Cat Behavior: Sniffing with Mouth Open ‘Flehmen Response’ or ‘Flehming’

Reader Question:
Sometimes my cat sniffs something that I can’t see and then opens his mouth for an extended period of time looking off into space with a confused look on his face.  Why does he do this?

Sarah B., Los Angeles, CA

Cat Flehmen Response, Smelling through mouth

Our cat, Bella, doing her flehmen response. This happens a couple of times a week. We were lucky enough to get it three times on this take.

Dear Sarah,

As cat’s we are especially equipped with a computer-like catalog (no pun intended) that keeps track of all sights , sounds and smells… we are particularity sensitive to smell and so when we uncover a smell that we are unfamiliar with, we take a deep whiff and then compute it in our brain’s smell catalog for future reference.  Humans refer to it as “flehming” or the “flehmen response…think of our open mouth as us thinking and trying to remember if we’ve ever smelled that particular smell before.