Dogs detect diseases

The brain of a dog is dominated by the olfactory cortex. Up to one-third of the canine brain is devoted to scent detection, and dogs have 220 million scent receptors, 200 million more than humans.

Of course I always knew dogs had an amazing sense of smell, but I learned even more about man’s best friend while watching an episode of “Blue Collar Dogs,” a new show on National Geographic Wild.

One segment of the episode (titled “Canine MD”) featured a company called Cancer and Bio-detection Dogs, which trains dogs to use their exceptional noses to identify human cancers. Several urine samples were held in a carousel, and the dogs were immediately able to identify which sample contained cancerous cells (in this case bladder cancer), and demonstrated so by sitting next to that particular sample. The program noted that dogs are especially good at detecting cancer in its early stages.

The hope is that this research will help in the development of a mechanical nose, a device that could sniff out cancer. The episode featured the appropriately named Touradj Solouki, Ph.D., and the work he is doing at his lab at the University of Maine.* Solouki uses an incredibly large machine to analyze the breath of cancer patients and separate the molecules by weight. However, the trick is learning what to look for in the samples. Dogs are able to do this, and Solouki is trying to replace that skill in the lab.

“Dogs come pretty close to something that can be a biological sensor,” Solouki said. “They are not only very sensitive to chemicals, but they are also smart enough that they can analyze the signals they are getting.” Solouki’s goal is to determine the biomarkers of cancer within the samples. Dogs are either noticing something that is or isn’t there, or recognizing a variation in the molecular pattern.

dog noseUp close and personal with some of those 220 million scent receptors. (Credit: Piotr Grzywocz)

The Cancer and Bio-detection dogs are trained, but the average pet canine has shown the ability to detect cancer and other illnesses in their owners in some cases. The episode included a dog that sniffed breast cancer in its owner, and another that alerts its diabetic owner before she has a hypoglycemia crash. Other dogs have been known to alert epileptic owners moments before they have a seizure.

On “Blue Collar Dogs,” a young woman with dystonia, a neuromuscular disorder that causes muscles to contract and spasm involuntarily, was able to better function on a daily basis because of a black Labrador from Canine Companions for Independence. The dog helps pull her wheelchair, picks up items she has dropped, and opens doors for her using a rope.

Dogs will continue to use their powerful noses—albeit in mysterious ways—to detect changes in the human body, and many will effectively communicate their findings with their owners. I hope one day scientists will be able to pinpoint this ability and develop portable devices that can replicate it.

*What, you’ve never heard of a saluki?

–Andrew Kahn

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