A Preliminary Protocol of Radiographic Image Processing for Quantifying the Severity of Equine Osteoarthritis in the Field: A Model of Bone Spavin

Abstract

Osteoarthritis (OA) of the tarsal joint, also known as bone spavin, is a progressive joint disease that increases in severity with age. It is a significant cause of hind limb lameness, leading to a deterioration in the quality of life of horses, particularly in old age. In this study, the tarsal joints of 20 older horses aged 15 to 35 years were radiographically imaged and processed using the computed digital absorptiometry (CDA) method for bone mineral density (BMD) assessment. The radiological signs of bone spavin were scored on a scale ranging from normal (0) to severe OA (3), and the examined joints were grouped according to the severity of OA. The percentage of color pixels (%color pixels), representing successive steps on the scale of X-ray absorption by a density standard, differed between the steps in a BMD characteristic manner for each group. Furthermore, two examined ranges of relative density allowed for the distinction of joints affected by severe OA from other joints, while another two ranges allowed for the differentiation of joints affected by moderate and severe OA from normal joints. The proposed color annotation-assisted decomposition of radiological images based on the CDA protocol shows promise for advancing research on the quantification of radiological signs of OA. This approach could be valuable for monitoring the progression of the disease in older horses.