Medical detection dogs continue to astound researchers with what their noses can do. Dogs can be trained to detect when a person with diabetes is experiencing low or high blood sugar, or when someone with a seizure disorder is going to have a seizure. They are able to sniff out several types of cancer in samples of blood, urine, sweat, saliva, and exhaled breath with great accuracy. Their noses are so sensitive that some of the trained pet dogs who enjoy the "detection game" at the Penn Vet Working Dog Center at the University of Pennsylvania can detect ovarian cancer in a single drop of plasma.
These olfactory feats all beg the question: Do dogs have what it takes to be able to detect SARS-CoV-2, the virus that causes COVID-19, in laboratory samples — or even to help screen people directly?
Scientists who know the power of a dog's nose are guardedly optimistic that dogs could be used to detect the novel coronavirus. "I suspect that they could if we could train them appropriately and safely," says Cindy Otto, DVM, PhD, founder and executive director of the Penn Vet Working Dog Center.
The Philadelphia-based organization is one of several respected institutions embarking on research to see if the virus has a detectable scent, and if dogs can safely and reliably alert to it. It's joined by the charity Medical Detection Dogs, in Milton Keynes, England, which is partnering with Durham University and the London School of Hygiene and Tropical Medicine, and Canine Performance Sciences at Auburn University's College of Veterinary Medicine.
Nestlé Purina Petcare is providing seed money to Dogs4Diabetics (D4D), in Concord, Calif., for a proof-of-concept experiment that could be completed in a month. The Bay Area organization is lauded for its scientific approach to training dogs to detect diabetic lows in their human partners, but is temporarily switching gears to focus on the pandemic.
Mark Ruefenacht, a measurement standards expert who founded D4D in 2004 after discovering that dogs can smell the scent of diabetic lows, hopes that if dogs are able to safely detect the virus, they could be working in the field three to four months after the proof-of-concept phase. He says D4D will have "complete transparency" so others can create similar programs. He will encourage the use of high-drive rescue dogs for the work.
"We aren't looking to make millions of dollars. We're looking to save lives and minimize the impact of COVID-19 on humankind," he says.
Ruefenacht and his team envision three ways dogs in their training model could help stem the virus's spread if they prove to be highly reliable:
- In clinical situations, such as at drive-up testing centers, dogs could be a first line of screening, especially while tests are in such short supply.
- Screening people entering public spaces like large office buildings or airports
- Detecting the virus on surfaces, much as the medical detection dogs in Vancouver hospitals do with C. diff.
The proof-of-concept phase will actually involve rats, not dogs. The rats at D4D normally spend free time hanging out with trainers, and enjoying foster homes on weekends. But during the early research, the rats will be hunkering down at headquarters for the month without the usual closeness to trainers to eliminate any chance they could transfer the virus in case they come in contact with it despite stringent safety protocols.
The rodents usually sniff out samples of saliva and sweat from diabetics in hypoglycemia to make sure the samples will work for training the dogs. (Their reward for a job well done? A stereotypical rat treat: cheese, though some prefer Milk Bones.) This month the rats will be trained on saliva and breath samples taken from people diagnosed with COVID-19. If the rats can learn to differentiate these samples from those of people without the virus, they'll move on to sweat samples.
Ruefenacht says sweat has not been shown to transfer the virus, and if the rats can detect the virus from sweat samples, they'll bring in the dogs to train on sweat for the next phase of research.
The World Health Organization states there is no evidence dogs can transmit COVID-19, and that there has been only one case of a dog with the virus, in Hong Kong. The Centers for Disease Control and Prevention's web page about animals and COVID-19 draws the same conclusion: "We do not have evidence that companion animals, including pets, can spread COVID-19." (A new article in Nature, however, indicates that cats may be susceptible to the virus, and can spread it to other cats. Cat owners shouldn't be alarmed, though, because "there is no direct evidence that the infected cats secreted enough coronavirus to pass it on to people," according to a virologist quoted in the article.)
Carefully selected dogs at Canine Performance Sciences (CPS) have been able to discriminate multiple viruses and bacteria during the past few years, according CPS co-director Craig Angle, PhD. He's hopeful that the research CPS is preparing to do will show that dogs are capable of detecting SARS-CoV-2 in laboratory samples.
"They [dogs] certainly have the capability to detect other viruses. We just have to figure out the best way to approach the problem…and conduct more studies to see if it is possible," he says.
Biosafety is paramount. Dr. Angle says CPS's multidisciplinary team of subject matter experts in virology, bacteriology, infectious disease, laboratory techniques, chemistry, and canine training have developed methods to capture viral target odors and sterilize them to a safe level, so they've already crossed that hurdle. But there are still significant challenges.
"It is a complex problem to solve because we are in uncharted waters of virology and analytical chemistry," he says. "We also have to be sure that our canine partners will stay target-specific to a certain strain and not generalize to other strains of coronavirus or other distractors associated with the virus."
If dogs could reliably detect the virus and distinguish it from other related viruses, it could be a game-changer. Widespread testing is essential in order to get ahead of the virus and "flatten the curve," as the mantra goes . With medical resource shortages rampant, the addition of hundreds of dogs could be a feasible way to rapidly screen tens of millions of people.
As I watch my dog Gus sleeping in the sunshine next to his toys, I hold out hope that his distant cousins around the world may be able to help prevent millions of deaths by doing what they do best: using their phenomenal noses for the simple paycheck of treats, toys, and loving praise.
BIO: Maria Goodavage is the New York Times bestselling author of Doctor Dogs: How Our Best Friends Are Becoming Our Best Medicine and other books about working dogs.