Longer-duration uses of tetracyclines and penicillins in U.S. food-producing animals: Indications and microbiologic effects

► U.S. approvals for tetracyclines and penicillins used ≥ 7 days in food animals. ► Majority of listed indications are for disease control or treatment. ► Early interruption of disease stages important for population animal health. ► Low-level exposures show limited increase in resistance, other microbiologic effects. ► Surveillance programs note stable trends, quantitative studies small risk probability.