TORONTO — Creating a fast and reliable test to detect COVID-19 has been expensive and challenging, but new research suggests a cheap and effective solution could be right under our noses — or rather, dogs’ noses.
Specially trained dogs are highly effective at sniffing out the presence of COVID-19 in human sweat, according to a new study, which bolsters existing evidence and suggests that dogs could play a key role in efforts to control the virus.
The proof-of-concept study in France and Lebanon trained six dogs for a month to detect the smell of patients who’d been sickened by the novel coronavirus. Researchers took sweat samples from more than 170 people, about half of whom were COVID-19 positive, and tested whether the dogs could differentiate between sick and healthy patients.
The animals with the least amount of training picked out the COVID-19 samples more than 76 per cent of the time. Two dogs already trained to sniff out cancer had a perfect record in the study, detecting COVID-19 in the samples 100 per cent of the time.
Results could be detected within one-tenth of a second.
When the idea to test dogs to sniff out COVID-19 was initially floated, it seemed ludicrous, said Dominique Grandjean, a professor at France’s National Veterinary School of Alfort and the study author.
“First I said, ‘No way. I mean, I think it’s crazy. We don’t see any viral disease that has been detected by dogs yet,’” Grandjean told CTV News. “I was really surprised and amazed because it seemed to me it was impossible.”
Health authorities across Canada have been given more than 3.8 million rapid tests for COVID- 19, but most jurisdictions are treating them with caution and verifying the results of those tests with lab-based tests, still considered the gold standard. Lab tests typically take at least one day to process.
Compared to rapid tests, sniffer dogs could provide a speedy and potentially even more accurate assessment of a patient’s condition. When a dog detects COVID-19 in a patient, it signals using a standard sign, such as barking or lying down. The dog is then rewarded with a treat or a toy.
“It’s kind of a game for them,” Grandjean said. “I do think it is one of the best tests.”
Dogs have already been trained to sniff out bombs, drugs and even certain kinds of cancer. For COVID-19, the dogs don’t sniff out the virus itself.
“The dogs actually, they don’t smell the virus, they smell for some molecules that are produced by the virus,” Grandjean said.
Other countries, including Australia, Belgium and Finland, have already started putting virus- sniffing dogs to work. One Russian airline company is using dogs to sniff passengers before they board flights.
One dog is able to sniff about 400 people per day, Grandjean said.
“If you have 1,000 dogs in a country, that means that you can check 400,000 people in a day,” she said.
Researchers in Canada are eager to begin training COVID-19 detection dogs here, too. Helene Carabin, a professor of epidemiology with the University of Montreal’s faculty of veterinary medicine, said dogs could be stationed outside hospitals, nursing homes and other places to protect the elderly and those who are immunocompromised.
“The vaccine is coming, but the full coverage won’t be before a while. And even after a vaccine, we will still need to surveil COVID. So I think this is excellent news for public health in general,” she said.
The biggest hurdle to implement such a plan at the moment, Carabin said, is lack of funding.
“In my mind, sniffing dogs are the most rapid tests we have on hand right now,” she said. “You get the answer immediately. You don’t need to wait. And this is a huge advantage when we’re trying to do contact tracing.”
But once trained, dogs could be an affordable long-term solution, according to Eric Troncy, a professor of pharmacology at the University of Montreal’s faculty of veterinary medicine.
“Compared to the expense we are doing with PCR tests, millions of dollars are spent on this aspect, where the dogs could do it for thousands of dollars,” he said.
Dogs could make a particularly big difference in developing countries with already limited healthcare capacity. As for payment, Grandjean said the dogs in the study were perfectly happy to accept treats “and lots of petting.”
But what about the role for Cats
Cats could play an important role in the search for a coronavirus vaccine, according to new research that builds on our current understanding of how COVID-19 affects pets.
Researchers found that, while cats can infect other cats through direct contact, the dogs did not spread the virus amongst each other. Neither the cats nor dogs actually developed clinical symptoms of the COVID-19 at any point in the study.
“We report that cats are highly susceptible to infection, with a prolonged period of oral and nasal viral shedding that is not accompanied by clinical signs, and are capable of direct contact transmission to other cats,” researchers wrote in their findings.
“Resistance to reinfection holds promise that a vaccine strategy may protect cats and, by extension, humans.”
Because cats can spread the virus to each other and have a natural immune response to the virus, researchers say they may be useful in helping test vaccine candidates. At least nine vaccine candidates are in stage three of testing, the final step involved in determining if a vaccine is able to stop the virus from infecting the body.
“Perhaps most importantly, cats develop significant neutralizing antibody titers and are resistant to reinfection, although the duration of immunity is not currently known. This could prove a useful measurement for subsequent vaccine trials for both human and animal vaccine candidates,” researchers wrote.
There is no evidence to suggest that dogs or cats spread the virus to humans.