Prevalence of radiographic changes in the metacarpal and carpal bones of South African endurance horses

Abstract

This study investigated the presence and prevalence of radiographic changes in the carpus and proximal metacarpus of endurance horses in South Africa during the 2018 endurance season. These regions were identified as areas that are subjected to multiples stressors due to the high impact of the endurance discipline, and so radiographic changes were expected to be present. The metacarpi and carpi were digitally radiographed in a total of 100 endurance horses, registered with Endurance Ride Association of South Africa (ERASA) to compete in 2018. The standard views for each of these regions were taken, as well as one dorsal tangential view (dorsal 35° proximal dorsodistal oblique) of the carpi. The radiographs were evaluated individually by three experts, using Digital imaging and communications in medicine (DICOM) software and a consensus was used to confirm the presence of lesions. From the frequency of changes, the prevalence was calculated. Kappa statistics were used to calculate the Inter-rater reliability (IRR) and to determine the level of agreement between the analysers. The results of this study demonstrated more radiological changes in the carpi than in the metacarpi, and more changes seen on the left than the right forelimb, correlating with the most commonly clinically identified lame limb in endurance horses. In the carpus, the most prevalent changes included subchondral bone sclerosis of the third carpal bone (77%), a present first carpal bone (27%), carpal osteophytes (9%) and carpal enthesiophytes (8%). The most prevalent changes in the proximal metacarpus included endosteal new bone formation at the proximopalmar aspect of the third metacarpal bone (34%), synostosis between the second and third metacarpal bones (9%), and periosteal new bone formation on the second metacarpal bone in 9% of horses. A major downfall of this study was that it did not correlate the radiographic findings with signalment, endurance riding level or clinical significance. This study has provided a baseline of the prevalence of radiographic changes in the proximal metacarpi and carpi that future studies in the endurance discipline in South Africa can build upon.