We found a positive correlation between active MMP-9 activities in the ileal mucosa and the CIBDAI score before treatment in dogs with CE, which is similar to the relationship between mucosal MMP-9 and the disease activity index in a rat model of colitis [31], and between fecal MMP-9 and clinical activities of ulcerative colitis in humans [32]. Here, MMP9 is linked to ulcerative colitis.