1. Department of Veterinary Clinical Sciences; Section for Veterinary Reproduction and Obstetrics; University of Copenhagen; Frederiksberg C Denmark
2. Department of Veterinary Clinical Sciences; Clinic for Obstetrics, Gynecology and Andrology of Large and Small Animals; Justus-Liebig University; Giessen Germany
3. Institute for Hygiene and Infectious Diseases of Animals; Justus-Liebig University; Giessen Germany