The lameness examination is a key feature in identifying musculoskeletal lesions. Evaluation is performed with the animal at rest, rising, and during locomotion on flat or inclined surfaces. Single or multiple limb lameness is noted, and the severity related to the type of activity. With a forelimb lameness, the head is elevated during weightbearing on the unsound limb. The stride is also shortened on the affected side. For hindlimb lameness, the head is dropped during weight bearing of the affected limb. Limbs should be assessed from a distal to proximal manner, and bones, joints, and soft tissue should be palpated. Abnormalities that should be noted 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 animals, sedation may be required; palpation, radiography, and arthrocentesis can often be performed while an animal is sedated with IV butorphanol and acepromazine, propofol, medetomidine (alone or combined with butorphanol or hydromorphone), or a combination of ketamine, diazepam, and acepromazine.
Imaging procedures that are helpful in diagnosing lameness include survey and contrast radiography, ultrasonography, nuclear scintigraphy, CT, and MRI. Animals undergoing these evaluations should be heavily sedated or anesthetized. Survey radiography of affected limbs or the spine requires multiple, orthogonal views. Subtle lesions are often identified following comparison with the contralateral normal limb. The most frequent contrast studies used to evaluate lame animals are arthrograms for joint diseases and myelography for spinal canal disorders. Ultrasonography is useful for evaluating musculotendinous injuries such as bicipital tenosynovitis, Achilles tendon rupture, and muscle contracture. Nuclear scintigraphy, CT, and MRI studies are usually available at large referral centers. Nuclear scintigraphy involves IV 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, while MRI is helpful for delineating soft tissue and joint injuries.
Arthroscopy is a minimally invasive tool used for diagnosis and therapy of lame animals. Advantages of the technique include improved visualization and diagnosis of joint pathology, ability to treat injuries by removal of damaged cartilage or ligament, and reduced surgical dissection. Disadvantages are costs of equipment and a prolonged learning curve. Common conditions that can be diagnosed or treated by arthroscopy include osteochondrosis, bicipital tenosynovitis, joint fractures, and cranial cruciate ligament and medial meniscal injuries.
Last full review/revision March 2012 by Joseph Harari, MS, DVM, DACVS