Facts and misconceptions: Why dogs’ noses are usually wet
It is a marvel of smell. And almost always wet. The moisture in a dog’s nose determines perception, cooling, and protection. Moreover, it fuels a myth.
When a dog greets us, it is almost always the first thing there: curious, cool, moist – its nose. It seems constantly in motion, as if scanning the atmosphere, perceiving scents hidden from us.
The dog’s literally brilliant nose is legendary. And for good reason. Hardly any other animal can sniff out the world so expertly. However, why is a dog’s nose almost always wet? Where does the moisture come from, and what role does it play in sniffing? Moreover, is it really true that a dry nose is an indicator that the animal is unwell?
The nose of a dachshund, Great Dane, or Doberman is a small hub: several sources converge here, keeping the tip of the nose almost constantly moist.
The most important source of moisture comes from within the nose itself. Paired glands located laterally in the nasal cavity secrete a thin, watery fluid. This fluid flows out through tiny openings and then spreads across a surface perfectly suited for this purpose: the nasal planum, also called the rhinarium, is covered by a network of surfaces crisscrossed by minute furrows. These furrows help retain moisture. The narrow groove between the nostrils also plays a crucial role: capillary action constantly transports moisture from the mouth towards the olfactory organ.
Several glands keep the dog’s nose wet.
Furthermore, the mucous membrane lining the nasal cavity is lined with numerous glands that continuously secrete mucus. This supply is particularly important when the dog is sniffing, following interesting scents, and inhaling air rapidly. The glands along the nasal passages also moisten the inhaled air. Moreover, in hot weather, these glands increase mucus production.
In addition, there is something you often see in dogs: a quick lick of the nose. This not only wipes dust and pollen from surfaces but also distributes saliva. Moreover, finally, a small amount of moisture comes from the eyes: tear fluid travels through the ducts to the rhinarium.
All that moisture would be of little value if it were merely a byproduct of anatomy. In fact, it is a key to what makes dogs so unique: their phenomenal sense of smell. The wet surface of the nose acts like a fine net. When scent molecules drift past the rhinarium, they adhere to the rhinarium, dissolve in the mucus, and thus become accessible to the olfactory cells in the nose. Without this moist film, many scents would simply pass by, too fleeting to be detected.
Around 300 million olfactory cells are located inside a dog’s nose; in humans, there are only five to six million. The surface area on which odors are processed is also in a different league: While our olfactory epithelium measures around five square centimeters, some dogs’ can reach 150 square centimeters.
However, the fact that dogs can perceive scents ten thousand to one hundred thousand times better than humans is not only due to this sheer ability, but also to a physical trick: Moisture prolongs the contact between odor molecules and sensory cells. Even extremely diluted traces thus have a chance of being detected.
A wet dog’s nose holds onto scent molecules for longer.
When sniffing, some of the air flows directly into the olfactory area, while the rest is warmed, moistened, and filtered. This effect is further enhanced by rapid, rhythmic breathing. The moist nose ensures that the scent information is not immediately lost but remains present for a moment longer.
However, the benefits do not end with smelling. Dogs have very few sweat glands. They release excess heat through their paws and, above all, by panting. They also lose some heat through their nose, from which water constantly evaporates. This cools the blood in the fine vessels beneath the surface. The nose is therefore part of the dog’s internal air-conditioning system.
Furthermore, antibodies in nasal secretions form a first line of defense against invaders such as viruses and bacteria. A moist nose thus also acts as a protective shield.
Moreover, recently, researchers have discovered something astonishing: dogs can apparently even perceive infrared radiation with their noses. In a study, scientists trained three dogs to distinguish between two objects placed some distance apart, which differed only in temperature. The result: all three dogs reliably chose the warmer object.
Brain scans revealed that whenever the animals were exposed to thermal stimuli, a specific area in the cerebral cortex became active: a part of the somatosensory cortex involved in processing sensory information from the nasal region. The moist nose of a dog is therefore not merely an organ of smell, a cooling surface, and a barrier against germs, but also a heat sensor.
Many myths surround the dog’s nose – for example, what it means when it is dry.
Precisely because the sense of smell is so prominent in poodles and similar breeds, we tend to overinterpret the information they provide about their nose moisture levels. Over time, numerous misconceptions have developed regarding a dog’s nose: some plausible, others stubbornly false. The most common one is: If the nose is dry, the animal is unwell.
The moisture level naturally fluctuates throughout the day. After sleeping, for example, when the dog has been lying still for a longer period and has licked less, the nose often feels drier. Warm air, wind, or sunbathing can also temporarily dull the nose. Conversely, it can appear particularly wet in humid weather or after a walk in the rain. None of this initially reveals much about the dog’s health.
What dogs want to tell us with their eyes
A dry nose is therefore by no means a warning sign, just as a wet nose is no guarantee of well-being. Dogs can be dehydrated or ill and still have a cool, wet nose. Conversely, there are perfectly healthy animals whose noses appear dry at times. What matters is not a single physical characteristic, but the overall picture.
However, if more than just the moisture level changes, you should be vigilant and seek veterinary advice if in doubt: for example, if the discharge is persistent, discolored, or even bloody; if the surface of the nose appears cracked, thickened, or inflamed; or if other symptoms develop, such as lethargy, fever, or breathing difficulties. In these cases, the nose could indeed be one of several indicators that the dog is ill.
A glance at the nose can provide clues, but never in isolation. If you want to know how your dog is doing, you should pay less attention to a single body part and more to behavior, appetite, activity, and mood. The nose is not an oracle, but it is part of a finely tuned system. It reveals a lot about the world the dog perceives, and sometimes even something about its state of mind. You just have to learn to look properly.