There’s no denying dogs have killer noses. But just because they win the pet olfactory prize doesn’t mean they’re the only ones with a powerful sense of smell. As cat lovers know, a feline’s ability to detect scents is nothing to sniff at. In fact, it’s pretty darn impressive — and far more complex than most of us realize.
Anatomy of smell
A kitty’s nose is more than just a cute boop button. It's also a precision instrument where some 45 to 80 million microscopic olfactory receptors recognize and process odors, according to Parade magazine. That’s not quite up to canine level. Dogs have between 149 million and 300 million smell receptors. But it’s far more than the 5 million we humans have — which means a cat’s sense of smell is several times keener than ours, capable of detecting aromas we can only faintly whiff or miss altogether.
Cats don’t just have the nose we see. They also smell through their mouths, thanks to the vomeronasal organ (or Jacobson’s organ), located in the roof of their mouth just behind the front teeth with ducts leading into the nasal cavity. You may notice your cat sometimes breathing through a slightly open mouth wearing an expression that looks like a smile or grimace. This is called a flehmen response, and it’s how your cat draws odors into its vomeronasal organ (VNO) for processing. Interestingly, felines share this smell-tasting ability with many other creatures that have VNOs, including horses, dogs, big cats, goats and snakes.
See the flehmen response in action in this video.
Double the smelling power
Why do cats have two sniffing systems? Each one handles different kinds of scents, and together they make for snout superpowers.
A cat’s visible nose (which, by the way, is unique to each kitty with its own pattern of ridges and bumps) detects regular smells in the environment, such as food aromas. Smells hit the olfactory receptors, which send signals to a cat’s brain for analysis and possible response.
Cats use their nose and vomeronasal organ to pick up both scents in their environment and pheromone messages from other cats. (Photo: Feliciano Guimaraes/flickr)
The VNO, on the other hand, picks up pheromones, chemical substances that communicate social, territorial and sexual information. Each cat releases its own unique pheromone signature from special glands located between its eyes, at the corners of its mouth, at the base of its tail, between the pads on its paws and on other parts of its body. The VNO captures these chemical communications from other cats and sends signals to the brain for processing.
Together, these two scent-seeking mechanisms provide cats with a purr-fect multidimensional picture of the world around them. In fact, felines rely on these odor maps far more than their eyes to “see” what’s going on nearby, putting smell among their strongest senses.
Making scents of their surroundings
Cats often greet by rubbing heads to release pheromones, odorless chemical messengers that help them learn about each other. (Photo: Hisashi/Wikimedia Commons)
Cats use environmental odors and pheromones to navigate their turf and communicate with other cats. Examples include:
Finding food — A cat’s nose can indicate the presence of a nearby mouse, prompting an immediate predatory response. Kittens, which are born with their eyes shut, also identify their mothers and an available nipple by her pheromone secretions. In fact, the information is so detailed it allows each litter mate to stick with its own preferred nipple and cut down on mealtime competition.
Marking territory — Cats delineate their home boundaries with urine and pheromones, making the rounds periodically to remark areas where the odor has faded. This can include your furniture and walls — and even you. Yes, those cheek rubs and gentle head bumps are your fur baby’s way of claiming you as one of its territorial prizes. It’s not clear whether cats mark territory to keep other cats away or to feel at home in their personal space, or some combination of the two.
Social communication — Felines don’t shake hands, give hugs or exchange phone numbers when they meet, but they do relate to one another and read tiny social cues via their remarkable sense of smell. They may rub or bump heads to release pheromones and sniff various anatomical parts for clues about each other (including the rectum, which also secretes pheromones). They may also check out each other’s urine and feces. All that sniffing provides a treasure trove of information, including whether a new acquaintance is a friend or foe, what they like to eat, what mood they’re in, how healthy they are and whether they’re male or female.
Looking for love — Not surprisingly, olfactory cues play a major role in feline mating. Female cats in heat, or estrus, can lure every tomcat up to a mile away with her powerful sexual pheromones. Think of it as a pungent dating profile. Unfortunately, she may also spray streams of “scentsual” urine around your house (not to mention yowl incessantly) in an effort to woo potential suitors -- another good reason to spay or neuter your cats.
Learn more about how cats communicate via odors and pheromones in this video.