Blood samples from 105 northern pintails (Anas acuta) captured on Hokkaido, Japan were tested for antibodies to avian influenza virus (AIV), Japanese encephalitis virus (JEV), and West Nile virus (WNV) to assess possible involvement of this species in the spread of economically important and potentially zoonotic pathogens. Antibodies to AIV were detected in 64 of 105 samples (61%). Of the 64 positives, 95% and 81% inhibited agglutination of two different H5 AIV antigens (H5N1 and H5N9), respectively. Antibodies to JEV and WNV were detected in five (5%) and none of the samples, respectively. Results provide evidence for prior exposure of migrating northern pintails to H5 AIV which could have implications for viral shedding and disease occurrence. Results also provide evidence for limited involvement of this species in the transmission and spread of flaviviruses during spring migration.

Objective: To determine the pharmacokinetic properties of 1 IM injection of ceftiofur crystalline-free acid (CCFA) in American black ducks (Anas rubripes). Animals: 20 adult American black ducks (6 in a preliminary experiment and 14 in a primary experiment). Procedures: Dose and route of administration of CCFA for the primary experiment were determined in a preliminary experiment. In the primary experiment, CCFA (10 mg/kg, IM) was administered to ducks. Ducks were allocated into 2 groups, and blood samples were obtained 0.25, 0.5, 1, 2, 4, 8, 12, 48, 96, 144, 192, and 240 hours or 0.25, 0.5, 1, 2, 4, 8, 24, 72, 120, 168, and 216 hours after administration of CCFA. Plasma concentrations of ceftiofur free acid equivalents (CFAEs) were determined by use of high-performance liquid chromatography. Data were evaluated by use of a naive pooled-data approach. Results: The area under the plasma concentration versus time curve from 0 hours to infinity was 783 h•μg/mL, maximum plasma concentration observed was 13.1 μg/mL, time to maximum plasma concentration observed was 24 hours, terminal phase half-life was 32.0 hours, time that concentrations of CFAEs were higher than the minimum inhibitory concentration (1.0 μg/mL) for many pathogens of birds was 123 hours, and time that concentrations of CFAEs were higher than the target plasma concentration (4.0 μg/mL) was 73.3 hours. Conclusions and Clinical Relevance: On the basis of the time that CFAE concentrations were higher than the target plasma concentration, a dosing interval of 3 days can be recommended for future multidose CCFA studies.