CLDN2 and pyometritis: The top five-upregulated genes in closed pyometra were LBP, CCL3, IL1B, CXCL10 and ITGAM; while in open pyometra were FABP3, IL7, TNC, SDC1 and CLDN2. With the aim of revealing potential biomarkers and therapeutic targets for closed pyometra, a gene set enrichment analysis by IPA was performed, revealing 21 genes exclusively expressed in closed pyometra (Table 4).