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What Is the Jacobson’s Organ (Vomeronasal Organ) In Dogs? Anatomy and Uses

Written by: Nicole Cosgrove

Last Updated on June 5, 2024 by Dogster Team

close up of white and tan dog's nose

What Is the Jacobson’s Organ (Vomeronasal Organ) In Dogs? Anatomy and Uses

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REVIEWED & FACT-CHECKED BY

Dr. Lorna Whittemore

BVMS, MRCVS (Veterinarian)

The information is current and up-to-date in accordance with the latest veterinarian research.

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Most people know that dogs have an incredible sense of smell and can smell things that people can’t. However, that ability extends far beyond what most people realize. Dogs not only can detect scents that people can’t, but they can also smell pheromones using a unique organ located on the roof of their mouth.

This organ is known as Jacobson’s Organ or the vomeronasal organ. Below, we’ll run through everything you need to know about the vomeronasal organ, including whether people have one of their own.

What Is the Vomeronasal Organ?

The vomeronasal organ is an accessory olfactory organ connected directly to a dog’s brain. It gets its name from the nearby vomer bone in an animal’s skull. This organ is present in all snakes and lizards and is also found in mammals such as dogs, cats, and cows. It is used to detect and interpret pheromones given off by other animals.

The vomeronasal organ is officially known as the vomeronasal organ but is also called Jacobson’s organ, or VNO for short. It gets its name from Ludvig Levin Jacobson, who studied it in various species in 1811.

Where Is It Located?

In dogs, the vomeronasal organ is located on the roof of the mouth and attached to the hard palate. It is located just behind a dog’s canine incisors. If you look closely at a dog’s mouth, you can often see it. It appears like a small mass on the roof of the mouth behind the front teeth.

border collie dog licking nose
Image By: malcolmthe, Shutterstock

What Do Dogs Use the Vomeronasal Organ For?

Dogs use the vomeronasal organ to smell pheromones, which are chemical signals given off by other dogs. Dogs do not have extensive vocal language like people do to communicate, so they use scents to figure out what is going on. Dogs use this ability to smell whether nearby dogs are happy, in the mood for mating, or scared. They give off pheromones in various situations, and other dogs can smell them.

For example, if a dog runs by and gives off fear pheromones, other dogs can deduce that the dog is scared and running away from something. This can also present itself in places like the veterinarian’s office and the shelter. Dogs can smell an overwhelming amount of fear pheromones in specific spaces, which can make them nervous.

The Jacobson’s organ is also one of the reasons why dogs sometimes sniff each other’s rear ends. Getting up into a dog’s space can give them clear access to the areas where pheromones are the most common. This allows them to get a good whiff of how the other dog is feeling in addition to what they’ve been eating and whether they are healthy.

You can see a dog attempting to use the organ to its fullest extent when they curls their lips back and opens their mouth while sniffing. This allows the organ to be exposed to the air and has a better chance of picking up the pheromonal scents, and it’s called the flehmen response. Goats and felines display the same behavior.

Do Humans Have a Vomeronasal Organ?

Do humans have a vomeronasal organ that they can use to smell pheromones? Unfortunately, they do not have one. Some people have remnants of the organ from ages long past, but the organ is not considered functional in humans. It is what is known as a vestigial organ. Many primates do not have a vomeronasal organ, which eliminates their ability to smell pheromones like dogs can. That means that anything that advertises calming pheromones for people is likely ineffective.

Summing Up

Dogs have a unique organ in their mouth that allows them to smell pheromones from other dogs. This allows them to get a picture of what is going on around them with other dogs without using language to communicate. The Jacobson organ lets dogs know when other dogs are happy or scared. It also contributes to the infamous butt-sniffing behavior that fascinates people.


Featured Image Credit: PICNIC-Foto-Soest, Pixabay

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