1. Clinic for Small Animals; Freie Universität Berlin, Oertzenweg 19b; D-14163 Berlin
2. Federal Institute for Risk AssessmentDiedersdorfer Weg 1, D-12277 Berlin; Germany
3. Institute for Veterinary Pathology; Freie Universität Berlin, Robert-von-Ostertag-Str. 15, D-14163 Berlin; Germany