1. Department of Veterinary Medicine, University of Perugia, 06126 Perugia, Italy
2. Department of Veterinary Medicine and Animal Sciences, University of Milan, 26900 Lodi, Italy
3. Istituto Zooprofilattico Sperimentale dell’Umbria e delle Marche “Togo Rosati” (IZSUM), Via G. Salvemini 1, 06126 Perugia, Italy