Can Dogs Smell Cancer In Humans?

Dogs have an amazing sense of smell. They can smell pheromones and low blood sugar. They can smell things that are buried 40 feet underground.

Because of these extraordinary olfactory abilities, you may have also heard some people say that dogs can even sniff out cancer. But is this true?

There's good news! Dogs really can be trained to sniff out cancer.

Texture on a dog's nose
credit: Bojanikus/iStock/GettyImages

Dogs have noses designed to smell diseases such as cancer.

Dogs have somewhere in the neighborhood of 220 million sensors in their noses, compared to a pathetic 5 million in humans. Their high number of sensors, plus a special organ called the Jacobson's organ, allow dogs to smell things that we humans could never imagine smelling.

Cancer has a scent that dogs can smell.

And it seems that cancer does, indeed, have a scent. That's why places like the Penn Vet Working Dog Center are training dogs to detect cancer (as well as many other things). Their video of Ohlin, a 17-month-old chocolate Labrador, is both adorable and fascinating. In the video, Ohlin sniffs metal "cages" on a large wheel, occasionally pausing to sit and paw at one of them. Each time he does this, Ohlin gets a treat and verbal praise from his handler. That's because the cages contain human plasma, and Ohlin is sniffing out cancer. (As you can tell from the number of times he receives praise, Ohlin is doing a great job.)

Ohlin is part of a study to find out how dogs can detect ovarian cancer, which is notoriously hard to diagnose. This study is based around the hypothesis that cancerous cells emit gasses and compounds with distinct smells. Dogs, of course, are the perfect candidates to sniff out such smells.

Dogs can smell a variety of cancers.

So far, dogs have proven to be quite accurate in their attempts to sniff out cancer. Lucy, a dog in the UK who has been trained to detect kidney, bladder, and prostate cancer, has correctly detected cancer over 95 percent of the time. That's a higher rate of accuracy than some lab tests.

For logistical reasons, dogs are not currently used to screen people for cancer. However, they can be extremely helpful in our quest to develop tools to do so. Plus, a dog sniffing you is much less invasive (and cuter) than most other lab tests. This fact, coupled with accuracy rates like Lucy's, means that dogs are a promising resource in the cancer detection process.

Dog looks at stethoscope .
credit: Natali_Mis/iStock/GettyImages