The Super-Sniffers

Dogs have an outstanding sense of smell. They can perceive even the tiniest scent molecules and follow a trail of odours over long distances. At the airport they help to track down prohibited substances in travellers' luggage. They are therefore often used in the search for missing people, for example after earthquakes or accidents.

Dogs have a far larger nose

The fact that dogs can smell so exceptionally well is closely linked to the anatomy of their nose. In most dogs it is larger than in us humans. Inside sits a bony nasal concha, which in dogs is extremely convoluted and therefore much larger than in humans. On this nasal concha lies the olfactory mucous membrane, which in dogs also takes up a much larger area. In us humans the two mucous membranes together are about 10 square centimetres, corresponding to the area of half a matchbox. The area of a German Shepherd, for example, is by comparison enormous and can measure more than 150 square centimetres.

Dogs have around 20 times more scent cells than humans

On this olfactory mucous membrane, in turn, sit the olfactory cells. Of these, most dog breeds have well over 200 million. In humans there are about 10 million. A dog's olfactory cells are very sensitive. The scent threshold is much lower in dogs, as the expert explains, and so the olfactory cells react to the tiniest amounts. In some cases a single scent molecule is enough. Animals that can smell so well are also known in technical terms as macrosmatic animals and nose animals. These include not only dogs, but also rodents such as mice, as well as deer.

• Outstanding smelling performance thanks to a complex nasal concha
• An enormous number of over 200 million olfactory cells
• A low scent threshold for perceiving individual molecules
• Biological classification as specialised nose animals

Smelling ability varies from one breed to another

However, the fact that these animals can smell well does not apply to all breeds to the same degree. A pug, for example, perceives odours less well than, say, a German Shepherd. This is directly connected to the shape of the nose. Some breeds no longer have a proper muzzle, as their face is quite flat with many folds and the nose turns out extremely small. Unfortunately, this is also a consequence of deliberate breeding. Because of the small nose, the nostrils and airways are often severely narrowed. This means that many of these animals constantly have problems with their breathing and frequently wheeze or snore. In addition, pugs cannot run as fast as other dogs.

This article serves as general information and to illustrate the impressive abilities of our four-legged friends.