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September 27, 2004

BehindTheMedspeak: Can dogs detect bladder cancer in humans?

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It would appear so.

The British Medical Journal this week published the results of a study in which dogs - ordinary pets - were able to distinguish the urine of patients with bladder cancer from that of healthy people.

Doctors believe the animals detect the scent of the abnormal proteins present in the urine of the patients with cancer.

It's thought that a dog's sense of smell is 10,000 to 100,000 times better than a human's.

The idea that dogs may be able to smell cancer was first put forward in 1989 by two London dermatologists, who described the case of a woman asking for a mole to be cut out because her dog would constantly sniff at it, even through her pants, but ignore all her other moles.

One day, the dog, a female border collie-Doberman mix, tried to bite the mole off when the woman was wearing shorts.

The mole turned out to be malignant melanoma, caught early enough to save her life.

Here's the recent news, as reported last week by the BBC.
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Dogs 'sniff out' bladder cancer

There have been anecdotal reports of dogs spotting cancer in their owners, but now researchers say they have proved this phenomenon scientifically.

The scientists at Amersham Hospital, Buckinghamshire, ultimately hope to build a tool that is as good at discerning these smells as dogs' noses.

Their findings appear in the British Medical Journal.

In 1989, researchers wrote a letter to the Lancet medical journal about how a woman claimed to have sought medical help as a direct result of her dog's inordinate interest in a skin lesion that turned out to be skin cancer.

Similar anecdotal claims have been made about cancers of internal organs like the breast and lung.

Cancers are thought to produce distinctive odours.

Even when present in minute quantities, it is possible that dogs, with their exceptional sense of smell, might be able to detect these odours.

Dr. Carolyn Willis and colleagues conducted a carefully controlled experiment to see whether dogs could be trained to spot bladder cancer based on the odour of urine samples.

Over seven months, they trained six dogs of varying breeds and ages to discriminate between urine from patients with bladder cancer and urine from patients without bladder cancer.

On nine different occasions, each dog was offered a set of seven urine samples, of which only one came from a patient with bladder cancer.

Overall, the dogs correctly selected the bladder cancer urine on 22 out of 54 occasions.

This success rate of 41% was significantly more than the 14% that could be expected by chance alone.

Also, all of the dogs indicated one of the "bladder cancer free" samples as positive.

This patient had been investigated prior to the study and no tumour had been found.

The patient's doctor was sufficiently concerned by the dogs' behaviour to do further tests.

These revealed a tumour in the patient's right kidney which had escaped diagnosis by usual medical tests.

Lead researcher Dr. Willis said: "We are very excited because this is the first time this has been scientifically proven.

"Dogs have these fantastic olfactory abilities."

"They are recognising a signature smell of cancer which is very difficult to pick up by any chemical methods.

"They are not just detecting a single chemical.

"They were having to pick out smells for bladder cancer amongst the hundreds in urine and that's no mean feat."

The dogs' trainer Claire Guest said it was a bit like naming the ingredients of a soup.

"We looked at a whole range of dogs. The spaniels did the best... but we are still keeping an open mind as to what breed of dog might be best for the job."

The researchers hope to be able to identify the exact cocktail of chemicals the dogs were smelling.

Then they might be able to design a medical device to detect these signature odours and pick up cancers in patients.

They will also investigate whether dogs can detect other cancers in a similar way, starting with skin cancer.

Cancer Research UK's Professor David Neal said: "Using sniffer dogs to detect the minute traces of molecules associated with cancer is a fascinating concept.

"Many cancer patients do have abnormal proteins in their blood and urine.

"The dogs might be smelling proteins from inflammation rather than the tumour itself, although the researchers have tried to minimise this possibility."

He questioned whether it would be practical to use dogs to detect cancers in real life, but said it might be possible to develop other detection methods based on future research in this area.

September 27, 2004 at 06:01 AM | Permalink


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Comments

To the person wondering if they should get a checkup because their daughters dog threw a fit at her vaginal area; always go with your gut feeling...If you think you should get checked out...you should. If it turns out the dog is right, let me know and I will add your story to my research paper I'm writing about dogs' abilities in detecting cancer, seizures, and other health issues. k9s_r_mor_than_mans_best_friend@yahoo.com

Posted by: theverg | Mar 4, 2006 9:18:35 AM

It'll never fly with the HMOs. Leave it to socialized medicine...Wait a minute the thought just occurred to me there is money to be MADE! First, we breed a breed specific to the cancer and put restrictions and patents on said breed. Enact severe penalties for unlawful possession...mmm, I think we can get this to fit our present system quite nicely.

Posted by: ScienceChic | Jan 21, 2005 10:20:40 PM

my daughters dog on my entrance to the house kept smelling my vaginal area and barking and carrying on. There hadn't been any contact to the dog in several weeks and it is a female dog. do you think this could be something to look into. Linda Wilson

Posted by: Linda | Jan 21, 2005 9:45:27 PM

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