BANGKOK – Bobby was a good boy. Well done too.
Angel was a good girl, and when she sat down with her hairy hindquarters slipping a bit on the tile, she lifted a paw to point out, as if to say, it’s that cotton ball that my nose sharpened identified, the one who smells of Covid -19.
The three Labradors, operating at a university clinic in Bangkok, are part of a global body of dogs trained to detect Covid-19 in humans. Preliminary studies, carried out in several countries, suggest that their detection rate may exceed that of rapid antigenic tests often used in airports and other public places.
“For dogs, the smell is obvious, and so is grilled meat for us,” said Dr. Kaywalee Chatdarong, associate dean of research and innovation at the Faculty of Veterinary Sciences at Chulalongkorn University. Bangkok.
The hope is that dogs can be deployed in crowded public spaces, like stadiums or transport hubs, to identify people with the virus. Their skills are developing in Thailand, France, Great Britain, Chile, Australia, Belgium and Germany, among other countries. They have patrolled airports in Finland, Lebanon and the United Arab Emirates, and private companies have used them at American sporting events.
Angel, a pale blonde with budding jowls and a penchant for crunchy plastic bottles, is the star of the pack at Chulalongkorn University. But as a group, the dogs trained in Thailand – Angel, Bobby, Bravo and three others, Apollo, Tiger and Nasa – accurately detected the virus 96.2% of the time in controlled environments, according to university researchers. Studies in Germany and the United Arab Emirates obtained inferior but still impressive results.
Sniffer dogs work faster and much cheaper than polymerase chain reaction, or PCR, tests, according to their supporters. A sniff of air through their sensitive snout is enough to identify in a second the volatile organic compound or the cocktail of compounds that are produced when a person with Covid-19 sheds damaged cells, according to the researchers.
“The PCR tests are not immediate and there are false negative results, whereas we know that dogs can detect Covid in its incubation phase,” said Dr. Anne-Lise Chaber, interdisciplinary health expert at the ‘School of Animal and Veterinary Sciences at the University of Adelaide in Australia which has been working for six months with 15 Covid sniffer dogs.
Some detection methods, such as temperature screening, cannot identify infected people who have no symptoms. But dogs can, because the infected lungs and windpipe produce a trademark scent. And dogs need fewer molecules to unearth Covid than is needed for PCR testing, Thai researchers have said.
The Thai Labradors are part of a research project jointly conducted by Chulalongkorn University and Chevron. The oil company had previously used dogs to test its offshore workers for illegal drug use, and a Thai official wondered if animals could do the same with the coronavirus. A dog’s ability to sniff Covid-19 is, in theory, no different from its prowess at detecting narcotics, explosives, or a Scooby snack hidden in a pocket.
The six dogs were assigned to six handlers, who exposed them to sweat-stained cotton balls from the socks and armpits of Covid-positive individuals. Researchers say the risks to dogs are low: the coronavirus is not known to be easily transmitted through sweat, a commodity plentiful in tropical Thailand. Instead, the main route of transmission appears to be respiratory droplets.
On rare occasions, companion cats and dogs in close contact with infected humans have tested positive for the virus, as have populations of mink and other mammals. (There are, however, no proven cases of pets transmitting the virus to humans.)
A few months after training, at around 600 sniffles a day, the Thai dogs sat obediently whenever they smelled the cell byproducts of Covid-19 on cotton balls, which the researchers placed at nose level on a carousel-shaped machine.
Dogs, whose wet snouts have up to 300 million scent receptors compared to around six million for humans, can be trained to memorize around 10 scent patterns for a specific compound, Dr Kaywalee said. Dogs can also smell through another organ tucked between their nose and their mouth.
Some research has suggested that dogs of different breeds may be able to detect diabetes, Parkinson’s disease, malaria, and certain cancers – that is, volatile organic compounds or body fluids associated with them.
Labradors are among the smartest breeds, said Lertchai Chaumrattanakul, who heads the Chevron portion of the Dog Project. They are also affable, which makes them the perfect dog detector: engaged and impatient.
Mr. Lertchai noted that Labradors are expensive, around $ 2,000 each in Thailand. But cotton swabs and other basic dog testing equipment is about 75 cents per sample. It is much cheaper than what is required for other types of rapid testing. Singapore last week announced it was tentatively approving some kind of breathalyzer to test for Covid-19.
Three of the Thai Labradors are stationed in the deep south of the country near the border with Malaysia, where the Ministry of Public Health said dangerous variants of Covid-19 have entered Thailand. The other three have been moved in recent weeks to the ninth floor of the Chulalongkorn Faculty of Veterinary Medicine building in Bangkok, where they live in former student dormitories.
There is artificial turf on the roof for quick stops, and the dogs have fun every day on a college football field. Their rooms are air conditioned.
For a few hours in the morning and afternoon, the recuperators take turns to survey a room fitted out with metal arms which hang samples of sweat. As they walk past, they sniff up to 10 times per second, as dogs are used to. (Humans tend to only handle one inhalation every second or so.)
Then they retire to their accommodation for a nap and an occasional belly massage.
“Their life is good, better than that of many humans,” said Thawatchai Promchot, the handler for Angel, who worked as a supplier to Chevron before moving on to animal health screening.
Mr Thawatchai said he grew up with 12 dogs in the southern province of Nakhon Si Thammarat, where the family’s pets dozed in the garden and sought shade under the trees. They did not appreciate the air conditioning.
Bangkok-based dogs are now examining sweat samples from Thais who cannot easily reach Covid testing sites, such as the elderly or bedridden. Guardians of the dogs are working to set up a program with the city’s prisons, where thousands of inmates have been diagnosed with Covid.
Thailand is suffering from its worst coronavirus outbreak since the start of the pandemic. Clusters proliferate in prisons, construction camps and other cramped quarters. Vaccines are scarce and less than 2 percent of the population has been vaccinated.
Chulalongkorn researchers have designed a mobile unit that they plan to drive to possible Covid hot spots, so dogs can identify areas needing mass testing.
There are still many questions about the use of dogs to detect the virus. What is the smell of vaccinated people? How easy will it be to train a large pack of Covid sniffer dogs around the world? What if people tested by a canine nose did not sweat? What if a dog catches Covid-19 and loses its sense of smell?
Still, Mr Lertchai said he believes dogs detecting viruses will be a boon, especially in countries that don’t have the resources for more expensive tests.
“Covid will not go away and there will be new variants,” he said. “Dogs want to be useful, so let’s use them.”
Muktita Suhartono contributed reporting.