Category D procedures must include what type of drugs?

Category D procedures are those that involve more than minimal pain or distress to the animals used in research. As a result, the use of analgesics or anesthetics is critical to ensure that the welfare of the animal is safeguarded during these procedures. Analgesics provide pain relief, while anesthetics help to minimize sensation and consciousness during surgical or invasive procedures, thus addressing the ethical and regulatory requirements set forth in the Animal Welfare Act.

Using analgesics or anesthetics is necessary for promoting humane treatment and ensuring that animals do not experience undue suffering. It is also a standard practice in veterinary and research settings to adhere to principles of humane use in animal research, making it a vital consideration in Category D procedures.

In contrast, options such as tranquilizers, vitamins, and supplements do not specifically address the primary concern of managing pain and distress in animals undergoing procedures that are classified in this category. Thus, the inclusion of analgesics or anesthetics is essential and is why it is the correct answer.