Under standard-of-care requirements, analgesia for painful procedures may be omitted only if:

• A. If the animal is not expected to feel pain.
• B. If the study is short.
• C. If a valid scientific justification is provided for its avoidance.
• D. If analgesia would interfere with data collection.

Answer: (D)

Pain relief is expected as part of standard-of-care for procedures that could cause pain. The only situation in which skipping analgesia is acceptable is when giving analgesia would alter or confound the data being collected, making it impossible to interpret the study results as intended. Analgesics can change physiological readouts, behavior, or other endpoints being measured, so withholding them is sometimes necessary to preserve data integrity. Any such exception must be supported by a specific, protocol-level justification and approved by the appropriate oversight body. Other reasons, such as the study being short or the animal not expected to feel pain, do not by themselves justify omitting analgesia because animal welfare remains the priority unless a formal justification and approval exist.