What Your Cat's Nose Knows

There’s a lot more to your cat’s nose than you think.

Do you ever pay much attention to that cute little nose your cat has? We’re used to thinking of dogs as being all about smells – but it turns out cats are very much into scent too. A literature review by Kristyn Vitale Shreve and Monique Udell (Oregon State University) explains what we know about the importance of olfaction and chemical detection to cats, from what it means for indoor cats to the possibility of trained scent detection cats.

Vitale Shreve and Udell say,

“Importantly, a better understanding of cat chemical signals has critical applied implications, as scent (and marking) plays an important role in many species-typical cat behaviors, problem behaviors, and can also serve as enrichment if properly understood and applied.”

Ultimately, if cat owners have a better understanding of the role of scent in their cat’s life, they can improve their cat’s welfare.

How cats process chemical signals

You probably already know cats have two different systems that are important organs of olfaction and chemical detection.

First of all, of course, there’s the nose: the two nostrils that allow scents in to the nasal cavity. Then there’s the vomeronasal organ (more easily called the VNO if you prefer). This is in the hard palate in the roof of the mouth. When you see a cat with their mouth open in a grimace, called the Flehmen response, they are utilising their VNO to make sense of chemical signals.

Beyond that, we don’t know as much as you’d think, showing the urgency of more research in this area. For example, we know that a part of the brain called the caudate is used in processing smells, and in many species it is also activated in anticipation of rewards. In dogs, we know that the caudate is activated in response to the smell of a familiar human. We don’t yet know if this occurs in cats or not.

And while we know the vomeronasal organ has three types of detectors, only one of them has ever been investigated.

The VNO detects what are known as pheromones – chemical signals that carry meaning for that and other cats. Cats release different types of pheromones from glands on their bodies, and while the purpose of some is not known, we know a lot more about others and synthetic versions of some are available (you’ve heard of Feliway).

The importance of scent and pheromones to cats

Medical detection cats?

Cats are able to tell the difference between many different scents. Vitale Shreve and Udell say their size, agility, and ability to fit in small spaces means that cats may make excellent scent detection animals. For people who are afraid of dogs, cats might make good medical detection animals. Of course, more research is needed, not just into a cat’s sense of smell but also into the practicalities.

How cats use chemical signals

Cats have scent glands on the head between the eyes and ears, on the side of the forehead, in the cheeks, under the chin, at the corners of the mouth, between the pads on the paws, at the base of the tail, in the ano-genital area, and around a female cat’s nipples. These glands produce pheromones.

Pheromones are used in social communication. As solitary animals, cats can use scent to mark their territory so other cats know to stay away, without them even needing to meet. When cats live in groups, they can maintain a ‘group scent’ that means familiar cats all smell similar. When you see cats rub against each other’s bodies, it is believed they are maintaining this group scent.

Pheromones are also used in sexual activity. When a tomcat rubs his head near a sexually intact female, he leaves F2 pheromone.

In addition to pheromones, cats deposit scent by scratching and with saliva, urine and faeces.

Scratching leaves scent from glands in the cat’s paws, and over time may build up on the scratched object. It may become an “olfactory reference point” for the cat, and so providing appropriate places for cats to scratch and leave their scent is important.

The importance of scent to kittens

Kittens are born with their eyes and ears closed. They use the feeling of warmth, their sense of touch and chemical detection to find their nest. The nest is full of chemical signals – secretions from the mother cat’s glands mark the area, and hair, saliva and urine from the kittens all add to the mix. This nest odour is thought to reduce stress in the kittens, have a calming influence and improve their well-being.

Photo: Rashid Valitov; top, Dziewul (both Shutterstock).

Did you know that within a litter of kittens, by the time they are one or two days old (and until about 32 days) each one has its own preferred nipple on the mother? The scientific term is “teat constancy.” Pheromones are released from glands around the nipples. We don’t know if each nipple has its own characteristic odour, or if saliva from the kitten adds its scent to the nipple.

As the kittens are able to move around more, “teat constancy” subsides and kittens will nurse from other female cats as well as their mother.

Scent in social relationships between cats

Olfaction plays an important part in social relationships between cats. The authors say that in one study, sniffing accounted for almost a third of the behaviours observed. Cats often sniff each other at the start of social interactions.

Male and female cats respond differently to smells from other cats; the Flehmen response and urine spraying are more common in males, whereas female cats pay more attention to skin secretions than to urine. Chemical signals seem to play both a sexual and a social role.

Chemical signals are also used in marking territory and there are several theories about how this works. It may be that marking is used to tell other cats to stay away, but an alternative idea is that it helps the cat feel at home within their own territory. This is another area where more research is needed.

What this means to you as a cat owner

Cat owners should recognize that chemical signals are important to cats, even if we are not always able to detect them ourselves.

Some of these signals help to make cats feel safe and secure – which means that if we get rid of them with too much cleaning, it may make our cats more anxious. The authors suggest the use of cleaning products should be limited near the cat’s rest areas, scratching posts and litterboxes. If we remove their scent from these areas, they may choose different areas for these activities instead, which we may be none too happy about.

You may notice that in places where your cat rubs frequently, the furniture or wall is marked and paint may even be rubbed off. Your cat gains comfort from these areas smelling like him- or her-self, so if you can hold off cleaning or re-painting as long as you can, your cat would prefer it.

Photo: Kristi Blohkin (Shutterstock).

Adding the cat’s own scent to new furniture or new environments may help it to feel calm and relaxed. This may be especially important in rehoming centres, where the cat is faced with a completely new and stressful environment.

The idea of scent as a reference point within the environment may be especially useful for people with blind cats.

Providing scents to cats can be an enrichment activity, especially for indoor cats. Catnip is an obvious example, and while many cat owners are aware of this there are other substances such as silver vine that fewer people have heard of. Sarah Ellis has a lovely idea in her book, The Trainable Cat (co-authored with John Bradshaw) of a sensory box – bringing things from the outside in for the cat to experience. Remember too that cats can get used to things, so rotating scents or bringing in new scents is a good idea.

Cats can be trained to go on leash walks to give them access to the outdoors. Alternately, safe enclosed ‘catios’ can give them outdoor spaces if it is not possible for them to have regular outdoor access. Simply leaving a window safely ajar can let them sniff the breeze.

Scratching is important to cats, and so they need to be provided with suitable scratching posts. When such posts are available, cats will use them – and you can reinforce this behaviour by rewarding them (e.g. with a cat treat) for scratching them.

If your cat is not using the litter box appropriately (peeing outside the box, urine spraying, pooping in the wrong place), then in addition to taking your cat to the vet to check for a medical problem, also consider that stress might be playing a role. Make sure you have enough litter boxes, that they are big enough and located in quiet areas, and take steps to reduce stress in all aspects of your cat’s life. Vitale Shreve and Udell note the unfortunate possibility that if litter box issues are a result of anxiety, the scent from them may make the cat feel more comfortable, and completely getting rid of that scent may cause more anxiety… Since humans are not likely to tolerate this scent, it emphasizes the importance of reducing stress in all other areas.

It’s worth thinking about where a cat’s scent glands are when stroking your cat too. A study by Sarah Ellis et al (2014) found cats prefer to be stroked around the head in the areas where the scent glands are, and suggests it may be a bit like allo-rubbing.

Of course, always give cats a choice of whether or not to interact with you or with particular scents.

Conclusions

It turns out that scent and chemical communication matters a lot to cats, and that cats can differentiate between many different smells. While we need more research on different aspects of how cats produce and utilise chemical signals, we can use what we already know to help make cats feel more comfortable and secure, and even use scent as enrichment.

My Pets