There’s not a lot of good news in the corridors of COVID, but could pandemic pooches be trained to sniff out the virus? Science is onto it like a bloodhound.
Normally testing for COVID involves either a gag-inducing swipe of the back of the throat with an extended cotton bud or similarly elongated swab inserted up the nose until your eyes water.
But what if a gentle sniff from a Labrador could establish whether you could come and go quarantine free from airports around the world?
Finland is already using sniffer dogs at Helsinki Airport in a test that’s cheap, quick and non-invasive. Researchers say dogs can be trained to detect the virus with close to 100 per cent accuracy even before people show symptoms.
Dubai also has a pilot program with sniffer dogs and Australia, France, Germany and the United Kingdom are also planning other forms of canine screening.
But what do detection dogs – already used to find some forms of cancer as well as explosives and drugs – have that science hasn’t?
For one thing, they possess up to 300 million olfactory receptors in their noses, compared with about six million in humans. And the part of a dog’s brain that is devoted to analysing smells is, proportionally speaking, 40 times greater than ours.
Dogs’ sense of smell overpowers our own by orders of magnitude—it’s 10,000 to 100,000 times as acute, scientists say.
“Let’s suppose they’re just 10,000 times better,” says James Walker, former director of the Sensory Research Institute at Florida State University, who, with several colleagues, came up with that estimate during a rigorously designed, oft-cited study.
“If you make the analogy to vision, what you and I can see at a third of a mile, a dog could see more than 3,000 miles away and still see as well.”
This all spells good news for COVID detection. But how does it work?
Travellers that agree to the screening will swab their own necks to produce a sweat sample which is placed in a beaker next to others containing control scents.
If the dog detects the virus – shown by yelping, pawing, or lying down – the passenger takes a free swab test to verify its verdict.
Although hunting dogs are said to be the best at this type of work, scientists say any breed – even mongrels – could, in theory, be trained in a process that takes between two and 10 weeks.
Professor Dominique Grandjean, of the National Veterinary School of Alfort, France said the canines were not sniffing the virus itself but rather volatile chemicals produced when the virus infects cells.
Results from Grandjean and his colleagues, which are yet to be peer-reviewed, show sweat samples from COVID patients were correctly identified by eight dogs at least 83 per cent of the time, with some making a correct identification in 100 per cent of the trials they underwent.
The team say they have since validated their approach in three separate trials, although the results have yet to be published.
Grandjean thinks the approach has potential to become widespread.
“We can have one dog per retirement house that is trained and this dog would be able every single morning to check everybody, just by walking by,” he said. His team plans to work with a French organisation to provide COVID-sniffing dogs to care homes.
“Pet owners could have their dog trained in order to search for COVID, but not only for them,” he added. “If we had 10,000 dogs able to sniff for COVID, well, that means that every dog should be able to sniff 200-300 samples a day, so that means 2-3 million samples a day.”
While the initial pilots have been promising, the program is not without its sceptics.
Professor Ian Jones, a virologist at the University of Reading, told The Guardian that such schemes detract from the real challenges of mass testing.
“All that dogs can detect is an odour difference,” he said. “For explosives and drugs and even chronic disease like MS, that is fine, but many viruses infect the same cells as COVID and lead to similar changes in metabolism – so the gas you exhale is the same.”
Authorities in Vantaa, the city where Helsinki’s international airport is located, said the pilot program, which is due to last four months, was costing €300,000, which it said was significantly lower than for laboratory-based testing methods.
Doggone it! It just might be the answer.