Yet Another Reason To Love Dogs: They Can Sniff Out COVID-19

Dog lovers know there are a lot of reasons to love dogs. They’re loyal. They’re cuddly. They can sense when you’re hurting—I watched my rescue dog curl up next to my husband without fail every time he took a nap during the last weeks of his battle with brain cancer.

Now, there’s another reason to love dogs. (As if we needed one.) Along with vaccinations and increasing testing capabilities, dogs could be on the front lines of ending our global health crisis. Dogs around the world are being trained to detect COVID by scent alone. Trainers in Thailand, France, Britain, Chile, Australia, Belgium, and Germany are among the countries training dogs to sniff out COVID. Dogs have already been used to sniff out COVID in airports in Finland, Lebanon, and the United Arab Emirates. A pilot study at the University of Helsinki found that dogs “might even be more sensitive than many of the tests that are now on the market.”

Dogs Have A Superior Sense Of Smell

To understand how this is possible, it’s first important to understand that dogs have a superior sense of smell. Dogs possess about 220 million scent receptors, as compared to humans, who have a measly 5 million. Their smell receptors are also 10,000 times more accurate than ours, which means, “their nose is powerful enough to detect…a single drop of liquid in 20 Olympic-size swimming pools!” Another fun fact (or two)—their noses can tell the difference between right and left, and they inhale up to 300 times per minute.

Dogs Can Detect COVID With A High Accuracy

Researchers from the University of Pennsylvania’s School of Veterinary Medicine found that “specially trained detection dogs can sniff out COVID-19-positive samples with 96% accuracy.” Eight Labrador retrievers and one Belgian Malinois who had never done medical detection work were recruited for that study. After just three weeks, all nine dogs could identify COVID-19 positive samples with astounding accuracy. The one hiccup came when the dogs continued to respond to a sample from a patient who had tested negative for COVID, but had previously been infected.

Even with that hiccup, the dogs’ accuracy is better than one of the current detection models employed at many places—temperature screenings, which frequently misses asymptomatic individuals. Even in those individuals with no symptoms, dogs can identify a COVID-19 infection because of a “trademark scent” produced in the lungs and trachea of an infected individual. The screening (by dogs) would be fast, effective, and non-invasive.

COVID Itself Probably Doesn’t Have A Smell

Most likely, the actual virus doesn’t have a smell. The dogs are not sniffing out the virus itself. It’s more likely that the dogs are “detecting subtle odors that occur in people infected with the virus,” says David Dorman, professor of toxicology in the Department of Molecular Biosciences at the NC State College of Veterinary Medicine.

Dogs are able to detect those subtle odors even against the backdrop of other naturally occurring odors. Cynthia Otto, director of the University of Pennsylvania School of Veterinary Medicine Working Dog Center, noted that “Dogs have to be specific about detecting the odor of the infection, but they also have to generalize across the background odors of different people: men and women, adults and children, people of different ethnicities and geographies.”

The Training Process Takes Some Time

Dorman described the training process in an interview with Veterinary Medical News. First, trainers introduce a sample of the odor the dog is supposed to detect. The trainer presents this sample over and over until the dog begins to recognize the scent. Then, the training becomes more complicated, with distracting odors present. Usually, there’s a reward when the dog sniffs out the scent correctly. The key, according to Dorman, is patience.

In the University of Pennsylvania’s School of Veterinary Medicine, the dogs had not been trained in scent detection previously. They started training in general scent detection first, and then, once they mastered that, they moved on to COVID specific training.

More Than Just A COVID Infection

I would venture to guess that most of us have seen scent detection dogs at work—whether in airports or even in the movies. Scent detection dogs at airports can sniff out drugs and explosive devices, among other things.

Bu dogs can also be trained to sniff out other diseases, as well. For example, dogs can sniff out a variety of types including skin cancer, breast cancer and bladder cancer. They’ve also been used to detect malaria and Parkinson’s disease. In some instances, “dogs have been trained to sniff out the markers of disease that might even go unnoticed with medical tests.”

Dogs have also been trained to help patients detect warning signs. They’ve been trained to help diabetics know when their blood sugar level is dropping or spiking.

Realistically, we’re probably a ways off before dogs are really used in large group settings like airports or concerts. But the capability is certainly there and has the potential to revolutionize the way we can control this virus, particularly in higher risk settings. And truly, anything that brings us closer to ending this pandemic is worth exploring.