Comparison of selected canine vaccines for their ability to induce protective immunity against canine parvovirus infection.

OBJECTIVE

To compare the ability of 6 commercially available multicomponent canine vaccines to stimulate antibody production in pups with variable amounts of maternally derived canine parvovirus (CPV) antibody and to induce protective immunity against challenge exposure.

ANIMALS

Sixty-three 5- to 6-week-old Beagle pups with passively acquired CPV antibody titer between 1: 20 and 1:320.

PROCEDURE

9 pups were assigned to each of 6 vaccine groups and 1 control group. Eight pups in each group were inoculated with vaccine or saline solution twice, with 3 weeks between administrations. The ninth pup served as an uninoculated contact control. Serum samples were obtained weekly and tested for CPV antibody by hemagglutination-inhibition assay. All pups were challenge exposed with virulent CPV-2a and CPV-2b at 14 to 15 weeks of age.

RESULTS

3 of the vaccines failed to provide protective immunity against challenge exposure because all pups in these groups became infected and most died. A fourth vaccine protected against death, but not infection and disease. Two of the 6 vaccines induced an immune response that was protective against infection and disease.

CONCLUSION AND CLINICAL RELEVANCE

Substantial differences existed among commercial vaccines available in 1994 in their ability to immunize pups with maternally derived CPV antibody. These differences caused many vaccinated pups to be susceptible to CPV disease for variable periods because some vaccines failed to immunize. Importantly, all 4 of the vaccines that performed poorly have recently been replaced by more effective products so that the 6 vaccines now perform similarly.