Have you ever seen your cat make a weird, “stinky face” after sniffing something? Don’t worry — we all have.
I remember thinking to myself, “Is my cat broken right now?” the first time I saw my cat make that face — almost as if he had to sneeze but couldn’t get it out. Sure enough, that “face” my cat was making is called the “flehmen response” — and there’s a practical reason why he did it.
Continue reading to learn more about what the flehmen response is and why your cat does it!
What Is the Flehmen Response?
The flehmen response is your cat’s way of investigating and processing a smell that they find interesting.
The term is derived from the German word flehmen, which means “to curl the upper lip,” referring to the ‘stinky face’ the cat makes when exhibiting the behavior.
There are three primary things at play here: pheromones, the vomeronasal organ and curiosity.
“[This response] is a particular way of taking in the air like sniffing,” says Dr. Joanna Woodnutt, a veterinarian at Petlearnia.
“But instead of getting a scent to the detectors in the nose, it’s designed to get pheromones to the vomeronasal organ where cats can read them,” Dr. Woodnutt continues.
In other words, the ‘weird face’ your cat makes is just a way of guiding the scent into the vomeronasal organ for further analysis.
What Are Pheromones?
Pheromones are tiny chemical compounds that cats and other animals secrete to communicate and relay messages to other members of their species. They’re released from glands in different parts of the body, such as the face, paws, and tail base.
Cats use pheromones in a variety of ways, but primarily use them to mark territory, identify each other and signal their gender for breeding purposes. It also tells them if other cats are spayed or neutered.
Perhaps one of the most common examples of your cat releasing pheromones is when it rubs its cheek or tail base up against you — which is its way of saying “this human is mine.”
If another cat were to come across those pheromones and found them interesting enough for a second whiff, then they would use their cat flehmen response.
What Is the Vomeronasal Organ?
The vomeronasal organ (VNO), also known as Jacobson’s organ, is an olfactory organ located on the roof of a cat’s mouth, just behind the upper front teeth. It’s the organ that processes the pheromones your cat finds interesting — which some studies have described as a combination of tasting and smelling.
“This special organ can be found at the base of the nasal cavity, and it acts as a sixth sense,” says Jen DeGroot, Associate Animal Curator.
“When a cat utilizes their VNO, it sends signals directly to their brain about what they’re smelling. It’s high-tech smell-o-vision!” DeGroot adds.
The pheromones are processed by the vomeronasal nerve before being sent through the accessory olfactory bulb and to the amygdala and hypothalamus of the brain. Since these regions of the brain are involved in emotions, behavior and hormone regulation, the flehmen response can, in turn, affect social and sexual behavior.
Why Do Cats Do This?
When most people see their cat doing the flehmen response for the first time, they immediately think it’s a negative reaction to something the cat doesn’t like. But that’s not necessarily true.
“The Flehmen response alone doesn’t usually indicate a specific emotional state, so you’ll want to look at the rest of your cat’s body language,” says Joey Lusvardi, a certified cat behavior consultant.
Most of the time, your cat will simply make a weird face for a few seconds and then go about their day — as if it never happened. Sometimes they’ll go in for a second sniff, but not always.
So, to answer the question, most cats do the flehmen response to process certain smells. It doesn’t mean they like or don’t like the smell — it just means it was worth investigating.
As for why they open their mouth, it helps them direct pheromones into the organ that processes them, which is located on the roof of their mouth.
Is the Flehmen Response Exclusive to Cats?
Believe it or not, cats aren’t the only animals to exhibit the flehmen response.
Perhaps one of the most common examples outside of cats is horses, which are known to lift their head up, curl their lip back, expose their teeth and inhale deeply. Like cats, they do this to enhance their sense of smell so they can detect pheromones related to reproduction and environmental changes.
Big cats, such as lions, tigers, leopards, cheetahs and jaguars, also utilize the flehmen response — as all of these animals have the vomeronasal organ. Even ungulates, such as goats and sheep, and some reptiles, such as snakes, join in on the fun.
Unfortunately, while humans do have a vomeronasal organ, we do not utilize the flehmen response.
Flehmen Response vs. Dental Problems
It’s important not to confuse the flehmen response with dental problems.
There’s a fine line between your cat making a weird face for a few seconds and them walking around with their mouth open for extended periods of time.
For example, some cats might open their mouths to soothe the pain from gingivitis or other dental issues. If your cat were doing this, it would warrant a trip to your local vet.
This is especially true if you notice drooling, bad breath, swollen gums, difficulty chewing or swallowing, loss of appetite or pawing at the mouth.
So, if your cat is just making a weird face for a few seconds, there’s no need to worry. If it persists longer than that, contact your vet.
Flehmen Response vs. Panting
If you own a dog, then you probably wouldn’t blink twice if you saw them panting. You’d probably think they were catching their breath from running around. With cats, it’s a little different — primarily because cats shouldn’t pant.
Breathing with their mouth open is their body’s attempt to increase oxygen intake and is a sign of severe respiratory distress. That could mean your cat is dealing with asthma, lung disease or an issue with their heart.
Again, while this might look similar to the flehmen response, panting is far more concerning in a cat and usually requires medical attention.
This is especially true if the panting is accompanied with behavioral changes, lethargy, withdrawing, weight loss, nasal discharge or vomiting.
