ECFR pet food drug product FDCA

The Federal Food, Drug, and Cosmetic Act draws the food/drug line that FDA uses for pet food enforcement. FDCA §201(g)(1) (21 U.S.C. 321(g)(1)) defines 'drug' to include articles 'intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease in man or other animals'. A pet food or pet supplement that makes disease-treatment or prevention claims (e.g., 'treats joint disease', 'cures kidney disease') is therefore a drug, not a food, and requires a New Animal Drug Application (NADA) approval under 21 CFR part 514 (New Animal Drug Applications) before marketing — covering safety, effectiveness, labeling, and manufacturing for the target species and indications; 21 CFR 514.80 additionally imposes post-approval records and reporting (pharmacovigilance) obligations. Marketing an unapproved new animal drug renders the product adulterated and the labeling misbranded. This intended-use distinction is FDA's primary enforcement lever against therapeutic claims on pet foods and supplements: the same product can be a food when labeled with ordinary nutrition/structure statements and an unapproved drug when labeled with disease claims. (Earlier version's numeric example — 'alpha-casozepine 75 mg/day' calming-claim threshold — has no basis in project sources or the cited statutes and was removed.)