Abstract

Canine distemper and parvovirus infections are amongst the most important infectious diseases of dogs. Recently, the range of reports of vaccinated dogs that developed canine distemper and parvovirus infections have multiplied throughout the world. The goals of this study were to evaluate the immune and hematological responses against canine distemper virus (CDV) and canine parvovirus (CPV) after vaccination using two commercially available vaccines. In addition, the antigenic differences between the vaccine strains of CDV and CPV and the current wild-type strains were analyzed to determine possible relationships between these vaccine strains and recent field outbreaks in vaccinated populations. The immune response of both vaccines was determined using serum neutralization and Dot-ELISA. Specific neutralizing antibodies against canine distemper and parvovirus were present in the sera of dogs three weeks after the initial vaccination for both vaccines. Peak antibody titers were documented from the second-month post-vaccination. Both vaccines were demonstrated to be safe and stimulate a humoral immune response. Results of the serum neutralization test and Dot-ELISA were closely similar and correlated with each other. Genetic variations between strains included in both commercial vaccines and circulating wild-type strains suggest that variant strains are most likely responsible for field outbreaks of CDV and CPV in vaccinated dogs.