The dominant/subordinate relationship between mice modifies the approach behavior toward a cage mate experiencing pain

Many species display approach behavior to conspecifics. This study evaluated approach behavior exhibited by mice toward a cage mate in pain according to the social relationship between the mice. The relative dominant/subordinate relationship among three cage mates was determined using a competitive food retrieval test. Social preference of the subordinate mouse for the mid-status or dominant cage mate was tested with and without pain induced in the dominant cage mate. Social preference of the dominant mouse was similarly tested with and without pain induced in the subordinate cage mate. Subordinate mice spent more time with the dominant cage mate in pain than with the mid-status cage mate but spent a similar amount of time with dominant and mid-status cage mates that were not in pain. Dominant mice spent a similar amount of time with subordinate and mid-status cage mates regardless of pain. The time that subordinate mice spent with the dominant cage mate in pain inversely correlated with dominancy distance between the two mice. These results demonstrate that social relationship can modify perception of the pain of others.