Canine distemper virus (CDV) induces a highly contagious, systemic, and often fatal disease in domestic dogs as well as in a broad, and seemingly expanding, range of wild carnivore species. Modified live-attenuated CDV vaccines are available for use in dogs and in general, they efficiently induce protective immunity. However, even in domestic dog populations in which a broad vaccination coverage is maintained, sporadic cases and outbreaks of canine distemper occasionally occur. Therefore, the examination of the CDV antibody in dog blood is very important to determine the ideal time point for vaccination of a pup, to evaluate vaccination success, and to determine the diagnosis and prognosis of acute CDV infections.