Did you ever see your cat turn up his nose to something smelly, such as a rivals urine mark or a good fish?
This is called the ‘Flehmen response‘. It’s a way for cats to use their vomeronasal organ (also called the Jacobson’s organs) to get a better smell of the object or smells like pheromones. This organ provides the cat extra sensory information to better understand what he is smelling.
In The Mouth
The organ is found between the hard palate of the mouth and the septum of the nose. The Jacobson’s organs link to the hypothalamus in the brains that functions as a soft of switchboard to direct the information to other areas. Tiny ducts connect them to the openings behind the cats teeth in the roof of their mouth.
All cats use this mechanism to analyze pheromones but boy cats show the flehmen sneer most often. That may be because they are particularly attuned to checking out sex-related information even if they’re neutered.
Pictures by maxhouse.com.