Orthopedic examination is a key method to identify musculoskeletal lesions in small animals. The patient is evaluated at rest, on rising, and during locomotion on flat, inclined, and irregular surfaces.
Single-limb or multiple-limb lameness might be noted; the severity is related to the type of injury and activity.
With forelimb lameness, the head might be elevated ("head bob") during weight bearing on the painful limb and might move down during weight bearing on the sound limb ("down on sound"). The stride might also be shortened on the painful limb.
Bilateral forelimb lameness in small animals can be more challenging to identify. It can include bilaterally shortened stride in the forelimbs and attempts by the animal to shift weight onto the pelvic limbs (pelvic limbs tucked under the body, head and neck raised).
For hindlimb lameness, the hips often move higher when the painful limb hits the ground ("hip hike") and drop lower when the sound limb bears weight ("hip drop").
Severe pelvic limb lameness can lead to the appearance of forelimb lameness because the head might be dropped during weight bearing on the affected limb. This head drop occurs as the animal attempts to shift weight off of a painful rear limb and onto a more comfortable front limb.
Bilateral hindlimb lameness can result in a bilaterally shortened stride in the rear, along with attempts to shift weight onto the more comfortable thoracic limbs (head and neck extended and low, more crouched position of the thoracic limbs).
Standing examination of small animals should include evaluation of the patient's limb position, joint position, muscle mass, and joint effusion. Palpation of both limbs at the same time enables evaluation of asymmetry.
Pearls & Pitfalls
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During recumbent examination, limbs should be assessed in a distal-to-proximal manner, and bones, joints, and soft tissues should be palpated.
Abnormalities to note in cases of lameness include swelling, joint effusion, pain, instability, crepitus, decreased range of motion, and muscle atrophy.
To evaluate subtle or obscure lameness, serial examinations before and after exercise might be necessary. For fractious patients, sedation might be required; palpation, radiography, and arthrocentesis can often be performed while the patient is sedated.
Several well-established protocols for sedating small animals with lameness have been published. Depending on the species, many of these protocols can be found in the topic Tranquilizers, Sedatives, and Analgesics for Treatment of Animals or in the tables or .
Diagnostic Imaging for Orthopedic Examination in Small Animals
Helpful imaging procedures to diagnose the cause of lameness in small animals include plain and contrast radiography, ultrasonography, nuclear scintigraphy, CT, and MRI (see Diagnostic Imaging). Patients undergoing diagnostic imaging should be heavily sedated or anesthetized.
Orthogonal radiography of the affected bone or joint should be performed. Radiography of the contralateral normal limb can provide a reference for comparison, which is especially helpful to identify and determine the importance of subtle lesions.
Historically, arthrography was the most commonly used contrast technique for evaluating lame animals in cases of suspected joint disease. However, this technique is not used routinely anymore, because of the availability of advanced imaging.
Ultrasonography is useful to evaluate musculotendinous injuries such as bicipital tenosynovitis, Achilles tendon rupture, and muscle contracture. Nuclear scintigraphy, CT, and MRI are usually available at private or academic referral centers.
Nuclear scintigraphy involves IV injection of a radioactive compound that localizes and highlights periosseous soft tissue and bone lesions. It is not commonly performed, but it can be helpful to identify lameness that is difficult to localize.
CT imaging permits high contrast and resolution of osseous structures; MRI is helpful to delineate soft tissue and joint injuries. Both CT and MRI can also be used to assess the spinal column.
Arthroscopy for Orthopedic Examination in Small Animals
Arthroscopy is a minimally invasive procedure used for diagnosing and treating lameness in small animals.
Advantages of the technique include improved visualization of joint pathologies, the ability to concurrently treat identified injuries (eg, via removal of damaged cartilage or ligaments), and its minimally invasive nature (less surgical trauma).
Disadvantages of arthroscopy are the costs of equipment and the learning curve in developing expertise in the technique.
Common conditions in small animals that can be diagnosed or treated via arthroscopy include osteochondrosis, osteochondritis dissecans, bicipital tenosynovitis, joint fractures, elbow dysplasia, cranial cruciate ligament disease, and meniscal injuries.
For More Information
Barnes K. Localizing thoracic limb lameness on orthopedic examination in dogs. Clinician's Brief. Updated March 2023.
Barnes K. Localizing pelvic limb lameness on orthopedic examination in dogs. Clinician's Brief. Updated August 2023.
Millis DL, Mankin J. Orthopedic and neurologic examination. In: Millis DL, Levine D. Canine Rehabilitation and Physical Therapy. 2nd ed. Saunders; 2014:180-200.
Also see pet owner content regarding lameness in dogs, cats, and horses.
