Radiographic examination of the equine thoracolumbar spine

The most common indication for obtaining radiographs of the equine thoracolumbar spine is ‘back pain’. This is commonly a result of impingement of the dorsal spinous processes, or less commonly because of osteoarthritis of the facet joints. Horses are commonly presented because of poor performance, bucking or altered gait, with most horses having a chronic history – in rare occasions, some are presented with acute signs after trauma.

Clinical signs of back pain besides pain on palpation include reduced flexion and extension of the spine, stiffness and alteration of gait (Denoix and Dyson, 2011). Distinguishing between primary back pain and secondary back pain, the latter as a consequence of lameness, might not always be straightforward and a thorough clinical examination should be performed before diagnostic imaging is considered. Therefore, a full lameness examination is advised to localise the cause of any clinical signs.

Radiographs of the thoracolumbar spine might also be taken as part of the radiographic examination during pre-purchase examinations. However, due to the limited scientific evidence of correlations between radiographic findings and clinical signs, the Federation of European Equine Veterinary Associations does not recommend this (Federation of European Equine Veterinary Associations, 2018). Furthermore, the German Equine Veterinary Association has recently removed the radiographic examination of the thoracolumbar spine from their radiographic guidelines during pre-purchase examination (German Equine Veterinary Association, 2018). Intra- and inter-observer agreements vary for different parameters and the wide variety of scoring systems should be kept in mind when evaluating radiographs, especially in sound horses (Looijen et al, 2022).