[1] Univ Nebraska Lincoln, Nebraska Vet Diagnost Ctr, Sch Vet Med & Biomed Sci, Lincoln, NE USA
[2] Univ Calif Davis, Dept Pathol Microbiol & Immunol, Calif Anim Hlth & Food Safety Lab Syst, Sch Vet Med, 620 W Hlth Sci Dr, Davis, CA 95616 USA
[3] Univ Calif Davis, Dept Populat Hlth & Reprod, Sch Vet Med, 1 Shields Ave,VM3B, Davis, CA 95616 USA