1. Pferdeklinik am Kottenforst; Wachtberg; Germany
2. Rood and Riddle Equine Hospital; Lexington; Kentucky; USA
3. Department for Medical Biometry; Informatics and ; Epidemiology; Medical School, University of Bonn; Bonn; Germany
4. Equine Reproduction Unit; Clinic for Horses; Freie Universität Berlin; Berlin; Germany