1. Department of Clinical Veterinary Medicine, Vetsuisse Faculty; University of Bern; 3012 Bern Switzerland
2. Medizinische Kleintierklinik; Ludwig-Maximilians-Universität Munich; 80539 Munich Germany
3. Small Animal Internal Medicine, VetAgro Sup, Research Unit RS2GP, USC 1233; University of Lyon; 69280 Marcy l'Etoile France
4. Clinic for Small Animals, Faculty of Veterinary Medicine; Freie Universität Berlin; 14163 Berlin Germany
5. Bacterial Diseases of Livestock Research Unit, National Animal Disease Center, Agricultural Research Service; United States Department of Agriculture; Ames IA 50010 USA
6. Department of Medicine & Epidemiology; University of California; Davis CA 95616 USA