With a sense of smell that is up to 100,000 times more sensitive than humans, dogs have been used to sniff out everything from contraband to plant mushrooms to cancer.
But while researchers first began to investigate whether dogs might be effective in the fight against Covid-19 at the beginning of the pandemic, it is only in the past few months that conclusive, peer-reviewed studies have begun to confirm the hypothesis that dogs have Covid recognize when you smell it.
In late 2021, scientists from Florida International University published a double-blind study to detect Covid in dogs, in which the four participating puppies showed an accuracy rate of 97.5% in identifying biomarkers related to Covid-19.
“It’s one of the highest percentages I’ve seen, and I’ve been doing this job with all types of sniffer dogs for over 25 years,” says Dr. Ken Furton of the FIU, a leading scientist in forensic chemistry specializing in odor detection. “It is really remarkable.”
Another study by the London School of Hygiene and Tropical Medicine found that dogs were able to identify Covid in 82-94% of cases, while more recent German studies put their success rate at 95%.
Dogs are able to generalize smells, which means they can recognize all currently known variants of Covid-19, much like they can detect all types of explosives when exercising, explains Furton.
However, Omicron has influenced search protocols used by Ohio-based Bio-Detection K9, a company that trained dogs to detect plant diseases prior to the pandemic and that began providing Covid detection services to clients like Nascar and the rock bands Metallica offer and tool.
“Omicron has changed the biology of the infection more than any other variant,” said company president Jerry Johnson. Prior to Omicron, Johnson’s team of 14 dogs were trained to approach a number of people and sniff their hands or feet – where people have many sweat glands – before sitting in front of those they believed were infected. Since Omicron is expressed less via the lungs, which transmits the virus throughout the body and into our sweat, and more via the bronchi, people now have to offer the dogs their worn mask to sniff.
Johnson’s dogs are capable of screening between 200 and 300 people per hour and need a break every 20 minutes to keep their excitement about the job going. When working with musicians, the dogs do not screen viewers on live shows; Instead, they hang out backstage and focus on a much smaller group of talent, engineers, and entourage.
“This is not a tool that you use to draw 70,000 fans into the Rose Bowl,” says Johnson. “But we can be very effective when you’re trying to maintain a protective bubble.” That effectiveness comes at a price; The daily rate for one of the Bio-Detection K9 teams – consisting of a dog and its trainer – is USD 5,000.
Based on his experience with detection dogs, Johnson has theorized that dogs are particularly adept at finding viruses because of a biological tendency to detect and avoid disease in their ranks. The logic is that a wolf in the wild cares no less about cocaine and explosives or other things we dogs train on, but of course is interested in the health of its pack.
Some institutions are training their own dogs to detect Covid, like the Freetown-Lakeville regional school district in Massachusetts, which worked with the FIU last summer to make Labradors Huntah and Duke school safety inspectors.
Dogs are not yet an FDA cleared diagnostic tool. So if they mark someone as infected, that person will still need to do a Covid-19 test to confirm this. However, some research suggests that dogs may be more sensitive to the virus than PCR tests, which identify infected individuals before they have accumulated enough viral load to sign up for a test.