A bipartisan group of senators led by Sen. Dianne Feinstein (D-CA) recently re-introduced the Preservation of Antibiotics for Medical Treatment Act (PAMTA) to curb the use of antibiotics in animals. Feinstein and Rep. Louise Slaughter (D-NY), who authored the bill and introduced a parallel House version, say that the livestock industry’s use of antibiotics has contributed to the evolution of treatment-resistant “superbugs.” The new bill would phase out all subtherapeutic use—small doses administered to an entire herd or flock to promote growth and prevent disease, as opposed to larger, therapeutic doses used to cure disease in individual animals—and raise the bar for Food and Drug Administration (FDA) applications for new animal antibiotics. A previous version of PAMTA stalled last year with only seven co-sponsors in the Senate, but this year’s bill has garnered 17 co-sponsors and the House version has earned 60, suggesting an increase in momentum for the measure.

A lawsuit filed in May by the National Resources Defense Council and other environmental groups would accomplish largely the same effect by forcing the FDA to make new rules limiting the use of antibiotics in animals. The suit alleges that the FDA has failed to exercise its statutory authority and asks that the agency revoke its approval for subtherapeutic doses of penicillins and tetracyclines, two common antibiotics. A similar suit against the Environmental Protection Agency (EPA) led to Massachusetts v. EPA, a landmark 2007 decision by the Supreme Court that increased pressure on the agency to regulate carbon dioxide emissions.

On its own initiative, the FDA is preparing new guidance on the use of antibiotics in livestock. FDA Draft Guidance #209, Judicious Use of Antimicrobial Drugs in Food-Producing Animals, released for public comment in July 2010, encourages the livestock industry to voluntarily reduce its use of antibiotics. Although the guidance would have no force of law by its own accord, it could signal the agency’s direction on the issue. A finalized document is expected to issue sometime before the end of 2011.