Man’s best friend just got a whole lot friendlier. Studies show that specially trained dogs are four times better than traditional testing methods when it comes to detecting prostate cancer cells in urine samples.1 A British charity called Medical Detection Dogs trains the friendly canines to identify the disease using their highly developed sense of smell. They have enjoyed tremendous success with the program, boasting a 90 percent accuracy rate.2 That figure flies in the face of traditional lab detection methods that are known to produce false positives, often requiring patients to undergo unnecessary invasive procedures. As students entering into medical careers, it is important to stay abreast of the latest developments in cancer testing and research.

Current Prostate Cancer Detection Test is Unreliable

The current standard test for prostate cancer is called the prostate specific antigen test. It measures the amount of a certain prostate-produced protein a patient has in their blood.3 High levels of this protein could indicate the presence of prostate cancer. However, there are many different reasons that a man could have elevated PSA levels that aren’t cancer. As a result, the test produces a false positive 75 percent of the time.2 Such a high frequency of false positives points to the need for a new, more reliable test.

Dogs Can Smell Cancer CellsDogs are the best test for prostate cancer.

Since the increased presence of the PSA protein can have several causes, researchers have begun looking for a more reliable biological structure to measure. The elements that scientists use to flag the existence of diseases such as cancer are called biomarkers, and it looks as though a new one has been found. Our sense of smell works by detecting the presence of volatile organic compounds (VOCs) in the air through our olfactory receptors. The human nose has about 5 million of these receptors while a dog has over 220 million.4 With such a large number of additional receptors, dogs are able to detect a number of VOCs that are imperceptible to the human nose. It appears as though cancer cells may have a specific VOC that dogs can detect with their powerful noses. This is the conclusion of a study conducted by the European Association of Urology titled “Olfactory Detection of Prostate Cancer by Dogs Sniffing Urine: A Step Forward in Early Diagnosis.”2

The results from these preliminary tests have been very reassuring for cancer researchers. Early detection is one of the best ways of developing a successful treatment when it comes to cancer. In order to promote early detection efforts, the group Medical Care Dogs has developed a way to train dogs to detect cancer cells by smell. These dogs are being used in tests to diagnose cancer patients with early-stage cancer. The dogs are able to smell a urine sample and determine whether it contains prostate cancer cells nine out of 10 times.5 This success rate is much higher than that of the existing PSA test and therefore presents an exciting opportunity for doctors and patients alike.

Applying the Test to Other Kinds of  Cancer

While prostate cancer cells have been the main area of focus, there are many other types of cancer. There have, however, been indications that dogs can detect other types of cancer cells as well. Preliminary research indicates that dogs can be trained to detect breast cancer cells in the breath samples of patients.6 Unfortunately, these findings are the results of very early testing, and much more study is necessary before any definitive results can be claimed. Medical Detection Dogs is currently in the process of acquiring the requisite funding to develop a proper scientific inquiry into whether or not dogs can be used as a viable breast cancer detection tool.

In addition, dogs are often trained to smell the blood sugar levels of diabetes patients. They can alert their owners whenever their blood sugar levels are getting too high or too low. The best part is, these blood sugar-detection dogs are “always on,” that is, no regular testing is required – they can detect your blood sugar just by smelling you.

Using Animals to Test for Disease

Using the highly developed sensory organs of different animals is not an unusual medical screening method. In Tanzania, an organization known as APOPO trains rats to detect tuberculosis in human patients.7 These rats are able to smell the TB bacteria in human mucus samples, thus providing one of the cheapest and most reliable tests on the market. As more animals are used in the early detection and diagnosis of various diseases, it is hoped that medical researchers will be able to learn more about how these ailments affect the body and why. This will lead to more reliable testing practices, making the jobs of those with medical careers easier and more fulfilling.

1 “Dogs are FOUR times better at detecting prostate cancer than traditional tests,” Emma Innes, The Daily Mail,

2 “Olfactory Detection of Prostate Cancer By Dogs Sniffing Urine: A Step Forward in Early Diagnosis,” Jean-Nicolas Cornu, et al., European Urology,

3 “Prostate-Specific Antigen (PSA) Test,” National Cancer Institute Fact Sheet, National Cancer Institute at the National Institute of Health,

4 “The Dog’s Sense of Smell,” Alabama Cooperative Extension System, Alabama A&M and Auburn Universities,

5 “Prostate Cancer Study,” Medical Detection Dogs,

6 “Breast Cancer Study,” Medical Detection Dogs,

7 “Tuberculosis Detection,” APOPO,