Introduction
Both cats and dogs have an excellent sense of smell, but there has been an ongoing debate about which animal has the better sniffing abilities. In this article, we will compare the sense of smell between cats and dogs by looking at the anatomy, scent detection abilities, scent recognition, brain processing, sniffing behaviors, scent marking, and tracking capacities.
We will examine the latest scientific research and real-world examples to shed light on the similarities and differences between feline and canine sniffing prowess. By the end, you will have a clear understanding of cats’ and dogs’ respective olfactory talents.
Anatomy of Smell
Cats and dogs have a highly specialized olfactory anatomy that allows them to detect odors with extreme sensitivity. Both animals have millions more olfactory receptors than humans, located in a large, convoluted olfactory epithelium lining the nasal cavity (1). However, studies have found key differences in the olfactory anatomy of cats versus dogs.
Dogs have up to 300 million olfactory receptors, while cats have up to 200 million (2). The olfactory epithelium in dogs covers an area of 170–220 cm2, compared to just 30–70 cm2 in cats. Dogs also have longer nasal passages, allowing more opportunity to detect smells before they reach the throat (1). So while both animals excel at scent detection compared to humans, dogs generally have a more expansive and sensitive olfactory anatomy.
One study found that cats may have more types of certain odor receptors, allowing them to detect a wider range of scents. But dogs have more total receptors overall (2). The superior olfactory abilities of dogs are likely due to their larger nasal cavity surface area and longer air passageways.
Sources:
(1) https://www.midoricide.com/blogs/midoricide-blog/dogs-vs-cats-a-comparison-of-the-5-senses
(2) https://www.catbreedslist.com/stories/cats-sense-of-smell-compared-to-dogs.html
Scent Detection Ability
Cats and dogs rely heavily on their sense of smell to navigate and understand the world around them. Studies show that dogs have a much keener sense of smell compared to cats. According to research published in Nature (https://www.nature.com/articles/s41598-021-02238-7), the absolute odor detection threshold (the lowest concentration of a smell that an animal can detect) is significantly lower in dogs compared to cats. The average odor detection threshold for dogs was found to be between 1 and 5 parts per trillion, while for cats it was between 1 and 10 parts per billion. This means dogs can detect odors at concentrations approximately 10,000 to 100,000 times lower than cats.
The superior scenting abilities of dogs can be attributed to the structure of their noses and number of scent receptors. The portion of a dog’s brain devoted to analyzing smells is about 40 times larger than in humans. Dogs have up to 300 million olfactory receptors in their noses, compared to only about 12 million in cats. The structure of a dog’s nose helps odors linger longer, allowing more scent molecules to bind to receptors. This gives dogs a heightened capacity to detect, discriminate, and recognize even minute amounts of a wide range of odors.
Scent Recognition
Both cats and dogs have an incredible sense of smell that allows them to recognize and process scents in unique ways. However, research shows cats may have a slight edge in scent recognition abilities.
Cats have nearly 200 million odor-sensitive cells in their noses, compared to a dog’s 125-300 million (source: Midoricide). With this huge number of scent receptors, cats can detect and recognize a wider range of odors at lower concentrations.
Additionally, cats have more genes devoted to scent detection than dogs do. A study found cats have around 20 functional olfactory receptor genes compared to dogs’ 8-11 (source: Canidae). This gives cats a larger scent vocabulary and ability to recognize nuances between odors.
When recognizing scents, cats rely more on the scent’s molecular structure while dogs pay attention to the overall smell profile. This allows cats to detect tiny concentrations of odor molecules and recognize scents even when slightly altered.
However, dogs also have incredible scenting abilities. While cats may detect more scents, dogs can follow a scent trail better. Dogs also use their sense of smell cooperatively for tasks like tracking and bomb/drug detection.
Overall, cats appear to have a slight edge in scent detection and recognition abilities. But both species have amazingly complex scent processing powers that play a crucial role in their lives.
Brain Processing
Recent scientific research shows some interesting differences in how cat and dog brains process scents. While both species have a large olfactory bulb in the brain dedicated to analyzing smells, a dog’s olfactory bulb makes up a larger percentage of their total brain mass compared to cats (source). This suggests dogs may devote more brain power to scent processing.
However, cats have nearly double the amount of scent receptors in their olfactory epithelium compared to dogs (source). This gives cats a high capacity for detecting scents. Cats also have a large scent detection area in their brains, though proportionally smaller than dogs. So while dog brains may be more finely tuned for picking apart complex scents, cats excel at detecting even minute amounts of odors important for territorial marking and communication.
Sniffing Behavior
Cats and dogs have different sniffing habits and purposes due to differences in their anatomy and behavior. Dogs have more scent receptors and a larger scent processing area of their brain, so they tend to sniff more frequently and for longer periods than cats (Source: https://www.catbreedslist.com/stories/cats-sense-of-smell-compared-to-dogs.html). Dogs will sniff objects thoroughly, even obsessively, to gather information. Their constant sniffing helps them construct a very detailed understanding of their environment.
Cats do not sniff as often or as vigorously as dogs. They rely more on their vision and hearing to collect information. Cats sniff briefly to gather only essential information about identity, emotional state, and markings. Their sniffing is usually connected to stimulus rather than general environmental scanning like dogs (Source: https://www.beverlyhillsvets.com/blog/do-dogs-really-have-more-sensitive-noses-than-cats/).
Scent Marking
Both cats and dogs engage in scent marking behaviors, but for different reasons. According to a research paper from Homeward Pet Adoption Center, cats use scent marking to identify their territory [1]. They have scent glands on their cheeks and forehead that they use to rub against objects, leaving their scent behind. This allows them to feel secure and establish their domain. Dogs, on the other hand, primarily use urine marking to identify their territory and convey information to other dogs [1]. Unneutered male dogs are especially prone to urine marking to signal their availability to potential mates.
While cats use scent marking on a regular basis to feel comfortable in their environment, urine marking in dogs is often a sign of anxiety or feeling the need to establish dominance. If a dog starts inappropriately urine marking in the house, it usually indicates a problem that needs to be addressed through training and environmental management.
Tracking Ability
When it comes to tracking prey or humans by scent alone, dogs have the advantage over cats. A dog’s sense of smell is 10,000 to 100,000 times more acute than humans. They have up to 300 million scent receptors compared to a cat’s 200 million. Dogs can pick up scents that are diluted to 1 or 2 parts per trillion (equivalent to finding a teaspoon of sugar in 2 Olympic sized pools). Their flexible nostrils can detect the change in odor plumes when tracking moving targets. Dogs also have specialized scent receptor genes that enable them to detect specific compounds.
Cats rely more on their vision for hunting rather than their sense of smell. While cats can detect odors 5 times better than humans, they only have 30-40 million scent receptors. Their noses are less versatile than a dog’s, built for detecting prey directly in front of them rather than following a trail. Cats also lack the scent receptor genes that allow dogs to key in on particular scents. When it comes to tracking by scent alone over long distances, dogs have superior olfactory talents.
According to an article on Catster, while cats may not match a dog’s tracking abilities, they compensate with other skills like speed, stealth, agility and night vision.
Real World Examples
Both cats and dogs rely heavily on their powerful sense of smell in everyday life. Dogs are renowned for their tracking abilities, using their sensitive noses to follow scents over great distances. Police and military dogs use this skill to track missing people, find illegal substances, and detect bombs (https://www.midoricide.com/blogs/midoricide-blog/dogs-vs-cats-a-comparison-of-the-5-senses). Dogs can also detect certain diseases and health conditions through scent, and may even be able to smell fear or anxiety in humans.
While less utilized, cats also rely on their acute sense of smell in remarkable ways. Cats have an ability to sniff out disease in their owners, and can detect subtle changes in scent that signal the early stages of cancer, low blood sugar, and seizures (https://www.catbreedslist.com/stories/cats-sense-of-smell-compared-to-dogs.html). Their sense of smell likely plays a role in bonding between cats and owners, as cats recognize each other through scent glands. And of course, cats depend on smell to locate food, avoid predators, mark territory, and recognize their humans.
Conclusion
To summarize, dogs have a better sense of smell than cats overall. Dogs have up to 300 million scent receptors in their noses, whereas cats only have around 200 million. This gives dogs a stronger ability to detect scents and track them. Dogs also have a larger olfactory epithelium area and far more scent-detecting genes. Their longer snouts likely help them better locate and analyze scents as well.
However, cats excel at detecting and distinguishing between similar scents. Their scent receptors seem highly attuned to subtle differences. While dogs beat them in sensitivity and tracking, cats are better at scent discrimination and recognition. Both animals rely heavily on their sense of smell for hunting, detecting threats, reading social cues, and exploring their environment. Though different in exact abilities, the incredible scenting prowess of dogs and cats are equally impressive marvels of biology and evolution.