The Flehmen Response in Domestic Cats

Updated on July 11, 2019
Allison Golden profile image

A. Golden is a writer and editor living in Alabama. They graduated with a B.A. in English.


Have you ever seen your cat make an odd expression akin to a grimace or sneer? It’s hard to miss when it happens. The nose wrinkles, the upper lip draws back, and their mouth opens and remains slightly ajar for a short time.

Contrary to its appearance, this comical face is not your kitty expressing disgust. It is a biological behavior known as the flehmen response.

Derived from the German verb “flehmen,” roughly meaning “to curl the lip,” the response functions as a way for cats to gather additional sensory information.

This behavior isn’t limited to domestic cats. Felids of all kinds exhibit the response, as well as many other animals: horses, giraffes, goats, buffalo, sheep, and deer, to name just a few.

A Siberian tiger demonstrating the flehmen response.
A Siberian tiger demonstrating the flehmen response. | Source

When a cat exhibits the flehmen response, they are not recoiling from an odor, but rather, investigating it further. So how does this physiological mechanism work, and what purposes does it serve?

Anatomy of the Flehmen Response

The flehmen response is made possible by a specialized sensory structure called the vomeronasal organ, or the Jacobson’s organ.

The vomeronasal organ consists of two fluid-filled sacs located in the roof of the mouth. The nasopalatine canal—two small ducts situated just behind the front teeth—connect these sacs to the nasal cavity, forming a passageway for scents.

The rather silly-looking gape cats adopt during the response is what allows them to draw odors into the mouth rather than the nose. The vomeronasal organ then analyzes the scent, transmitting information to the cat’s brain.


In the context of senses, the flehmen response is difficult for us as humans to describe, as we lack the structures necessary to experience it. However, it is believed that the process is something akin to a hybrid between smell and taste.

But enough about the mechanics of the response—why do cats actually do it?

What Is Its Function?

In cats, the flehmen response is most commonly used in the detection and inspection of pheromones—chemicals animals use to communicate among their own species. Cats typically distribute pheromones in the form of urine marking or face rubbing.

On average, male cats utilize the response more frequently than females do, usually for mating purposes. Pheromones are particularly valuable for breeding, providing details on a cat’s sex, age, location, and reproductive status. By engaging in the response, a tomcat can ascertain whether or not a female is in estrus (heat) and thus in an ideal condition for mating. Female cats sometimes use the flehmen response when familiarizing themselves with the scent of their newborn kittens.

The response isn’t solely used in relation to pheromones, though. Any odor a cat finds interesting, unfamiliar, or novel can prompt the behavior. This varies with each individual cat and ranges from plants (especially catnip) to food to household objects.

In the video below, an electric toothbrush elicits the response from a curious Abyssinian cat.

The intense reaction catnip incites in many felines comes from the plant’s active ingredient, nepetalactone. One study suggests that nepetalactone simulates pheromones, which would explain why so many cats show the response around it.

This is where the details get murky. The link between the flehmen response and pheromones is relatively straightforward, but we're not sure why exactly cats perform the response around so many miscellaneous objects—such as the electric toothbrush seen above. Research on the behavior is still ongoing.

For now, though, we can at least appreciate this fascinating biological phenomenon and enjoy the ridiculous facial expressions it produces.

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

© 2018 A Golden


    0 of 8192 characters used
    Post Comment
    • K S Lane profile image

      K S Lane 

      2 years ago from Melbourne, Australia

      Really interesting read! I've always wondered why my cats do this!


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)