1. Department of Histology and Pathological Anatomy; Veterinary Faculty; University of Las Palmas de Gran Canaria; C/Francisco Inglott Artiles 12A 35016 Las Palmas de Gran Canaria Spain
2. Institute of Pathology; Faculty of Veterinary Medicine; W-3000 Hannover Germany
3. Department of Pharmacology and Pathobiology; The Royal Veterinary and Agricultural University of Copenhagen; Frederiksberg C Denmark