Which criterion involves suspension of normal behavior and possible appearance of abnormal behavior during pain?

• A. Presence of brain structures for sensory processing
• B. Gait changes
• C. Opioid receptors and substances involved in pain modulation
• D. Suspension of normal behavior and possible appearance of abnormal behavior during pain

Answer: (D)

In pain assessment, focusing on how pain changes an animal’s behavior is essential because behavior is a direct, observable clue to distress when the animal can’t report it. The described criterion—suspension of normal behavior and possible appearance of abnormal behavior during pain—captures this behavioral shift itself. It recognizes that pain can cause an individual to withdraw from typical activities, reduce engagement, or show unusual actions as a direct response to discomfort, making it a practical and reliable indicator across species. Other choices relate to how pain is processed in the body or how it might manifest physically (for example, gait changes or underlying brain chemistry and receptors), but they do not define the behavioral change pattern used to judge pain in animals.