Hyaluronate and large molecular weight proteoglycans in synovial fluid from horses with various arthritides

OBJECTIVE: To investigate the presence of large molecular weight (MW) proteoglycans (PG) and hyaluronate (HA) in synovial fluid (SF) from horses with various arthritides and from control joints. DESIGN: Horses with acute (< 2 weeks) or chronic (> 4 weeks) lameness were examined by clinical examination, intrasynovial anesthesia, radiography, arthroscopy, and SF analysis. Joints were grouped on the basis of diagnosis: acute traumatic arthritis, chronic traumatic arthritis (with a subgroup of degenerative joint disease), intra-articular fracture, and infectious arthritis. ANIMALS: 31 horses with arthritis and 9 control horses; altogether 43 SF samples were analyzed. PROCEDURE: High-performance liquid chromatography was used to assess HA and large MW PG in SF samples. RESULTS: A PG peak was identified in 8 of 23 SF samples of joints with chronic traumatic arthritis, 4 of which had no or minimal abnormal radiographic findings but mild articular cartilage fibrillation detected by arthroscopy, and in 3 joints with intra-articular fracture and 1 with resolving infectious arthritis, but not in joints with acute traumatic arthritis or in control joints. There was significant difference (P < 0.01) in mean (+/- SEM) HA concentration between control joints and joints with chronic traumatic arthritis (0.32 +/- 0.04 g/L; n = 9 vs 0.18 +/- 0.01 g/L; n = 23). CONCLUSION: Large MW PG fragments are released into equine SF in the course of articular disease and can be detected simultaneously with HA by high-performance liquid chromatography. CLINICAL RELEVANCE: The SF HA concentration can be used as diagnostic marker for chronic traumatic arthritis. However, SF PG or other marker cannot be used for diagnosing or monitoring degenerative joint disease.