Dogs trained to sniff out COVID in schools are getting a lot of love for their efforts

Freetown Elementary School students Mason Santos, left, and Mila Talbot, right, pet Hunter the dog after she finishes checking a classroom. (Jodi Hilton for NPR)

Since last fall, Hunter the dog, a not-quite-two-year-old black lab, has been sweeping classrooms and common areas at Freetown Elementary School nearly every week in search of … COVID.

One afternoon in early June, she sniffs around a first-grade classroom while the kids work at their various math stations. She smells the garbage can, desks, students’ book bags and other surfaces. Although the risk of transmission of the virus on surfaces is low, it’s not zero.

“So, if the dog indicates on COVID,” explains Capt. Paul Douglas, who handles Hunter and runs the K-9 Unit of Bristol County Sheriff’s Office, “the dog will sit.”

If that happens, Douglas alerts the school administrator to evacuate students from the infected area and spray it down with decontaminant before allowing the students to return.

Hunter is part of a program developed by scientists at Florida International University in Miami who have trained dogs to detect COVID on surfaces and in people. The researchers started working with the animals in the early months of the pandemic — and have successfully deployed them in Florida, Hawaii and Massachusetts to sniff out the virus. Similar projects are underway in other countries, including Finland and France.

A dog’s nose knows

Courtney Daigle, an animal welfare scientist at Texas A&M University not involved in FIU’s research, says the work is “totally legit and [the dogs] can totally do it.”

That’s because dogs have a powerful sense of smell. They can detect “things such as missing people, drugs or explosives,” says Julian Mendel, a forensic biologist at FIU who helped develop the COVID program for dogs for his doctoral work.

Within the nasal cavity of most mammals, there’s a sheet of tissue called the olfactory epithelium that converts odor molecules into the neural signals that the brain interprets as smells. In humans, this tissue is a single flat sheet. But in dogs, it’s a convoluted maze that folds and tumbles over a series of bony bumps. In addition, canines have hundreds of millions more of the specialized odor-detecting neurons than humans. These differences give dogs a leg up — or perhaps four legs up — in the realm of smell. “The way they perceive the world is much different than how we perceive it,” adds Daigle.

In early 2020, when COVID came ashore in the U.S., Mendel witnessed the unfolding public health crisis and wondered whether dogs could play a role. He and his colleague at FIU, forensic microbiologist DeEtta Mills, decided they would try to teach dogs how to sniff out the virus.

To do that, they worked with a local hospital to gather discarded masks from patients who’d tested positive. Turns out that the masks emitted a particular COVID odor. “All of the immune responses that your body turns on in order to fight off this virus combines to make a unique scent that people breathe out [and is] captured on the masks,” says Mills.To protect the dogs from COVID during training, the researchers “UV-irradiated them to inactivate the virus, and then we used those masks to train the dogs,” says Mills.

And even if dogs were to smell COVID in a mask or on a surface that hadn’t been irradiated, the risk to the animals is very low, says Mills. “We’ve checked with several different veterinarians, including one from the [Centers for Disease Control and Prevention]. Even if the dog gets [COVID], it’s a very mild cold. It doesn’t affect them as it does us.”

After a month of training, Mills and Mendel wrote up their findings, which was published in the journal Forensic Science International: Synergy in June 2021. They reported that the dogs were accurately detecting COVID more than 96% of the time.

Other research groups around the globe have confirmed similar findings. A team in France worked with dogs that successfully identified COVID in sweat samples collected from people’s armpits. In Finland, four dogs were trained to detect COVID at the Helsinki-Vantaa International Airport using skin samples collected from participants’ necks, throats, foreheads and wrists.

There are benefits to using dogs to detect COVID, says Daigle. Compared to swabbing everyone’s nose with an antigen test, deploying dogs to hunt down the virus saves time and is easier logistically. Authorities can “assess a large group of individuals in a quick manner without the need for all these different supplies or a laboratory,” she says. Plus, she adds, it’s possible to scan a physical environment and its surfaces more rapidly and thoroughly than a painstaking human effort to sample the same space.

Every canine program works with their dogs a little differently. But here’s how FIU’s COVID program operates. First, Mendel and Mills make sure they’re working with highly motivated animals. “You want to have a dog that is obsessive about his toy,” explains Mills. “And he’ll work all day long just for that few minutes that you give him to play with that toy.”

A handler brings the dog into a room where it’ll sniff for COVID for 5 to 10 minutes. If there’s no virus present in the room, the handler will sometimes hide a special training scent for the dog to find to keep the animal’s motivation up. Once a successful detection is made — in which the dog sits to indicate it has found COVID — the handler will toss a ball or other toy for the dog to play with as a reward.

FIU has certified four dogs in its COVID-detection program. They are part of a kennel of trained canines at a company spun out of FIU called Innovative Detection Concepts. Mills says that organizations, towns and companies can reach out for help finding established handlers who can be instructed on how to train dogs to detect COVID. The fee for such consults varies depending on the request.

And the program has been busy. Since FIU started deploying dogs in early 2021, the dogs have screened the masks of wedding guests and a group of American Airlines employees returning to work. They helped reopen the Miami Wine and Food Festival by sniffing out the masks of large numbers of attendees. If the dog detected COVID on the mask, that person would be asked to step out of line to take a rapid test. The Volcano School of Arts & Sciences in Hawaii worked with FIU to help keep classes open. And private companies from France and Italy even reached out to Mills to inquire about purchasing their trained canines.

But there are some drawbacks to using dogs to detect COVID, says Daigle. It takes work to train these animals and visit a place often enough to scan for the virus consistently. Also, in the real world, she says there are a lot of distractions for a dog that might interfere with their ability to detect the target scent, like perfume or soap.

Another way to prevent COVID

Despite the downsides, some people are just excited to have a new tool in their COVID prevention arsenal.

FIU’s program made its way to Bristol County in southeastern Massachusetts last year after Sheriff Thomas Hodgson caught wind of the dogs’ success from a friend. So he had Capt. Paul Douglas partner with the team from FIU to train a couple of dogs in his K-9 Unit: Hunter and a yellow lab named Duke.The dogs have been sweeping the county jail and the five schools in the Freetown-Lakeville Regional School District pretty much every week. It’s an initiative funded by the police department and private donations.

“We’re trying to keep our kids in school safely. We’re trying to get them back in person, and we feel this is one more mitigating way to do that,” says Richard Medeiros, superintendent of the school district. Other preventative measures, he adds, have included masking, social distancing and having all students eat in the cafeteria facing forward to minimize sitting in the path of respiratory droplets.

Back in the first-grade classroom of Freetown Elementary School, once Hunter finishes her inspection, Douglas announces, “This room’s clear. She didn’t alert to any presence of COVID.”

But before they move on to the next classroom, Hunter needs to be paid for her work. Douglas brings her around to the students, who spend a couple minutes scratching Hunter behind the ears. Not a bad trade for peace of mind.

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