Wild and domestic animal populations are known to be sources and reservoirs of emerging diseases. Members of Pasteurellaceae cause an array of deadly illness including bacterial pneumonia known as "pasteurellosis", a particularly devastating disease for bighorn sheep. We analyzed the usefulness of rpoA, RNase P, sodA and hsp gene sequences for the identification of 16 unknown Pasteurella strains on the basis of Multilocus sequence analysis. The phylogenetic trees constructed with the different genetic loci were roughly in agreement with each other, including the 16S rRNA based phylogeny of Pasteurella spp and supported by Multi-gene phylogeny. The data generated in this study could also be alternative to 16S rRNA gene sequences. In all trees the unknown isolates formed a separate cluster and loosely related to each others, which suggests that these are new species and not related to known Pasteurella spp.