With just one week of training, a pack of dogs in Germany has learned how to detect COVID-19 in human samples.
Researchers with a German veterinary university trained eight dogs from the country’s armed forces to sniff out the saliva of more than 1,000 healthy and infected people. They used a specially designed machine with six “scent holes.” The machine uses an algorithm to randomize the samples — five containing negatives and one containing a positive.
The dogs were able to accurately identify the virus with a 94 per cent success rate. While only preliminary, the authors suggest the findings could help form a reliable screening method for the virus.
“We think that this works because the metabolic processes in the body of a diseased patient are completely changed,” Maren von Koeckritz-Blickwede, a professor at the University of Veterinary Medicine Hannover, said in a YouTube video.
“We think that the dogs are able to detect a specific smell.”
Dogs have long been used to sniff out everything from drugs and explosives to other diseases, like malaria and cancer.
The possibility they may be able to do the same for COVID-19 is a “stunning development,” said Dr. Isaac Bogoch, an infectious disease specialist at Toronto General Hospital, especially as the world grapples with how to safely reopen larger indoor spaces, like schools.
If scalable, it’s “just one more addition to the toolbox in our fight against COVID-19 to keep public places safe,” he said.
But it doesn’t mean the problem is solved.
“Just because it works in a study, doesn’t mean it jumps from the study to implementation in real-world scenarios.”
Animal infection risk
One major “wrinkle” in using detection dogs is that they, too, can get the virus, said Colin Furness, an infection control epidemiologist and assistant professor at the University of Toronto.
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“It happens, it’s been documented. We just don’t know how easily it happens,” he said.
“What’s concerning about going between species is that it gives the virus an opportunity to mutate quite substantially. You do not want COVID moving through animal populations because that can mutate and boomerang on us.”
A small number of pet cats and dogs have been reported to be infected with the virus in several countries since the pandemic first ballooned, including the United States, the Netherlands and Hong Kong.
At this point, experts agree that animals play no significant role in the spread of the virus, and the risk of animals spreading the virus to people is considered to be low.
Cats, however, are believed to be somewhat more susceptible, according to the World Health Organization.
“The concerns are extremely low, but nonetheless, they’re the reality,” said Dr. Ian Sandler, the CEO of Gray Wolf Animal Health in Toronto and a member of the National Issues Committee of the Canadian Veterinary Medical Association.
“This pandemic has done many things on the scientific front that we would have only seen with germ warfare. We’re seeing things move fast. … But there are some logistical questions that come into play.”
When humans come into contact with a carrier of the virus, they’re asked to self-isolate and monitor for symptoms. Should the same be said for a detection dog? Do they get tested?
Sandler believes questions like that are unanswered at this point.
“Let’s say you have 10 or 20 service dogs working. How many areas or how many patients or how many potential cases can they actually interact with?” he asked. “What’s their ability to oversee large populations of people, given these risks?”
Race against time
While the German study only trained the dogs for a week and found success, other studies show that the length of time it could take to make scent identification a reality varies.
In the U.S., the University of Pennsylvania’s School of Veterinary Medicine launched a pilot training project in April to study the same thing. The researchers are using eight dogs over a three-week training period, however, the study is still ongoing.
In the U.K., trainers have so far seen positive results in a similar study using six dogs. The dogs are being trained to smell the virus on sterilized socks, stockings and face masks worn by NHS staff in London.
Chile has a smaller program, re-training four police dogs to detect the smell of COVID-19 patients. Training, if successful, could take anywhere between two weeks to eight months, the Catholic University of Chile told CNN.
The time it will take to train the dogs is one barrier, the experts agree, but rallying up enough trained dogs to take on a global scale is another.
“There’s always been a supply issue with dogs,” Sandler said. “Those needs are only going up as service animals play an increasingly important and valid role in society for people with other specific needs.”
The use of dogs will come up against scientific development, Sandler added.
Apart from blood tests, which can take up to 24 hours to produce results, faster detection is needed. But Sandler said technology might move faster in this case. He pointed to a coronavirus breathalyzer being developed by an Israeli company that touts testing results in 30 seconds.
“The question becomes, as technology ramps up really quickly to find safe, effective and accurate ways of detecting COVID-19 quickly and early, is there actually going to be a need for detection dogs in the first place?”
Not to mention, “the race is on” against a vaccine, Furness added.
“How long would it take to train dogs for all the schools in Canada? Probably longer than it will take to get a vaccine.”
More research needed
There are viable scenarios where a detection dog could come into play — if the risks are weighed and accounted for properly, the experts agree.
The researchers in Germany believe the method could be introduced to public areas like airports, sporting events, borders and other mass gatherings as an “alternative or addition” to laboratory testing.
It’s possible, said Bogoch, but it’s not likely to happen anytime soon.
Holger Volk, the chair of the university’s department of small animal medicine, said it must be “crystal clear that this study is just a pilot.”
The samples the sniffer dogs were tested with were chemically rendered harmless, begging the questions whether the canines can detect active coronavirus cases in people.
“There’s a lot of potential to take this further,” Volk said, “to really use these dogs in the field.”
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