Principal Scientist Merck Animal Health Elkhorn, NE, United States
Abstract:
Background: Canine infectious respiratory disease complex is a highly contagious disease caused by multiple bacterial and viral pathogens. A combination oral vaccine containing an attenuated strain of Bordetella bronchiseptica and a modified live strain of canine parainfluenza virus (CPI) has recently been introduced to the market to provide broader protection against the disease complex.
Objective: The duration of immunity was determined in dogs following challenge with virulent CPI one year after vaccination. Animals: Forty-six, 7-week-old antibody profile defined purpose-bred beagles were used in the study.
Methods: Dogs were randomly assigned to 2 treatment groups. On study day 0, dogs were orally vaccinated with either a placebo vaccine (n=23) or the bivalent test vaccine (n=23). Neutralizing CPI antibody titers were evaluated throughout the study. One year following vaccination, all dogs were challenged with virulent CPI by the intranasal route. Following challenge, dogs were observed for 14 days for clinical signs of disease, and nasal swabs were collected for 10 days to evaluate duration of shedding.
Results: The median duration of CPI viral shedding in the placebo-vaccinated control group was 6 days, which was significantly longer than the 1 day observed in the vaccinated treatment group (p = 0.001). In addition, the vaccinated treatment group demonstrated significant reduction in viral load.
Conclusions: Oral vaccination with a combination oral vaccine containing Bordetella bronchiseptica and CPI is effective at significantly reducing CPI viral shedding at least one year following vaccination.
