Final answer:
The most appropriate unique identifier for a veterinarian when receiving a prescription for an animal is their DEA number.
Step-by-step explanation:
When receiving a prescription for an animal from a veterinarian, the most appropriate unique identifier for that clinician for routine fills of non-controlled substances is their DEA number. The DEA number, short for Drug Enforcement Administration number, is issued to veterinarians who are authorized to prescribe controlled substances. It serves as a unique identifier and helps ensure proper tracking and accountability.
Learn more about Veterinary prescriptions