Abstract: The invention relates to a synergistic veterinary composition and/or a fodder premix useful for preventing or curing bacterial, fungal and protozoic infection particularly occurring at poultry species. Furthermore the invention relates to a process for preparing same. The composition or premix contains 1 to 100 parts by mass of 2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidine and/or 1 to 100 parts by mass of 2,4-diamino-5-(3,4-dimethoxybenzyl)pyrimidine as well as 1 to 100 parts by mass of 2,6-dimethoxy-4-sulfanilamidopyrimidine or a pharmaceutically acceptable salt thereof and 1 to 100 parts by mass of 8-hydroxyquinoline or a pharmaceutically acceptable acid addition salt thereof optionally in admixture with carrier(s) and/or additive(s) commonly used in the pharmaceutical industry or for the preparation of premixes.