Several authors have shown that Matrix Metallo-Proteinases (MMP), and in particular MMP2 and MMP9, are implicated in cartilage degradation occurring in most joint diseases. The aim of this study was to compare MMP2 and 9 activities in synovial fluid (SF) from metacarpo-phalangeal (MP)-joint in healthy horses and in horses with a MP disease.

SF from healthy horses was collected by arthrocentesis immediately post-mortem in a slaughterhouse. SF from horses with a MP-joint disease was collected by arthrocenthesis in a veterinary clinic.

Samples were analysed by zymography. Briefly, it is an electrophoretic method with an incubation of gels at 37°C for 48h after migration. After coloration, gels were scanned and spots of lysis were measured with an informatic software.

Mean MMP2 and MMP9 activities (in Arbitrary Units of Lysis) in healthy horses and in horses with MP joint disease.

	Healthy MP Joints (n = 13)	Diseased MP Joints
MMP2	3789  319a	12329  2717b (n = 5)
MMP9	3490  1324a	15423  4971a (n = 4)
Data with different superscripts significantly differ, p<0.05

MMP2 activity is significantly higher in SF from diseased MP joints and MMP9 activity tends to be higher also although the differences did not reach significance (P= 0.059).

It appears thus that SF MMP2 and 9 activities are increased in diseased MP joints. Further studies are necessary to determine if the type of disease has an influence on MMP activities and correlate them with clinical signs and cartilage appearance and joint histology.