Circulating anti-Canine Parvovirus Antibody Titer Is Impacted by Colostrum Production in Breeding Bitches

This prospective study aimed to determine the impact of colostrogenesis on circulating serum titer against canine parvovirus (CPV-2) in the gravid bitch, and subsequent implications for timing of sample collection for nomograph analysis. CPV-2 is a deadly virus of global concern which mainly impacts susceptible puppies, inducing severe lymphopenia, gastroenteritis, and organ failure. Vaccinal blockade by maternally derived antibody is one of the main causes of modified-live CPV-2 vaccine “failure to immunize” in the puppy. Nomograph analysis intends to improve puppy immunization outcomes by providing a tailored vaccination schedule for a specific litter based on a conservative estimation of blockade length. To generate a nomograph, individual bitch antibody levels are determined and known half-life degradation is applied. The current study was undertaken to ensure optimal timing for serum sample collection to achieve the best diagnostic accuracy, and to prove our hypothesis that active transport and sequestration of immunoglobulin type G (IgG) specific for CPV-2 induces a temporary decline in circulating anti-CPV-2 antibody titer. Serum samples were collected from 56 pregnant beagle bitches at four timepoints: 4 weeks and 2 weeks pre-whelp, at whelp, and 2 weeks post-whelp. Sera were analyzed for specific antibody against CPV-2 by hemagglutination inhibition assay (HIA). Geometric mean titer values were statistically analyzed via repeated measures, one-way analysis of variance (ANOVA) test and Tukey’s multiple comparisons <i>post hoc </i>correction, with p-value set at <0.05. Seven of the 56 bitches (12.5%) showed a significant decrease in circulating anti-parvovirus titer at whelp (p<0.0001). These results prove our hypothesis and indicate that serum for titer and nomograph analysis of breeding bitches should be collected outside of the colostrogenesis window for the greatest accuracy.