1. Department of Clinical Sciences of Companion Animals; Faculty of Veterinary Medicine; Utrecht University; 3508TD P.O. Box 80154 Utrecht the Netherlands
2. Animal Breeding and Genomics Centre; Wageningen University; 6700AH P.O. Box 338 Wageningen the Netherlands
3. Department of Veterinary Clinical Sciences; School of Veterinary Medicine; Purdue University; West Lafayette IN 47907 USA