Anyone who has watched a cat investigate a shopping bag for five minutes or a dog find a snack from what appears to be miles away has seen how different the sense of smell is in pets than ours. So, which one of these animals is the better sniffer? Previously, at mybestie.gr, we have covered some of the myths around the amazing sniffer that is the dog's nose. Now, it’s the cats’ turn to shine – and, as always, they might have some interesting facts to share with us.

Dogs are the sniffing champions - But there is more than meets the eye

Dogs' sense of smell has been rightly lauded because their noses are anatomically designed to deal with odors in an efficient way, and there are an incredible number of olfactory-receptor genes in their genome. Genome-based research into the DNA of cats and dogs reveals that cats have about 700 olfactory-receptor genes, whereas dogs have more than 800 olfactory genes. Genomic research on the olfactory abilities of dogs has found more than 1,000 olfactory-receptor genes in dogs, both functional genes and pseudogenes combined. This explains why figures like "200 million receptors in cats" and "300 million in dogs", even though often quoted, must be approached carefully. There may be differences in the definitions used by different resources, and an estimate of receptor cells does not equate to the figure of receptor genes. One thing that can definitely be said is that the dogs have a better developed olfactory system. However, this does not end the competition.

Smelling superpower of cats

While cats might have fewer olfactory receptor genes than dogs, they seem to have all the equipment required to sense something else chemically. The presence of the vomeronasal organ in cats, also known as Jacobson's organ, aids them in processing chemosignals, including pheromones. While canines also have a vomeronasal organ, genomics studies have revealed an interesting discrepancy between the two groups regarding a certain type of receptor that goes with it: around 21 functioning V1R genes in the cat group compared to eight in canines. To put it another way, while the canine may rule the olfactory senses when it comes to sniffing smells, the feline olfactory sense system seems to be geared toward communicating through chemical messengers. Smell for cats isn't just for finding things. It is also for identifying whom it belongs to.

What's that weird open-mouthed thing your cat is doing?

Have you ever watched your cat snarl and pause with its mouth opened wide, looking like it was offended by something? No, your cat hasn’t just remembered that you bought the less expensive treats. The behavior has a name; it’s known as the flehmen response. It aids in the transfer of chemicals to the vomeronasal organ. Studies on feline behavior have associated flehmen with the analysis of chemical messages like urine and other important social chemicals. Through smell, cats can obtain useful information regarding territory, recognition of familiar objects and interaction with other cats. So that ridiculous-looking face is quite an elaborate analysis of chemicals after all!

Cats leave messages with scent too

It’s not all about smelling in the feline world. Cats also leave scents behind. When your cat cheek-rubs or body-rubs against furniture, another cat – or even yourself – it is sending a message through scent. Other behaviors like scratching may add to the chemical information present in the environment. This head-bump to your leg is thus not just an adorable hello, but a complex interaction. Scent plays an important role in how the cat interprets its surroundings. In effect, your house is covered in invisible feline Post-it Notes.

Cat vs dog: Who wins?

If the battle is about "Who has the more powerful sense of smell?", the award must go to the dog. Dogs have a bigger complement of functional olfactory receptors and are anatomically highly specialised to detect smells. But cats deserve their own award. Their sense of smell and of chemosensing through the vomeronasal system are highly suited for the cat's territory, identity, and chemical communication-filled environment. There is also an interesting difference in the genomics of the two species that suggests evolution has armed each with a unique scent-based capability rather than just having one inferior to the other.

What's the score then?

Dog: scent detection specialist.

Cat: chemical intelligence specialist.