Acta Vet. Brno 2007, 76: 87-95

Diagnostic Value of MMP-2 and MMP-9 in Synovial Fluid for Identifying Osteoarthritis in the Distal Interphalangeal Joint in Horses

P. Zrimšek, V. Kadunc Kos, J. Mrkun, M. Kosec

Clinic for Reproduction and Horses, Veterinary Faculty, University of Ljubljana, Slovenia

Received July 14, 2005
Accepted September 5, 2006

Our aim was to examine the diagnostic potential of matrix metalloproteinases MMP-2 and MMP-9 for identifying osteoarthritis in the horse. Horses were divided into two groups - a positive group consisting of 28 horses with cartilage damage in the distal interphalangeal joint and a negative group of 17 control horses. Clinical examination of the horses included evaluation of lameness, flexion test, diagnostic nerve blocks, X-ray and arthroscopy. MMP-2 and MMP-9 were detected in synovial fluid using gelatin zymography. Monomers of MMP-2 and MMP-9 appeared not to be specific for osteoarthritis since they also occurred in control samples. In contrast, detection of active forms of MMPs was found to be more effective than radiological examination in identifying horses with osteoarthritis, on the grounds of higher sensitivity. Active forms of MMP-2 and MMP-9 were observed with 88.24% and 82.35% specificity respectively, indicating the high accuracy in correctly identifying horses without osteoarthritis. Thus, as an addition to clinical examination, detection of MMPs could improve the diagnosis of osteoarthritis. Detection of active forms of MMP-2 and MMP-9 was evaluated as an additional diagnostic tool in diagnosing osteoarthritis, especially in the case of a negative X-ray result. The proportions of animals with confirmed osteoarthritis, which tested positive, were found to be 81.82% and 76.92%, respectively. The results of this study confirm that active forms of MMP occur in synovial fluid of osteoarthritic joints more frequently than in synovial fluid from normal joints of the horse. Detection of active forms of MMP-2 and MMP-9 is shown to have an important diagnostic potential.