Man's Best Friend: The Ultimate COVID-19 Screening Solution?

Researchers across the world are conducting canine studies to examine if dogs can detect a distinct smell in people infected with SARS-CoV-2 with the aim of developing a quicker, more accurate test for the coronavirus.

The extremely sensitive olfactory sense of dogs might prove to become a groundbreaking new tool in the fight against the COVID-19. Dogs have earlier been trained to detect diseases like malaria, cancer, Parkinson’s and bacterial infections and are also able to detect subtle changes in temperature of the skin to tell if someone has a fever. With up to 300 million smell receptors - compared to six million in humans - dogs are uniquely positioned to aid in disease detection. Studies are already underway to prove that man’s best friend can play a role in preventing the spread of COVID-19 by training them to detect coronavirus. For instance, a pilot training program utilizing scent detection dogs to discriminate between samples from COVID-19 positive and COVID-19 negative patients is the focus of a new research initiative at the University of Pennsylvania’s School of Veterinary Medicine (Penn Vet Philadelphia, PA, USA). The pioneering study – that will explore the sensitivity and specificity of scent – sets the stage for dogs to be a force multiplier in the mission to detect COVID-19, particularly among asymptomatic patients, or hospital or business environments where testing is most challenging. Over the course of the study period through a process called odor imprinting, the dogs will be exposed to COVID-19 positive saliva and urine samples in a laboratory setting. Once the dogs learn the odor, the investigators will document that the dogs can discriminate between COVID-19 positive and COVID-19 negative samples in a laboratory setting, establishing the platform for testing to determine if the dogs can identify COVID-19 infected people.


According to preliminary tests, trained scent detection dogs seem to be quick in performing the new task and might even be more sensitive than many of the tests that are now on the market. In a new study, a research team led by the University of Veterinary Medicine Hannover (Hannover, Germany) has shown that dogs can sniff out people infected with the SARS-CoV-2 virus. The dogs only needed to be trained for one week to differentiate between samples from SARS-CoV-2 infected patients and non-infected controls. In the study, eight specialized scent detection dogs that were trained correctly identified 94% of 1,012 saliva or tracheobronchial secretion samples. The samples were automatically distributed at random and neither the dog handlers involved nor the researchers on site knew which samples were positive and which were used for control purposes. The dogs were able to discriminate between samples of infected (positive) and non-infected (negative) individuals with an average sensitivity of 83% and a specificity of 96%.

Similarly, researchers at the veterinary and human medicine faculties at the University of Helsinki (Helsinki, Finland) have joined forces to identify COVID-19 infected individuals using canine scent detection. The first dogs that now have been trained, have succeeded in differentiating COVID-19 patient’s urine samples from urine samples of healthy individuals. The researchers are now starting a large collection of patient samples to ascertain the first observations and to be able to continue training more dogs. The researchers also need to clarify what the dogs are identifying in the patient samples and how long the smell stays after the infection has passed. Based on the preliminary tests, it seems that the dogs are able to learn and work fast and even perform better than the current COVID-19 tests that are based on molecular techniques. In fact, dogs' noses have now been put to test at the Helsinki-Vantaa Airport where a pilot project has been started with four dogs sniffing samples. When a passenger at the airport comes to the corona dog sampling station, he or she steps into a small space delineated by screens, where he or she takes a skin swipe from him or herself according to the instructions given and drops the sample into the container provided for it. The dog and its trainer are behind a wall, where the dog sniffs the given sample. In this way the allergic passengers, among others, are taken into consideration, and care is taken that the trainers are not subjected to the coronavirus.

Medical Detection Dogs (London, UK), a charity that has spent years successfully researching the science behind dogs’ sense of smell, also believes that dogs could detect COVID-19. Its team of COVID-19 detection dogs can passively screen, i.e. without physical contact, any individual, including those who are asymptomatic, and indicate to dog handlers whether they have detected the COVID-19 virus. The charity believes that once trained, the detection dogs could be deployed in airports or other venues to screen large numbers of people, providing a rapid non-invasive screening for COVID-19. A single dog can screen up to 250 people per hour. COVID-19 detection dogs could also assist in mapping and intelligence gathering to provide estimates of likely percentage of infected travellers on flights from ‘hotspot’ locations from around the world. This would provide rapid information of risk and likelihood of rapid spread, helping to prevent an uncontrolled second wave of COVID-19 in the autumn.

“Scent detection dogs can accurately detect low concentrations of volatile organic compounds, otherwise known as VOCs, associated with various diseases such as ovarian cancer, bacterial infections, and nasal tumors. These VOCs are present in human blood, saliva, urine or breath,” said Cynthia Otto, DVM, PhD, professor of Working Dog Sciences and Sports Medicine and director of Penn Vet’s Working Dog Center. “The potential impact of these dogs and their capacity to detect COVID-19 could be substantial.”


Related Links:
University of Pennsylvania’s School of Veterinary Medicine
University of Veterinary Medicine Hannover
University of Helsinki
Medical Detection Dogs