Introduction

Traditionally, bivalent canine leptospirosis vaccines containing strains from serogroups Icterohaemorrhagiae and Canicola have been used to immunise dogs. Over the last few years in the USA, there have been a number of tetravalent vaccines launched containing in addition, strains from serogroups Grippotyphosa and Pomona. In Europe, the epidemiological picture appears somewhat different with an increase in cases associated with serogroups Grippotyphosa and Australis.

This report describes the results of four challenge studies which demonstrate the ability of a new, tetravalent leptospirosis vaccine to prevent both disease and infection of dogs following challenge with strains from the four main European serogroups.

Materials and Methods

For each study two groups of conventional beagle dogs, free of serum antibodies against the four serogroups, were used. Two days prior to the date of first vaccination both groups received intravenous serum containing antibody against the four vaccine antigens in order to mimic the presence of maternal antibody. One group was subcutaneously vaccinated with the tetravalent Leptospirosis vaccine at the age of 6 and 10 weeks. The second group (control group) was left unvaccinated. All dogs were challenged at 13 weeks of age.

For four weeks following challenge, the dogs were evaluated for signs of clinical disease, the presence of thrombocytopenia, and the presence of challenge organisms in blood or urine. At the end of the study the kidneys were examined histopathologically for any evidence of interstitial nephritis and were cultured for evidence of renal infection.

Results

See Table.

Conclusion

Vaccination of passive antibody positive pups with a new tetravalent Leptospirosis vaccine is effective at preventing the signs of clinical disease and infection following challenge with strains from the four main serogroups associated with canine disease in Europe.