Specific humoral response and effect on rectal temperature of two clostridial vaccines in lambs.

CLOSTRIDIAL diseases are a serious threat in sheep farming. As therapeutic treatment is considered ineffective, vaccination with multivalent clostridial vaccines is commonly applied (Brown and others 1976). A number of multivalent clostridial vaccines for sheep are commercially available in the EU. As with other bacterial vaccines, immunisation with multivalent clostridial vaccines may cause both local and systemic reactions (Green and others 1987, Schijns 2000). In cases of severe reactions, the growth of the animals might be negatively affected. Therefore, the safety of a clostridial vaccine may be an important parameter for both the veterinarian and the farmer when choosing a vaccine. The efficacy of a vaccine is the other important criterion when choosing a vaccine. The commercially available clostridial vaccines vary in their composition in terms of the Clostridium species included and the adjuvant, and they therefore differ considerably in efficacy against the various Clostridium species (Crichton and others 1986, Green and others 1987). The antibody response induced by a multivalent clostridial vaccine is generally accepted as an immunological marker for protection. All vaccines licensed for use in the EU have been tested for safety and efficacy, and the data from licensing studies are often in the public domain. However, a comparison of two products is possible only if they are tested side-by-side in the same study. In the present study, two multivalent clostridial vaccines were compared for systemic reactions in terms of rectal body temperatures, as well as the specific immune response, after their use in sheep. Fifty lambs of either sex, between two and three weeks of age and with a birthweight of at least 2.5 kg, were included in the study. All the animals were from dams that had not been vaccinated against clostridiosis. The lambs were randomly assigned to one of three treatments (vaccination …