The dog's ignoring you -- that's fantastic!

I was lucky enough to write this story for Parade about detecting cancer by the sense of smell. It starts with dogs and moves on to technological nose equivalents. Check it out -- there's video.

The electronic and chemical noses researchers in this story are working on will do only a fraction of what a dog does -- they will look for a few biomarkers for a given disease.

While working on this story I talked to Jim Walker, a psychobiologist whose specialty is measuring the sense of smell. He's optimistic about the specialized devices researchers are working on, but overall, he says, "for many years the best we're going to be able to do is a dog."

"The dog is the best at chemometrics, taking a complicated chemical picture and making sense of it. That's why a dog can trail someone through the woods. Nobody thinks we have come close to a machine that can do that."

He's not just speaking anecdotally, since he's conducted careful laboratory research to learn just how small a wisp of amyl acetate a dog can smell. (The hard part of this research isn't getting dogs to show what they can do. It's precisely controlling the airborne concentrations of the chemical.) How small? One part per trillion.

That's why "the president doesn't get on the plane till the dog says it's okay."

Comments

[Fred Wickham]

That's fascinating stuff. A question (and I'm not being facetious), but can dogs be trained to detect diseases in other dogs? Or, what if a dog can detect a disease and then comes down with the same disease. Would he go crazy?

[Susan McCarthy]

Sure, dogs could be trained to detect diseases in other dogs. They probably detect some already. (Useful to know what shape your friends and rivals are in....)

Sometimes dogs that haven't been trained at all detect disease. In one famous -- but not unique case -- a family dog got so obsessed with a mole on a young woman's leg that after a few months she went to the doctor, who wasn't impressed but did a biopsy anyway. It turned out to be a malignant melanoma, very unusual in someone in their 20s. They took out a big chunk of that leg and saved her life. The dog was a Dalmatian, not a famed scent breed.

I don't think a dog that detected disease in itself would go crazy. Doctors who know they're sick don't act any crazier than other sick people, as far as I've heard.

Although, I once knew a bloodhound with a habit of licking his legs. Although he had a large ranch to rove, he spent hours sorrowfully licking his front legs. He had a "lick granuloma" on each one. So perhaps that was crazy: he'd licked until he had sores and now he obsessively licked the sores. Let's just say neurotic.

[Reva]

I will no longer mindlessly recycle Parade!