How much more does a dog smell than a human?
Dogs’ noses can process odors 10,000 to 100,000 times better than ours.
Its moist truffles are able to detect the smell of:
- Objects or individuals that are no longer present, receiving information from the past .
- Objects or individuals that are about to arrive, receiving information from the future .
- Molecules that we secrete when we are nervous or stressed, capturing our mood and emotions .
- Molecules that we secrete when we are sick, capturing our state of health .
A unique nose in each dog
The nose of dogs is an exceptional organ.
The shape and relief of the nose are an exclusive feature in each dog. Exactly like the fingerprint on people. This nasal architecture is called the canine nasal pattern .
How do they breathe and smell at the same time?
The nose of dogs, like ours, must fulfill two functions:
- Breathe: The particular shape of their nostrils allows them to extract part of the inhaled air, while a new flow of air enters with a greater number of odor molecules. That is, with more information.
- Extract information: With a much larger brain area dedicated to smell than in humans and a set of structures dedicated to extracting olfactory information, dogs are excellent at search, detection and tracking tasks.
The most important structures in the smell of dogs
The most important structures in the olfactory system of dogs are represented in Figure 1 and are:
- Holes or nostrils: the nose of dogs is kept moist, which facilitates the capture of odor molecules. In addition, dogs smell in three dimensions: each nostril works independently, allowing the dog to locate the directionality of the scent source.
When the nostrils inhale air, it follows two different paths: one for smelling and one for breathing. The exhaled air in the breath is evacuated through the open side of each nostril, leaving space for more air to enter. In this way, the amount of odor molecules that reach the olfactory detection structures such as the olfactory epithelial turbines and the vomeronasal organ increases.
- Olfactory epithelial turbines: ducts covered with an epithelium composed of 300 million olfactory cells responsible for receiving odorous information. Humans have 5 million of these receptors.
- Vomeronasal organ or Jacobson’s organ: it is a structure specialized in the detection of social information, such as hormones and pheromones secreted by other animals. When your dog snorts loudly through his nose while sniffing or in front of a very powerful perfume, he is cleaning his vomonasal organ.
- Olfactory bulb: structure of the nervous system that connects the olfactory receptors with the central nervous system or brain, in charge of processing all the information.
Dogs recognize each other by smell
When your dog looks at himself in the mirror for the first time, he is almost certainly going to bark. This is because dogs do not recognize that the dog reflected in the mirror is him.
However, when a dog sniffs his own urine, he recognizes that it is him , even when the urine is placed in a different place than where he deposited it. This is deduced because before his own urine the dog spends a short time sniffing. However, when its scent has been modified by some substance, for example, the urine of another dog that came later, the dog spends much more time gathering information.
Why do some dogs have a better sense of smell than others?
Scientific studies have found that there are differences in the olfactory epithelial cells of different individuals (polymorphisms). It is not yet clear whether these differences affect functionality and make some dogs better at detecting odors than others.
What is clear is that breeds such as the German Shepherd or the Labrador Retriever are better options to be dedicated to olfactory tasks, when we compare them with breeds such as the Pekingese or the Pug. And this is mainly due to their anatomy and health.
Your dog’s nose speaks of his health
Surely you have heard the importance of ensuring that your dog’s nose or nose remains moist and without cracking. Since the opposite could, for example, indicate that your dog has a fever or is sick.
Particularly, dogs that suffer from brachycephaly , present structural modifications associated with this cranial conformation, which complicate both respiratory and olfactory tasks. Subject, which is highly debated, for compromising animal welfare.
These structural changes include:
- Very narrow nostrils that make it difficult for air to pass through ( stenosis )
- Hypertrophy or thickening of the turbines and olfactory epithelium
- tongue hypertrophy
- extension of the soft palate
Buzek, A. et al. 2022. The Shape of the Nasal Cavity and Adaptations to Sniffing in the Dog (Canis familiaris) Compared to Other Domesticated Mammals: A Review Article. Animals, 12(4), 517.
Horowitz, A. 2017. Smelling themselves: Dogs investigate their own odours longer when modified in an “olfactory mirror” test. Behavioural processes, 143, 17-24.