New immunological bioactive parameters are needed for the early detection of arthritis in foals. A total number of 90 serum and synovial fluid samples were collected from clinically normal foals (20), suspected foals (43) and foals showing signs of clinical arthritis (27) for the measurement of haptoglobin (Hp), serum amyloid A(SAA) and Cyclooxygenase-2 (COX2)
concentrations .The level of Synovial fluid Hp recorded a significant elevation (P<0.05) in foals showing signs of clinical arthritis. Meanwhile its elevation wasn't significant in the suspected foals. At the same time, the serum Hp levels did not record a significant elevation for both groups. A significant increase in the levels of serum and synovial fluid SAA
concentration for both suspected foals and foals showing signs of clinical arthritis. The levels of COX2 displayed a significant increase in serum and synovial fluid of both suspected foals and foals showing signs of clinical arthritis. Additionally, a strong positive correlation between COX2 concentration in synovial fluid and its concentration in blood at. 0.985 On the similar ground a positive correlation at 0.983 was found between SAA concentration in synovial fluid and its concentration in blood. It was concluded thatCOX2 and SAA have a potential usefulness as inflammatory markers in horses, showing joint inflammation, when their concentrations are measured either in synovial fluid or in blood serum