RESUMO
Secondary osteoarthritis (OA) is a slow progressive, common disorder of synovial joints in dogs. It is characterized by a loss of balance between the synthesis and degeneration of articular cartilage components. Its diagnosis is currently based on the presence of clear radiographic changes, which only occur in the later stages of the disease. Hence, early diagnosis of OA remains a major problem. Therefore, interest in synovial fluid (SF) biomarkers has emerged. Besides pro-inflammatory and degenerative markers, i.e. tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta), tenascin-c (TN-C) and matrix metalloproteinase-2 (MMP-2), metabolic parameters, i.e. pH, glucose and lactate, can potentially be used to detect OA. The current study demonstrated statistically significant differences in the SF levels of pH, glucose and lactate between OA-affected and normal joints. In addition, the in-house validated immuno-assays for TNF-alpha, IL-1beta, TN-C and MMP-2 allowed to demonstrate also statistically significant differences in the SF concentrations for all these biomarkers - except TNF-alpha - between OA-affected and normal joints. However, no correlation was found between any of these biomarkers and the currently used radiographic scoring system for OA in dogs. Future research is warranted to explore the potential of these biomarkers in the early detection of OA and in the severity characterization of this disease.