If answering briefly: a dog's sense of smell is significantly stronger.
Cats also have an excellent sense of smell and largely rely on it, but in terms of olfactory capabilities, most dogs are noticeably superior.
Why dogs have a better sense of smell
Dogs' olfactory system is designed to literally "read" the world around them with their noses.
Many breeds have about 200–300 million olfactory receptors, whereas humans have only a few million. Cats also have a great many receptors, but on average significantly fewer than dogs.
What is especially impressive is not only the number of receptors, but also how large a portion of a dog's brain is devoted to processing smells.
For a dog, smell is almost a separate information channel.
It can distinguish:
- the trail of a specific person;
- the scent of another animal after a long time;
- barely noticeable changes in the composition of the air;
- some substances in extremely low concentrations.
That is why dogs are used in search-and-rescue operations, at customs, in the police, and even in some medical research.
And what about a cat?
A cat's nose should not be underestimated either.
Cats perfectly distinguish the smells of food, other animals, territory, and familiar people.
In addition, they have a well-developed vomeronasal organ, or Jacobson's organ. With its help, cats analyze chemical signals, including pheromones.
That is why sometimes a cat seems to "freeze" with its mouth slightly open after sniffing something. This is not a strange grimace — it is how it additionally analyzes the smell.
Who will win?
If we compare specifically sensitivity and the ability to track faint odors, a dog will almost always be ahead.
This especially applies to breeds bred specifically for scent work — for example, bloodhounds, beagles, or shepherd dogs.
But a cat's sense of smell is also very important and subtle. It is just used a little differently.
A dog more often seems to "scan" the space with its nose.
And a cat uses smell as part of its system of orientation, communication, and recognition of territory.
An interesting point
Smell is so important to a cat that it may become wary even next to a well-known person if that person smells unusual — for example, after a hospital, another animal, or strong perfume.
Dogs experience roughly the same thing, but they usually "sort out" a complex mixture of smells faster.
So
A dog has a stronger sense of smell.
Moreover, in some breeds — by many times.
But a cat also has a very good sense of smell and perceives the world through its nose much more strongly than we think.
If a person sees with their eyes, a dog largely "sees" with its nose.
And a cat — with its nose, ears, and eyes all at once.
