1. Department of Veterinary Clinical Sciences, University of Bologna, Via Tolara di Sopra 50, 40064 Ozzano, Emilia, Italy
2. CEA, Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle D'Aosta, Torino, Italy
3. Institute of Animal Neurology, University of Berne, Switzerland