1. School of Biosciences and Veterinary Medicine, University of Camerino, Via Circonvallazione 93/95, 62024 Matelica, Italy.
2. College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA 50011-1134, USA.
3. Gastroenterology & Hepatology Section, Department of Medicine, University of Perugia Medical School, Santa Maria della Misericordia Hospital, Piazzale Menghini 1, 06156 Perugia, Italy.
4. Clinic ‘St. Antonio’, Strada Statale 415, km 38,50, 26020 Madignano (CR), Italy.
5. Gastrointestinal Laboratory, Texas A&M University, College Station 4474, 77843 TX, USA.