On November 19, 2019, the U.S. Food and Drug Administration (FDA) released revised guidance concerning the compounding of animal drugs from bulk drug substances—in particular, the circumstances under which the FDA would not plan to take enforcement action for certain violations of the Federal Food, Drug, and Cosmetic Act (FDCA) when pharmacists and veterinarians compound or oversee the compounding of animal drugs from bulk drug substances. The guidance is intended to replace a withdrawn draft guidance concerning the compounding of animal drugs initially released in May 2015.