[1] Univ Bern, Vetsuisse Fac, Inst Anim Pathol, Bern, Switzerland
[2] Univ Zurich, Inst Vet Pathol, Zurich, Switzerland
[3] Univ Zurich, Div Swine Med, Zurich, Switzerland
[4] Univ Zurich, Inst Vet Pharmacol & Toxicol, Vetsuisse Fac, Zurich, Switzerland