What Is the Flehmen Response in Cats?

10.7K
962
269
2025-11-10
What Is the Flehmen Response in Cats?

Does your cat sometimes make a weird sneering face? Cats lift their lips after a particularly long sniff and hold the mouth slightly open to sniff cat pheromones. Flehmen—a German word that means "lip curl"—might be mistaken for an aggressive snarl but is a perfectly normal and peaceful cat behavior.

Pheromones

Cats use pheromones, or scent hormones, to communicate with other cats. Each animal has its own unique pheromones, which can signal different messages to other cats. For instance, a cat may rub its cheek against an object and release pheromones to mark its territory and pheromones in cats' urine signal their gender. 

A cat grimaces when its tongue traps pheromones, then flick-transfers the pheromones to the duct in the roof of its mouth. That's when the so-called flehmen response occurs: The cat curls the upper part of its mouth in what appears to be a sneer. All cats use this second sniff-mechanism to analyze pheromones but male cats show the flehmen kitty sneer most often. That may be because they are particularly attuned to checking out sex-related information even if they are neutered. 

Cat's will also mark their favorite humans with pheromones as well. A headbutt or cheek rub from a cat is its way of saying "this human is mine." It's a sign of true affection from your feline companion. 

Jacobson's Organs

Jacobson's organs, or vomeronasal organs, are found between the hard palate of the mouth and the septum of the nose. Tiny ducts connect them to openings behind cats' teeth in the roof of the mouth. Jacobson's organs ultimately link to the hypothalamus in the brain and can affect social and sexual behavior.

Jacobson's organ is named for Ludvig Levin Jacobson, the Danish physician who discovered it in 1811. Cats are not the only animals with Jacobson's organs. Strangely enough, even humans have them. According to Dr. Anne Marie Helmenstein, while humans don't display the Flehmen reaction, recent studies have demonstrated that Jacobson's organ functions as in other mammals to detect pheromones and to sample low concentrations of certain non-human chemicals in the air. There are indications that Jacobson's organ may be stimulated in pregnant women, perhaps partially accounting for an improved sense of smell during pregnancy and possibly implicated in morning sickness.

Probably the most well-known animal with a Jacobson's organ other than cats is the common snake, which, of course, is a reptile.

Flehmen's Response

There are a wide variety of animals that show flehmen's response to various scents. Cats and horses are the best-known, but giraffes and elephants frequently show this behavior as well. Buffalo, goats, llamas, rhinoceros, pandas, and hippos also have been observed showing flehmen's response to a scent, usually another animal of their species. 

 

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.

Top Articles

Related Article

How Cats Show They Love You
31.2K
311
52

How Cats Show They Love You

Cats show their love in many ways and it usually involves body language and other behaviors. Find out if your cat is trying to tell you they love you.
Why Your Cat Is Meowing So Much—and Other Ways They Seek Your Attention
35K
2.1K
945

Why Your Cat Is Meowing So Much—and Other Ways They Seek Your Attention

Attention-seeking behavior in cats and excessive vocalization often go hand-in-hand. Learn about the types and causes of these behaviors.
Why Do Cats Groom and Lick Themselves So Often?
48.1K
4.3K
2K

Why Do Cats Groom and Lick Themselves So Often?

Cats may spend as much as half their time grooming and licking themselves. What leads to this behavior, and how does it help your cat?
Why Does My Cat Scratch the Floor After Eating?
30.7K
1.5K
767

Why Does My Cat Scratch the Floor After Eating?

Many cats paw at the floor or bury their food. It's a natural behavior, but it's easy to modify.
How to Stop a Cat from Spraying
2K
39
15

How to Stop a Cat from Spraying

Urine spraying, or marking, is different than urinating outside of the litter box. Learn about why cats will urine spray and what to do about it.
Do Cats Cry When They Are Sad or in Pain?
3.8K
150
70

Do Cats Cry When They Are Sad or in Pain?

Cats don't cry the way people do. Your cat can produce tears, but not ones of sadness. Explore the truth behind a cat's emotions and what those tears mean.
How to Train Your Cat to Not Be Mean
31.6K
315
122

How to Train Your Cat to Not Be Mean

Learn about mean cats and angry cat behavior. Understand why cats sometimes hate hugs and learn steps to make cats happy (or happier).
How to Crate Train Your Cat
44.7K
3.6K
1.6K

How to Crate Train Your Cat

Crate training is not just for dogs. Follow these steps to train your cat to the crate so you can have less stressful car rides and vet visits.
Why Cats Stare at You While You Sleep and How to Stop It
9.3K
650
299

Why Cats Stare at You While You Sleep and How to Stop It

Cats are known to stare at humans while they sleep. Find out why and how to stop it.
How to Stop Your Cat From Tracking Litter and Poop
13.4K
400
144

How to Stop Your Cat From Tracking Litter and Poop

While they're generally clean animals, sometimes cats get poop on their paws, and track litter outside the box. Learn how to stop this behavior.
Is My Cat Happy?
8.2K
81
28

Is My Cat Happy?

Cats tell us that they are happy by vocalizing their pleasure, showing their moods by their body language, and plainly acting happy.
How to Stop Your Cat From Pooping in the Sink or Bathtub
40.8K
815
342

How to Stop Your Cat From Pooping in the Sink or Bathtub

It's frustrating and unpleasant when your cat defecates in the sink or tub, but you can stop the unwanted behavior with some of these techniques.
22 Weird Cat Behaviors You're Not Sure About
13.2K
132
51

22 Weird Cat Behaviors You're Not Sure About

Explore 22 weird cat behaviors and why they do them. Many are methods of cat communication, from winking to bunting, rolling, sneering, and kneading.
Understanding the Purring of Cats
8K
643
315

Understanding the Purring of Cats

Get a better understanding of variations on cat purring. Cats purr to communicate and even have special purrs.
What Is Scruffing in Cats?
7.1K
567
90

What Is Scruffing in Cats?

Learn more about the origins of cat scruffing and why you should not be scruffing your cat.
Understanding How Cats Speak Through Ear Movements
10.4K
415
170

Understanding How Cats Speak Through Ear Movements

Cat owners can learn "cat talk" and get a deeper understanding of how cats use their cat ears to communicate different emotions.
Safe Solutions for Indoor Cats That Want to Go Outside
49.5K
2K
673

Safe Solutions for Indoor Cats That Want to Go Outside

Cat lovers who want their cats to enjoy fresh air and sunshine often feel guilt by confining their cats to the indoors. Here are safe compromises.
How to Discipline Your Cat the Right Way
32.2K
643
308

How to Discipline Your Cat the Right Way

Cats are mischievous but sometimes they also misbehave. Learn how to safely and effectively discipline a cat and positively change their behavior.
How to Stop Cats From Biting and Scratching
48.2K
481
177

How to Stop Cats From Biting and Scratching

Cats learn to bite and scratch as kittens and may need to be retrained when they grow older. These behaviors can be changed with time and patience.
Reasons Why a Cat Doesn't Meow
49.1K
2.9K
1K

Reasons Why a Cat Doesn't Meow

When a cat doesn't meow, it is often just natural behavior, but when its silence is accompanied by other symptoms, have a vet examine your pet.
Top 10 Big House Cats
20.3K
405
145

Top 10 Big House Cats

Larger cat breeds, like Maine coons and savannahs, deserve just as much love as their petite counterparts. These big house cats tip the scales.
Toyger: Cat Breed Profile, Characteristics & Care
25K
2.5K
949

Toyger: Cat Breed Profile, Characteristics & Care

The toyger (toy tiger) cat is a beautiful, rare breed with an easygoing demeanor. These cats are hard to come by but make excellent pets.
Elf Cat: Breed Profile, Characteristics & Care
31.2K
1.9K
748

Elf Cat: Breed Profile, Characteristics & Care

Elf cats are a new, rare cross between a sphynx and American curl with curly ears and a playful personality.
American Wirehair: Breed Profile, Characteristics & Care
46.3K
462
73

American Wirehair: Breed Profile, Characteristics & Care

The rare American wirehair breed has a distinctive wiry coat and quiet, gentle demeanor. Learn about the American wirehair breed.
Turkish Angora: Cat Breed Profile, Characteristics & Care
49K
4.9K
882

Turkish Angora: Cat Breed Profile, Characteristics & Care

The elegant and silky Turkish Angora cat is a playful, affectionate, and sometimes mischievous pet. Learn about the Turkish Angora breed.
Himalayan: Cat Breed Profile, Characteristics & Care
35.7K
3.2K
770

Himalayan: Cat Breed Profile, Characteristics & Care

Himalayan cats—crosses of Persian and Siamese breeds—are sweet felines with silky hair. They're great pets if you're willing to care for their coat.
Ocicat: Breed Profile, Characteristics & Care
11.6K
232
51

Ocicat: Breed Profile, Characteristics & Care

The ocicat has wild markings, but it is a completely domestic cat that loves to socialize and play. Learn about the ocicat breed.
10 Popular Cat Breeds for Many Types of Households
35.3K
1.1K
201

10 Popular Cat Breeds for Many Types of Households

Discover 10 of the most popular cat breeds, including the Maine coon and ragdoll. Learn which types of cats are right for your lifestyle.
9 Calmest Cat Breeds for Laid-Back People
25.9K
1K
476

9 Calmest Cat Breeds for Laid-Back People

Calm cat breeds like the Persian and ragdoll are ideal for people who like a mellow pet. Meet nine of the calmest cat breeds.
Persian Cat: Breed Profile, Characteristics & Care
21.6K
649
123

Persian Cat: Breed Profile, Characteristics & Care

The Persian cat is sweet, laid-back, and regal, with a luxurious long coat. Learn more about this long-cherished cat breed.
Mixed-Breed Cat (Moggy): Breed Profile, Characteristics & Care
2.5K
247
32

Mixed-Breed Cat (Moggy): Breed Profile, Characteristics & Care

"Mixed-breed" is a catch-all term for cats without pedigrees. Called moggies in the UK, these cats make perfect pets. Learn about the mixed-breed cat.
7 Hybrid Cats Breeds
9.7K
876
210

7 Hybrid Cats Breeds

Hybrid cat breeds can make appealing pets since they look more exotic than domestic house cats, but they aren't for everyone.
Japanese Bobtail: Cat Breed Profile, Characteristics & Care
5.8K
289
40

Japanese Bobtail: Cat Breed Profile, Characteristics & Care

The Japanese bobtail is recognized for its bunny-like tail and is loved for its friendly, playful personality. Learn about the Japanese bobtail breed.
10 Cat Breeds That Are Rare to Find
3K
59
25

10 Cat Breeds That Are Rare to Find

Most house cats in the U.S. are not pedigreed or purebred, so even the most common breeds are rare. Take a look at the rarest of the purebreds.
Ragamuffin: Cat Breed Profile
4.4K
444
115

Ragamuffin: Cat Breed Profile

Learn about the personality, history, and care for Ragamuffin cats.
How to Know When to Call the Vet for Your Cat
19.5K
194
69

How to Know When to Call the Vet for Your Cat

How to know when to call your veterinarian for your cat.
How to Tell if a Cat Is Pregnant
41.7K
833
133

How to Tell if a Cat Is Pregnant

Could your cat be pregnant? Learn about the signs of pregnancy in cats. If you spot these telltale signs, it may be time to schedule a vet appointment. Here's how to tell if your cat is pregnant.
Are Tulips Toxic to Cats?
15K
150
48

Are Tulips Toxic to Cats?

Tulips are one of many flowers that are toxic to cats. Learn the dangers, what to do in the case of ingestion, and how to keep your cat safe from tulip toxicity.
Constipation in Cats
13.9K
139
23

Constipation in Cats

Constipation in cats is a common, but uncomfortable, digestive disturbance. Find out what causes cat constipation and its treatment and prevention.
Feline Immunodeficiency Virus (FIV) in Cats
13.7K
1.4K
506

Feline Immunodeficiency Virus (FIV) in Cats

FIV is a common and potentially deadly feline disease. With good veterinary care, though, cats with FIV can survive many years after diagnosis.
How to Help a Pregnant Cat Give Birth
48K
1.4K
389

How to Help a Pregnant Cat Give Birth

Your pregnant cat may be able to give birth with no problems. However, if trouble arises, knowing in advance what to look for will help the process.
Can Indoor Cats Get Fleas?
40K
3.6K
1.4K

Can Indoor Cats Get Fleas?

It may be surprising to learn that indoor cats can and do get fleas too. Learn what to look for and how to treat these itchy pests.
Kitten Constipation: What to Do When You Kitten Can't Poop
12.3K
615
239

Kitten Constipation: What to Do When You Kitten Can't Poop

Kittens usually experience more diarrhea than constipation, but a kitten that has trouble passing stool, or is not defecating can be just as serious.
How to Take Your Cat's Temperature
32K
3.2K
607

How to Take Your Cat's Temperature

Your cat's temperature should be between 100.4 and 102.5 degrees Fahrenheit. Learn how to take its temperature and determine if it has a fever.
Why Is My Cat Throwing Up Its Food?
1.3K
51
16

Why Is My Cat Throwing Up Its Food?

Cats throw up food for many reasons, and it may be a sign of a serious illness. Find out why your cat is vomiting undigested food and what to do about it, including when to call the vet.
Asthma in Cats
26.8K
1.3K
201

Asthma in Cats

Cats with asthma may wheeze or cough, and they require medical intervention to manage the condition. Learn the causes, treatment, and prevention.
8 Ways to Help a Blind Cat Keep Safe in Your Home
37K
1.5K
710

8 Ways to Help a Blind Cat Keep Safe in Your Home

Blind cats are much like any other cats, except you might want to do some things around the house to help them get around safely.
Are Mums Toxic to Cats?
16.7K
1.3K
414

Are Mums Toxic to Cats?

Mums can be dangerous to cats if they eat them or if they come into contact with the skin. Here's what you need to know about chrysanthemum toxicity in cats, including when to contact the vet.
Glaucoma in Cats
10K
99
28

Glaucoma in Cats

Glaucoma is a disease that creates painful eye pressure in cats. Learn the causes, treatment, and prevention.
Signs of Heat in Cats
34.1K
2K
409

Signs of Heat in Cats

A cat in heat will show several physical and behavioral signs. Here's how to tell if your cat is in heat and how to care for her during this time. Learn the signs and how to prevent pregnancy, even if her cycle has begun.