Peer-reviewed studies and systematic reviews report that trained dogs can detect human cancer by scent in biological samples such as urine and breath, though secondary evaluations caution that methodological variability and the need for standardized, double-blind replication leave the clinical validity debated.
Abstract Background: Remote medical scent detection of cancer and infectious diseases with dogs and rats has been an increasing field of research these last 20 years. If validated, the possibility of implementing such a technique in the clinic raises many hopes. This systematic review was performed to determine the evidence and performance of such methods and assess their potential relevance in the clinic.Methods: Pubmed and Web of Science databases were independently searched based on PRISMA standards. We included studies aiming at detecting cancers and infectious diseases affecting humans with dogs or rats. We excluded studies using other animals, studies aiming to detect agricultural diseases, diseases affecting animals, and others such as diabetes and neurodegenerative diseases. Only original articles were included. Data about patients’ selection, samples, animal characteristics, animal training and testing configurations, and performances were recorded.Results: A total of 62 studies were included. Sensitivity and specificity varied a lot among studies: While some publications report low sensitivities of 17% and specificities around 29%, others achieve rates of 100% sensitivity and specificity. Only 6 studies were evaluated in a double-blind screening like situation. In general, the risk of performance bias was high in most evaluated studies, and the quality of the evidence found was low.Conclusions: Medical detection using animals’ sense of smell lacks evidence and performances so far to be applied in the clinic. What odours the animals detect is not well understood. Further research should be conducted, focusing on patient selection, samples (choice of materials, standardization), and testing conditions. Interpolations of such results to free running detection (direct contact with humans) should be taken with extreme caution.
Canine cancer detection is an approach to cancer screening that relies upon the claimed olfactory ability of dogs to detect, in urine or in breath, very
Canine cancer detection is an approach to cancer screening that relies upon the claimed olfactory ability of dogs to detect, in urine or in breath, very low concentrations of the alkanes and aromatic compounds generated by malignant tumors. While some research has been promising, no verified studies by secondary research groups have substantiated the validity of positive, conclusive results.
While anecdotes abound, there is scant literature to support this ability. One unimpressive pilot study looked at dogs’ potential ability to detect bladder cancers from urine samples. The idea behind cancer dogs is that there may be volatile compounds produced in cancer patients that dogs can detect by scent. In these studies, the compounds are not identified, not tested for, not named. There are many confounders, for example, in the few samples used, there may be other differences being detected by the dogs.
In the other study (I found very few) dogs were “trained” to detect lung and breast cancers in humans. The methodology of breath sampling is not validated as far as I can see, and once again, the putative compounds in breath are not identified. Statistically, the efficacy is marginal at best… I don’t doubt the social and emotional value of dogs as companions, and as active helpers in many circumstances. But beyond this, the evidence is wanting.
Several researches have evidenced that cancer cells can produce volatile organic compounds (VOCs) which are released not only in breath but also in other organic fluids, such as blood and urine. This study has evaluated the olfactory capability of trained dogs to detect human lung cancer VOCs in urine. We recruited 150 subjects from European Institute of Oncology (IEO) divided into three groups: 57 patients with lung cancer (group 1); 38 patients with lung disease, other than cancer (group 2); 55 healthy control subjects (group 3).The results are referred to the last 45 days of training, and evidenced that dogs reached a mean success rate that exceeded 80%, with a sensitivity of 0,72 and a specificity of 0,94 for two out of three dogs enrolled. The important novelty is that dogs can discriminate lung cancer not only from healthy subjects, but also from patients with other lung diseases. The results obtained so far are encouraging and lead us to persevere with the training session in order to improve the success rate, reaching values as close as possible to 100%. If so, we believe that, in the future, dogs may be used to perform early diagnostic tests, useful in improving the chances of survival in cases of human lung cancer.
Several researches have evidenced that cancer cells can produce volatile organic compounds (VOCs) which are released not only in breath but also in other organic fluids, such as blood and urine. This study has evaluated the olfactory capability of trained dogs to detect human lung cancer VOCs in urine. We recruited 150 subjects from European Institute of Oncology (IEO) divided into three groups: 57 patients with lung cancer (group 1); 38 patients with lung disease, other than cancer (group 2); 55 healthy control subjects (group 3).The results are referred to the last 45 days of training, and evidenced that dogs reached a mean success rate that exceeded 80%, with a sensitivity of 0,72 and a specificity of 0,94 for two out of three dogs enrolled. The important novelty is that dogs can discriminate lung cancer not only from healthy subjects, but also from patients with other lung diseases. The results obtained so far are encouraging and lead us to persevere with the training session in order to improve the success rate, reaching values as close as possible to 100%. If so, we believe that, in the future, dogs may be used to perform early diagnostic tests, useful in improving the chances of survival in cases of human lung cancer.
<h4>Background</h4>In 2004, researchers in the United Kingdom were able to train six dogs to distinguish between urine samples from bladder cancer patients and healthy controls using smell, achieving a detection rate of 41% (95% confidence interval [CI]: 23-58%), far above the 14% expected by chance. After numerous subsequent studies validated that the odor of breath and urine samples could be used by dogs to detect cancer, researchers pivoted to electronic noses (eNoses), sensor-based systems that mimic the sense of smell using arrays of chemical detectors. In this study, we review the potential efficacy of eNoses in the detection of selected cancer types in human biological samples.<h4>Methods</h4>We identified and performed a meta-analysis on 37 studies of eNose technology, comprising 1 365 cancer patients and 2 249 control subjects. We calculated the pooled sensitivity and specificity stratified by cancer type, sample type, and sensor type. Meta-regressions were conducted on these variables as well as the number of sensors used in the sensor array.<h4>Results</h4>All six cancer types analyzed-breast, colorectal, gastric, lung, ovarian, and prostate-achieved pooled sensitivities and specificities above 70%, with most around 85%. The overall pooled sensitivity was 85.9% (95% CI: 82.3-88.9%) and specificity was 83.6% (95% CI: 78.6-87.7%). Meta-regression revealed that the number of sensors in the sensor arrays, up to 15 sensors, was predictive of sensitivity with PFDR < 0.001.<h4>Conclusion</h4>This analysis found that eNoses constitute a promising tool in the early detection of cancer. However, more research is necessary before it can be introduced into clinical settings.
Dogs' abilities to respond to concentrations of odorant molecules are generally deemed superior to electronic sensors. This sensitivity has been used traditionally in many areas; but is a more recent innovation within the medical field. As a bio-detection sensor for human diseases such as cancer and infections, dogs often need to detect volatile organic compounds in bodily fluids such as urine and blood. Although the limits of olfactory sensitivity in dogs have been studied since the 1960s, there is a gap in our knowledge concerning these limits in relation to the concentration of odorants presented in a fluid phase. Therefore, the aim of this study was to estimate olfactory detection thresholds to an inert substance, amyl acetate presented in a liquid phase. Ten dogs were trained in a “Go/No go” single scent-detection task using an eight-choice carousel apparatus. They were trained to respond to the presence of solutions of amyl acetate diluted to varying degrees in mineral oil by sitting in front of the positive sample, and not responding to the 7 other control samples. Training and testing took place in an indoor room with the same handler throughout using a food reward. After 30 weeks of training, using a forward chaining technique, dogs were tested for their sensitivity. The handler did not assist the dog during the search and was blind to the concentration of amyl acetate tested and the position of the target in the carousel. The global olfactory threshold trend for eac
A review of literature published between January and July 2013 was undertaken to explore the findings relating to the viability of the use of dogs to detect the presence of cancer in human subjects. It was found that a significant percentage of the dogs used in the studies could successfully detect the presence of cancer biomarkers in urine or exhaled breath. The review explores and discusses the methodology of training the dogs, the viability of the cancer research, ethics and the types of cancer that dogs are being trained to detect.
demonstrating that dogs can effectively detect low densities of invasive plants. Detection dogs are able to discern individual scents even when the scents are combined
A detection dog or sniffer dog is a dog that is trained to use its senses to detect substances such as explosives, illegal drugs, wildlife scat, semen, currency, blood, and contraband electronics, such as illicit mobile phones. The sense most used by detection dogs is smell. Hunting dogs that search for game, and search and rescue dogs that work to find missing humans are generally not considered
Bed bugs
Cancer
Currency (e.g. large amounts of money carried by passengers in airports that should be declared to customs)
Drugs
Endangered animal species (e.g., black-footed ferret)
Explosives
Fire accelerants (e.g., arson investigation)
Firearms
Gourmet fungi, such as truffles (e.g. French black truffle (Tuber melanosporum), Italian white truffle (Tuber magnatum), chanterelles (Cantharellus cibarius), porcini (Boletus edulis), morels (Morchella esculenta), and other varieties of mushroom.
Human remains
Invasive species (e.g., quagga mussel)
Ivory
Mineral desposits
Mobile phones (e.g. as contraband in prisons)
Mold
Plants, animals, produce, and agricultural items that have to go through customs
SIM cards
Termites
Diabetes
USB drives
Wildlife scat
Sniffer dogs can be trained to locate small infestations of invasive and non-native weeds. The world's first spotted knapweed canine detection program successfully completed field-testing for Montana State University in 2004. Upon completion of the testing, Knapweed Nightmare was finding low densities of non-native invasive knapweed rosettes in the field with a 93% overall success rate. She followed it up with 98% in the final trials in open fields, demonstrating that…
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