Scent Detection Dogs Can Accurately Identify Individuals Infected With COVID-19

Author Tommy Dickey, PhD shows how he conducts basic dog odor detection training with his own dogs. These dogs were not part of the reviewed study. Credit: Tommy Dickey, PhD

The use of trained smell recognition dogs to detect volatile organic compounds associated with the COVID virus shows promise in early studies.

In a recent article in the Journal of Osteopathic Medicine, authors gathered previously published research to summarize current thinking about the feasibility and efficacy of using odor detection dogs to screen for the COVID-19 virus. The researchers report that the sensitivity, specificity, and overall success rates reported by the canine odor detection studies are comparable or better than standard RT-PCR and antigen testing procedures.

These findings indicate that scent detection dogs can likely be used to effectively screen and identify individuals infected with the COVID-19 virus in hospitals, senior care facilities, schools, universities, airports and even large public gatherings for sporting events and concerts.

“Accurate and prompt screening of individuals who may be carriers, symptomatic or asymptotic, of the COVID-19 virus will continue to be important in slowing and limiting the spread of infection,” said Tommy Dickey, PhD, professor at the University of California , Santa Barbara. “These preliminary studies suggest that the use of medical olfactory dogs offers a promising approach.”

Documented success in detecting disease

Dogs can perceive a wide variety of molecules with extremely small concentrations: 1 part in a trillion compared to 1 part in 1 billion for humans. This capability is used to search for and identify diseases with their individual chemistry and smells.

Using inhaled air molecules and particles, dogs can detect fragrant human molecules (volatile organic compounds or VOCs) that come from exfoliated skin or hair cells, blood, breath, saliva, sweat, tears, nasal mucus, urine, semen, or feces. Because smells linger, dogs can keep a historical library of the scents of complex molecules.

“The science behind and the effectiveness of using dogs in detecting medical conditions and diseases such as cancer, diabetes, malaria, Parkinson’s disease and more have been documented,” said Heather Junqueira. “These new studies provide support for additional research to determine whether they can detect COVID-19 at scale.”

The qualified studies

For their review, the authors reviewed four recent studies analyzing the success of scent detection dogs in identifying VOCs associated with COVID-19. First, they described the work of a team of collaborating researchers from France and Lebanon, who tested with 8 dogs previously trained to detect both explosives and colon cancer.

These dogs independently received cotton or wool netting samples soaked with sweat from one of the 198 human armpits of patients in different hospitals. Although the COVID-19 virus itself has no odor, the researchers hypothesized that the resulting infection triggers metabolic changes, causing the release of a distinctive type of sweaty odor that can be detected by a dog.

The dogs were trained to sit in a box with a sample canister for a COVID-19 positive sample only. After four days of training with COVID-19 samples, the success rate for the dogs ranged between 83 and 100%.

Saliva or tracheobronchial secretions

In another study described by the authors, a research team in Germany conducted a randomized, double-blind, controlled pilot study to determine whether previously trained scent hounds could successfully detect the presence of the COVID-19 virus. Dogs were trained for 1 week to detect the COVID-19 virus in samples of saliva or tracheobronchial secretions collected from infected patients.

Each dog, its handler, and the person observing the study were blindfolded. The number and duration of each dog’s ‘nose dips’ in the scent holes, along with the location of the positive and negative samples, were automatically recorded and verified using time-stamped video analysis, automating the process and reducing the interference of the trainer was reduced.

The results, derived from 1,012 automated sample presentations, showed an overall mean detection rate of 94%: 157 correct indications from positive, 792 correct rejections from negative, 33 false positives and 30 false negative indications. Interestingly, the team reported no significant difference in detection capability between the use of sample saliva and tracheal secretion from samples.

While that pilot study had limitations – specifically, the positive samples were only from critically ill COVID-19 patients in the hospital and the negative samples were from healthy individuals with no evidence of respiratory infections – the authors of the current study found those results encouraging.

Support for additional research

A third study conducted by a team in Colombia tested 6 trained scent hounds of different and mixed breeds to develop a screening method for detecting COVID-19 in individuals who may be asymptomatic, presymptomatic, or symptomatic.

The researchers developed a device to safely expose the scent-trained dogs to VOC samples collected from respiratory secretions of COVID-19 positive patients, and their detailed study was conducted in 3 phases, with the third phase underway.

“Of the 6,000 samples, the performance of the dogs [in that study] resulted in a sensitivity of 95.5% and a selectivity of 99.6%, ”says Dickey. “The high success rates in different types of dogs suggest that a range of breeds or mixed breeds can be trained to screen effectively for COVID-19.”

Challenges remain

“The results of recently reported and ongoing research are encouraging; however, challenges remain to be considered before a large scale implementation of scent detection dogs to identify and screen COVID-19 is to be widely implemented, ”said Junqueira. “Nonetheless, the study supports the use of scent detection dogs for pilot studies of COVID-19 screening in locations such as airports and sporting events.”

The authors hope that their research evaluation, which provides recent information and perspectives on the potential for wide application of trained scent hounds for screening of COVID-19 infected individuals, can be used to aid in the development of future studies and the implementation of screening programs. for the benefit of preventive medical examination.

To learn more about this study, read How Dogs Can Be Our Next Allies Against COVID-19.

Reference: “Toward the Use of Medical Odor Detection Dogs for COVID-19 Screening” by Tommy Dickey, PhD, MS, MA and Heather Junqueira, CVT, February 2021, Journal of Osteopathic Medicine.
DOI: 10.1515 / yom-2020-0222

About the Journal of Osteopathic Medicine

Founded in 1901 and known as The Journal of the American Osteopathic Association for 119 years, The Journal of Osteopathic Medicine is the most important scientific, peer-reviewed publication of the osteopathic medical profession. JOM conducts peer review of academic research manuscripts from a wide variety of medical specialties, covering the full spectrum of clinical settings in which osteopathic physicians practice. All submissions are vetted by a leading group of section editors led by editor-in-chief Ross Zafonte, DO, and supported by a full editorial board.