Have you ever caught your dog sniffing something intently and then lifting their lip or making a strange facial expression? It might look a little silly, but there’s a fascinating reason behind it.
This behaviour is called the Flehmen Response, and it’s one of the many ways dogs gather information about the world around them.
What Is the Flehmen Response?
The Flehmen response happens when a dog encounters an especially interesting scent or pheromone and wants to investigate it more closely.
By slightly curling their lip and opening their mouth, they help direct scent particles and pheromones towards a special sensory organ called the Jacobsons organ (also known as the vomeronasal organ). You may also see your dog licking another dog’s urine. While this might seem strange to us, it’s a normal behaviour for dogs and another way for them to gather information from the environment in more detail.
This organ sits within ducts above the roof of the mouth and at the base of the nasal cavity. Think of it as your dog’s second scent detector. While their nose does an incredible job of identifying smells, the Jacobsons organ helps them detect chemicals like pheromones that their regular sense of smell might miss.
What Can Dogs Learn from It?
Dogs collect scents and pheromones to understand their world in ways we can barely imagine.
The Flehmen response can help them gather information about:
🐾 Other animals and potential mates.
🐾 Wildlife that has recently passed through
🐾 Reproductive status of other animals
🐾 Territorial markings left by other animals
🐾 Information that helps them navigate their environment
To us, it’s just a smell. To a dog, it’s a story.
Why Is Smell So Important to Dogs?
Dogs experience the world primarily through their noses.
While humans are highly visual, dogs rely heavily on scent to understand who has been somewhere, what they’ve been doing, and even how long ago they were there.
Walks aren’t just a physical workout; they are also an opportunity for dogs to catch up on what’s going on in the world. Much like we might read the morning news.
Can Dogs “Smell” the Time?
One of the most fascinating theories about canine scenting is that dogs may be able to estimate the time of day using scent changes.
As scents naturally fade and disperse over time, dogs can detect these subtle differences. This may help them work out how recently a person, animal, or object was present. This may even help explain why some dogs seem to know when it’s nearly dinner time.
Imagine being able to tell whether someone walked down a path five minutes ago or two hours ago just by smelling the air!
What the Flehmen Response looks like in action
Not every dog performs a dramatic lip curl, but you might notice:
✅ Intense sniffing
✅ Slightly raised upper lip
✅ Mouth partly open or teeth chattering
✅ A brief pause while they process the scent
✅ Repeated investigation of the same spot
Whilst dogs can exhibit the flehmen response, it is often much subtler than in other animals. Many owners don’t even realise it’s happening, as the signs can be easy to miss.
Let Them Stop and Sniff
The next time your dog suddenly becomes fascinated by a lamppost, patch of grass, or mysterious woodland scent, try giving them a moment to investigate.
Those sniffing stops aren’t wasted time. They’re an important way for dogs to gather information, process their environment, and meet their natural behavioural needs.
After all, while we’re enjoying the scenery, our dogs are busy reading an entire world written in scent.
If you enjoyed learning about the Flehmen Response, make sure to check out our other blogs.
