[1] Univ Zurich, Clin Small Anim Internal Med, Vetsuisse Fac, CH-8057 Zurich, Switzerland
[2] Univ Bern, Inst Genet, Vetsuisse Fac, Bern, Switzerland
[3] Univ Bern, Dept Clin Vet Med, Dept Clin Vet Med, Bern, Switzerland
[4] Univ Zurich, Inst Vet Pathol, Vetsuisse Fac, CH-8057 Zurich, Switzerland