1. Institute of Veterinary Physiology (M.O., T.A.L.), Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland
2. Clinic of Small Animal Internal Medicine (E.Z., M.H., C.E.R.), Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland
3. Institute of Virology (M.F., M.A.), Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland
4. Institute of Food, Nutrition and Health (C.W.), Swiss Federal Institute of Technology, 8603 Schwerzenbach, Switzerland
5. Institute of Veterinary Pathology (F.G.), Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland