The present invention relates to polyclonal antibodies directed against at least one non-human biological pathogen, or against at least one molecule derived from said pathogen, towards a human or a non-human animal organism, wherein the said polyclonal antibodies are devoid of an antigenic determinant selected in a group comprising (i) N-glycolneuraminic acid (Neu5Gc) and/or (ii) a-1,3-galactose, and their use as a medicament.