Why should a researcher verify a mouse's age when planning procedures?

• A. Check official records, ear tagging, or breeding records.
• B. Estimate age by fur color.
• C. Age is not relevant.
• D. Check official records, ear tagging, or breeding records; age can influence physiology and anesthesia risk.

Answer: (D)

Verifying age before procedures matters because an animal’s developmental stage directly influences physiology, drug metabolism, and surgical risk. Younger mice often have different cardiovascular reserve, slower or differently tuned anesthesia clearance, and distinct wound-healing dynamics compared to adults. Older mice may have reduced organ function or comorbidities that change how they respond to anesthesia and recovery needs. Knowing the exact age allows you to tailor anesthesia plans, dosages, analgesia, and post-procedure care to the animal’s stage of development, improving safety and the reliability of results. The most reliable way to obtain age is from official records, ear tagging, or breeding records, which provide documented ages rather than estimates. Estimating age by fur color isn’t dependable, as coat color can vary with strain and individual development and does not accurately indicate age.