Equine Lameness: Clinical Judgment Meets Advanced Diagnostic Imaging

When I graduated, it was accepted wisdom that lameness was assessed by watching horses move in hand. As an experienced rider, I became increasingly aware of the value of ridden exercise to assess lameness and performance. This has become an essential part of lameness and poor performance diagnosis. Diagnostic analgesia is now commonplace, but it is only comparatively recently that we have become aware of some of its limitations. Since I graduated, diagnostic imaging has evolved from radiography to include ultrasonography, nuclear scintigraphy, magnetic resonance imaging (MRI), and computed tomography. We are still learning how to interpret what we find and to integrate this with clinical findings. I aim to discuss the science and art of lameness diagnosis. Accurate lameness diagnosis requires recognition of the lame limb(s), identification of any significant palpable abnormalities, determination of the source(s) of pain, and appropriate diagnostic imaging to identify the potential cause(s) of pain, with high quality images, correctly interpreted. This is an acquired art requiring careful observation, pattern recognition, a logical deductive process, and a questioning mind. By continuing to look, I believe that we can all continue to learn and to make new discoveries. My aim is to review some of the advances in lameness recognition, diagnostic analgesia, and advanced imaging, especially MRI. With respect to MRI, my focus is on the foot, because this is the area about which we have learned most and that has the best validation by comparison of imaging findings with postmortem examinations. However, throughout, I aim to emphasize the complexities and the many unanswered questions that remain. This is a challenging field. 2. Looking at the Horse and Learning to Read the Horse