Analysis: it takes years of experience, dedication and a lot of scientific knowledge to train and work a search dog
From finding human scent in a vast open area to following a specific person's scent to bring them back home, search dogs have worked in local communities across Ireland for many years to help find missing people. Search dog teams are made up of a handler and their dog, who work together and dedicating their time to saving others. Each search is unique and can be anything from a family member that has gone missing from home to an injured or lost hillwalker.
It isn't a job that suits everyone, or indeed every dog. The dog will need to be able to search for human scent for several hours, day and night, and navigate difficult terrain. The handler, in addition to the above, needs to have an understanding of search tactics, scent theory, dog behaviour, weather and air movement to make sure the dog is working effectively.
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From RTÉ Archives, Tom MacSweeney reports for RTÉ News on a mountain rescue team and search dogs looking for a missing climber in the Kerry Mountains in 1989
What is human scent?
Human scent is dead skin cells (called rafts) that each one of us are constantly shedding at a rate of 40,000 per minute. These rafts contain bacteria and have a unique scent for each individual human due to genetics, lifestyle habits and other environmental factors. The rafts fall off our bodies and get stuck in our clothes, or escape into the air around us. Some rafts in the air will land quickly onto nearby surfaces such as footpaths, furniture etc, while others float around in the air for hours or even days after we have left the area.
While humans can’t smell these skin rafts, dogs can - and some breeds perform better than others. For example, the beagle has about 50 times more scent receptors that the average human, making them a powerful tool in search and rescue.
How does a search dog find these people?
A search dog is taught to hunt for human scent to find missing people. The Search and Rescue Dog Association of Ireland (SARDA Ireland) was formed in 1987 and has been training and deploying search dog teams since to help find people that have gone missing across Ireland.
In SARDA Ireland, there are two types of search dogs: air-scenting dogs and trailing dogs. Air-scenting search dogs work in an open areas like hillsides and forests and can sniff out a person who is hundreds of meters away due to human scent being blown downwind of the missing person.
Human searchers generally need to be able to see or hear a missing person in order to be able to find them, which makes searching in dense vegetation or night searching difficult. However, it doesn't matter to a search dog if the missing person is out-of-sight and they will still be able to find them, even in the dead of night.
What does the search dog do when they find a missing person?
Air-scenting dogs work off-lead and freely zig-zags across a large area to hunt for human scent. Once an air-scenting dog detects human scent, it can quickly determine which direction the scent is coming from and rush towards the missing person. When the dog finds them, they will run back to the handler and give a trained response (or indication), like barking to show that they have found someone. The dog will then run back and forth between the handler and the missing person until the handler gets to the missing person.
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From O2UKBusiness, how the National Search and Rescue Dog Association save lives with air-scenting search and rescue dogs
Can they find a specific person based on the smell of their belongings?
Remember we said that each person has a unique scent that gets deposited on the person's clothing and falls onto the surfaces around us? This allows dogs to differentiate between people and to follow the route of a missing person.
Trailing dogs start a search by smelling an item clothing belonging to the missing person, and searching the area where the person was last seen. The dog searches for human scent in the air and on surfaces and it will indicate to the handler if it detects a scent that matches the smell of the clothing. Once this happens, the handler is sure that the person has been in this area, and then lets the dog trail or follow the person’s scent along the route that the missing person walked.
Trailing dogs work on long lines allows the dog to circle around the missing person’s route, sniffing out pockets of human scent that have settled on the ground, or got stuck on surfaces such as walls, hedges etc. A trailing dog can search in a busy area. It will ignore everyone else as their scent doesn’t match that of the missing person and will continue searching along the route until they find the missing person. If the trail ends - for exampe, if the missing person headed off in a car with someone else - the dog will stop and tell the handler that it has run out of scent, which can help inform the Gardaí of a new location to check for CCTV etc.
It takes years of experience, dedication and a lot of scientific knowledge, to train and work a search dog. But if that dog team can find a missing person using their unique skills, then the hard work pays off.
The author is a volunteer with SARDA Ireland
The views expressed here are those of the author and do not represent or reflect the views of RTÉ