The objective here was to evaluate the acute effects of induced
arthritis on synovial fluid (SF) levels of
matrix metalloproteinases (
MMP) -2, -8 and -9 in horses. To evaluate MMP-2 and -9 activities and the effect of non-steroidal anti-inflammatory
drug (
NSAID)
bufexamac during remission from acute
arthritis. Aseptic
arthritis was induced in 24 Standardbred horses using 20 mg of
amphotericin B as a single intra-articular (IA) injection in the right intercarpal joint. After 1 week and 2 weeks, horses were treated intra-articularly with 10, 20, or 40 mg of
bufexamac suspension or with sterile
saline solution as control. SF was sampled prior to induction and at weekly intervals for 5 weeks. Fluids were evaluated for MMP-2 and MMP-9 activity by
gelatin zymography or for MMP-8 immunoreactivity by Western Blotting. IA injection of
amphotericin B consistently resulted in significant increase in the immunoreactivity of MMP-8 and activity of both the latent and the active forms of MMP-2 and -9, among which the active form of MMP-2 increased the most. MMP-9 levels declined to pre-induction levels within 2 weeks, whereas levels of MMP-2 remained still high after 5 weeks. Treatment with
bufexamac did not significantly affect levels of gelatinolytic
MMP. Results suggest that after acute
arthritis of horses, elevated
MMP activity is present in the joint, for several weeks, to a degree that could promote cartilage degradation, and treatment with the
NSAID bufexamac is not likely to affect that. Furthermore, analysing levels of MMP-9 activity and especially levels of active forms of MMP-2 activity may be valuable to predict the time of occurrence of
arthritis in horses.