The present work deals with the use of previously tetanus immunized horses for preparation of rabies
antiserum in addition to investigate the effect of simultaneous immunization of horses against rabies
and tetanus in order to prepare a bivalent anti-rabies and tetanus serum. The obtained results of applied
serological tests revealed that the presence of tetanus antibodies in previously immunized horses did not
affect the levels of induced rabies antibodies while simultaneous immunization resulted in high titers of
rabies antibodies (256 IU/ml) as compared to such titers resulted in horses immunized with rabies
vaccine alone (128 IU/ml). These findings suggest an enhancing action of tetanus antigen on antibody
response against rabies and the prepared anti-serum can be used in emergency bite injuries in animals
protecting them against both of rabies and tetanus infections as noticed in experimentally rabies infected
mice.