Influence of age and vaccination interval on canine parvovirus, distemper virus, and adenovirus serum antibody titers.

Canine core vaccine titer screenings are becoming increasingly popular in veterinary practice as a tool to guide vaccination decisions, despite a lack of supportive, peer-reviewed evidence-based literature. Additionally, it has been suggested that the canine core vaccine duration of host protective immunity can persist past the currently recommended vaccination interval. Thus, this study evaluated serum antibody titers against three core antigens in dogs with known vaccination histories and lifestyles, analyzing the effect of life stage, exposure risk, and time since last vaccination (TSLV). Clinically healthy dogs (n = 188) presenting to the primary care services of three colleges of veterinary medicine were selected to represent a variety of ages, breeds, and vaccination history. Serum antibody titers for canine parvovirus (CPV), canine distemper virus (CDV), and canine adenovirus-2 (CAV2) were measured via virus neutralization and hemagglutination inhibition. CAV2 and CPV titers decreased, while CDV titers had a decreasing trend with increasing time since last vaccination or vaccination interval. When assessing circulating antibody levels historially associated with protective immunity across various vaccination intervals, 62% (95%CI 36-82%; 8/13) of dogs had positive titers for CDV 5 years post last vaccination, while 92% (95%CI 67-99%; 12/13) of dogs were positive for CAV2 and CPV. Both advanced age and life stage were associated with lower titers and thus, identify a canine population cohort likely at higher disease risk. The results of this study revealed that patient duration of core vaccine-mediated immunity changes with a number of variables, with animal aging and time since vaccination influencing host humoral immunity. This provides further support for the performance of canine core antibody titers to assess whether a vaccine booster and/or specific type of booster is warranted.