Jaap E. Van Dijk, DVM, Dipl. ECVO, PhD, Emeritus Professor, Veterinary Pathology, Department Pathobiology, Faculty of Veterinary Medicine, Utrecht University, The Netherlands; Erik Gruys, DVM, Dipl. ECVP, PhD, Emeritus Professor, Veterinary Pathology, Department Pathobiology, Faculty of Veterinary Medicine, Utrecht University, The Netherlands; and Johan M. V. M. Mouwen, DVM, Dipl. ECVP, PhD, Emeritus Professor, Veterinary Pathology, Department Pathobiology, Faculty of Veterinary Medicine, Utrecht University, The Netherlands