Using their incredible sense of smell, dogs today do many types of work for humans.  They detect signs of diabetes, Parkinson’s disease, and cancer, among many other ailments.  They are allies in military operations, smelling out hidden explosives.  They partner with customs officials searching for contraband, such as drugs and elephant ivory.  They find truffles and mushrooms for our culinary pleasure.  And, as I have written about before, dogs are invaluable partners in search and rescue teams following natural disasters.  (See posts on “Search Dogs” from February 2018 and “The Search Dog Foundation” from August 2021.)

Dogs have 300 million olfactory receptors versus 6 million in humans.  The part of the brain devoted to analyzing smells is 40 times greater than ours.  Hence, a dog’s sense of smell is between 10,000 and 100,000 times more acute.  Let’s say it’s only 10,000 times better.  If you make the comparison to vision, then what we can see at a 1/3 mile away, a dog could see more than 3,000 miles away—that’s clear across the United States.

It is no wonder that dogs have been called upon in the war on Covid-19.  As early as spring 2020, researchers at the University of Pennsylvania began training dogs to sniff out the virus from urine and saliva samples.  And now researchers there and from countries around the world, including Italy, Germany, Finland and France have launched sniffer dog trials based on human sweat.

One of the first trials to achieve excellent results was based in Milan.  It is an ongoing collaboration between the University of Milan, the Carabinieri (the national military police) and the Sacco Hospital.  The hospital provided gauze soaked in sweat taken from hospitalized Covid patients.  (The virus itself cannot be transmitted to humans or animals through sweat.)  The dogs are then trained in two phases:  olfactory conditioning to recognize the volatile organic compounds in Covid, and then olfactory discrimination to distinguish positive and negative samples. 

A similar project is being conducted at Rome’s Campus Bio-Medico University Hospital.  If these experiments are found to be reliable, using trained Covid dogs could prove to be a faster and cheaper method of detection in crowd situations, such as a football match or a rock concert.  “If we have 1,000 people to screen with an antigen swab, it would take about 20 minutes for each person,” says Massimo Ciccozzi, a professor of epidemiology at the university.  “A dog, using its olfactory senses, would take 30 seconds maximum.” Rome’s project plans to focus next on patients at a drive-through testing center on the campus.

Covid detection dogs could offer an extraordinary resource where there is an influx of large masses of people, such as sporting events, demonstrations, and airports.  In fact, dogs have already been deployed at Finland’s Helsinki-Vantaa international airport to detect infected passengers.  Trained dogs could also be used to complement other efforts.  For example, they could provide an initial screening that a laboratory test could later confirm, allowing a potentially infected person to take immediate precautions.

What’s next?  Testing whether canines can detect the variants of COVID-19.