29 September 2023

COVID Scent Dogs

Welcome back. In August 2021, a Distinguished Professor Emeritus with the University of California Santa Barbara together with the founder of BioScent Inc., which focuses on using canine scent detection to develop non-invasive screening for disease, published a review on scent dogs for COVID-19 screening.

I either missed or let that one go, but I couldn’t do that with their recent update. The earlier review found only four peer-reviewed COVID-19 scent dog papers. The recent review identified 7,843 references after screening, considered 100 for full-text eligibility, identified 43 studies for qualitative synthesis and 29 studies for a quantitative meta-analysis.

Using the results of the reviewed papers, the researchers compiled statistics to compare and summarize basic information concerning the scent dogs and their training, populations of the study participants, sampling methods, comparative tests and the effectiveness of the scent dog screening.

Three examples of scent dog clinical study information (from www.degruyter.com/document/doi/10.1515/jom-2023-0104/html).

Three examples of scent dog field study information (from www.degruyter.com/document/doi/10.1515/jom-2023-0104/html).

Key Sampling Items
The 29 studies included clinical and field studies (e.g., Helsinki Airport, Mexican health center, German concerts, Colombian metro system, California school) with over 31,000 samples or direct scenting of humans.

The studies used an average of 6 dogs, male and female, ages 0.5 to 12 years.

In all, 19 different and mixed breeds were used, with Labrador Retrievers and Belgian Malinois the most common, having been involved in other scent detection work.

53 of the dogs had been previously trained for other detection work; 37 were untrained. The untrained dogs’ performances were generally comparable or slightly superior since they did not respond to scents other than COVID-19.

Dog training periods for the COVID-19 scent detection studies varied from 3 days to 7 months, with typical periods lasting a few weeks.

The types of samples used in these studies included sweat, saliva, urine, masks and clothes.

Comparisons with Accepted Tests
Scent dog results in the 29 studies were compared primarily with the real-time reverse-transcription polymerase chain reaction (RT-PCR) test (often labeled the “Gold Standard Test”) or the rapid antigen (RAG) lateral flow test. The RT-PCR test can detect lower COVID-19 viral load levels than the RAG test and has a higher specificity.

(Specificity is defined as the number of true negative results divided by the sum of the numbers of true and false negatives. Sensitivity is defined as the number of true positive results divided by the sum of the number of true positives and the number of false positives.)

The RT-PCR test is reported to have sensitivities ranging from 32% to 97% and specificities from 90% to 100%. RAG tests have shown sensitivities of 34% to 90% and specificities of 58% to 99%.

For comparison, 92.3% of the reviewed scent dog studies reached sensitivities exceeding 80%, and 32.0% of the studies exceeded specificities of 97%. However, 84.0% of the studies reported specificities above 90%, suggesting that scent dogs can yield results at least comparable to those of the RT-PCR and RAG tests.

Wrap Up

Based on their assessment of COVID scent dog studies, the researchers conclude:
-Handlers can safely use scent dogs to screen and test individuals who may be infected with the COVID-19 virus.
-The effectiveness of trained scent dogs is comparable to and in some cases superior to the RT-PCR test and the antigen RAG test.
-Trained scent dogs can provide quick (seconds to minutes), nonintrusive and accurate results in public settings.
-Scent dog research can serve to increase the medical community’s and public’s knowledge and acceptance of medical scent dogs as major contributors to global efforts to fight diseases.

Like me, you may find all that rather impressive. Thanks for stopping by. 

Training scent dogs: (A) three cup sniffing experiment with the first author’s Great Pyrenees, (B) one of second author’s COVID-19 scent dogs sniffing a test canister (from www.degruyter.com/document/doi/10.1515/jom-2023-0104/html).

Study of COVID scent dog research in Journal of Osteopathic Medicine: www.degruyter.com/document/doi/10.1515/jom-2023-0104/html
Article on study on EurekAlert! website: www.eurekalert.org/news-releases/998564
Earlier study of COVID scent dog research in Jou
rnal of Osteopathic Medicine: www.degruyter.com/document/doi/10.1515/jom-2020-0222/html

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