[1] Univ Bern, Vetsuisse Fac, Inst Genet, CH-3001 Bern, Switzerland
[2] Univ Padua, Dept Vet Clin Sci, I-35100 Padua, Italy
[3] Univ Bologna, Vet Clin Dept, I-40126 Bologna, Italy
[4] Univ Padua, Dept Expt Biomed Sci, I-35100 Padua, Italy
[5] Univ Padua, Dept Expt Vet Sci, I-35100 Padua, Italy