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In Neighboring Sonora, Detector Dogs Are Sniffing Out Cases Of COVID-19

Four stainless steel canisters with perforated lids are lined up along one wall in a chilly, white room on the second floor of Sonora’s largest COVID-19 testing site.

A few feet away, a golden retriever named Leia looks up expectantly at her handler, decked out from head to toe in a blue protective suit, mask and gloves.

“Search!” he shouts.

On his command, Leia leaps up and begins to sniff the metal containers, each one filled with gauze scented with the sweat of a person who has been tested for COVID-19. Three negative, one positive.

Within seconds, Leia’s found the one she’s looking for, puts her paw over it and lies down.

“That’s it!” her handler congratulates her, rewarding her with praise and a toy for correctly spotting the COVID-positive sample, as the canisters are swapped out with a new set.

Leia is one of nine dogs in Sonora who have been trained to detect COVID-19 — the first COVID-sniffer dogs in Mexico. For now they’re working at Sonora’s mass testing centers, providing screenings for asymptomatic patients.

“There aren’t enough resources to give everyone PCR tests. It’s the same problem all over Mexico,” said Juan Mancilla, Leia’s owner and the director of OBI: Caninos Contra El Covid, a private initiative that partnered with the state health department in August to train COVID-19 detector dogs. “So we’re using the dogs.”

In Sonora, tests are only available to people who have active coronavirus symptoms. And while dogs aren’t a substitute, Mancilla said they are a cheap, fast and effective screening tool to help identify who might need further testing.

Some can correctly detect 90% of positive cases, he said, and are also good at early detection.

“The use of dogs for the detection of illnesses is something that’s been studied for years, for decades,” Mancilla said. “The only difference here is that we’re using it for COVID-19 now.”

In fact, the idea for this project stemmed from Mancilla’s own long-time service dog Obi, who could recognize when Mancilla was about to have epileptic seizures.

“He was with me for 11 years,” he said. “And the project is named after him.”

After Obi died last January, Mancilla adopted Leia and started training her to be a seizure alert dog. One day, her trainer mentioned new studies showing that dogs might be able to detect COVID-19. So, they decided to try it.

Within days, Mancilla said, he had secured financial support from state health officials, and the assistance of local and international researchers who helped design the training program.

So far, they’ve had good results. The problem now is convincing people it really works.

“There are a lot of people who don’t believe it,” Mancilla said. “And it’s not easy to convince them. I think you’ll just change their minds with time. And with results.”

Sniffer Studies

“I think there’s a rough dichotomy of people that have dogs and get it, and those that don’t,” said Steve Lindsay, a professor of Infectious Diseases at Durham University in northern England.

He started working with sniffer dogs several years ago to detect malaria parasites.

Dogs’ noses have been trained to identify everything from drugs, firearms and explosives, to medical conditions like cancer, diabetes and Parkinson's disease.

“You name it and they can do it. They have an extraordinary sense of smell,” he said. “I think it’s amazing. Extraordinary animals we live with.”

When the pandemic started, researchers around the world, including Lindsay’s team on the malaria study, started looking into whether dogs could smell COVID-19.

Though research is still ongoing, sniffer dogs are already being deployed to detect cases at airports in Helsinki, Dubai and Santiago, Chile. And the Miami Heat has used them to screen fans for the virus at home games.

“All I can say at this time is that we are encouraged and pretty convinced from our research and elsewhere that there is a distinct COVID smell,” Lindsay said.

Of course, scientists are cautious and are continuing to study their findings to make sure they’re right, he said. Plus, dogs require rigorous training to do the job.

“So if I have a query,” Lindsay added, “It would be that one needs a lot of skill and experience to do this.”

Here To Stay

At the OBI training center in Sonora, dogs bark as a handler brings new-trainee Krillin out of his kennel to practice sniffing.

“At the beginning of a project, you go through trial and error sometimes,” said trainer Adrian Orduño, who has been working with detector dogs in Mexico for decades.

He said teaching dogs to identify COVID-19 has been challenging, because you have to make sure they aren’t picking up on other smells in the samples of sweat or saliva rather than the virus itself. It took about four months to be sure the first group had picked up on the right scent.

“But training a dog’s nose, it’s the base of all the work I do,” he said.

Whether for drugs or disease, it’s largely the same process to prepare a dog for detection, he said. And the next generation of COVID sniffer dogs will be ready more quickly, he thinks

Three of the dogs OBI has trained belong to the state, but the others might soon start working at airports, hospitals, factories, baseball stadiums — anywhere crowds gather and the virus can easily spread, Mancilla said, calling them a tool for start Sonora on the path to economic reactivation after the pandemic.

And while vaccines are starting a slow roll out in Sonora, he’s not worried about decreasing demand for COVID-19 sniffer dogs.

“The truth is, I think COVID is here to stay,” he said. “Vaccinations will take time, and not everyone can or will get one. There will always be a demand for detectors dogs."

And his dogs’ noses will be ready to sniff out cases wherever they’re needed.

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Kendal Blust was a senior field correspondent at KJZZ from 2018 to 2023.