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Italian Scientists Train Dogs to Detect Presence or Absence of COVID-19 in Humans with Remarkable Accuracy

Dogs’ acute sense of smell can even surpass effectiveness of some clinical laboratory testing in detecting certain diseases in humans

When it comes to COVID-19 testing, a recent Italian study demonstrates that trained dogs can detect SARS-CoV-2 with accuracy comparable to rapid molecular tests used in clinical laboratories. The researchers wanted to determine if dogs could be more effective at screening people for COVID-19 at airports, schools, and other high-traffic environments as a way to detect the coronavirus and reduce the spread of this infectious disease.

Scientists at the State University of Milan in Italy conducted a study that shows dogs can be trained to accurately identify the presence of the COVID-19 infection from both biological samples and by simply smelling an individual. 

For their validation study, the Italian team trained three dogs named Nala, Otto, and Helix, “to detect the presence of SARS-CoV-2 in sweat samples from infected people. At the end of the training, the dogs achieved an average sensitivity of 93% and a specificity of 99%, showing a level of accuracy highly consistent with that of the RT-PCR [reverse transcription polymerase chain reaction] used in molecular tests and a moderate to strong reproducibility over time,” Nature reported.

RT-PCR tests are the current gold-standard for SARS-CoV-2 detection. This is yet another example of scientists training dogs to smell a disease with “acceptable” accuracy. This time for COVID-19.

The researchers published the results of their study in the journal Scientific Reports titled, “Sniffer Dogs Performance is Stable Over Time in Detecting COVID-19 Positive Samples and Agrees with the Rapid Antigen Test in the Field.” Their findings support the idea that biosensing canines could be used to help reduce the spread of the SARS-CoV-2 coronavirus in high-risk environments.

Frederica Pirrone, PhD

“We only recruited dogs that showed themselves predisposed and positively motivated to carry out this type of activity. One of the fundamental aspects was not to cause stress or anxiety in the subjects used,” Federica Pirrone, PhD (above), Associate Professor, Department of Veterinary Medicine and Animal Sciences, University of Milan, and one of the authors of the study told Lifegate. “Training always takes place using positive reinforcement of a food nature: whether it’s a particularly appetizing morsel, a biscuit, or something that associates the dog’s search with a rewarding prize.” In some instances, dogs have been shown to be as good or more effective at detecting certain diseases than clinical laboratory testing. (Photo copyright: Facebook.)

Dogs More Accurate than Rapid Antigen Testing

Nala and four other dogs (Nim, Hope, Iris and Chaos) were later trained by canine technicians from Medical Detection Dogs Italy (MDDI) to identify the existence of the SARS-CoV-2 virus by directly smelling people waiting in line in pharmacies to get a nasal swab to test for the coronavirus.

Working with their handlers, the five dogs accurately signaled the presence or absence of the virus with 89% sensitivity and 95% specificity. That rate is “well above the minimum required by the WHO [World Health Organization] for rapid swabs for SARS-CoV-2,” according to Nature.

“The results of studies published so far on the accuracy of canine smell in detecting the presence of SARS-CoV-2 in biological samples (e.g., saliva, sweat, urine, trachea-bronchial secretions) from infected people suggest that sniffer dogs might reach percentages of sensitivity and specificity comparable to, or perhaps even higher, than those of RT-PCR,” the scientists wrote in Scientific Reports.

“However, although most of these studies are of good quality, none of them provided scientific validation of canine scent detection, despite this being an important requirement in the chemical analysis practice. Therefore, further applied research in this field is absolutely justified to provide definitive validation of this biodetection method,” the researchers concluded.

Other Studies into Using Dogs for Detecting Disease

In a similar study published in the journal Frontiers in Medicine titled, “Dogs Detecting COVID-19 from Sweat and Saliva of Positive People: A Field Experience in Mexico,” researchers found that dogs could be trained to detect the presence or absence of the SARS-CoV-2 coronavirus from human sweat and saliva samples. 

Scientists from the Division of Biological and Health Sciences, Department of Agriculture and Livestock at the University of Sonora; and the Canine Training Center Obi-K19, both in Hermosillo, Mexico, conducted the study “as part of a Frontiers of Science Project of the National Council of Science and Technology (CONACYT), in which in addition to analyzing sweat compounds, trained dogs are put to sniff the samples and make detections in people who show symptoms or could be positive for coronavirus,” Mexico Daily Post reported.

The researchers trained four dogs with sweat samples and three dogs with saliva samples of COVID-19 positive patients. The samples were obtained from a health center located in Hermosillo, Sonora, in Mexico. The dogs were restricted to spend five minutes per patient and the researchers calculated the performance of the dogs by measuring sensitivity, specificity, and their 95% confidence intervals (CI).

The researchers concluded that all four of the dogs could detect COVID-19 from either sweat or saliva samples “with sensitivity and specificity rates significantly different from random [sampling] in the field.” According to the Frontiers in Medicine study, the researchers found their results promising because, they said, it is reasonable to expect the detection rate would improve with longer exposure to the samples.  

The objective of the Mexican researchers is for the dogs to ultimately reach the sensitivity range requested by WHO for the performance of an antigen test, which is at least 80% sensitivity and 97% specificity. If that goal is achieved, dogs could become important partners in the control of the COVID-19 pandemic, the scientists wrote. 

In “German Scientists Train Dogs to Detect the Presence of COVID-19 in Saliva Samples; Can a Canine’s Nose Be as Accurate as Clinical Laboratory Testing?Dark Daily reported on a pilot study conducted by researchers at the University of Veterinary Medicine Hannover (TiHo), the Hannover Medical School, and the University Medical Center Hamburg-Eppendorf involving eight specialized sniffer dogs from the Bundeswehr (German armed forces) to determine if the dogs could find people infected with the SARS-CoV-2 coronavirus. After only one week of training, the dogs were able to accurately detect the presence of the COVID-19 infection 94% of the time.

And in “New Study Shows Dogs Can be Trained to Sniff Out Presence of Prostate Cancer in Urine Samples,” we covered how scientists from Johns Hopkins University School of Medicine, University of Texas, Harvard Medical School, Massachusetts Institute of Technology (MIT), and others, had conducted a pilot study that demonstrated dogs could identify prostate samples containing cancer and discern between cancer positive and cancer negative samples.

Data obtained so far from these studies indicate that biosensing dogs may represent an effective method of screening for COVID-19 as well as other diseases. More studies and clinical trials are needed before the widespread use of dogs might become feasible. Nevertheless, scientists all over the world are finding that Man’s best friend can be a powerful ally in the fight against the spread of deadly diseases.

In the meantime, the gold standard in COVID-19 testing will continue to be the FDA-cleared assays used by clinical laboratories throughout the United States.

—JP Schlingman

Related Information:

Sniffer Dogs Performance is Stable Over Time in Detecting COVID-19 Positive Samples and Agrees with the Rapid Antigen Test in the Field

COVID: Goodbye Swabs, the Dogs Will Sniff It

There Are Dogs That Are Able to “Sniff Out” Diseases

Antigen-detection in the Diagnosis of SARS-CoV-2 Infection

Dogs Detecting COVID-19 from Sweat and Saliva of Positive People: A Field Experience in Mexico

German Scientists Train Dogs to Detect the Presence of COVID-19 in Saliva Samples; Can a Canine’s Nose Be as Accurate as Clinical Laboratory Testing?

New Study Shows Dogs Can Be Trained to Sniff Out Presence of Prostate Cancer in Urine Samples

New Study Shows Dogs Can be Trained to Sniff Out Presence of Prostate Cancer in Urine Samples

Determining how dogs do this may lead to biomarkers for new clinical laboratory diagnostics tests

Development of new diagnostic olfactory tools for prostate and other cancers is expected to result from research now being conducted by a consortium of researchers at different universities and institutes. To identify new biomarkers, these scientists are studying how dogs can detect the presence of prostate cancer by sniffing urine specimens.

Funded by a grant from the Prostate Cancer Foundation, the pilot study demonstrated that dogs could identify prostate samples containing cancer and discern between cancer positive and cancer negative samples.

This is not the only research study to focus on the ability of dogs to detect cancer and other health conditions. During the COVID-19 pandemic, dogs were used to spot people infected with the SARS-CoV-2 coronavirus. Dark Daily covered this in “German Scientists Train Dogs to Detect the Presence of COVID-19 in Saliva Samples; Can a Canine’s Nose Be as Accurate as Clinical Laboratory Testing?

The “end goal” of this latest pilot study is “to pave the way towards development of machine-based olfactory diagnostic tools that define and recapitulate what can be detected and accomplished now via canine olfaction,” according to a research paper published in the peer-reviewed journal PLOS ONE, titled, “Feasibility of Integrating Canine Olfaction with Chemical and Microbial Profiling of Urine to Detect Lethal Prostate Cancer.”

Research institutions, hospitals, and laboratories that participated in the pilot study included:

Canine Olfactory Combined with Artificial Intelligence Analysis Approach

The part of a canine brain that controls smell is 40 million times greater than that of humans. Some dog breeds have 300 to 350 million sensory receptors, compared to about five million in humans. With their keen sense of smell, dogs are proving to be vital resources in the detection of some diseases.

The pilot study examined how dogs could be trained to detect prostate cancer in human urine samples.

Claire Guest, CEO and Chief Scientific Officer of Medical Detection Dogs

Claire Guest, CEO and Chief Scientific Officer of UK-based Medical Detection Dogs and one of the study authors, is shown above with one of her cancer detecting dogs. In a Prostate Cancer Foundation article, she said, “Prostate cancer is not going to turn out to be a single note. What dogs are really good at discovering is a tune. Think of Beethoven’s Fifth Symphony, those first few notes. We suspect the cancer signature is something like that. It’s a pattern; the dogs are really good at recognizing the pattern. Machines that recognize the notes but can’t read the pattern are not reliable biomarkers,” she noted. The researchers believe the best solution for developing a clinical laboratory diagnostic that detects prostate cancer may be a combined approach using canine olfaction and AI neural networks. (Photo copyright: Janine Warwick/NPR.)

To perform the study, the researchers trained two dogs to sniff urine samples from men with high-grade prostate cancer and from men without the cancer. The two dogs used in the study were a four-year-old female Labrador Retriever named Florin, and a seven-year-old female wirehaired Hungarian Vizsla named Midas. The dogs were trained to respond to cancer-related chemicals, known as volatile organic compounds, or VOCs, the researchers added to the urine samples, and to not respond to the samples without the VOCs.

Both dogs performed well in their cancer detection roles, and both successfully identified five of seven urine samples from men with prostate cancer, correlating to a 71.4% accuracy rate. In addition, Florin correctly identified 16 of 21 non-aggressive or no cancer samples for an accuracy rate of 76.2% and Midas did the same with a 66.7% accuracy rate.

The researchers also applied gas chromatography-mass spectroscopy (GC-MS) analysis of volatile compounds and microbial species found in urine.

“We wondered if having the dogs detect the chemicals, combined with analysis by GC-MS, bacterial profiling, and an artificial intelligence (AI) neural network trained to emulate the canine cancer detection ability, could significantly improve the diagnosis of high-grade prostate cancer,” said Alan Partin, MD, PhD, Professor of Urology, Pathology and Oncology, Johns Hopkins University School of Medicine and one of the authors of the study, told Futurity.

The researchers determined that canine olfaction was able to distinguish between positive and negative prostate cancer in the samples, and the VOC and microbiota profiling analyses showed a qualitative difference between the two groups. The multisystem approach demonstrated a more sensitive and specific way of detecting the presence of prostate cancer than any of the methods used by themselves.

In their paper, the researchers concluded that “this study demonstrated feasibility and identified the challenges of a multiparametric approach as a first step towards creating a more effective, non-invasive early urine diagnostic method for the highly aggressive histology of prostate cancer.”

Can Man’s Best Friend be Trained to Detect Cancer and Save Lives?

Prostate cancer is the second leading cause of cancer deaths among men in the developed world. And, according to data from the National Cancer Institute, standard clinical laboratory blood tests, such as the prostate-specific antigen (PSA) test for early detection, sometimes miss the presence of cancer.

Establishing an accurate, non-invasive method of sensing the disease could help detect the disease sooner when it is more treatable and save lives.

The American Cancer Society estimates that there will be about 248,530 new cases of prostate cancer diagnosed in 2021 and that there will be approximately 34,130 deaths resulting from the disease during the same year.

Of course, more testing will be needed before Man’s best friend can be put to work detecting cancer in medical environments. But if canines can be trained to detect the disease early, and in a non-invasive way, more timely diagnosis and treatment could result in higher survival rates.

Meanwhile, as researchers identify the elements dogs use to detect cancer and other diseases, this knowledge can result in the creation of new biomarkers than can be used in clinical laboratory tests.

JP Schlingman

Related Information:

Feasibility of Integrating Canine Olfaction with Chemical and Microbial Profiling of Urine to Detect Lethal Prostate Cancer

German Scientists Train Dogs to Detect the Presence of COVID-19 in Saliva Samples; Can a Canine’s Nose Be as Accurate as Clinical Laboratory Testing?

Olfactory Sensations! Meet the Dogs Leading the Revolution in Prostate Cancer Detection (Part 1)

Olfactory Sensations Smell Like Cancer (Part 2)

Prostate Cancer-Detecting Dogs’ Olfactory Capacity Trains Neural Network for Combination Diagnostic Approach

Dogs Sniff Pee for Signs of Prostate Cancer

Thailand Researchers Train Labrador Retrievers to Detect COVID-19 in Human Sweat

University of East Anglia Researchers Develop Non-Invasive Prostate Cancer Urine Test

New Twist for Pathology Laboratories: Genetic Cancer Test for Dogs

OncoPet Diagnostics hopes to create revenue stream while testing human RECAF technology

Genetic cancer testing for dogs is now available. A clinical pathology laboratory in Canada performs the tests on specimens referred by veterinarians. The molecular diagnostics test for dogs uses a blood specimen and can detect 85% of canine cancers. Pre-market studies showed the standard 95% specificity level.

Owners of the 72 million pet dogs in the United States are often as anguished over possible cancer in their dogs as they would be over the possibility of cancer in a human loved one. That is why OncoPet Diagnostics of Richmond, British Columbia, believes the availability of a cheap ($40) cancer test will be welcome news. According to some surveys, about half of dog owners view their pets as members of the family.

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