Can dogs detect coronavirus? Research suggests the nose knows
GREENCASTLE, Pa.— The black Labrador circled a giant horizontal metal wheel, sniffing the cans at the end of each spoke before stopping abruptly in front of one. Head up and ears pricked, Blaze froze, staring intently ahead.
“That’s the grail!” exclaimed Cynthia Otto, director of the Penn Vet Working Dog Center at the University of Pennsylvania School of Veterinary Medicine.
“That’s amazing! Just amazing!”
Kibble tumbled out of a dispenser, and Blaze bounded across the small training facility to devour it.
Blaze is one of nine dogs enrolled in a University of Pennsylvania study into whether dogs can detect a distinct smell in people infected with the novel coronavirus. His triumph on that early July day — selecting a can containing urine from a hospitalized coronavirus-positive patient over an array of potentially confusing alternatives — is a key step in a training process that may one day allow dogs to pick out infected individuals, including those who are asymptomatic.
Blaze’s success also marks an advance in the evolving field of olfactory disease detection — the concept that many human illnesses, including emerging diseases, are characterized by distinct “odorprints” that can be identified by both dogs and artificial noses, which could be quicker, less invasive and more accurate than current forms of clinical testing.
“This is a major field of research worldwide,” said Kenneth Suslick, a professor of chemistry at the University of Illinois who invented an electronic nose for detecting toxic gases and explosives as well as diagnosing diseases, in much the way that a simple breathalyzer can identify the distinctive chemicals of alcohol.
As the coronavirus continues to ravage the world, those possibilities put the spotlight on research like this and a similarly rigorous study at the London School of Hygiene and Tropical Medicine. With demand high, scientists are emphasizing the need to proceed with caution.
“As eager as we are to put this out there, we want to make sure it is responsible, ethical, scientific and safe,” Otto said, even as she admitted that seeing Blaze perform with such accuracy after just 10 weeks of training gave her chills. Moving from the controlled setting of the training facility to finding the scent on thousands of travelers in busy airports is a huge step.
“Done wrong, it could be more damaging than helpful,” Otto said.
The Penn team’s research, funded largely by private donations, is based on two established principles: that changes in our health often alter the way we smell; and that dogs, with 50 times as many smell receptors as people, make great biosensors with a proven ability to detect not only drugs and explosives but some diseases, such as hidden cancers, the sudden shifts in blood sugar levels caused by diabetes, parasitic infections like malaria, and bacterial and viral infections including, potentially, the novel coronavirus, which causes the disease COVID-19.
Blaze and eight other dogs — seven more young Labs and a more experienced Belgian Malinois — are learning their coronavirus-sniffing skills at the Good Dog boarding and training facility on the Pennsylvania/Maryland border. Pat Nolan, who trains dogs for elite military teams, and his wife and fellow trainer, Connie Cleveland-Nolan, imprinted the new scent on the dogs by offering them several smells and rewarding them when they sniffed a coronavirus-positive sample.
The trainers keep a record of each dog’s performance, the air temperature and the humidity. They wipe down the sample cans with alcohol between dogs. And they monitor their own body language to avoid involuntary cues.
“We’re very careful,” said Nolan. The researchers have been changing the positive samples they are using as the work evolves.
Despite some distractions, the canine trainees performed with stunning accuracy until one Labrador suddenly froze, head up and ears pricked, in front of can containing a urine sample from a hospitalized patient who had tested negative for the virus.
It was one of the few mistakes of the day. Unless it wasn’t a mistake.
Clinical tests give more than 10 percent false negative results, raising the possibility that the urine could actually have come from a coronavirus-positive patient.
That appeared to be true a few weeks later, when the dogs all alerted on a sample from a patient who had recently tested negative. They were so insistent — and consistent — that Otto went back to the hospital to learn the patient had previously tested positive, suggesting there may have been some lingering odor from the earlier infection.
“There’s a phrase in dog training,” Otto said: “Trust your dog.”