By Sonia Fernandez, UC Santa Barbara
Dogs have been our hunting partners, colleagues, helpers and companions for some 15,000 years. Could they also be our next allies in the fight against COVID-19?
According to UC Santa Barbara professor emeritus Tommy Dickey and his associate, BioScent researcher Heather Junqueira, they can. And with a review paper published in the Journal of Osteopathic Medicine, they added to a small but growing consensus that trained medical scent hounds can be used effectively to screen individuals who may be infected with the COVID-19 virus.
This follows a comprehensive review of research devoted to the use of trained dogs of smell to detect COVID. “The most striking result is that studies have already shown that dogs can identify humans who are COVID-19 positive,” Dickey said of their findings. “Not only that,” he added, “they can do it non-intrusively, faster and with comparable or possibly better accuracy than our conventional detection tests.”
Not surprisingly, the magic lies in dogs’ sense of smell, which enables dogs to detect molecules in small concentrations – “part in a trillion compared to part in a billion for humans,” the paper said. Add to that other optimizations for scent, such as a large nose area and the structure of their noses, allowing inflow through the nostrils and outflow through nasal folds. Additionally, with 125-300 million olfactory cells and a third of their brains dedicated to interpreting smells, dogs are well-equipped with the ability to detect the volatile organic compounds that indicate the presence of COVID.
Professor Emeritus Tommy Dickey and one of his therapy dogs in the Great Pyrenees
“The dogs are actually smelling the person’s sweat,” Dickey said of a series of experiments by French and Lebanese researchers testing dogs’ ability to detect COVID infection. Although the virus itself has no odor, metabolic products secreted by COVID-positive individuals through their sweat glands were detected by the 18 dogs selected for the study (16 Belgian Malinois, a German Shepherd, and a Jack Russell Terrier) with an accuracy of 83 -100% after just four days of training. Real failures could be attributed to “distracting external smells or movements by a film crew on TV,” the study said.
“One dog gave two positive results that could not be confirmed,” said Dickey. “Two weeks later, they found that both people who took those samples with COVID had to be hospitalized.”
Meanwhile, a German research group employed eight scent-detection dogs in a randomized, double-blind controlled pilot study. The group trained the dogs for a week and then had them snort 1012 samples of saliva or tracheobronchial secretions. They returned an average detection rate of 94% with a sensitivity (ability to detect a true positive) of 67.9% to 95.2% and a specificity (ability to detect a true negative) of 92.4 % to 98.9%. This pilot study used positive samples from severely affected individuals and negative samples from people without symptoms. Future studies, according to that paper, could focus more on identifying different phases of infection or perhaps on the detection of different disease phenotypes.
The use of dogs to detect disease is not new. Co-author Junqueira has previously published results showing that her scent hounds (beagles, bassett hounds, and mixtures of the two) can effectively detect non-small cell lung cancer.
“Canines are able to detect other types of cancer, as well as malaria, Parkinson’s disease and diabetes,” Junqueira said, adding that “research on medical scent hounds has really only been gaining momentum in recent years and that there are many more peer-reviewed tests. Articles are needed before the idea of using dogs for disease detection hits the mainstream. ”
Dickey’s own interest in the topic was sparked in the course of his work as a therapy dog handler of three Great Pyrenees (over 3,000 therapy dog visits), a lengthy pursuit he leaned on after cancer forced him to retire from UC Santa Barbara’s Department of Geography in 2013 “I loved UCSB,” he said. “I loved to teach and I brought my therapy dogs to class all the time. I just had life, what can I say? ”
In fact, he couldn’t stay away – he and his dogs were ready to see the UCSB community through tough times, with their shaggy coats, wet noses, and calm manners through tragedy and stress. After retirement, Dickey has published three therapy dog books for kids, some of which tell stories of their UCSB therapy dog adventures. In addition, he and his dogs have given educational demonstrations at the California Science Center and the Los Angeles Public Library, work that sparked his interest in the power of a dog’s sense of smell for medical detection.
So when the new disease COVID-19 hit, Dickey was ready to ask, Can dogs detect the new coronavirus? Of course, there was little referenced research on the topic, so he teamed up with Junqueira, who already conducted her own COVID detection research with her scent hounds in Florida. “One of our big motivations was to write a peer-reviewed paper that basically produced a progress report,” he said. “Where are we? Is this really possible?”
Dickey and Junqueira found that researchers used different dogs. “Many Belgian malinois were used, and dogs trained on explosives and colon cancer. So they were professional sniffers, ”Junqueira said. “Other groups, such as those behind a Colombian study, were motivated by the need to find a rapid, accurate, and cost-effective form of COVID early detection.” The Colombian group used a variety of dogs – four Belgian Malinois, an Alaskan Malamute-Siberian mix, and an American pit bull terrier.
“The pit bull had been mistreated before,” said Dickey, “but they rehabilitated him, and he was perfectly capable and did a great job sniffing.” After nearly two months of training and thousands of samples later, this Colombian dog cohort performed with a remarkable 95.5% sensitivity and 99.6% specificity.
During the various blind, controlled experiments, the total detection time was a matter of minutes or less. Such speed is a huge asset in real world scenarios. In particular, a UK-based research group has outlined their plans to train and eventually deploy dogs at airports and ports in the UK as part of the COVID-19 screening process.
With all the sniffing in the presence of airborne illness, it’s natural to worry about whether dogs can catch and pass on COVID-19. It is still the subject of ongoing research, but there is some evidence that the paper says there is a low probability of transmission, although precautions should be taken to protect all involved.
“Current research supports the use of olfactory detection dogs for pilot studies of COVID-19 with humans in locations such as airports and sporting events,” said Dickey. “In addition, the JOM paper points out that another line of research may use medical scent detection dogs, involving the development of medical electronic noses.”
In principle, you wouldn’t even need a dog to sniff COVID if you could mimic the way it smells and processes odors, the researchers said. Through sensors and artificial intelligence, they said, it may be possible someday to match a dog’s performance using wearable electronic noses, similar to wristband sensors for reporting heart rate and patterns, blood pressure and oxygen, which it sweat from a person for metabolites and biomarkers that could indicate diseases such as COVID-19.
news.ucsb.edu