Concentration of the CS-846 Epitope in Serum and Synovial Fluid of Horses with Different Grades of Osteochondral Fragments in the Carpal Joints

The aim of this study was to determine serum and synovial concentrations of the CS-846 epitope of articular cartilage aggrecan, in horses with a radiological diagnosis of osteochondral fragmentation (OF). For this purpose, 20 thoroughbred horses with unilateral radiocarpal or intercarpal OF were used, and 10 clinically and radiologically healthy Thoroughbred horses were assigned to the control group. Serum and synovial concentrations of the CS-846 epitope were measured in both groups by means of ELISA. The concentration of the CS-846 epitope in synovial fluid was significantly higher in carpal joints with moderate articular damage (grade 2 OF) than in the control group or in horses with severe disease (grade 3 and 4 OF). In serum, non-statistical differences in the concentration of the CS-846 epitope were observed between horses with OF and controls. We conclude that the concentration of CS-846 epitope in synovial fluid suggests an increase in cartilage aggrecan synthesis, which may be associated with the presence of moderate clinical disease. The CS-846 epitope concentration in synovial fluid may be a useful biomarker for the study of carpal OF in horses, providing a measure of the balance between cartilage synthesis and degradation in this equine disease.