Pastruella multocida is a mucosal pathogen that colonizes the upper respiratory tract of rabbits. Respiratory infections can result, but also the bacteria can invade the circulatory system producing abscesses or septicemia. Pasteurella mulocida (P.multocida) produce extracelluler sialidase that encode enzymes which is believed to augment colonization of the respiratory tract and the production of lesions in the active infection. The recombinant antigen enzyme-linked immunosorbent assay (ELISA) based on the sialidas enzyme of P.multocida and rabbits that were experimentally colonized with P.multocida produce detectable immunoglobulin (IgM) and (IgG) in serum, although they demonstrated no clinical signs of pasteurellosis. In addition clinically ill pet rabbits infected with P.multocida possessed IgM and/orIgG antibody against sialides. The sialides ELISA may be useful for the diagnosis of P.mulocida infection in sick rabbits as well as for screening for carriers rabbits.