What Is Flehmen Response?
The flehmen response in cats is an involuntary reaction where a cat curls its upper lip, opens its mouth, and inhales deeply. This exposes the cat’s vomeronasal organ in the roof of its mouth, allowing it to detect pheromones or other interesting scents more accurately1.
When a cat encounters an intriguing scent, it will lift its head, open its mouth slightly, and curl back its upper lip in what looks like a grimace or sneer. The cat may inhale through its mouth and then close its mouth and transfer the scented air to the vomeronasal or Jacobson’s organ via the ducts in the roof of its mouth. This allows the cat to thoroughly analyze and detect pheromones and other chemical cues that provide information about other animals.
Reasons For Flehmen Response
The most common triggers for the flehmen response in cats are smells that provide information about other cats. These can include:
- Smelling urine or feces from other cats – Cats have a keen sense of smell and can gather a lot of information from the urine and feces of other felines, including identity, health status, and sexual receptiveness. The flehmen response allows them to thoroughly analyze these chemical signals. Source
- Smelling vaginal secretions from a female cat in heat – When a female cat is in estrus, she secretes pheromones that signal her readiness to mate. The flehmen response helps male cats assess those pheromones and determine if the female is truly in heat. Source
- Smelling anal gland secretions – Cats have anal glands that produce strong-smelling secretions they use to mark territory and identify themselves. The flehmen response helps cats thoroughly analyze the anal gland scents of other cats. Source
- Smelling interesting or unusual scents – Any new or intriguing smells may trigger a cat’s flehmen response as they try to gather more sensory information. Things like perfumes, essential oils or strange foods can pique their interest enough for a flehmen.
The flehmen response allows cats to make full use of their Jacobson’s organ and gain a detailed understanding of the different feline scents around them.
Flehmen Response and Jacobson’s Organ
The flehmen response is closely linked to a cat’s Jacobson’s organ. The Jacobson’s organ is a special sensory organ located in the roof of a cat’s mouth, behind the front teeth. It contains sensory receptor cells that allow cats to detect pheromones and other chemical stimuli (https://catbehaviorassociates.com/what-is-the-vomeronasal-organ/).
When a cat performs the flehmen response by curling back its upper lip, it enables scents and pheromones to enter the mouth and come into contact with the Jacobson’s organ. This allows the cat to thoroughly analyze and interpret the scents (https://pubmed.ncbi.nlm.nih.gov/1007653/).
The Jacobson’s organ provides cats with key chemical information about other animals, including cats. It aids in communication and gives cats insight into other cats’ territories, reproductive status, and more.
When Flehmen Occurs
Flehmen response usually occurs when a cat encounters interesting or strong smells, especially pheromones. Some common triggers for flehmen response include:
– After smelling urine or feces: Cat urine and feces contain pheromones and other scents that prompt the flehmen response. When investigating these smells, a cat will exhibit the flehmen lip curl.[1]
– Encountering new smells: Unfamiliar scents from objects, places, or other animals can also trigger flehmen as the cat tries to discern more information from the smell.[2]
– Smelling scents of other cats: A cat may flehmen when smelling the scents of other cats, such as their urine markings or facial pheromones, to gather more social and reproductive information.[3]
– During mating behaviors: Flehmen frequently occurs during courtship and mating behaviors as cats smell pheromones indicating reproductive status and interest.[2]
Flehmen in Other Animals
The flehmen response is not unique to cats. It has also been observed in other animals such as horses, tigers, lions, llamas, and giraffes [1]. This response aids these animals in picking up pheromones used for communication. Horses for example will exhibit flehmen to pick up on pheromones in urine and dung from other horses, which provides them information on reproductive status [2]. The flehmen response is also a prominent part of mating rituals in certain animals. Male tigers will flehmen to assess the readiness of female tigers for mating.
Is Flehmen Response Normal?
The flehmen response is completely normal behavior for cats. It is not a sign that something is wrong or that the cat is ill in any way. The flehmen response is simply an instinctive reaction that is natural for cats.
When a cat encounters an interesting or intriguing scent, the flehmen response is triggered involuntarily as part of their investigative process. Cats have a highly developed sense of smell thanks to the vomeronasal organ, which detects pheromones. The flehmen response allows them to fully process new scents by drawing in molecules through their mouth.
There is nothing abnormal about a cat exhibiting flehmen behavior. Owners should not worry if they notice their cat’s upper lip curling, unless it is accompanied by other problematic symptoms. The flehmen response on its own simply indicates a cat is exploring scents in its environment, which is completely natural behavior.
When to Seek Help
While the flehmen response is normal cat behavior, excessive or constant lip curling may indicate an underlying health issue. According to PetMD, you should contact your veterinarian if your cat’s flehmen response seems excessive or constant. Frequent lip curling can be a sign of illness, discomfort, or a neurological disorder.
You should also seek veterinary care if the flehmen response is accompanied by other concerning symptoms, like loss of appetite, lethargy, or signs of respiratory distress. If your cat is unable to eat normally or seems distressed due to constant flehmen, this warrants an exam. Your veterinarian can check for dental disease, nasal obstructions, and other health problems that may be causing persistent lip curling.
While the occasional flehmen response is harmless, excessive or distressing lip curling may indicate an underlying issue. Contact your vet promptly if your cat’s flehmen interferes with normal functioning or is combined with other symptoms. With treatment for any underlying condition, your cat’s flehmen response should return to normal.
Encouraging Flehmen Response
You can encourage your cat to exhibit the flehmen response by introducing novel scents and pheromones. According to PetMD, catnip, mint, and certain perfumes can trigger the flehmen response in cats. These strong aromatic compounds can stimulate your cat’s vomeronasal organ and elicit lip curling. When introducing new scents, do so carefully and sparingly, as too much stimulation can be overwhelming.
You can also encourage flehmen response by carefully introducing new cat scents into your home. For instance, rubbing a cloth on a new cat and presenting it to your cat can result in flehmen as they analyze the pheromones. However, introducing foreign cat scents should be done with caution, as it may stress territorial cats. Go slowly when presenting new scents and stop if your cat shows signs of aggression or anxiety. With patience and care, novel scents can be an effective way to observe your cat’s fascinating flehmen response.
Discouraging Flehmen Response
While flehmen response is natural cat behavior, some pet parents may want to discourage it from happening too frequently. Here are some tips:
Remove or cover up triggers like litter boxes. Since urine and feces can trigger flehmen response, keeping the litter box clean and covered can reduce exposure to those smells. You can also place litter boxes in low-traffic areas to minimize curious sniffing.
Clean up urine, feces, sexual fluids quickly. Any biological fluids from cats or other animals can cause flehmen response. Be diligent about cleaning any accidents immediately.
Limit roaming to avoid outside smells. If your cat goes outside, they will encounter many intriguing scents that may cause flehmen. Keeping them indoors or supervised when outside reduces access to smelly stimuli.
With some changes to their environment and stimuli access, you can curb frequent flehmen in your cat. However, it’s important not to completely eliminate this natural behavior long-term.
The Takeaway
Flehmen is a natural scent analysis instinct seen in many animals, especially cats. It’s not a sign of illness, but you should see your vet if your cat displays this behavior excessively. While flehmen itself is harmless, you can encourage or discourage it depending on what triggers this response in your cat.
When a cat encounters an interesting scent, the flehmen response causes them to open their mouth and inhale deeply. This draws the scents towards an organ behind their top front teeth called the vomeronasal or Jacobson’s organ. This organ sends signals to the brain for analysis. So flehmen allows cats to better understand the scents around them.
Flehmen is perfectly normal behavior you can expect to see periodically in healthy cats. It does not indicate a medical issue. However, if your cat flehmens constantly without an obvious scent trigger, take them to the vet to rule out a problem. Otherwise, consider flehmen a natural part of your cat’s routine scent investigation and analysis.
You may want to encourage flehmen if your cat seems to enjoy it or if you want to provide mental stimulation. Try introducing new scents using treats, toys, or catnip. However, discourage excessive flehmen by removing any undesirable triggers. Overall, moderate flehmen response is nothing to worry about in cats.