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The Doctor Game: Dogs outsmart MDs in detecting cancers

Extraordinary skill at smelling disease

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What do dogs have that's lacking in humans? Harry Truman, the straight-talking former president of the United States, remarked that, "If you want a friend in Washington, get a dog." But friendship is not the dog's only virtue. A dog's nose has 220 million cells that detect odours, compared with a mere five million in humans. And although none has yet graduated from the Harvard Medical School, they can often outsmart doctors in recognizing serious disease.

In 1989 the British Journal Lancet reported a female half-border collie was indeed a woman's best friend. Her dog kept sniffing at a mole on her thigh, but ignored other moles. In fact, the dog had actually tried to bite off the mole when she was wearing shorts. The woman consulted her doctor, the mole was excised and the diagnosis confirmed a malignant melanoma.

Since 1989, increasing evidence suggests dogs can differentiate between normal skin cells and cancerous ones. For several years it's been known tumours exude small amounts of alkanes and benzene derivatives that are not present in healthy tissue. And that dogs can detect odours in parts per billion.

Dr. Larry Meyers, associate professor at the Auburn College of Veterinary Medicine in Auburn, Ala., has tested the smelling capabilities of more than 4,000 dogs for 20 years. He says a dog's sense of smell is so sensitive it can detect either a single chemical or a combination of them.

Meyers adds there's a mythology about bloodhounds tracking down criminals. But he has tested miniature poodles. He claims they could give bloodhounds a run for their money. And that even among the same breed there's an enormous variability in sensitivity to smell.

But are dogs smarter than doctors? In one study, tissue samples of melanomas were obtained from two research centres. A schnauzer was then trained to find a specific test tube containing malignant tissue. Then he was trained to discover a melanoma sample placed in one of 10 holes. The dog was right 99 per cent of the time.

So how do doctors rate in detecting malignant melanoma? A study showed dermatologists, surgeons and plastic surgeons were right only 66 per cent of the time! That's why I'm not being facetious when I say I'd rather have a well-trained dog sniff my mole than a Harvard graduate. A one per cent error appeals to me more than a 34 percent one. Particularly when a missed diagnosis could end my life.

But if a dog can detect melanoma, why not other cancers? A study published in the Journal of Integrative Cancer Therapies shows a dog's extraordinary scenting ability can distinguish between patients who have early- and late-stage lung and breast cancers.

The study was conducted by Dr. Michael McCulloch of the Pine Street Foundation in San Anselmo, Calif., and Tadeusz Jeziersk of the Polish Academy of Sciences, Institute of Genetics and Animal Breeding.

Five Labrador dogs and two Portuguese water dogs were borrowed from owners of guide dogs for the blind. It required only three weeks of training for them to diagnose lung and breast cancer.

The dogs were trained in the same way as if they were going to detect bombs. Researchers collected breath samples in plastic tubes from 55 patients who had been diagnosed with lung cancer, from 33 patients with breast malignancy and from 83 volunteers who were free of cancer.

The dogs identified the cancers by lying down in front of the test station. They were right 99 per cent of the time and received a treat for identifying the cancer. The report provides no mention of the treat. But if they diagnosed an early curable cancer, I'm sure grateful patients would order for them the best steak money could buy.

This accuracy is amazing when you consider current methods of diagnosis don't come close to matching it. Besides, dogs provide another major asset. They don't expose patients to radiation to make the diagnosis.

So sorry, doctor, I'd prefer to be referred to the dog.

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Republished from the Winnipeg Free Press print edition July 12, 2013 A19

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