[1] Univ Calif Davis, Vet Med Teaching Hosp, Sch Vet Med, Davis, CA USA
[2] Univ Calif Davis, Sch Vet Med, Dept Pathol Microbiol & Immunol, Davis, CA USA
[3] Washington State Univ, Washington Anim Dis Diagnost Lab, Pullman, WA USA
[4] Univ Florida, Coll Vet Med, Dept Comparat Diagnost & Prevent Med, Gainesville, FL USA
[5] Univ Calif Davis, Sch Vet Med, Dept Pathol Microbiol & Immunol, Davis, CA 95616 USA