[1] Univ Liege, Fac Vet Med, Dept Small Anim Clin Sci, B-4000 Liege, Belgium
[2] Univ Liege, Fac Vet Med, Dept Genet, B-4000 Liege, Belgium
[3] Univ Liege, Fac Vet Med, Dept Immunol & Infect Dis, B-4000 Liege, Belgium
[4] Univ Zurich, Fac Vet Med, Dept Small Anim Med, Sect Reprod, CH-8006 Zurich, Switzerland
[5] Univ Bristol, Dept Vet Clin Sci, Bristol BS8 1TH, Avon, England
[6] Katholieke Univ Leuven, Lab Expt Otorhinolaryngol, Louvain, Belgium
[7] Univ Liege, Fac Med, B-4000 Liege, Belgium