The Nose Knows – Doggie Howser May Save Your Life
- Created on Thursday, 13 September 2012 11:49
- Written by Maria Tadd
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Dogs are born to sniff. Their noses dominate not only their faces but also their brains. Their ability to find deer poop in minutes, if not seconds, never ceases to amaze me! When it comes to their sense of smell, they win hands down as their sniffers are generally 10,000-100,000 times superior to that of humans. We have roughly five million olfactory cells in our noses which seem like a lot but that pales in comparison with the 200 million cells in a typical dog’s nose.
Anyone who has owned a dog knows that a dog is indeed man’s best friend. Loyal and trainable they have served as service dogs aiding people with disabilities, notifiying and protecting its human before the onset of a seizure, helping autistic children attend school, rescuing earthquake survivors, detecting IUDs, uncovering drugs at airports and seaports, and the list goes on.
However over the past several years, their keen ability to smell has given them yet another distinction – yes, they can smell diseases, particularly cancer. Initially, there were just anecdotal stories of dogs saving their owners’ lives - the lady with a lump on her leg that her Pomeranian wouldn’t stop smelling or the woman whose King Charles Cavalier kept smelling her breast and tucking his face into her armpit. As these dogs became more persistent, the owners eventually sought medical advice and learned that their dogs indeed were right.
How do they do it? What do they smell?
It turns out that malignant tumors exude tiny amounts of chemicals called alkanes and benzene derivatives not present in healthy tissue. If a dog can identify chemical traces in the range of parts per trillion, is it really crazy to think they can detect cancer, even before people know they’re sick?
This sharpened sense of smell in canines is exciting. And now the proof is finally here as study after study is proving that dogs can indeed detect cancer.
The latest study, done by German researchers in August, showed that dogs are able to detect early-stage lung cancer better than any doctor or any fancy medical equipment. The study was conducted at Schillerhoehe Hospital in Germany with four specially-trained dogs: Two German shepherds, a Labrador retriever and an Australian shepherd. Each dog was given a test tube to sniff that contained the breath of 220 patients, some of whom had lung cancer and some of whom were cancer-free.
Out of 400 samples, the dogs were able to correctly identify the 71 out of 100 patients with lung cancer as well as 372 out of 400 samples that were cancer free. In addition, the dogs could distinguish between lung cancer and other lung problems such as chronic obstructive pulmonary disease (COPD), as well as sniffing accurately through the breath of patients that just smoked a cigarette.
What are they smelling? We know that cancer of the lungs causes cells to release specific volatile organic compounds, emitted as they undergo mutations caused by tumors. Furthermore, these early-stage emissions, while undetectable by medical tests or current diagnostic technology, can indeed be identified by Doggie Howser.
Lung cancer is the leading cause of cancer deaths in the US, killing more people than prostate, breast, ovarian, lymph and colon cancers combined. As with most cancers, early detection of lung cancer can have a much better outcome and could potentially save around 200,000 lives each year. And it is not just lung cancer that canines can detect. Studies are showing promise in the detection of other cancers such as breast, bowel, and colon as well as Type 1 Diabetes.
Other studies – Dogs are more accurate than machines
The first scientific test of canine cancer-detecting, seems to have been in 2004. Researchers at the Sensory Research Institute at Florida State University trained two dogs to detect melanoma tissue samples hidden on the skin of healthy volunteers. The dogs were trained and tested with methods typically used for forensic bomb- or drug-sniffing dogs. One dog “confirmed” the presence of melanoma on five patients, and even detected cancer in a sample that was initially found to be negative, but subsequent tests revealed melanoma in a fraction of the cells.
A 2006 study by the Pine Street Foundation, a cancer research organization in San Anselmo, California, used more dogs and samples for even more impressive results. The researchers selected three Labrador retrievers and two Portuguese water dogs with no prior training. Lung and breast cancer patients breathed into tubes which captured samples of their breath. The dogs then underwent several weeks of training with the samples. For testing, the researchers used a new batch of breath samples. The dogs correctly detected 99 percent of the lung cancer samples, and made a mistake with only 1 percent of the healthy controls. With breast cancer, the dogs identified positive samples 88 percent of the time with no false positives. The dogs performed as well as the most recent screening tests for the diseases. It is important to note that all the tests were double-blind, meaning neither the dog handlers nor the experimenters knew which samples were which. By the scent of breath samples alone, the dogs identified 55 lung and 31 breast cancer patients as well as 83 healthy people.
“In a 2011 study from Japan, a Labrador retriever trained to sniff out colorectal cancer was at least 95 percent as accurate as a colonoscopy when smelling breath samples and 98 percent correct with stool samples. The dog was especially effective at detecting early-stage cancer and could also discern polyps from malignancies, which a colonoscopy cannot do.”
Studies like these are fascinating for what they tell us about dogs’ keen sense of smell, but medical professionals also see practical and technological implications. Dogs’ noses are inspiring scientists to create an artificial sniffer with similar acuity for quick and easy use in hospital laboratories — this involves precisely identifying the compounds dogs are picking up on in the samples from cancer patients. For some diseases, like prostate cancer, the blood tests currently used are notoriously inaccurate. Could man’s best friend become a tool in early screening?
Whether actual dogs will be making future diagnoses is uncertain, but it is clear they possess a pretty powerful tool we are only beginning to understand and appreciate.
OK, what about cats?
Not known for their olfactory acuity, there is one documented story of a cat named Oscar who has an uncanny ability to determine who is going to die at the Nursing Home where he was adopted as a kitten. The nursing home which specializes in caring for patients with severe dementia has five other cats, but only Oscar has this “gift”.
Apparently, Oscar is generally an unsociable critter, but he knows who has just hours to live. He spends his days pacing from room to room, rarely spending any time with patients except those who are on the brink of death. If kept outside the room of a dying patient, he will scratch on the door trying to get in.
When nurses once placed him on the bed of a patient they thought was close to death, he "charged out" and went to sit beside someone in another room. And as usual he was right - the second patient died that evening, while the first lived for two more days. How does he know? Perhaps like dogs who can smell cancer, Oscar can smell the ketones that are given off by dying cells. Families find great comfort in knowing that their loved ones never die alone.
Since dogs are so accurate in detecting cancer, perhaps they should replace some of the current diagnostic devices – let’s face it, how much could insurance companies charge for a Canine Sniff Test? CAT scan = many thousands of dollars, Canine Sniff Test = a dog biscuit.