Which of the following describes prescription drugs?

Prescription drugs are specifically defined by their regulatory requirements and the necessity for oversight in their use, particularly in veterinary medicine. One key characteristic of these drugs is that they carry a required caution statement or legend, which typically indicates that the medication should only be used under the guidance of a licensed practitioner, such as a veterinarian. This labeling serves to inform both the veterinarian and the pet owner of the need for professional oversight in the medication's administration, ensuring that it is used safely and effectively.

This aspect is fundamental in distinguishing prescription medications from over-the-counter drugs, which can be obtained without a prescription and do not carry the same regulatory warnings. Furthermore, the regulation of prescription drugs falls under the purview of the U.S. Food and Drug Administration (FDA) rather than the U.S. Department of Agriculture (USDA), which focuses more on agricultural products. Additionally, unlike over-the-counter medications, prescription drugs always require a veterinarian's approval before they can be dispensed and used, ensuring a higher level of safety and appropriateness for the animal's specific condition.