1. Department of Veterinary Clinical Pathology; Faculty of Veterinary Medicine; Federal University of Rio Grande do Sul; Avenida Bento Gonçalves 9090, CP 15094 Porto Alegre CEP 91540-000 Brazil
2. Department of Toxico-Pathology; National Institute of Animal Health; National Agricultural Research Organisation; 3-1-5 Kannondai Tsukuba Ibaraki 305-0856 Japan