The lameness examination is a key method to identify musculoskeletal lesions. Evaluation is performed with the animal at rest, rising, and during locomotion on flat or inclined surfaces. Single- or multiple-limb lameness may be noted, with the severity related to the type of activity. With a forelimb lameness, the head is elevated during weight-bearing on the unsound limb. The stride is also shortened on the affected side. For hind limb lameness, the head is dropped during weight-bearing on the affected limb.
Limbs should be assessed from a distal to proximal manner, and bones, joints, and soft tissues should be palpated. Abnormalities to note include swelling, pain, instability, crepitation, reduced range of motion, and muscle atrophy. In evaluation of a subtle or obscure lameness, serial examinations before and after exercise may be necessary. For fractious patients, sedation may be required; palpation, radiography, and arthrocentesis can often be performed while the patient (dog, cat) is sedated with intravenous administration of either: butorphanol and acepromazine; propofol; medetomidine (alone or combined with butorphanol or hydromorphone); or a combination of ketamine, diazepam, and acepromazine.
Diagnostic Imaging Techniques for Lameness Examinations in Small Animals
Helpful imaging procedures to diagnose lameness include plain and contrast radiography, ultrasonography, nuclear scintigraphy, CT, and MRI. Patients undergoing these evaluations should be heavily sedated or anesthetized. Plain (survey) radiography of affected limbs or the spine requires multiple, orthogonal views. Subtle lesions are often identified after comparison with the contralateral normal limb. The most frequent contrast studies used to evaluate lame animals are arthrograms for suspected joint disease and myelography for spinal canal disorders.
Ultrasonography is useful to evaluate musculotendinous injuries such as bicipital tenosynovitis, Achilles tendon rupture, and muscle contracture. Nuclear scintigraphy, CT, and MRI studies are usually available at private or academic referral centers. Nuclear scintigraphy involves intravenous injection of a radioactive compound that localizes and highlights periosseous soft tissue and bone lesions. CT imaging permits high contrast and resolution of osseous structures, whereas MRI is helpful to delineate soft tissue and joint injuries. Both techniques can also be used to assess the spinal column, although MRI preferable for evaluation of nervous tissues.
Arthroscopy for Lameness Examinations in Small Animals
Arthroscopy is a minimally invasive procedure used for diagnosis and treatment of lameness. Advantages of the technique include improved visualization of joint pathologies, ability to concurrently treat identified injuries (eg, via removal of damaged cartilage or ligaments), and the minimally invasive nature (less surgical trauma). Disadvantages are costs of equipment and the learning curve required for development of expertise in its use. Common conditions that can be diagnosed or treated via arthroscopy include osteochondrosis, bicipital tenosynovitis, joint fractures, and cranial cruciate ligament and medial meniscal injuries.
