1. Department of Veterinary Pathology (B.P., N.C., D. G-T.), Department of Veterinary Clinical Sciences (J.C.), College of Veterinary Medicine, Iowa State University, Ames, IA; Department of Small Animal Medicine and Surgery (M.K., S.P., A.F.), Diagnostic Laboratory (U.B-M.), College of Veterinary Medicine, University of Georgia, Athens, GA; and Pathology & Infectious Diseases, The Royal Veterinary College, Herts, United Kingdom (B.S.).