Trained dogs may be more effective at detecting Covid-19 than nasal swab PCR tests, according to a new study.
Dogs are better at detecting the presence of Covid than PCR antigen tests in both symptomatic and asymptomatic people, a study published Wednesday in the peer-reviewed journal Plos One found.
In the study, trained dogs were able to detect the new coronavirus in 97 percent of symptomatic cases and nearly 100 percent of asymptomatic cases.
“Dogs don’t lie,” study author Dominique Granjean, a professor at the National Veterinary College in Alfort, France, told Science News, noting that PCR tests can make different errors.
The study included 335 participants from the Paris Covid screening center. Of the participants, 109 tested positive for Covid, 31 of whom were asymptomatic.
The detection dogs, provided by the French fire service and the United Arab Emirates, were trained for three to six weeks, depending on whether they had previous training in smell detection.
Dogs sniff out samples of human sweat placed in olfactory cones. If a dog detects the new coronavirus, it sits in front of the cone.
Ultimately, trained dogs are more sensitive to positive cases. Nasal PCR tests are better at detecting negative cases.
In two false-positive cases, dogs misidentified other strains of the coronavirus respiratory disease that were not Covid.
While the ability of dogs to detect Covid has been studied before, this is believed to be the first time the dog’s accuracy has been compared to an antigen test.
According to NBC News, a study published in May by British researchers found that well-trained dogs were able to detect the new coronavirus with 82 to 94 percent accuracy.
A 2021 study in Florida found that dogs were 73 to 93 percent accurate after a month of training.
The authors of the French study say more dogs could soon be used to test for Covid-19 in mass screening settings, including at airports.
PCR tests may take several days to produce results. Grandjean told NBC that a well-trained dog was able to analyze 20 samples in 15 seconds.
The authors say the use of dogs for coronavirus testing could also benefit those who cannot tolerate nasal swabs, such as Alzheimer’s patients.
Experts unrelated to the study warned that translating its positive results into everyday use could be difficult.
“The ideal — and I think it’s the Holy Grail — is that the dogs just stand there and a person walks by and they say, ‘Yes, no, yes, no, yes, no,'” Dr. Cynthia Otto, The director of the Penn Veterinary Working Dog Center at the University of Pennsylvania told NBC.
“It can be done eventually, but making sure it’s done with all the proper controls, quality assurance and safety – that’s a big step. I haven’t seen anyone come up with how to do this in a scientific and safe way change.”
Dogs are starting to be used at mass testing sites. In September 2021, Miami International Airport became the first airport in the United States to deploy Covid dogs.
Airports in the UAE, Finland and other countries use dogs to sniff out the coronavirus. Schools in Massachusetts and Hawaii have also hired dogs to test students.