Our canine companions continually remind us of their desire to serve and protect. Some do that as pets, but others make it their profession. Because of their keen sense of smell—which is up to 1,000 times more sensitive than human’s—dogs can be invaluable in searching for things undetectable to the human nose. “They toil daily on our behalf, snuffling out contraband, explosives and human bodies buried beneath tons of collapsed cement,” says Bill Benda, MD, who has written extensively about the healing power of animals. 

But science is showing us that these beloved animals have abilities that go beyond airport security and into the field of medicine: “They can also detect covert cancer cells, or predict a hypoglycemic event or epileptic convulsion,” Benda says. Which begs the question: Is it time to put a Lab in the lab?

The nose knows

Researchers at the Pine Street Foundation in San Anselmo, Calif., have performed several studies showing that dogs can detect cancer just by smelling a person’s breath. While this may sound fantastical, the proof is in the data. Michael McCulloch, PhD, and colleagues from Pine Street, a nonprofit cancer research and education organization, published a literature review on the subject in the May/June 2010 issue of the Journal of Veterinary Behavior and concluded that canine scent detection of exhaled breath was more accurate than urine analysis. Some of the cancers the dogs identified, such as lung cancer, are very hard to detect so McCulloch believes this could have important implications in the future.

“Work toward the development of an ‘electronic nose’ for cancer detection has been underway for several decades,” explained McCulloch and colleagues in an editorial published in the March 2012 issue of the European Respiratory Journal. “However, dogs still appear to be ahead in the race and seem to have sniffed their way to the front of the line.” 

A study in that same issue had dogs sniff the breath of 60 lung cancer patients, 110 healthy individuals and 50 patients with nonmalignant lung disease. Remarkably, the dogs were able to detect 99 percent of lung cancer cancer samples. They have similar success detecting colon cancer, according to a January 2011 paper in the journal Gut. And McCulloch and his colleagues published data in the journal Integrative Cancer Therapies showing that the dogs were successful in detecting 88 percent of breast cancer samples. McCulloch has a study underway involving the detection of ovarian cancer, which can be extremely difficult to detect early.

To put these high percentages into perspective, the National Cancer Institute says that mammography, an effective screening tool for breast cancer, only detects breast cancer 79 percent of the time. And the Pap test, the routine cervical cancer screening, only has about 51 percent sensitivity, according to an article in the February 2001 issue of the Journal of Family Practice.  

In an interview with Wellness Times, McCulloch explained that his studies used exhaled breath samples, which are provided by patients at a different location than where the dogs are trained. “The dogs and patients never actually meet during the study,” he said. “On the training and testing days, the dogs are allowed to sniff the samples but not touch them with their noses.” Based on this study design, he feels strongly that it is the dogs’ sense of smell, and not some other mechanism, that allows them to detect the cancer. 

Television host Mehmet Oz, MD, sees the promise of canine cancer detection. “If it gets inexpensive enough, maybe we’ll all have a breath analysis once a year to spot early, otherwise undetectable, disease,” he wrote in his Cleveland Clinic blog on June 11, 2012. 

The scent of a healer

It’s not just cancer that gets Fido’s attention. Mark Ruefenacht, a diabetic and volunteer puppy raiser for Guide Dogs for the Blind, Inc., believes dogs can be invaluable to type 1 diabetics as well. Ruefenacht, who is also the founder of Dogs4Diabetics Inc., says dogs can be trained to warn of changes in blood sugar before the situation becomes dire.

The reason, explains Ruefenacht, is that a chemical is released in the breath as blood sugar levels decline. If levels drop significantly in a short period of time, more of that chemical is emitted for the dog to detect. 

It’s also believed that people who are about to have a seizure emit a specific scent that dogs can detect. Roger Reep, PhD, of the University of Florida’s veterinary program, cites anecdotal evidence and a couple clinical studies showing that dogs can sense the onset of a seizure and alert others. While more research is needed, it’s likely that if there is such a thing as a “seizure odor,” dogs will be able to sniff it out. 

Cinematic canine icons like Lassie and Rin Tin Tin are metaphorically coming to life in a healthcare system desperate for heroes. Whether or not these “sniffer dogs” find careers in clinics or diagnostic labs is yet to be seen. Regardless of their medical contributions, it’s sure that they will continue to be man’s best friend—continuing to serve, protect and love their two-legged companions.