Tracking and trailing dogs


Trailing is a technique used to search for individuals by their scent, which may be present on a piece of clothing or an object. In tracking, the dog follows a trail by using non-human odours, such as those emitted by disturbed soil or plants. It may also be used to find objects or simply to indicate the general direction in which the search should continue.

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Putting together the right team


In theory, all dogs have a good enough sense of smell to follow a person’s trail, but given the complexity of the discipline, special training is demanded and not all dogs are able to cope with this so a good selection process is essential.

Suitable dogs will be dynamic, hardy and strong, with great stamina, a very well developed sense of smell and an ability to concentrate for a long time, which is essential if they are not to be distracted by other scents. They also need to be brave and unfazed by gunfire and other ambient noise.

The handler must be phlegmatic, level-headed and physically fit. Long distances will sometimes have to be covered at a fairly high speed. Good observation and interpretation skills are also required, so the handler is able to register and act on even minor reactions from the dog.

© Diffomédia/Royal Canin
© Diffomédia/Royal Canin

The trail


The person who is being searched for gives off a scent at all times. The dogs will have to deal with a number of factors: specific scents (individuals and groups), chemical odours (leather, fat, clothing), breaks in the terrain (trampled vegetation, bacteria brought to the surface when the soil is broken), the surroundings (woodland, grassland, farmland) and atmospheric conditions.

The following factors can change the way the dog perceives scents. When encountered simultaneously they can seriously complicate the search operation.

External factors

Temperature. This can have a positive impact (cold air stops the diffusion of scent molecules) or a negative impact (warm air accelerates this diffusion, causes the dog’s nasal mucosa to dry out and reduces its resistance to fatigue).

Wind. This can physically alter the trail, cause the dog’s nasal mucosa to dry out and diffuse scent molecules at a much faster rate.

Precipitation. This can have a positive or negative impact on the trail, depending on the intensity. The trail will be preserved in the event of low humidity, frost or light snow. Heavy precipitation will “clean” the trail and impact on the dog’s olfactory acuity by depositing fine droplets or snowflakes on the nasal mucosa, which will make tracking impossible.

Terrain. This has a strong impact on the quality of the trail. There are three main types of terrain:

- Hard, dry terrain (sand, stone, rock, road), which scents do not cling to.

- Loose / wet terrain (grasslands, undergrowth), which is very good at retaining scent for up to 24 hours or more

- Ploughed terrain, which is good in overcast and damp weather but bad in dry and warm weather.

Electromagnetic field. The trail is disturbed by stormy weather or the closeness of high-voltage power lines.

Animal-related factors

Breed. German Shepherds, Bloodhounds and Belgian Shepherd Dogs (Malinois) are the breeds with strong scenting potential which are most commonly used.

Sex. Males are very distracted by the presence of another dog, especially a female in oestrus (season).

Physiological condition. Dogs will only work optimally when they are in good health.

Tiredness. Following a trail demands intense nervous physical activity. Regular and gradual training slows down the onset of tiredness and improves scenting quality.

Nutrition. Any deficiency due to low intake or low quality nutrition will have an impact on the dog’s general heath and may have an adverse effect on its sense of smell.

Trail-related factors

Length. The dog will only be able to detect a scent if the reference scent – a piece of clothing or an object – is of adequate quality and freshness. Likewise the dog needs to get a good run at the trail, i.e. it should not present immediate difficulties. A single trail of scent is often not enough for the dog to pick up. As it follows a trail, minimal quantities of body scent molecules will amalgamate, enabling the dog to identify the right scent.

Time. Scent molecules are diffused and evaporate in the ambient environment. In doing so, they decrease in intensity until they are no longer detectable, sometimes within a few hours, sometimes within a few days.

Trail. The form of the trail has an impact on how the dog works. If the trail is straight and simple it will be a lot easier to follow than one that changes direction frequently.

Human factor

The handler must be as neutral as possible, so as not to encourage the dog to invent things simply to try to please its handler.

© Diffomédia/Royal Canin
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Tracking and trailing dogs
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