|B||Experiments which cause little or no discomfort or stress.|
|C||Experiments which cause minor stress or pain of short duration.|
|D||Experiments which cause moderate to severe distress or discomfort.|
|E||Experiments which cause severe pain near, at, or above the pain tolerance threshold of unanesthetized conscious animals.|
The CCAC requires institutional animal care committees (ACCs) to ensure that any potential pain and/or distress is minimized. Anesthetics and analgesics must be used; any exceptions require scientific justification and ACC approval.