Canine distemper virus neutralising antibodies in vaccinated dogs

The associations between the levels of canine distemper virus neutralising antibodies and vaccination history, age and gender were investigated in a c ross-sectional study of a sample of 4627 dogs from the Finnish urban dog po pulation. Dogs vaccinated with either Canlan (Langford Laboratories) or Doh yvac (Solvay Animal Health) or with both, had significantly lower titres th an those vaccinated with Candur (Behringwerke), Duramune (Fort Dodge Labora tories) or Nobivac (Intervet), or with combinations including at least one of these. The vaccines were classified as having low and high immunogenicit y on the basis of the geometric mean titre achieved by the vaccine when com pared with the geometric mean titre of the entire dataset. The low geometri c mean titre of Canlan, Dohyvac and their combination groups resulted from the large proportion of dogs without detectable titres, especially dogs und er one year of age, rather than from uniformly low titres. An age-stratifie d comparison of vaccine usage and titres showed that the division of the va ccines into low and high immunogenicity vaccines was apparent in the dogs l ess than two years of age but not in the older dogs. The first vaccination with the high immunogenicity vaccines resulted in a higher proportion of do gs with detectable antibodies than even repeated vaccination with the low i mmunogenicity vaccines. Neither the time elapsed since the most recent vacc ination nor the gender of the dogs was associated with the titre of antibod y.