1. Clinic for Small Animal Surgery and Reproduction; Ludwig-Maximilians-University; Veterinärstrasse 13 Munich 80539 Germany
2. Department for Basic Veterinary Sciences; Ludwig-Maximilians-University; Professor-Huber-Platz 2 Munich 80539 Germany
3. Small Animal Clinic; University of Veterinary Medicine of Hannover; Bünteweg 2 30559 Hannover Germany