Why Do Cats Make the “Stinky Face”?

As most cat owners can attest, cats do some strange things. Today, we’re here to talk about “stinky face.” Stinky face is what happens when a cat sniffs something, then proceeds to hold their mouth open resulting in a shocked expression … like one would get when you smell something stinky.

So, why do cats do this? “Stinky face” is actually called the flehmen response (or flehmen grimace) and is a cat’s way of analyzing an unfamiliar scent, most often in the form of pheromones. When the cat breathes in the scent through their mouths, the flehmen response allows the scent to travel through the roof of the mouth via two tiny ducts behind their incisors to the vomeronasal organ.

Also called the Jacobson’s organ, the vomeronasal organ is a region of sensory cells within the olfactory system of mammals – and even amphibians and reptiles, too. Some scientists believe that the flehmen response is something between a sense of smell and taste – making it almost like a sixth sense.

Big cats such as lions and tigers also exhibit the flehmen response, and even other animals like horses, camels, and dogs!

Photo Copyright Tambako The Jaguar via Flickr, CC

Interestingly enough, the average house cat has 30 different type of receptors in their Jacobson’s organ – whereas dogs have only 9. So they’re able to tell a lot more than just by simply sniffing!

Okay, okay. We know how it works. But what are they sniffing? What are they trying to analyze? Mainly: pheromones! The flehmen response is important for mating, marking territory, and intraspecific communication.  Male cats tend to use the flehmen grimace more often than female cats. “Male cats use the flehmen response in relation to mating,” Dr. Gibbons of Just Cats Veterinary Hospital explained to Catster.

“Scents can help indicate compatibility and if timing is right.” Of course, as with most things involving cats, they don’t only use this “sniffing” technique. Some cats use the flehmen response to interpret all kinds of different smells – like when you take your shoes off after a long day and your kitties sniff your feet. Lots of cat owners can probably say this has happened before. 

So in summation, cats make the “stinky face” to help further analyze and interpret the world around them in a way that us humans can’t. It’s pretty awesome! Interestingly enough, it’s likely that humans used to have this incredible ability, that our ancestors once “flehmened.”

When human fetuses are developing, they actually begin to form a vomeronasal organ – but at some point, it just fades away. The only traces of it at birth are a pair of pits at the bottom of our nostrils where the ducts would have connected to the organ.

Have you ever witnessed a flehmen grimace in person? Do you have any funny nicknames for it besides “stinky face”? Let us know in the comments!