While every household pet has its own personality, the reputation of dogs as humble and loving companions may actually be a disguise that helps to conceal their superhero-esque abilities.

With up to 300 million smell receptors – compared to six million in humans – dogs possess a sense of smell that is more sensitive than any man-made machine.

In fact, a dog’s nose is so powerful that it can actually detect substances at concentrations of one part per trillion – this roughly equates to sniffing out one single drop of liquid amongst 20 Olympic-size swimming pools.

Although dogs have been used to detect substances like illegal drugs, explosives and human remains for many years, recent studies have shown that our four-legged friends can actually be used to detect disease.

Scientists in the US say that they have recently begun training dogs to identify COVID-19 by sniffing out the disease in saliva and urine samples.

This study, which is currently underway at the University of Pennsylvania’s School of Veterinary Medicine, will explore the sensitivity and specificity of scent in training dogs in an attempt to assist in detecting COVID-19 infections in asymptomatic patients.

Researchers will initially begin the study with eight dogs that will undergo a process called odour printing across a three week period in a laboratory setting.

The odour printing process involves exposing the dogs to saliva and urine samples and then documenting which dogs can discriminate between samples that have tested positive for COVID-19 and other samples that have tested negative.

These tests will then provide a platform to determine if dogs can actually identify COVID-19 in infected people and preliminary testing in humans could actually begin as early as July.

The Smells in our Cells

When a disease hits the human body, changes to our cells produce chemicals that are known as volatile organic compounds (VOCs).

As these VOCs enter the bloodstream they are removed from the body through both urine and saliva, leaving behind odour molecules that then vaporise. These extremely minute odours then appear in our blood, urine and breath; and dogs can actually smell them.

Over the last few years, dogs have proven themselves to be able to sniff out the molecular signature of a variety of diseases ranging from cancer through to Parkinson’s disease and even tumours.

In November 2016 a team of scientists from the Medical Research Council in Gambia began handing out nylon socks to school children and asking the children to wear the socks until they returned the next day.

After collecting the socks, researchers found that two dogs were able to successfully identify socks that were worn by children who had been infected with malaria parasites at a rate of 70% accuracy.

Generally, dogs are only ever trained to identify one disease as detecting one odour among the thousands of other odours can be extremely challenging and increases the likelihood of error.

In terms of having smell detection as a career, dogs are actually classified as neophiles, which means that they are attracted to new and interesting things like odours, so it’s highly-likely that detection dogs have greater job satisfaction than almost anyone else.

Photo Credit – iStock – grandriver

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