BANGKOK – Bobby was a good boy. It was Bravo too.
Angel was a good girl, and as she sat, hairy buttocks slid a little on the tile floor, she lifted a paw to emphasize, as if to say: It is this cotton ball that my sharp nose has identified, the one that smells like Covid – 19.
The three Labradors, which operate from a university clinic in Bangkok, are part of a global dog corps trained in sniffing Covid-19 in humans. Preliminary studies conducted in several countries suggest that their detection rate may exceed the rapid antigen test often used at airports and other public places.
“For dogs, the smell is obvious, just like grilled meat for us,” said Dr. Kaywalee Chatdarong, Deputy Dean of Research and Innovation of the Faculty of Veterinary Science at Chulalongkorn University in Bangkok.
The hope is that dogs can be deployed in crowded public spaces, such as stadiums or transport hubs, to identify people carrying the virus. Their skills are developed in Thailand, France, the United Kingdom, Chile, Australia, Belgium and Germany, among others. They have patrolled airports in Finland, Lebanon and the United Arab Emirates, and private companies have used them for US sporting events.
Angel, a pale blonde with incipient jaws and a penchant for crunchy plastic bottles, is the star of the package 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 percent of the time in controlled settings, according to university researchers. Studies in Germany and United Arab Emirates had lower but still impressive results.
Sniffer dogs work faster and far cheaper than polymerase chain reaction or PCR testing, their supporters say. An intake of air through their sensitive snout is enough to, within a second, identify the volatile organic compound or cocktail of compounds produced when a person with Covid-19 discards damaged cells, researchers say.
“PCR tests are not immediate and there are false negative results, while we know that dogs can detect Covid in its incubation phase,” said Dr. Anne-Lise Chaber, an interdisciplinary health expert at the Department of Animal and Veterinary Sciences at the University of Adelaide in Australia, who has worked for six months with 15 Covid sniffing dogs.
Some detection methods, such as temperature screening, cannot identify infected people who do not have symptoms. But dogs can, because the infected lungs and trachea produce a trademark odor. And dogs need fewer molecules to nose Covid than what is required for PCR testing, Thai researchers said.
The Thai Labradors are part of a research project run by Chulalongkorn University and Chevron. The oil company had previously used dogs to test its offshore employees for illegal drug use, and a Thai manager wondered if the animals could do the same with coronavirus. A dog’s ability to sniff Covid-19 is in theory no different from its ability to detect drugs, explosives or a Scooby’s snack hidden in a pocket.
The six dogs were assigned six handles that exposed them to sweat-colored cotton balls from socks and armpits in Covid-positive individuals. Researchers say the risk to dogs is low: It is not known that it is easy to transmit coronavirus through sweat, an abundant commodity in tropical Thailand. Instead, the main transmission route appears to be respiratory droplets.
In rare cases, cats and dogs in close contact with infected humans have tested positive for the virus, as have populations of mink and other mammals. (However, there are no documented cases of domestic animals transmitting the virus to humans.)
Within a few months of training, about 600 sniffs a day, the Thai dogs sat obediently each time they sensed the cellular by-products of Covid-19 on cotton balls that researchers placed at nose height on a carousel-like device.
Dogs whose wet snout has up to 300 million olfactory receptors compared to approx. six million for humans, can be trained in remembering about 10 odor patterns for a particular compound, said Dr. Kaywalee. Dogs can also smell through another organ lying between their nose and mouth.
Some studies have suggested that dogs of different breeds may be able to detect diabetes, Parkinson’s disease, malaria and certain cancers – that is, the volatile organic compounds or body fluids associated with them.
Labradors are among the smartest breeds, said Lertchai Chaumrattanakul, who leads Chevron’s part of the dog project. They are also lovable, making them the ideal doggy detector: committed and eager.
Sir. Lertchai noted that Labradors are expensive, about $ 2,000 each in Thailand. But the cotton swabs and other basic equipment for dog testing work for approx. 75 cents pr. Sample. It is much cheaper than what is needed for other types of fast screening. Last week, Singapore announced that it had provisionally approved a type of respirator for testing 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 says dangerous Covid-19 variants have entered Thailand. The other three were moved to the ninth floor of Chulalongkorn’s veterinary faculty in Bangkok in recent weeks, where they live in former student quarters.
There is artificial turf on the roof for quick pit stops, and the dogs get a daily frolic on a university football field. Their rooms are air conditioned.
For a few hours in the morning and afternoon, the retrievers shift obligatory pace up and down in a room set up with metal arms dangling sweat samples. When they pass by, they sniff up to 10 times a second, which dogs do not usually do. (Humans tend to control only one inhalation every second or so.)
Then they retire to their residence for a nap and occasionally their stomachs rub.
“Their lives are good, better than many people,” said Thawatchai Promchot, Angel’s dealer who worked as a Chevron supplier before redirecting to animal health research.
Mr. Thawatchai said he grew up with 12 dogs in the southern province of Nakhon Si Thammarat, where the family’s pets snoozed in the garden and sought shade under trees. They did not enjoy air conditioning.
The Bangkok-based dogs are now screening sweat samples from Thais who cannot easily reach Covid test sites, such as the elderly or bedridden. The dog’s memorial is 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 outbreak of coronavirus since the pandemic began. Clusters grow in prisons, construction camps and other cramped neighborhoods. Vaccines are lacking and less than 2 percent of the population has been vaccinated.
Researchers at Chulalongkorn have designed a mobile device that they plan to drive to possible Covid hotspots so dogs can locate areas that need mass testing.
There are still many questions about using dogs to detect the virus. How do vaccinated people smell? How easy will it be to train a large pack of Covid sniffing dogs around the world? What if people who are being tested by a nose are not so sweaty? What if a dog gets Covid-19 and loses its sense of smell?
Still, Mr. Lertchai that he thought virus-detecting dogs would be a blessing, especially in countries that do not have the resources for more expensive testing.
“Covid is not going away and there will be new variants,” he said. “Dogs will be useful, so let’s use them.”
Muktita Suhartono contributed reporting.