When a cat smells an odor, it is a cleft lip sniffing reaction, because there are two small holes on the cat's palate. These two small holes are connected to the vomeronasal organ. After inhaling the odor from here, it can be conveyed to the brain for recognition. It emits smell, so the cat will open its mouth when it smells the smell, especially when it smells some special smell or pungent smell, the mouth will open more obviously.

Cats are very sensitive to smells, so try not to use irritating smells, such as:

1. Mint smell: Mint is not catnip. Humans think the smell of mint is fresh and good. It smells bad, but cats are different. If you have mint planted at home, it is best to move it to the balcony or not plant it at all.

2. Citrus smell: For cats, this smell is very unpleasant and pungent, and can drive them crazy.

3. The smell of chemicals: Cats cannot stand the smell of chemicals. There are many chemicals, such as bleach, insecticide, gasoline, alcohol, essential oil, paint, etc.

4. The smell of onions and garlic: The pungent smell of onions and garlic itself is very pungent to cats, especially garlic, which is very lethal to cats.

5. Cigarette smell: The smell of cigarettes is also very irritating to cats. Smelling the smell of cigarettes will make them uncomfortable. Smelling cigarettes for a long time will affect the cat's sense of smell.