1. Veterinary Epidemiology Unit, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
2. A7 Noord Dierenartsen, 9207 JA Drachten, The Netherlands
3. MSD Animal Health, Wim de Körverstraat 35, 5831 AN Boxmeer, The Netherlands