List common behavioral and physiological pain indicators in rodents that researchers should monitor.

• A. Changes in activity and posture, guarding, limping, reduced grooming, piloerection, vocalizations, and facial grimacing.
• B. Color variations in fur.
• C. Increased appetite and exploration.
• D. Sleep patterns and rest.

Answer: (B)

Recognizing pain in rodents comes from looking at a pattern of changes that reflect distress, not a single sign. The most informative cues include shifts in activity and posture, guarding of a painful area, limping or an altered gait, reduced grooming, piloerection (fur standing on end), vocalizations, and facial grimacing. These together capture both how the animal is behaving and how its body is reacting to pain, and they’re commonly used in validated pain assessment tools like grimace scales. Color variations in fur aren’t a reliable pain indicator and can be influenced by coat condition, lighting, or genetics. Increased appetite and exploration typically suggest the animal is not in pain, and while sleep changes can occur with discomfort, they’re nonspecific and not sufficient on their own. Use a composite assessment that combines these behavioral and physiological cues to gauge pain and inform humane care decisions.