When I take my little dog out for a walk he stops and sniffs just about everything. The In Situ Foundation, which trains dogs to detect early stage cancer in humans, describes a dog's nose as 'an exquisite piece of machinery'. Humans have about 5 million scent receptors. It is estimated dogs have between 200 and 300 million, depending on the breed, resulting in their ability to smell all sorts of things humans can't. In addition, a greater percentage of a dog's brain is used for analysing what it smells.
Image courtesy of Pixabay
A dog primarily uses its sense of smell to interpret the world whereas humans use sight. Puppies are unable to see or hear at birth so their excellent sense of smell is vital to their survival.
Dogs can pick up a lot of information about another animal or a human from smell. The information may include the sex, what they have eaten, things they have touched, places they have been and the mood they are in.
A dog's acute sense of smell can be helpful to people and some breeds of dogs are especially efficient at picking up a scent. These include:
Bloodhound (estimated to have 300 million scent receptors)
English Springer Spaniel
Bloodhounds have more scent receptors than any other breed Image courtesy of Pixabay
Trained dogs can detect health issues including
various types of cancer
low blood sugar
oncoming narcolepsy attack
Some dogs can detect other health conditions in their owners, often without training. Sometimes the dog picks up on a particular scent and other times is sensitive to a change in behaviour.
Dogs are also used to detect:
Experienced dogs have been known to have a 90% rate of success in their field and the ability to recognise about 50 distinct smells.
Some dog breeds are able to pick up a scent from the air in addition to the ground. When it comes to detecting a trail on the ground some have the ability to follow a 'cold' trail which is several days old or across running water.
German Shepherds are good at picking up a scent from the air. They are often used by the police, army and rescue groups. Image courtesy of Pixabay
A dog can smell hormones given off by a person when he/she is happy or afraid. So, yes, a dog can smell fear. It will also be able to detect when a woman becomes pregnant.
Dogs are able to 'layer scent' meaning they can detect the footprints of an individual even though other people have walked on the same path. A human might smell cake baking but a dog can pick up the scent of the various ingredients.
A dog's sense of smell tells it so much about the world around it. It is no wonder my dog spends so much time sniffing everything when we go out for a walk