1. Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St Paul, MN 55108
2. Department of Pathology, Case Western Reserve University, Cleveland, OH 44106-7288
3. Department of Medical Microbiology and Immunology, Creighton University, Omaha, NE 68178
4. Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St Paul, MN 55108
5. Diagnostic Medicine and Pathology, Kansas State University, Manhattan, KS 66505, USA