Research overview: flehmen and vomeronasal chemoreception in cats

The flehmen response, in which a cat draws back its lips, opens its mouth, and appears to grimace, delivers chemical signals to the vomeronasal organ in the roof of the mouth for processing of non-volatile molecules such as pheromones. This overview surveys research on the behaviour and its sensory basis, including how males perform flehmen after investigating urine marks and the role of the vomeronasal system in assessing reproductive status and individual identity. It explains why flehmen is most often seen during social and sexual investigation and how chemical communication complements visual and vocal signals in felid social life.