This paper thoroughly reviews the mechanism of veterinary drug carryover in feed manufacturing facilities, factors resulting in varying concentrations of drug carryover in processing equipment, the impact of chemical and physical properties of drugs, and the effect of equipment type and design. The Google Scholar database (from 1998 to 2023) was searched with words and phrases such as drug carryover, feed manufacturing, equipment cleaning and validation, food allergen control, sources of drug carryover, and process parameters in drug carryover. Some papers were from the Iowa State University Library database and PubMed. Drug carryover is a function of ingredients, nature of drugs, equipment type, process parameters, and cleaning procedures. The gaps are the lack of commercial feed mills data on the role and interaction of nanomaterials, molasses, equipment type, and process parameters in drug carryover in animal feed. Modification of process parameters, e.g., airflow in bucket elevators and the interaction of feed ingredients, composition, equipment type, and design, need to be investigated in the commercial setting to address drug carryover. Rhetorically, can big data facilitate the standardization of cleaning procedures at feed mills? The findings can result in drug carryover prevention/control in animal feed and animal-based human food.