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COVID: Trained dogs can detect virus, study finds


Dogs have been trained to detect bombs, drugs and even cancer. Now, a new study has found that dogs may also be able to detect COVID-19 simply by smelling skin swabs.

For a study published last week in the journal BMJ Global Health, Finnish researchers trained four sniffer dogs to determine whether or not a person had COVID-19, and found that the dogs were 92% accurate.

Even when taken to a real environment – an airport – the dogs were able to correctly identify passengers as negative for COVID-19 almost every time.

“Scent dogs can provide an invaluable tool to limit viral spread during a pandemic, serving for example at airports and seaports,” said Anu Kantele, professor of infectious diseases and chief medical officer at the University of Helsinki. and Helsinki University Hospital, in a press release. “Such a reliable and inexpensive approach to rapidly screen large numbers of samples or to identify passing virus carriers among large crowds is particularly useful when testing capacity with traditional approaches is insufficient.”

Scent detection dogs have been trained to use their sense of smell to identify and locate substances or people.

Since the start of the pandemic, many researchers and organizations have speculated that dogs might be able to help quickly identify cases of COVID-19 using their superior sense of smell. Several institutions have even started training dogs to identify the smell of the virus.

But few studies have tested this ability in a real environment.

In this new study, the researchers set out to do just that by first training a set of dogs to identify samples of COVID-19, then testing their skills in the lab before finally presenting them with the final test: getting the dogs to an airport to screen passengers.

The four dogs trained for this study — three Labrador retrievers named Silja, Rele, and Kosti, and a white shepherd named ET — all had previous experience with scent work.

They were trained using samples provided by inpatients and outpatients who had been recruited from Helsinki University Hospital.

A skin sample meant a strip of gauze that the volunteers had dabbed on the neck, throat, forehead and wrists.

Once the dogs showed they could recognize the scent of a positive COVID-19 case, the researchers introduced samples from patients who had aggravating factors such as asthma, cancer or diabetes to see if dogs would still be able to tell who had COVID-19 or not, even with these competing elements.

To indicate a positive test, the dogs would show their handler a signal that had been decided upon during training. One dog waded in the direction of the positive sample, another froze and put its paw over its nose after sniffing a positive sample, and the other two were trained to sit to signal a positive sample.

In the second stage, the ability of the dogs was tested in the laboratory.

The researchers designed a study in which neither the dog, the handler, nor the researcher presenting the swabs to be sniffed would have any idea of ​​the positive and negative samples, in order to reduce the risk of bias.

Dogs sniffed an identical set of samples to allow comparisons between dogs.

During this phase, the dogs sniffed a total of 420 samples – 114 samples from COVID-19 patients confirmed by PCR tests and 306 control samples from healthy individuals.

The dogs were able to recognize whether a sample was positive or negative correctly 92% of the time.

The final leg of the experiment took place at Finland’s Helsinki-Vantass International Airport. At the airport, a specially designed cabin was set up in the arrivals terminal to replicate the cabin environment the dogs had been trained and accustomed to.

Between September 2020 and the end of April 2021, more than 10,000 travelers and airport employees took part in the experiment, 48 of whom were tested positive for COVID-19 by the dogs.

Of this large sample, 303 travelers or airport employees agreed to participate in the validation part of the experiment and take a PCR test as well as provide a skin swab for the dogs to sniff.

Using data from the 303 people, the dogs were found to be 98.7% accurate in identifying whether a sample was negative for COVID-19.

One limitation is that the number of people who tested positive by PCR in the airport experiment was so small that the researchers could not get a clear idea of ​​the accuracy of the dogs in terms of positive cases. However, the dogs were given samples known to be positive throughout the experiment at the airport to familiarize them with the scent they were looking for, and the researchers said the dogs’ ability to recognize these samples was quite high.

Overall, the research seems to indicate that dogs can be easily trained to identify COVID-19 with a high level of accuracy – which could be useful in situations where quickly understanding the positive or negative status of a dog is imperative. ‘a person.

“Our research group will continue to study how scent dogs can best help our society. We hope this newly published study will help allocate funds for the development of this new ‘tool,'” said Anna Hielm-Björkman, DogRisk Research Manager. “There are many other diseases for which research could benefit from the excellent sense of smell that these dogs possess.”

The researchers pointed out that even when the dogs struggled, it highlighted their discernment abilities.

“I was particularly impressed that the dogs performed worse with samples we had taken from patients with disease caused by a variant of the coronavirus,” Kantele said. “The explanation is simple: the dogs had initially been trained with the initial wild-type virus, and therefore they did not always identify the variant samples as positive. This reveals their incredible ability to discriminate.

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