Centre for Service and Working Dog Health and Research, Veterinary Teaching Hospital, Massey University, Palmerston North, New Zealand
Step 1: Gait Assessment
Examine the patient from three directions: Walking towards you, walking away from you and also from the side. Look for a 'head bob' for forelimb lameness or 'hip hike' for hind-limb lameness. Observe the length of the stance phase and the position of the contact point. When an animal is lame, the swing and stance phases are shortened, thereby reducing the length of time spent on the affected limb. The hind foot should follow in the track of the fore. Note the plane of the stride and if the animal abducts or adducts the limb during the cycle. If the forelimbs are wider than the hind, then bilateral forelimb problems may be present. Conversely, if the hind are wider than the fore then bilateral hind-limb problems should be suspected. Look for alterations in joint range of motion; a reduction in flexion is common with joint disease.
Recognising Hind-Limb Lameness
With hind-limb lameness, weight is shifted forward by extending the neck and lowering the head. There may be a change from the normal side to side oscillation of the tail to a more vertical oscillation. The "up" motion of the tail occurs when the affected limb contacts the ground. The stride length is shortened and the pelvis is tilted in the axial plane so that the hemipelvis on the affected side is more dorsal. With unilateral hip disease, the pelvis is tilted sideways, and an oscillating motion is seen towards the affected side. This manoeuvre minimises hip motion by using lateral bending of the spine to achieve forward motion. When viewed from the rear, the pelvis of an animal with bilateral hip disease swivels from side to side.
Recognising Forelimb Lameness
With lameness in a forelimb, the animal lifts its head when the affected limb bears weight (and appears to dip its head when the sound limb contacts the ground).
Step 2: The Orthopaedic Exam
Commences with evaluation of the affected limb and begins distally. Avoid the temptation to immediately focus on the most likely cause of disease; rather, develop a systematic approach so that nothing is missed. Work your way up the limb until swelling or tenderness is noted. If by now I have found a focal area of discomfort, I will complete the examination above and beyond that site, then come back to the sore area last to maximise the patient's tolerance for manipulations. Localisation of solitary limb lameness is based around the demonstration of pain and pathology. Loss of joint range of motion, presence of crepitation or effusion and periarticular thickening indicate presence of pathology and, in the latter, evidence of chronicity. The other limbs should not be neglected either, especially if a potentially genetic disease is present. A pup with mildly subluxated hips has a good prognosis, but if there is bilateral elbow dysplasia, it may not be a viable proposition for working.
Forelimb Examination in Working Dogs
Toe injuries are very common in farm dogs. Check for broken nails and squeeze across the nail bed to detect infection. Palpate the prescapular lymph node for enlargement consistent with infection. Nail bed infections can be difficult to treat, and anaesthesia and surgical removal of the nail may be necessary for resolution.
Toe dislocation or collateral ligament injury is diagnosed by careful palpation at each level of the digit; fix the proximal segment and apply a valgus/varus stress. Acute injuries respond to primary repair with sutures. Chronic injuries may be best managed with amputation.
Sesamoid fragmentation or fracture may cause pain on hyperflexion of the digit or direct pressure on the metacarpophalangeal joint caudally. It is important to establish repeatable pain on palpation, as sesamoid pathology can be a radiographic finding of no clinical relevance. Intraarticular steroids can be used as a therapeutic trial to establish the relevance of sesamoid pathology.
Carpal injury is common in farm dogs. Individual carpal bones can fracture, but ligamentous injury is more typical. Dogs can be injured by a fall, jumping down from a height, and trapping the foot in a bike rack when jumping off a four-wheeler. The carpal angle during weight-bearing should be noted. The contralateral paw can be lifted to shift weight to the lame leg. The carpus will adopt a more palmigrade stance if there is injury to the extensor support. Also check for collateral support. With the carpus in full extension, there is very limited motion in the mediolateral plane. With the carpus flexed at 90 degrees, there is 45 degrees of internal and 15 degrees of external rotation in normal animals. Check for effusion of the antebrachiocarpal joint by flexing and comparing the dorsal joint pouch with the other side.
Elbow: Effusion in the elbow is typically evident at the caudolateral joint aspect. Look for periarticular swelling. Check for range of motion in flexion and full extension. Find the medial epicondyle; let your finger drop 1 cm distally to the location of the medial coronoid process. Apply pressure to the MCP whilst supinating and pronating the joint (can be painful with elbow dysplasia).
Don't forget to palpate for bone pain around the elbow in German shepherds, as panosteitis is a common cause of forelimb lameness.
Biceps disease (ddx bicipital tenosynovitis, biceps avulsions, biceps calcifying tenopathy) is seen in working dogs as a chronic repetitive strain injury or acute tear. Examine the shoulder for medial pain and tenderness over the biceps tendon within the intertubercular groove. Biceps retraction testing can be performed in two ways, which will be demonstrated by video.
Medial joint support from the glenohumeral ligaments should be checked with the animal under deep sedation or anaesthesia. With the dog in lateral recumbency, the scapula is fixed parallel to the table. The humerus is then abducted to test for medial joint laxity. Bardet showed that < 30 degrees is normal and > 50 degrees is indicative of pathologic instability. The range from 30–50 degrees is a grey area and should not be over-interpreted.
Nail beds/toes and sesamoid exam is the same as for the forelimb.
The tarsus has three distinct joint levels that should be examined individually (tarsometatarsal, distal intertarsal and proximal intertarsal. Grip the tarsus circumferentially, supporting the joint/s above the one to be examined. Then test the individual joint levels with stress in the craniocaudal and mediolateral planes. Injury to the short ligaments laterally or medially are amenable to primary repair and/or support with a suture prosthesis. Injury to the plantar support (hyperextension injury) requires joint arthrodesis. Dorsal injuries do not require surgical intervention if the tarsal bones are intact and load bearing.
The talocrural joint is the main hinge for the hock joint. It should be manipulated to check ROM and collateral support. The short and long collaterals require differential examination. With the tarsus flexed, a valgus/varus stress is applied; if subluxation occurs, there is loss of short collateral support. The examination is repeated with the talocrural joint in extension to test injury to a long collateral ligament.
Injury to the common calcanean tendon (Achilles) can lead to a plantigrade stance. In an incomplete tear, this may be subtle but can be exacerbated by lifting the contralateral limb and increasing weight on the affected leg. The head of the gastrocnemius muscle should be palpated for pain/swelling and the palpation continued distally to the musculotendinous junction and the tendon itself. Avulsions are common, and a thickening is normally evident at its insertion on the calcaneus. Check the toe position. An incomplete rupture (SDF tendon remains intact) is characterised by curling of the toes at stance.
Traumatic injuries to the stifle are common. Dogs attempting to jump a gate/fence can trap a foot, causing hyperextension and/or excessive internal rotation. Injuries can also occur when a dog forcibly hyperextends during running on broken ground. In working dogs, acute cranial cruciate injury may be accompanied by other significant ligamentous injury. We commonly see stifle disruptions with not only CCLR but MCL and/or LCL injury and a joint capsule that is ripped open. The meniscus can be avulsed from its attachments (and may be amenable to suturing into place rather than removal). The joint should be tested with cranial/caudal drawer and tibial thrust tests. The collaterals should be tested by locking the femur and applying a stress in the mediolateral plane (stress radiographs can be helpful).
The hip joint should be examined for pain on ROM. Whilst pain on extension is typically used as an indicator of coxofemoral pain, it also stresses the lower back so is not specific for hip disease. The hip should also be abducted, as pain on abduction is a more true reflection of coxofemoral joint pathology.
The huntaway can suffer from hip dysplasia, and evaluation for hip laxity in pups can be used for selecting working dogs. From 12 weeks of age, the Ortolani test is very sensitive but not highly specific. It will readily detect dogs with hip laxity, but not all dogs with a positive Ortolani will be at great risk of developing coxofemoral pathology. The next step is a distraction radiograph (PennHIP) to quantify the laxity. In young lame dogs, the Bardens' test can be used conscious and is often painful with hip dysplasia. Lumbosacral disease can lead to lameness as the result of nerve root compression; therefore, it needs to be differentiated from other causes.