Section 530.21 - Prohibitions for food-producing animals(a) FDA may prohibit the extralabel use of an approved new animal or human drug or class of drugs in food-producing animals if FDA determines that: (1) An acceptable analytical method needs to be established and such method has not been established or cannot be established; or(2) The extralabel use of the drug or class of drugs presents a risk to the public health.(b) A prohibition may be a general ban on the extralabel use of the drug or class of drugs or may be limited to a specific species, indication, dosage form, route of administration, or combination of factors.