IL1RN and bacterial arthritis: However, neither MMP8 nor IL1RN mRNA transcripts met our criteria of the >3-fold difference between the minimal count value in the horses with septic arthritis at PID1 and horses post eradication of septic arthritis at PID4, and the >2-fold difference between the minimal count value in the horses with septic arthritis at PID1 and horses with experimentally induced non-septic synovitis at PID1, and are, therefore, not included in the list of putative mRNA biomarkers.