The notion of using dogs to sniff out undetected cases of cancer in humans has been around for a long time. If you can find a tumor early, there's a higher chance of removing it surgically and putting and end it to it before it spreads.
It hardly seems implausible. When I had non-Hodgkin's lymphoma in 1996, I developed such terrible bad breath that other people noticed something was wrong with me. Six rounds of chemotherapy later, my halitosis (along with my hair) was gone.
It's easy to find anecdotal evidence online from owners who swear Old Fido became agitated months before the oncologist discovered a tumor. That raises the question of whether dogs could be trained to notice cancer in strangers or if what they are noticing is changes in the smell of beloved owners.
From the NYT, a story about an organic chemist at the U. of Pennsylvania attempting to invent a mechanical bloodhound, as it were, to sniff out ovarian cancer, a particularly hard-to-detect cancer.
What Does Cancer Smell Like?
By VERONIQUE GREENWOOD
Cancer cells, though they don’t alter human metabolism overall, can have altered metabolisms themselves. That means the substances they release could differ from those generated by healthy cells. This idea has been around for decades, but only very recently have biochemical and sensor technology advanced to the point where we can develop portable, hand-held sniffing machines.
Electronic noses have the potential to detect even very small amounts of molecules — but they need to be programmed to look for specific signs wafting up from patient samples. ...
A work in progress, the electronic nose is, for now, an example of how modern medicine can look for answers in unusual places. The impetus that finally pushed Preti and his team to seriously investigate the possibility of cancer detection by smell traces its roots to a dog. In 1989, a letter published in The Lancet reported that a woman had come into the doctor’s office to have a mole looked at. She hadn’t noticed it until her collie-Doberman mix began to sniff the spot intently — even through her pants — and tried to bite it off when she wore shorts. The mole turned out to be an early-stage malignant melanoma, inspiring researchers to test whether dogs, whose smell machinery is at least 10,000 times as sensitive as ours, can tell healthy samples from cancerous ones.
The results from the dog tests have been inconclusive, but to Preti, who has mulled the idea that hidden cancers could be detected from smell molecules since the 1970s, they suggested that there was a real possibility for a new diagnostic. “We think that they’re present very early in the carcinoma process,” Preti said of the scents. “The main question is: Can we be as sensitive as the dogs in picking these things up?”
Here's an article about the three puppies (two Labradors and a Springer Spaniel) at Penn who are being trained to detect ovarian cancer to help calibrate the mechanical nose.
While I'm all in favor of robot noses catching up with dog noses, why not also try to breed dogs to get even better at cancer-sniffing than they already are? (We're talking about fighting cancer, after all. Dog breeding isn't all that cheap, but the idea of testing 100 dogs, finding the best male and female, mating them, and continuing on from there in the usual manner (lots of inbreeding) isn't all that expensive compared to the hundreds of billions invested in fighting cancer in other fashions.
Maybe there are reasons that wouldn't work. Perhaps all the possibilities in canine DNA have already been exploited.
But, mostly, the idea of breeding dogs for functional reasons doesn't seem to come up much these days. I read through a lot of public comments on the topic of cancer-sniffing dogs, and breeding just doesn't occur to people.
The general issue seems to be that people these days conceive of dog breeding in terms of looks rather than function. There are some dog breeders who make a fair amount of money breeding and training excellent gun dogs, but they are more in the business of brands than breeds.
Breeding today reflects the Spirit of the Age: Breed is only skin deep, you know. They're all the same on the inside. All that matters is looks.
I'm sure that livestock breeding continues apace to come up with cows that produce more milk and the like. But dog breeding has always been an amateur and semi-pro activity. Back in the Darwin-Galton age, it produced an unbelievable profusion of dogs for different functions. (Let me make clear that Darwin's and Galton's intellectual achievements were more the product of living in an age fascinated by the scientific breeding of animals than the progenitors of that age.)
It's an interesting example of how the zeitgeist can cripple a seemingly unrelated field.