If you have a cat, I’m sure you’ve seen it sniff something and then raise its head with its mouth open as shown in the video above.
This gesture is called the flehmen response or flehmening and it’s how cats inhale and analyze pheromones.
Many mammals flehmen in response to pheromone laden scents. They bare their teeth, close their nostrils and breathe through their mouths to direct the scent into the vomeronasal organ (VNO) located above the roof of the mouth. In felines, there’s a duct just behind their front teeth that leads to the VNO.
Horses flehmen, too. When I was a kid there was a TV show called Mister Ed, the Talking Horse, whose face looked like this when he “talked.”
Now that I’ve seen this photo, I’ll bet the trainers put an interesting smell under Mister Ed’s nose to provoke the flehmen response. And they said he was “talking.”
(video by Kyle Hayes on YouTube. photo of horse flehmen response from Wikimedia Commons; click on the image to see the original)