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Dogs Can Save Lives by Sniffing Out Human Cancers

Dogs Can Save Lives by Sniffing Out Human Cancers

Story at-a-glance -

  • A new study reveals dogs are able to accurately detect lung cancer, even at its early stages, with a high degree of accuracy.
  • In another study, dogs were able to detect lung and breast cancer with 90 percent accuracy.
  • Dogs have also been used to detect colon and bladder cancer, and blood sugar drops in insulin-dependent diabetics.
  • Dogs get cancer, too. In fact, your dog is more likely to die of cancer than you are.

By Dr. Becker

All dog owners know how keen the canine sense of smell is.

That's one of the reasons dogs make excellent partners for human search and rescue teams and law enforcement.

Dogs can be trained to locate disaster survivors, dead bodies, narcotics, undetonated bombs, people who've gone missing – pretty much anything that gives off a scent.

So it comes as no huge surprise to learn dogs are also able to detect lung cancer in humans with their noses.

Dogs Detected Lung Cancer in Breath Samples

According to a paper published recently in the European Respiratory Journal, a five-month study of four canine and 220 human subjects revealed the dogs were able to accurately detect lung cancer 71 percent of the time.

They were also able to rule it out 93 percent of the time.

The dogs were two German shepherds, an Australian shepherd and a Labrador retriever. The humans included a group of 110 in good health, 50 with chronic obstructive pulmonary disease (COPD), and 60 with lung cancer.

The dogs were able to distinguish the lung cancer breath samples not only from healthy breath samples, but also from COPD, tobacco and food odor breath samples.

Researchers definitively concluded there is a specific volatile organic compound (VOC) contained in the breath of lung cancer patients, and dogs are able to detect it at an early stage of the disease. A positive prognosis for lung cancer depends on early detection, and early detection has proved difficult. The presence of a stable marker for the disease – which this study indicates exists – could help researchers develop a diagnostic test to detect lung cancer early.

Before scientists can move forward using the results of this study, however, they must rule out the possibility the dogs were detecting a common chemical in the breath of lung cancer patients -- certain medications, for example.

What Are the Dogs Able to Smell, Exactly?

Chemists consider a dog's nose to be one of the most powerful olfactory 'medical devices' in the world.

Studies of dogs and cancer detection are based on the premise that cancer cells release different metabolic waste products than healthy cells. The differences are so significant dogs are able to detect them even in the early stages of disease.

In research conducted by the Pine Street Foundation, breath samples of 55 lung cancer patients, 31 breast cancer patients and 83 healthy people were presented to five trained scent dogs (three labs and two Portuguese Water Dogs). The dogs were able to detect or rule out lung and breast cancer, at all stages of the disease, with about 90 percent accuracy.

Not only that, they did it consistently through four months of research and over 12,000 separate scent trials.

These recruited animals were 'ordinary household dogs' with only basic behavior training who in a short three week period learned to accurately distinguish among breath samples of healthy subjects, lung cancer patients, and breast cancer patients.

According to

What is important about this study is that (1) ordinary dogs, with no prior scent discrimination training, could be rapidly trained to identify lung and breast cancer patients by smelling samples of their breath, when compared to blank unused sample tubes; (2) dogs could accurately and reliably distinguish breath samples of lung and breast cancer patients from those of healthy controls; and (3) the dog's diagnostic performance was not affected by disease stage of cancer patients, age, smoking, or most recently eaten meal among either cancer patients or controls.

Pine Street is currently conducting a study of ovarian cancer detection using dogs and breath samples. The goal is to distinguish patients with ovarian cancer from both healthy women and women with unrelated disorders like endometriosis or polycystic ovaries. Researchers also hope to use breath sample analysis to predict the probability ovarian cancer will recur after treatment, or be resistant to treatment.

Other Cancer Studies Using the Canine Sense of Smell

According to U.S. News and World Report, a black lab named Marine was able to detect colon cancer in a study of 200 humans with an incredible 97 percent accuracy rate. Marine was more accurate than routine fecal occult blood tests by about 25 percent. She was able to pick up early-stage disease and advanced malignancies.

Trained as a cancer sniffer in 2005, Marine has been able to detect 12 different types of cancer in breath samples.

Dogs can also be trained to detect bladder cancer in the urine of patients with the disease. A study published in 2004 showed dogs were able to detect the scent of bladder cancer with 41 percent accuracy. Watch dogs in training to detect human cancer.

Diabetes-Detecting Dogs

Dogs4Diabetics is a non-profit organization that provides medical alert dogs to insulin-dependent diabetics.

These dogs are trained to not only identify but also to act upon subtle scent changes created by hypoglycemia. These changes are undetectable to the people experiencing them.

According to

Low blood sugar causes stomach cramps, disorientation and a sweat, but after awhile the system gets accustomed to the lows and stops sending out danger signals. That's where the dog earns the right to sleep in the room with its owner. Everyone's different, but 3 a.m. seems to be the favored time for a crash.

The dogs alert their owners upon detecting the scent of a change in blood sugar level. If the owner is non-responsive, the dog is trained to go for help and lead the way back.

Dogs Get Cancer, Too

Our canine companions add so much to our lives, in an infinite number of ways. Wouldn't it be wonderful if we could return the favor by discovering why so many of them die so young of diseases like cancer?

In fact, our dogs are more likely to die of cancer than we are.

There are many organizations dedicated to canine cancer research, prevention and treatment, including:

"He is your friend, your partner, your defender, your dog. You are his life, his love, his leader. He will be yours, faithful and true, to the last beat of his heart. You owe it to him to be worthy of such devotion."

– Unknown