Study shows that all dogs know exactly one trick

The latest installment on my trip down Science Friday lane, a segment from February 2011: Can Dogs Smell Cancer? My initial reaction was that this seems like something new and exciting — you can teach (old?) dogs new tricks:

Researchers in Japan say they have trained a Labrador retriever to sniff out cancer in people. Writing in the journal Gut, the scientists say the dog was better than conventional tests in identifying people with colorectal cancer.

The dog, named Marine, sniffed the breath and the stool samples of more than 300 people and had a whopping 98 percent accuracy rate, picking out the 40 people in that group who actually had cancer.

98% is pretty good, so I was curious to find out how far the field of study had advanced over the intervening two and a half years. But the only development I could turn up was a piece that appeared in this past May’s Penn Current, Penn researchers use dogs to detect ovarian cancer. The article started off with some helpful background:

When it comes to the sense of smell, dogs far surpass the capacity of human beings. Humans sniff out odors using about 350 different olfactory receptors, but canines utilize more than 1,000 to inhale a world jam-packed with smells, including the volatile organic compounds or odorants altered in the earliest stages of ovarian cancer.

But as I kept reading, I quickly discovered that in spite of the article’s title, dogs cannot yet detect ovarian cancer. Unlike the Japanese dogs discussed on Science Friday — who actually could detect one kind of cancer — the Penn lab’s detection ability is, for now, merely aspirational [bolded for emphasis]:

The ability to smell cancer is seldom used by doctors. But, combined with chemical and nanotechnology methods, Penn researchers hope to use dogs to develop a new system of early cancer screening that could save lives.

For this study, [scientists] will analyze tissue and blood samples from ovarian cancer patients. They will look for the chemical signature of the odorants from the patients, and check them against the volatile compounds emitted by healthy samples to confirm that they differ.

Currently, doctors use expensive diagnostic tools to detect ovarian cancer, instruments that still fail to find the cancer until it has reached an advanced stage. Tanyi says more than 70 percent of ovarian cancer cases are diagnosed in Stage 3.

If we could make a new screening method, it would be much easier to detect early stage cancer, and early stage treatment is much more effective,” he says.

It would seem that in two and a half years, science has progressed hardly at all. One day, dogs will be trained to sniff ovarian cancer — but we’re not there yet.

And while that might seem disappointing, it shouldn’t be all that surprising. After all, the original findings from Japan don’t seem so impressive in hindsight [pun intended, and will make sense momentarily]. Sure, the study found that dogs can detect colorectal cancer — but sniffing bottoms is the same trick they’ve been perfecting over the last 30,000 years of doggie evolution:



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