Giovanni Di Guardo , DVM, Dipl. ECVP, Former Professor of General Pathology and Veterinary Pathophysiology , University of Teramo, Faculty of Veterinary Medicine, Località Piano d'Accio, 64100 Teramo, ItalySante Roperto , DVM, PhD, Professor of Infectious Diseases, Department of Veterinary Medicine and Animal Productions, , Department of Veterinary Medicine and Animal Productions, University of Naples ‘Federico II’, 80137 Naples, Italy