Cats have an incredible olfactory system that is approximately fourteen times more sensitive than humans.
In addition to an extra organ that helps them sniff out potential mates and dangers from miles away, cats have anywhere from 45 to 80 million scent receptors in their noses.
With such a keen sense of smell, it's no wonder they use their noses everywhere to learn everything they can about their surroundings. New discoveries aren't the only reason a cat suddenly starts sniffing around.
Introducing new furniture or item
If a new item (such as a new piece of furniture) is introduced into the home, your cat will likely begin sniffing it. She does this to learn more about the unfamiliar object, looking for clues as to whether it belongs to another cat, what it is made of, and whether it is safe.
After the cat has thoroughly sniffed the object, it may decide to rub its face against it to leave pheromones and claim the object. Over the next few days, it may be seen approaching the same object from time to time, sniffing it, and renewing its “claim” to it.
The unfamiliar object does not have to be large or obvious. For example, it could be a blanket the cat has never seen before or a coat.
Surveillance of the territory
Cats are territorial creatures. While they may not hiss at everyone who passes by, they have an instinctive need to be attentive to both unfamiliar animals and people.
If a person brings a new scent into the home, the cat may begin sniffing around, trying to determine if its territory is under threat.
New person or pet
The new person smells different, which will make the cat want to sniff him. If the owner brings home a new pet, the cat will need time to get used to the new smells.
If a cat smells another animal from guests, it may begin to sniff its territory, leaving repeated marks.
Smells food
If a cat can smell food but can't see it, it may start sniffing around looking for it.
This also applies to prey. If a cat thinks it has scented prey, such as a rodent, it will not stop sniffing until it finds it.
I smelled another cat
Using the vomeronasal organ, also known as the Jacobson's organ, cats can sense the pheromones of other cats and even determine their reproductive status.
If there is a cat in the house and someone brings home the scent of a cat, he will probably sniff around to learn more about the potential new mate. In particular, the cat will try to determine whether she would be a suitable mate and, of course, where she might be.
Just chatting
Cats sniff their surroundings to gain new information. From understanding another animal's boundaries to checking on another's health, cats learn a lot just by sniffing. For example, if a human is sick, they will give off new smells. The same goes for another cat in the house who may be unwell.
Sometimes, gently sniffing a person's hands or shins can be a cat's way of saying hello. Other times, it may be expecting a person to feed it, or it may be asking to be petted.
