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

Written by: Nicole Cosgrove

Last Updated on April 10, 2024 by Dogster Team

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


Dr. Lorna Whittemore  Photo


Dr. Lorna Whittemore

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. Dogs can smell things that people can’t. But that ability extends far beyond what most people realize. Dogs not only have the ability to detect scents that people can’t, but they can also smell pheromones using a special organ located on the roof of their mouth. This organ is known as Jacobson’s Organ or the vomeronasal organ. But what is this special sniffer used for? This quick guide will 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 that is connected directly to a dog’s brain. It gets its name from the nearby vomer bone located in an animal’s skull. It is present in all snakes and lizards and is also found in mammals such as dogs, cats, and cows. This organ is used to detect and interpret pheromones given off by other animals.

The organ is officially known as the vomeronasal organ but is also called Jacobson’s organ or VNO for short. The organ gets its name from Ludvig Levin Jacobson, who studied the organ across 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, 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 really going on. Dogs use this ability to smell whether nearby dogs are happy, in the mood for mating, or scared. Dogs will give off pheromones in a variety of situations, and other dogs can smell these pheromones. This gives them a picture of what is going on around 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 certain 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 if they are healthy.

You can see a dog attempting to use this organ to its fullest extent when it curls its lips back and opens its mouth while sniffing. This allows the organ to be exposed to the air and has a better chance of picking up on those good pheromonal scents. This behavior can also be prevalent in goats. This behavior is known as the flehmen response.

Do Humans Have a Vomeronasal Organ?

Do humans have a vomeronasal organ that they can use to smell pheromones? No. According to current understanding,they do not. Some people have some 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 special organ in their mouth that allows them to smell pheromones from other dogs. This allows dogs to get a picture of what is going on around them with other dogs without using language to communicate. This 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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