The new antibiotics regulations will require pig farmers to have a valid veterinary-client-patient relationship. To know if your state or federal definition of a VCPR prevails, review the table in the above link.
The final rule by FDA was published on June 2, 2015. The link above provides links to the meaning of this regulation, Q&A and more.
List of Antibiotic Compounds Affected by New FDA Regulation
This link to the U.S. Food and Drug Administration goes into the details (see Appendix A) of what antimicrobial drugs will be affected by a new veterinary feed directive rule that is scheduled to go into effect in December 2016. Check with your veterinarian, feed manufacturer or pharmaceutical representative for more information regarding how specific antibiotic products and their uses may be affected.