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What is the Vomeronasal Organ?

Cats are equipped with a very special piece of equipment known as the Jacobson’s organ or vomeronasal organ. Located in the roof of the mouth, it contains ducts that lead to the mouth and to the nose. This is essentially a scent analyzer. It’s used primarily for analyzing pheromones (scent chemicals) from other cats, especially the ones found in urine.jacobson's organ in cats

How it Works

The scent is collected in the mouth where the cat then uses his tongue to flick it up to the vomeronasal organ. You can tell when the cat is in the process of using his vomeronasal organ because his facial expression is similar to a grimace. His upper lip will be curled and his mouth will be partially open. This expression is known as the flehmen reaction.

The Purpose of the Vomeronasal Organ

Although all cats have this organ and can use it whenever they come across any scent they feel requires more in-depth analysis, it’s often used by intact males reacting to the pheromones in the urine of females in heat.

Want More Information?

You can find more specific information on cat behavior and training in any of Pam’s books. Be sure and check out CatWise, the latest release of best-selling author Pam Johnson-Bennett, where she answers 150 of the most-asked cat behavior questions.



Pam is unable to respond to comments. If you have questions about cat behavior you can find many answers in the best-selling books by Pam Johnson-Bennett as well as in the articles on our site. If your cat displays a change in behavior, contact your veterinarian because there may be an underlying medical cause. This article is not intended as a replacement for your cat’s veterinary care.





One Response to What is the Vomeronasal Organ?

  1. i am having a major problem with my 7 yr mal old cat that I’ve had since he was 8 wks old. It’s wildly viscious agression and he flat out attacks me and i dont’ even see it coming; i’m not sure if it’s redirected, fear or unprovoked but it’s vicious. It doesn’t happen on a reg basis as respects to the viscious aspect; that’s occurred 5-6 times since I’ve had him. He just attacks me using his claws and teeth, screaming, snarling, hissing and he doesn’t back off. las tsunday was the most recent. I was holding him at bay with a broom scratched and bitten and called my neighbor and her husband over to divert him into another room. I so love animals, even this one and I don’t want to have to put him to sleep but i am at my wits end. i can’t be a prisoner and i also feel bad for him locked up in one bedroom. is there any hope for him?

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