How COVID-sniffing dogs are aiming to change the game
Content submitted by AnimEd Solutions, a dvm360® Strategic Alliance Partner
I’m a Belgian national who moved to the States in 1973. I graduated from UTCVM in Knoxville, Tennessee, in 1993 and worked as a vet and in veterinary pharmaceuticals in the States until my move back to Belgium in 2003. I am a firm believer in the need for science and society to accelerate the One-Health approach to human and animal health and in the power of the human-animal bond.
I write this article in support of my French and Belgian colleagues from the Ecole National Vétérinaire d’Alfort (ENVA-Paris) and the Université de Liège (Belgium, from which I obtained a second veterinary degree in 2005).
As planes full of potentially COVID-infected passengers from China now enter the global air space and land in countries just beginning to recover from three crippling years of the COVID pandemic, I’d like to draw your attention to evidence of how our canine companions could be the answer to another three years of global viral mayhem.
The potential use of early canine olfactory detection of COVID has been evaluated in research centers across the globe since the early 2020’s when the pandemic hit and rocked our world. Pioneers in this research include but are not limited to the Ecole National Vétérinaire d’Alfort (ENVA - Paris), the veterinary Universities of Liège and Gent in Belgium, Florida International University (FIU), and Helsinki University.
In December 2020, in the early days of the pandemic, a study was published (PLoS One) by Dr Prof Dominique Grandjean (ENVA and Nosaïs) that demonstrated the ability of trained dogs to detect the presence of COVID-19 from human sweat samples. Humans infected with COVID-19 emit volatile organic compounds (VOCs) that the dogs are trained to detect. Grandjean states that it only takes a few molecules for a dog to detect a positive case. Pilot study results demonstrated that dogs detected the presence of COVID-19 in human sweat samples with 90% accuracy, 100% sensitivity, and a success rate of 83-100%.1
Validation of the test method and protocol was then performed by Professor Grandjean in collaboration with researchers from the Université de Liège and using working dogs from the Belgian civil defense, fire, police, and civil protection services. The aim was to determine whether the dogs could distinguish between COVID-positive and -negative patients.
Dogs were trained using PCR-confirmed COVID-positive patient sweat samples, with blank (no odor) samples used as controls. It is of note that no virus is excreted in sweat. As such, the samples were deemed safe for both the dogs and the humans handling the samples.
Results, published in June of 2022 (PLoS One), showed that after an intensive 4-week training period, dogs working in pairs could distinguish between positive and negative samples but required further training to perfect their accuracy. Interestingly, dogs previously trained in explosive detection were “faster learners” than search and rescue dogs.2
Although the final number of Belgian dogs completing the training and testing was small (6 dogs), results showed an average specificity (no false positives) of 98%, with 2 dogs reaching 100%. The detection of asymptomatic carriers was nearly 100%. The average sensitivity (no false negatives) was 81%. Researchers feel this number could be improved with better sampling and/or training techniques.2
Researchers list the following advantages of using COVID detector dogs2:
A survey of the Belgian public on the acceptability of the test showed a potential obstacle of 10% of the population self-identifying as being afraid of dogs. As sampling is done by taking a swab of the armpit and presenting it to the dog, a simple solution is keeping dogs behind a wall, out of sight of the test subjects.
After Grandjean’s pilot study, dogs trained in COVID detection were deployed to Finland, the United Arab Emirates, Chile, and Lebanon to be used for detection of infected passengers at the border or in airports.
Finnish researchers went on to conduct a triple-blinded real-life screening study at Helsinki-Vantaa International Airport. The May 2022 publication (BMJ Journals) reported the overall accuracy and sensitivity of test dogs in detecting the virus to be 92%, with a specificity of 91%, as compared with RT-PCR testing. Study dogs had been trained to detect wild-type virus and were shown to have lower accuracy in detecting the alpha variant (89% for wild-type versus 36% for alpha variant). This finding highlighted the importance of continued re-training of dogs as new variants emerged.3
Meanwhile, in the US, Dr Julian Mendel and DeEtta Mills at Florida International University conducted complementary studies on dogs trained to detect the virus on irradiated face masks. Their June 2021 publication (Forensic Science International: Synergy) reported similar results to the French/Belgian studies, showing more than 96% accuracy. Since then, FIU has been successfully deploying detection dogs to schools, festivals, jails, airline companies, and other institutions.4
One observation made by Courtney Daigle, an animal welfare scientist at Texas A&M University not involved in the FIU study, is that, in the real world, there are a lot of distractions for a dog that might interfere with his ability to detect the target scent. Examples are perfumes or soaps. More research could be needed to evaluate this potential obstacle to detection accuracy.
Also in the US, in September 2021, the CDC Foundation (Georgia), in partnership with the Association of Public Health Laboratories (APHL), Early Alert Canines, and the Department of Public Health, acquired and trained 2 dogs to detect COVID-19 in group settings. This team used a “scent wheel” as the pre-training method, which offers a variety of non-target scents to which the dogs are desensitized. Dogs were then trained to detect the virus in sweat from a sock worn by people testing positive for the virus.
Since inception of the CDC foundation program, trained dogs have been deployed in multiple schools, screening thousands of individuals. With a 90% accuracy rate, positive canine tests were confirmed by PCR tests. If a positive dog test yielded a negative PCR test, a second PCR test was run later that day or on the following day. Predominantly positive second-test results showed that dogs often detected a positive result before the PCR test did.
Surveys of parents, students, and teachers from participating school programs revealed a unanimous agreement as to the positive impact of the canine detection program, not only from a scientific and logistical point of view but from the well-being the dogs bring to the people they interact with.
And now, just when you thought it was safe to go back into the water, the world is facing a new wave of COVID-19 outbreaks in China. We are all holding our breaths as the airlines bring planes full of potentially infected passengers to all parts of the world.
According to Grandjean, passengers arriving from China are required to show a negative PCR test 72 hours before departing or show a negative test result on arrival at the airport of destination. Many in the scientific community find these measures to be way too little, too late, and a massive waste of resources.
As we have seen, multiple studies across the globe have demonstrated the consistently high level of accuracy of trained dogs in detecting asymptomatic carriers or early infections, and this is at a tiny fraction of the cost of the PCR test. In this highly charged global climate, many criticize the lack of action taken by government agencies to implement detection dogs as the first line of protection before potentially infected passengers board their planes, as well as after landing but before they cross the border at their destination airports.
This issue is heavy with geopolitical and financial implications. Many big players stand to lose out if fewer PCR tests are sold. As such, it is utopic to think we can consistently count on scientific evidence or good sense to guide regulators and political deciders. As veterinarians, we can continue to support research, One Health, and dissemination of the facts to those in our immediate environments. For those of you with influence, please spread the word to the decision-makers who could promote the use of this valuable one-health tool to keep the world a little safer in 2023.