It's not always spavin or DIRT – other diseases on equine tarsus radiographs

The tarsal region is a common source of hindlimb lameness in horses. Radiographic evaluation remains the cornerstone of diagnosis, requiring precise limb positioning and inclusion of the distal tibia and proximal metatarsal bones. Standard projections can detect most pathology, but flexed or different angled projections should be considered for visualisation of specific structures. Developmental conditions such as incomplete ossification and osteochondrosis dissecans affecting the distal intermediate ridge of the tibia are well known. However, osteochondrosis can also affect other structures. Degenerative changes, notably osteoarthritis of the small tarsal joints (bone spavin), are one of the most common pathologies of the tarsal area. However, in rare cases, osteoarthritis of the talocalcaneal or tarsocrural joint might be diagnosed. Fractures of the small tarsal bones can be seen in horses of different disciplines. Radiographs provide indirect evidence of soft tissue pathology, such as synovial effusion, and help to detect secondary bone involvement. While a radiographic examination helps to reach a diagnosis in many cases, advanced imaging modalities, including computed tomography, are recommended for complex or inconclusive cases. Accurate interpretation of radiographic findings is essential for prognosis and management, given the intricate anatomy and diverse pathologies of the tarsal region.