of the scapula is assessed for fractures and prominence of the spine of the scapula, which might indicate muscle atrophy if it is readily palpable and differs from the other side. The acromion and greater tubercle of the humerus are palpated next. The distance between the two landmarks and the amount of soft tissue between the two points should be equal on both sides. The shaft of the humerus is palpated next to locate any areas of swelling or muscle atrophy.

The elbow is a difficult joint to assess because many structures are present in a relatively small area, including the medial and lateral epicondyles of the humerus and the flexor and extensor muscles that arise from them, the head of the radius, the region of the medial coronoid process of the ulna, the joint capsule, and other soft-tissue structures in the area. The task is made easier by standing behind the dog and placing the thumbs of each hand on the lateral epicondyles. The fingers are then wrapped around the cranial aspect of the elbow, and the index fingers are placed in the region of the medial coronoid processes of the ulnas. The area of the medial coronoid process is firmly pressed to assess for pain and discomfort, which may indicate a fragmented medial coronoid process. Following palpation of this area, the cranial and caudal aspects of the medial joint are assessed for joint effusion, swelling, and increased or decreased soft-tissue mass. The caudolateral joint compartment is assessed next between the lateral epicondyle and the olecranon process for joint effusion or swelling, which might indicate osteoarthritis or an ununited anconeal process. This swelling is usually palpable caudal and parallel to the lateral epicondyle, and compression forces the effusion medially. By palpating the elbows simultaneously with the dog standing, subtle abnormalities may be detected by assessing the area for asymmetry. It may also be helpful in certain cases to pronate and supinate the distal extremity when evaluating each individual elbow. These maneuvers help to concentrate the forces in the medial or lateral joint compartment, accentuating any subtle discomfort.

The shafts of the radius and ulna are palpated from proximal to distal to assess the bones for any pain or swelling. The carpi and digits are usually best assessed with the dog in lateral recumbency, although the standing angle of the carpus should be observed to be certain that carpal hyperextension is not present.

The hindlimbs are evaluated next. The dorsal aspect of the wings of the iliums are located to be certain that one is not located further cranially or dorsally than the other, which might indicate a sacroiliac luxation. The gluteal muscles are assessed for atrophy throughout the ilium. The area between the greater trochanter and the tuber ischium is located and compared with the other side. Asymmetry may indicate the presence of muscle atrophy on the side that has less soft tissue between the two points, or a hip luxation if the distance between the two points differs. The thigh musculature is evaluated for atrophy. The stifles are simultaneously palpated in a manner similar to that of the elbows to assess for joint effusion, the presence of firm tissue on the medial aspect of the distal femur (often referred to as a medial buttress) that might indicate a chronic rupture of the cranial cruciate ligament, and the position of the patellae, which should be symmetric.

The tibias are assessed for any asymmetric swelling or pain, and the angle of the tarsus is observed to evaluate the integrity of the common calcaneal tendons. The tarsus and digits are best evaluated with the patient in lateral recumbency.

Orthopedic Examination

A systematic approach to the orthopedic examination is necessary to reduce the risk of missing a condition and to create an evaluation that can be consistently repeated. In many cases the contralateral limb may be used as a reference for comparison of limb circumference, range of motion, and sensitivity to palpation. Comparison with the contralateral limb may be especially helpful when a subtle condition exists and there is uncertainty regarding an abnormality. Concentrating on anatomy during the examination, and referring to an anatomy book as necessary, helps in confusing or unusual situations. The patient is usually examined in lateral recumbency, but may be evaluated while standing if it is anxious.

Rear Limbs

Evaluation of the rear limbs first may be safer for the examiner while the patient is becoming accustomed to the examiner. The phalanges and metatarsals of the distal limb are evaluated first. The toes are spread apart to evaluate the nail beds, webbing between the toes, and the pads for any infection, trauma, or cracks. The phalanges, interphalangeal joints, metatarsal bones, and metatarsophalangeal joints are individually palpated and assessed for pain, crepitus, swelling, fractures, luxations, or collateral ligament instability (Figure 10-4). The range of motion of the joints is also assessed. The area over the plantar sesamoid bones is palpated for pain and proliferative changes that might be associated with an old fracture or arthritis. Joint stability is further assessed by flexing and extending individual joints and placing varus and valgus stresses on the joints. It is helpful to be familiar with the origin and insertion of the interphalangeal ligaments to properly evaluate instability (Box 10-2).

Box 10-2 Common Conditions of the Hindlimbs

Common Conditions of the Digits, Pads, and Feet

Paronychia

Lacerations of the interdigital skin or foot pads

Luxations of the interphalangeal joints

Luxations of the tarsometatarsal joint

Fractures of the metatarsal bones

Fractures of the phalanges

Fractures of the sesamoid bones

Common Conditions of the Tarsus

Osteochondritis dissecans of the talus

Fracture of the calcaneus

Fracture of the central tarsal bone

Fracture of the third or fourth tarsal bones

Luxations of the tarsus with damage to the short or long tarsocrural ligaments

Osteoarthritis

Disruption of the common calcaneal tendon

Rupture of the plantar ligaments

Common Conditions of the Tibia and Fibula

Fractures of the tibia and fibula

Panosteitis

Traumatic periostitis

Osteosarcoma

Common Conditions of the Stifle

Cranial cruciate ligament disruption

Osteochondritis dissecans of the femoral condyle

Injuries to the medial and lateral collateral ligaments

Medial and lateral patellar luxation

Medial and lateral meniscal damage

Fractures

Congenital absence of the patella

Caudal cruciate ligament disruption

Osteoarthritis

Common Conditions of the Femur

Fracture of the femur

Panosteitis

Osteosarcoma

Common Conditions of the Coxofemoral Joint

Hip dysplasia

Fracture of the acetabulum

Fracture of the femoral head or neck

Fracture and separation of the proximal capital femoral physis

Legg-Calvé-Perthes disease

Traumatic luxation of the coxofemoral joint

Osteoarthritis

The tarsus is a complex series of joints. It is first assessed for joint effusion and instability. Palpation of the dorsal aspect of the tarsocrural joint is especially rewarding in cases of joint effusion. The joint is placed through a full range of motion to assess the joint for limitations, crepitus, and pain. The examiner’s finger is used to palpate the tarsal bones, with particular attention to the central, third, and fourth tarsal bones. The tarsus has short and long components of the medial and lateral collateral ligaments that are taut in different degrees of flexion and extension. To assess the long components of the collateral ligaments, valgus and varus stresses are applied while the tarsus is placed in full extension (Figure 10-5). Normally, there should be little varus or valgus movement with the hock extended. The short portions of the collateral ligaments are assessed by placing varus and valgus stresses on the tarsus with the tarsocrural joint flexed to 90 degrees. Assessment of these structures while the hock is flexed is more difficult because there is some normal motion in this position. After stabilizing the metatarsus with one hand and the tuber calcis with the other, dorsal and plantar stresses are placed on the hock to determine if subluxation is present or if there has been damage to the supporting plantar structures. With the stifle maintained in an extended position, the hock is flexed to evaluate the calcaneus and common calcaneal tendon. Normally, there should be little ability to flex the tarsus. Excessive flexion may indicate that there has been a fracture of the calcaneus or damage to the common calcaneal tendon. It is also helpful to palpate the insertion of the tendon on the calcaneus to rule out partial avulsion injuries, which may be manifested as a firm swollen area. It is valuable to compare the suspected limb with the contralateral limb to assess subtle findings.

Figure 10-5 The tarsus is evaluated for evidence of medial or lateral collateral ligament damage by applying varus and valgus stresses to the joint.

Palpation of the tibia is relatively easy because the medial aspect has little muscle covering. The metaphyseal and diaphyseal regions are palpated for periosteal or bone pain, which might indicate hypertrophic osteodystrophy, panosteitis, fractures, neoplasia, or traumatic periostitis (Figure 10-6). It is helpful to palpate the medial and lateral malleoli distally and the head of the fibula proximally.

Figure 10-6 The tibia is palpated for evidence of pain, swelling, or inflammation.

The stifle joint is frequently afflicted with orthopedic conditions. Sedation may be necessary in some larger patients that are tense. The joint is initially assessed for swelling. The tibial tubercle is located first, and the path of the patellar ligament is traced proximally. The joint is palpated medial and lateral to the patellar ligament. Normally, the ligament feels like a pencil and the medial and lateral edges can be distinctly felt, but with joint effusion, the patellar ligament is less distinct and fluid may be palpable in cases of moderate to severe joint effusion. The femoral condyles and the region of the trochlear ridges are palpated next. In some cases, osteophytes or joint capsule thickening may be palpable. Thickening of the medial aspect of the distal femur is often present in dogs with chronic rupture of the cranial cruciate ligament. This is easily felt by placing the examiner’s hand and fingers across the stifle so that the fingers rest over the medial surface of the joint. The other stifle may be simultaneously palpated to compare the two limbs. Swelling of the craniolateral joint in a young dog might indicate the presence of an avulsion of the long digital extensor tendon, although this condition is rare. The stifle is flexed and extended to evaluate for crepitus, grating, clicking, or snapping, which might indicate osteoarthritis, a damaged meniscus, or joint instability. The examiner’s hand may be placed on the patella to assess crepitus. Often dogs with a partial rupture of the cranial cruciate ligament or chronic osteoarthritis secondary to cranial cruciate ligament rupture have marked pain with full stifle extension.

The patella is assessed for medial or lateral luxation. To test for medial patella luxation, the stifle is extended, the distal limb is internally rotated, and pressure is applied to the lateral aspect of the patella to try to displace it medially (Figure 10-7). While maintaining pressure, the limb is slowly flexed and extended to see if luxation occurs with the limb in a position other than full extension. Medial patella luxation is common in toy and miniature breeds and in larger breeds such as Labrador retrievers. In small dogs, the patella may be difficult to locate if patella ectopia exists. In these cases, the tibial tubercle is located and the path of the patellar ligament is traced proximally until the patella is located. To test for lateral patella luxation, the stifle is placed in extension or slight flexion while the distal limb is externally rotated. Pressure is applied to the medial aspect of the patella, trying to force it laterally. Although medial patella luxation is most common in all breeds, if a lateral patella luxation is present, it is most likely a large dog or a chondrodystrophic breed.