Federal Register Final rule: FDA is amending the animal drug regulations to reflect approval of two Bayer Healthcare NADAs that provide for the topical use by veterinary prescription of topical solutions containing imidacloprid and two strengths of moxidectin, one for use on dogs and the other for use on cats, for preventing heartworm disease, treating flea infestations, and treating and controlling several internal parasites. To view this final rule, click here.