After cats smell smelly feet, they often open their mouths with a frightened expression. However, they are not about to be vomited. On the contrary, they are turning up their upper lips to allow the smell to enter the organ in front of the nasal cavity to perceive the smell more carefully. This behavior is called the "cleft lip sniffing reaction."

Why do cats open their mouths when they smell smelly feet

After cats smell smelly feet, they often open their mouths with a frightened expression. However, they are not about to be vomited. On the contrary, they are turning up their upper lips to allow the smell to enter the organ in front of the nasal cavity to perceive the smell more carefully. This behavior is called the "cleft lip sniffing reaction."

Many mammals have the behavior of turning up their upper lips, such as horses, lions, pandas, etc. In daily life, when domestic cats smell a strong or unfamiliar odor, they will also open their mouths half-open, raise their upper lips, expose their teeth, and squint their eyes, as if they are affected by the strong odor. This is cleft-lip sniffing.

There are two small holes at the roots of the front teeth of the cat's palate (the upper arched part of the mouth), which are connected to the vomeronasal organ. The odor molecules absorbed here can be transmitted to the brain through a different path than the odor smelled through the nose. In order to allow the vomeronasal organ to absorb odor molecules, the mouth must be half-open and the upper lip raised.