The long-awaited guidance document has been in the works since 2022, and the final version changes how drugs used on farms are ranked based on their importance in human medicine.

That matters because when the same antibiotics used in hospitals also are put to work in animal agriculture, it can contribute to the development of resistant bacteria. That then can make it harder or impossible to treat infections in humans.

While the volume of medically important antibiotics used in animal agriculture dropped significantly in 2016 after the FDA banned the use of the drugs solely for growth promotion, widespread preventative use has continued. Sales of drugs recently increased, especially for use in cattle and pigs.