Smell you later – dogs proving they are our best friends (again)


Dogs can smell things really well. No, really, really well. We’ve known that for a long time. Dogs’ noses have roughly 300 million scent receptors – which is roughly 60 times the number that humans have.

Imagine increasing your eyesight by a factor of 60 – which is probably the only way we can really picture it. You’d be able to read the labels on a players’ boots from the upper decks of Croke Park.

A dog can perceive tiny amounts of odour that would be completely undetectable to a human. Which is why dogs have been used to sniff out a variety of things – from drugs to diseases to dead bodies buried deep below the ground.

Dogs have been trained to smell diabetes and types of cancer in patients. And while they may not replace doctors just yet, they seem to have a remarkable success rate of pinpointing particular diseases.

Which would make it somewhat ironic, therefore, if dogs could sniff out Covid-19. It’s a disease that makes its presence known initially by removing or damaging the smell sense. And yet, its own smell might give it away.

Dogs can smell diseases

The research on why this happens isn’t completely clear. But scientists believe that illness causes the body to release specific gases. These gases create a scent that is detectable to dogs. If a trained dog is allowed smell the body of a sick person, they can tell if the person has the disease. Even if they are asymptomatic. In previous studies for diabetes, for example, dogs have been nearly 100% successful when indicating a positive sample.

Of course the dog doesn’t ‘know’ that what they’re smelling is diabetes or cancer. But they can identify the smell of the disease from practice.

With the outbreak of COVID-19, researchers realized that dogs could be used to identify its particular smell.  Canines could therefore do what hadn’t been done before.  They could separate people with Covid-19 from people without disease easily, quickly and efficiently.

One of the first studies took sweat samples from 177 possible COVID-19 patients in five different hospitals in Paris and Beirut. They then used these sweat samples to train 14 dogs, six of which were further tested in the study.

These dogs were then asked to detect a positive sample from a line-up of cones that contained negative samples. The dogs did dozens of trials, with a success rate of between 76% and 100%. Two dogs had a 100% success rate of the 68 tests they completed. These dogs had already shown they could identify colon cancer.

That could be an incredible statistic. It could mean that economies and general life could be opened again. And all because of man’s best friend.

Dogs could be used to help open up social and business life

It’s possible that these canine medics may even be able to detect false negative tests. During the testing, two samples collected from individuals who tested negative were repeatedly marked by the dogs. The relevant hospitals were informed, and in subsequent tests these individuals tested positive.

In addition, a surgeon at Saint Joseph University in Beirut, Riad Sarkis, further tested the best two performers by taking them to an airport. The dogs screened 1,680 passengers and found 158 positive SARS-CoV-2 cases. These cases were then confirmed by other viral tests.

Amazingly, Sarkis found that his dogs correctly identified negative results 100% of the time, and correctly detected positive cases 92% of the time. The results, however, have yet to be published.
Now another project is being launched in Italy along the same lines.

The project involves training dogs to detect the presence of coronavirus in human sweat. It began two weeks ago at Rome’s Campus Bio-Medico University Hospital

If found to be reliable, it could prove a faster and cheaper method of detection in crowd situations. Airports, football matches, parades – wherever people gather.

“If we have 1,000 people to screen with an antigen swab, it would take us about 20 minutes for each person,” said Massimo Ciccozzi, a professor of epidemiology at the University.

“A dog, using their olfactory senses, would take 30 seconds maximum.”

Researchers in Finland, Germany, France and the UAE have launched sniffer dog trials since the pandemic hit.

Some believe such research has not yet been widely adopted because of a lack of peer-reviewed literature.

However, if the accuracy and speed of sniffer dogs turns out to be anything like the initial tests, dogs could become a hugely important tool in the management of Covid-19.

The Simpsons predicted it

All this, of course, like the election of Donald Trump, and the defeat of Hillary Clinton, was predicted by the TV show The Simpsons. Nelson Muntz’s parting greeting ‘Smell you later’ may turn out to be – literally – what we do when we want meet up again.

So it’s quite possible that when saying goodbye in future, we refer to the next time we meet as a time when we will be ‘smelled’ to see if we are Covid-19 free.

Smell ya later.

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