Abstract
Two hundred and twenty‐four dogs with clinical signs of distemper were examined for the presence of canine distemper virus (CDV) in mucous membranes by direct immunofluorescence assay. The study showed that 22% of the animals were CDV‐positive. Most (33/50; 66%) of the infected dogs had never been vaccinated against distemper, whereas only 11 of 50 (22%) CDV‐positive animals were immunized at least once. The difference in the infection rate between vaccinated and unvaccinated animals was statistically significant (P < 0.001), as assessed by the χ2 test. It is concluded that distemper is an important disease among dogs in Warsaw and the vaccination significantly reduces the risk of this disease.