Procalcitonin and carbonylated protein concentrations in equine synovial fluid

Early diagnosis of joint diseases is fundamental for prompt and appropriate management, particularly in septic arthritis. Procalcitonin (PCT) and protein carbonylated content (PCC) have been investigated in both human and veterinary medicine. An increase in PCT has been shown in infectious bacterial diseases, while higher levels of PCC have been shown in inflammatory pathologies characterized by oxidative damage. This study evaluated PCT and PCC in plasma and synovial fluid (SF), in healthy and pathological equine joints, affected by different types of arthropathy. Twenty-nine joints were evaluated and underwent orthopedic, radiographic, ultrasonographic and SF evaluation. The joints were divided in three groups: healthy, septic, and non-septic arthritis. PCT and PCC were measured in horse plasma and SF. Data distribution was evaluated and results were expressed as median, quartile values. Statistical differences in SF values among groups and correlations were assessed between plasma and SF of both PCT and PCC. The groups of joint disease included: 8/29 healthy, 13/29 non-septic and 8/29 septic. Significant differences were obtained for SF PCC and plasma PCT between healthy and septic joints, while no differences were found for plasma PCC and SF PCT. A positive correlation was found between plasma and SF PCT. To the best of our knowledge, this is the first study reporting PCT in equine SF. SF PCC could be a useful biomarker to differentiate between septic and healthy joints.