Using Trained Dogs to Detect COVID-19

Since the outbreak of the COVID-19 pandemic, students in the United States have faced interruptions to in-person learning. While the need for fast, effective screening is vital to minimizing the spread of infection and keeping schools open, traditional methods such as reverse transcription polymerase chain reaction (RT-PCR) and rapid antigen detection tests (RADT) are time consuming, expensive and invasive.

Leveraging donations to the Emergency Response Fund generously provided by our donors, the CDC Foundation partnered with the Association of Public Health Laboratories (APHL), Early Alert Canines and the California Department of Public Health to acquire and train two Labrador retrievers—Scarlett and Rizzo—to detect COVID-19 infections.

When a person is positive for COVID-19, they produce unique volatile organic compounds. To train the dogs to detect those compounds, Scarlett and Rizzo were presented with socks worn by previously tested COVID-19 infected individuals. Through a device called a scent wheel, both dogs were also presented with a multiple-choice scenario of scents that helped to desensitize them to non-target odors.

After Early Alert Canines completed the first phase of training, the dogs began visiting school sites in the San Francisco Bay Area. For each screening, students and staff lined up, typically outside, and the dogs were led by handlers to sniff the ankles and shoes of each participant. If the dogs detected COVID-19, they alerted their handlers by sitting down beside the suspected infected person. Those individuals were then tested with a rapid antigen test to verify the results of the dog screening.

In cases where a dog identified a person as positive, but the antigen test was negative, a follow-up PCR test was done the same day, or consecutive antigen tests were done over the following days to verify results.

“We’ve had a few instances where the dogs have indicated on somebody and that day their immediate antigen comes out negative, and within the following day or two you get a positive antigen or PCR confirmation,” said Alysia Santos, Scarlett’s handler. “It seems that we have been able to catch it earlier [with the dogs].”

Through the project, Early Alert Canines carried out 50 visits to 27 school sites, conducting 3,897 total screenings. Compared to rapid antigen testing, Scarlett was able to detect between 8 to 9 out of every 10 infections confirmed by antigen tests, while Rizzo detected 8 of every 10.

Having access to the detection dogs gave schools tremendous flexibility, particularly in special needs school programs where many students were unable to self-swab. The dogs allowed schools to have a positive and individualized interaction with these students while also receiving accurate test results.

“I could go on and on about the impact [the detection dogs] had on our programs,” said one representative from a special needs program that worked with the dogs. “Our students with disabilities asked questions and talked about it for days at school and, according to a partner, at home as well.”

In addition to being accurate in their detections, survey results showed dogs were more popular than traditional testing methods. “I have a deaf/blind student that participated in the program,” said one school parent. “She didn’t realize what was going on at the time of the test, but when Scarlett got to come up to her after and sniff her hand as she held it out, she got the biggest smile on her face. She loved the interaction.”

In all, 100 percent of schools who used the dogs responded that both children and parents were receptive to the program. All of the participating schools also asked to continue the dog screening process within their COVID-19 testing programs. The success of the project showed that dogs provide a faster and less-invasive testing capacity that requires less staffing and materials than traditional COVID-19 tests. Thanks to the performance of Scarlett and Rizzo, project partners are looking at ways to scale up the use of canines for disease testing and train them for future epidemiological events.