2015 ACVIM Forum Research Abstract Program

Fifty-one, sixteen-week old Quarter Horse foals born to mares that had received a booster dose of a multicomponent vaccine during the last 2 months of gestation were randomized into five groups based on the pre-vaccination WNV IgG level determined by a WNV-IgG ELISA. The WNV assay has been described previously in detail for WNV-specific IgM detection using the antiequine IgM mAb. Here, an IgG1 mAb was used instead of anti-IgM to capture IgG1 from equine serum. ELISA results are expressed as P/N ratios. A non-vaccinated foal CONTROL group was included to confirm field exposure to WNV did not occur. The four vaccinated groups were designated Group A with pre-vaccination response <2, Group B with pre-vaccination response between 2 and 4, Group C with pre vaccination response between 4 and 8, and Group D with pre-vaccination response between 8 and 16. Foals were vaccinated on T17 and T21 and blood was drawn on week 16 (pre vaccination), then on weeks 19, 21, 22 and 24. A repeated measures analysis of variance was used to analyze the data where a covariance matrix with unequal variances and unequal correlations between the draw weeks. Statistical significance was determined at P ≤ 0.05.