Correlation of prostaglandin E2 concentrations in synovial fluid with ground reaction forces and clinical variables for pain or inflammation in dogs with osteoarthritis induced by transection of the cranial cruciate ligament

Objective - To evaluate the temporal pattern of prostaglandin (PG) E₂ concentrations in synovial fluid after transection of the cranial cruciate ligament (CCL) in dogs and to correlate PGE₂ concentrations with ground reaction forces and subjective clinical variables for lameness or pain. Animals - 19 purpose-bred adult male Walker Hounds. Procedure - Force plate measurements, subjective clinical analysis of pain or lameness, and samples of synovial fluid were obtained before (baseline) and at various time points after arthroscopic transection of the right CCL. Concentrations of PGE₂ were measured in synovial fluid samples, and the PGE₂ concentrations were correlated with ground reaction forces and clinical variables. Results - The PGE₂ concentration increased significantly above the baseline value throughout the entire study, peaking 14 days after transection. Peak vertical force and vertical impulse significantly decreased by day 14 after transection, followed by an increase over time without returning to baseline values. All clinical variables (eg, lameness, degree of weight bearing, joint extension, cumulative pain score, effusion score, and total protein content of synovial fluid, except for WBC count in synovial fluid) increased significantly above baseline values. Significant negative correlations were detected between PGE₂ concentrations and peak vertical force (r, -0.5720) and vertical impute (r, -0.4618), and significant positive correlations were detected between PGE₂ concentrations and the subjective lameness score (r, 0.5016) and effusion score (r, 0.6817). Conclusions and Clinical Relevance - Assessment of the acute inflammatory process by measurement of PGE₂ concentrations in synovial fluid may be correlated with the amount of pain or lameness in dogs.