Introduction
The COVID-19 pandemic has claimed over 6 million lives worldwide since 2020 (Source). The highly infectious nature of the SARS-CoV-2 virus made containing its spread difficult. As the world opens up again, there remains a need for accurate, non-invasive COVID-19 screening methods to prevent outbreaks. This is where training dogs to detect COVID-19 comes in. Dogs have a powerful sense of smell that can be leveraged to identify COVID-19 positive individuals.
Using dogs as a screening tool provides a rapid way to detect potential COVID-19 infections, without the need for invasive nasal swabs or lab tests. Their mobility allows them to screen large groups of people quickly. Dogs can also identify COVID-19 days before an infected person develops symptoms or tests positive on a nasal swab. This allows for early isolation and contact tracing to prevent outbreaks (Source). Overall, COVID-sniffing dogs are a promising complement to existing screening measures due to their speed, accuracy, and non-invasive nature.
Breeds Used
Certain dog breeds are well-suited for scent detection work due to their trainability, work ethic, and physical abilities. The breeds commonly used in COVID-19 detection include:
- Labrador Retrievers – Intelligent, eager to please, and have a great sense of smell. They are one of the most popular breeds used for detection work. https://www.medicaldetectiondogs.org.uk/covid-19-detection-dogs/meet-the-dogs/
- German Shepherds – Loyal, highly trainable, and physically able to work long hours. Their mix of trainability and work drive make them well-suited.
- Belgian Malinois – Energetic, focused workers that can quickly and accurately detect scents. Their athleticism also allows them to work in various environments.
- Cocker Spaniels – Friendly dogs with a keen sense of smell and a strong work ethic. Their smaller size can be beneficial in crowded areas.
- Beagles – Curious, gentle dogs often used for their scenting ability. Studies have shown Beagles can accurately detect COVID-19.
- Pit Bull Terriers – Tenacious workers that aim to please their handlers. Rescued pit bulls have successfully been trained for COVID detection. https://news.ucsb.edu/2023/021174/dogs-can-detect-covid-19-infections-faster-and-more-accurately-conventional-technology
The key is choosing motivated breeds with strong scenting abilities that can handle rigorous training. This allows them to accurately and efficiently screen for COVID-19 odors.
Odor Detection Process
Dogs have a remarkable sense of smell thanks to having around 300 million olfactory receptors in their noses, compared to only 6 million in humans (https://www.frontiersin.org/research-topics/5868/canine-olfactory-detection). This allows them to detect odors at concentrations up to 100 million times lower than humans can. When a dog inhales, air enters the nose and odor molecules bind to the olfactory receptors. The receptors then send signals to the olfactory bulb in the brain for processing and identification. Each odor has a unique pattern of receptor activation that the dog’s brain learns to recognize during training. This is how dogs are able to discriminate between COVID-19 positive and negative odors.
Collecting Samples
To train COVID-19 detection dogs, sweat samples need to be properly collected from confirmed COVID-19 patients. According to the Medical Detection Dogs organization, sweat samples are gathered by asking COVID-19 patients to wear absorbent cotton pads in their armpits for a period of time to allow sweat to accumulate (https://www.medicaldetectiondogs.org.uk/c-19-sample-collection/). The pads are then sealed in sterile jars and sent to the training facilities.
The sweat samples contain volatile organic compounds that are released through the sweat glands. Dogs can detect subtle differences in these compounds to identify COVID-19 positive samples (https://www.frontiersin.org/articles/10.3389/fmed.2022.1006315). Proper collection and storage of the sweat samples is crucial to preserve the volatile compounds for dog training.
Training Methods
The most common training method to teach dogs how to detect COVID-19 is through positive reinforcement and reward-based techniques. Dogs are social animals that thrive on interactions with their handler and positive feedback. When a dog correctly identifies a COVID-19 positive sample, they are immediately rewarded with toys, treats, praise, or play. This reinforces the desired detection behavior
According to dog trainer Craig Moore, “I utilize operant conditioning and positive reinforcement to shape detection behaviors in dogs. This reward-based training is the most effective way to develop accurate, enthusiastic working dogs.” (Moore) Dogs view training as a fun game where their correct responses earn them things they value.
Harsh corrections or punishment are never used, as they undermine trust between the handler and dog. The goal is to develop happy dogs that love searching and indicating on target odors. Proper detection dog training should emphasize the relationship between handler and dog and create a confident working team.
Accuracy Rates
Studies have shown that dogs can detect COVID-19 infections with remarkably high accuracy. In research conducted by the University of California, Los Angeles, specially trained dogs were able to identify COVID-19 infection from sweat samples with 97% accuracy. Study. Another study published in PLOS ONE found that across three different test settings, trained dogs correctly identified COVID-19 positive samples between 68.6% and 95.9% of the time. The dogs performed as well or better than RT-PCR tests in the field. Study.
Researchers at the University of California, Santa Barbara concluded that dogs can detect COVID-19 infections faster and more accurately than conventional diagnostic technologies. There is strong scientific consensus that dogs have an impressive capability to sniff out COVID-19 infections. Their detection accuracy either meets or exceeds the most widely used COVID-19 tests.
Real-World Application
Dogs have been utilized in airports and other transportation hubs as an additional screening measure for COVID-19. Teams of specially trained dogs were deployed to airports in Helsinki, Finland starting in September 2020 to sniff passenger samples for potential COVID-19 infections (https://www.uclahealth.org/news/specially-trained-dogs-can-sniff-out-covid-19-infection). The dogs screened travelers by smelling skin swabs taken from their necks, and could detect a COVID-19 infection in just 10 seconds with high accuracy. Similarly, COVID-19 detection dogs were used at the Helsinki-Vantaa Airport in Finland and at a major soccer match in Helsinki as a rapid screening measure (https://www.cdcfoundation.org/stories/project-uses-dogs-detect-covid-19). Using dogs as an initial screening step allowed potentially infected individuals to be identified quickly and referred for confirmatory lab testing. The success of COVID-sniffing dogs at these events demonstrates their practical real-world application as a supplemental screening tool, especially in high-traffic public places like airports, stadiums, and schools.
Limitations
There are several limitations with using dogs to detect COVID-19. One major limitation is that dogs cannot differentiate between COVID-19 strains. Although dogs can detect the presence of COVID-19 through odor detection, they cannot determine specifically which variant is present, such as Delta or Omicron (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8255683/). This makes it difficult to track the spread of new variants. Dogs can simply identify if COVID-19 is present, but not provide details on the exact strain (https://jamanetwork.com/journals/jamapediatrics/fullarticle/2804205). Additional testing would be required to determine the variant.
Future Research
While early research into dogs’ ability to detect COVID-19 shows promise, more rigorous studies are still needed. Some areas that require further research include:
– Testing detection accuracy in real-world settings: Initial studies have been limited to controlled lab environments using known positive and negative samples. It’s unclear if dogs can maintain the same accuracy when screening large numbers of people in busy spaces like airports or event venues.
– Evaluating the impact of asymptomatic and pre-symptomatic cases: Existing samples have come from people with active infections showing symptoms. It’s unknown if dogs can reliably detect COVID-19 in people not showing symptoms.
– Assessing dogs’ ability to differentiate COVID-19 from other respiratory diseases: Dogs appear able to identify COVID-19 odor signatures, but it’s uncertain if they can distinguish the virus from colds, flu, and other illnesses.
– Analyzing the shelf-life of samples: Additional research is needed on how the odor signature degrades over time and dogs’ accuracy with older samples.
– Standardizing training: There’s currently no consensus on the optimal way to train dogs for COVID-19 detection. More work is needed to determine best practices.
– Scaling up implementation: Moving from small studies to widespread, real-world screening brings challenges like maintaining training standards across different groups.
While dogs show potential for COVID-19 screening, more rigorous controlled studies are needed before considering wide-scale deployment. As research continues, a clearer picture will emerge of how dogs can reliably play a role in the pandemic response.
Conclusion
In summary, dogs can be trained to detect COVID-19 through their incredible sense of smell. By collecting novel coronavirus samples and using positive reinforcement training methods, dogs can learn to alert on COVID-19 odors. Certain breeds like Labrador retrievers and German shepherds are well-suited for this scent detection work. While the accuracy rates are still being refined, COVID-sniffing dogs show promise for real-world applications like medical screening. However, more research is needed to standardize training protocols and determine their full capabilities. The use of dogs for COVID-19 detection highlights their versatility in utilizing their exceptional olfactory abilities. Overall, these canine programs could provide a valuable new tool in managing the pandemic through rapid, non-invasive screening.