1. Department of Comparative Pathology, Veterinary Faculty, University of Las Palmas de Gran Canaria. Trasmontana, 35416 Arucas, Las Palmas de Gran Canaria, Spain
2. Department of Anatomy and Comparative Pathology, Veterinary Faculty, University of Córdoba, Avda Medina Azhara s/n, 14005-Códoba, Spain
3. Department of Pathology, New York State College of Veterinary Medicine, S2 110 Schurman Hall, Cornell University, Ithaca, New York 14853, USA
4. Department of Pharmacology and Pathobiology, Royal Veterinary and Agricultural University, 17 Bülowsvej, DK-1870 Frederiksberg C, Denmark