Canine parvovirus (CPV2) infection is a major disease of dogs, especially when it spreads in kennels where it results in a high morbidity (up to 100%) and mortality in pups. Following an outbreak in the State kennel of Bizerte, Tunisia, in 1999 which lead to a mortality of 100% of newborn pups, an intensive vaccination program using a highly titrated parvovirus modified live (MLV) vaccine (Primodog^TM, Merial) was successfully implemented, with four successive injections between week 6 and 9 (Touzani et al, 2000), followed by two injections of a normotitrated parvovirus vaccine (Parvodog^TM) at week 10 and 11.

The aim of this trial was to test in the same environment a lightened vaccination protocol based on the same highly titrated CPV2 vaccine (Primodog^TM). Along the former protocol, 28 pups from 4 litters were separated and vaccinated at 4 and 6 weeks of age followed by a vaccination with a combo Distemper, Adenovirus, Parvovirus and Parainfluenza vaccine (Eurican^TM DHPPI2, Merial) at 8 and 10 weeks of age. 5 pups, one to two in each litter, were not vaccinated and kept as sentinels.

Seroconversion was followed by bi-weekly blood testing up to 14 week of age using the Hemagglutination Inhibition test (HAI). Titres were expressed as the last dilution where complete agglutination was inhibited. At day of first vaccination (W4), the mean CPV2 titre, reflecting maternal derived antibodies, was 59.15 (sd = 35.88). After two weeks (W6), 33% of the dogs had shown seroconversion and after 4 weeks (W8), 63% of dogs had seroconverted. At 12 weeks of age (8 weeks after start of the vaccination protocol), 100% of the dogs had seroconverted with all pups displaying an antibody titer higher than the usually accepted protective titre of 160. Average titre was 4437 [1024-8192]. These results were comparable with those from the above described Touzani protocol.

The use of a lightened vaccination protocol with a highly titrated MLV vaccine against CPV2 starting at 4 weeks of age together with appropriate sanitary measures should allow controlling effectively the spread and the clinical expression of the disease in a contaminated environment. Implementing vaccination from 5 weeks of age may also be considered, in order to increase efficiency of first vaccination.