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Cancer-sniffing canines

 | June 4, 2012

Did you know that dogs could identify a unique odour or ‘odour signature’ associated with cancer?


A dog’s world exists in her nose. Being directly wired to her brain, her nose determines her sense of security and familiarity or fear and danger. That is what nature intended considering a newborn pup develops her sense of smell first before the senses of hearing and sight kick in weeks later.

While humans have in the region of five million olfactory cells in their noses, a dog has over 200 million. That’s pretty impressive. It also means that your pooch’s sense of smell is generally 10,000 to 100,000 times superior to yours.

While using dogs for hunting and tracking were commonplace before, in recent years dogs have made great strides in medical science with an increasing body of research supporting findings that dogs can detect when something is off with our bodies. This is because some diseases like cancer release odours that only a dog’s powerful sense of smell can pick up.

Way back in 1989, a certain Dr John Church sent a letter to The Lancet, describing in detail how a dog had recognised a lesion on her owner’s skin. The lesion turned out to be a malignant melanoma (skin cancer) and was subsequently treated with great success. Soon after, he met another patient with a similar story.

Fired by this coincidence, Dr Church gathered a team of doctors, dog trainers and scientists in 2003 to test this theory and in 2004 the team’s preliminary proof of study was completed.

This study became the first clinical trial to be completed and published in the world, proving without a doubt that dogs could identify a unique odour or ‘odour signature’ associated with cancer.

How is this so? Malignant tumors exude tiny amounts of chemicals called alkanes and benzene derivatives not present in healthy tissue. While the human nose cannot pick it up, our canine friends do it with relative ease.

More cancer studies

In a 2011 study, German researches found that highly trained dogs were able to consistently sniff out lung cancer in human breath. This was yet another medical breakthrough when one considers that lung cancer has few symptoms in the early stages, making it difficult for doctors to detect. Now trained dogs can detect lung cancer in its early stage while it is till treatable.

Supporting this study is another conducted in Japan where a Labrador Retriever succeeded in detecting early-stage colorectal cancer in patients. The dog was also able to discern polyps from malignancies, which even a colonoscopy cannot do.

Cancer aside, dogs have also made their mark in other areas. In recent years, they have been trained to sniff out explosives, drugs, bodies and other scents.

There is even a service in the US offering sniffer dog services to residential and commercial premises.

Should you have a teenage child you suspect to be on drugs, Sniff Dogs, the company that offers this confidential drug detection service will send one of their trained dogs to locate the odour of drugs like marijuana, cocaine, heroin, methamphetamine, Xanax or ecstasy in your home. This offers some peace of mind for parents and school authorities though none whatsoever for their drug taking kids.

So next time your dog takes off with her nose to the ground, you can be sure she’s sniffed out something pretty interesting, at least to her.

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