Can Dogs Smell Cancer in a Person? : Dogs could be the best tool for diagnosis
As far back as 1989, according to Live Science, reports and stories of cancer-sniffing dogs have surfaced. In 2015, The Baltimore Sun reported that Heidi, a shepherd-lab mix, had sensed cancer in her owner’s lungs. The Milwaukee Journal Sentinel described Sierra, a husky who detected and alerted her owner of ovarian cancer on three separate occasions. And in September, the American Kennel Club reviewed the book “Doctor Dogs,” which shares stories of dogs detecting a host of diseases, including cancer.
According to Medical News Today, research indicates that, with training, dogs can detect a variety of cancers — even at early stages — in humans. “Like many other diseases, cancers leave specific traces, or odor signatures, in a person’s body and bodily secretions. Cancer cells, or healthy cells affected by cancer, produce and release these odor signatures.” With proper training, dogs have been able to smell cancer in humans’ skin, breath, sweat and waste and to alert them.
Some dogs can detect cancer, but the aforementioned training component is key. The In Situ Foundation is nonprofit that’s dedicated to just that: rescuing and training dogs to detect early stage cancer in humans. The foundation “uses high drive dogs, such as German shepherds, Australian shepherds, shepherd/lab mixes, beagles, Belgian Malinois, and most mixed breeds containing any of these combinations. Occasionally, we will test a dog who is not one of these breeds, who detects cancer with flying colors. The temperament and drive of the dog is what matters.”
How Do Dogs Act When They Smell Cancer?
Stories of dogs’ reactions to the smell of cancer vary. According to the Milwaukee Journal Sentinel, when Sierra the husky first detected ovarian cancer in her human, she exhibited intense curiosity — then ran off. “She put her nose on my lower belly and sniffed so intently that I thought I spilled something on my clothes. She did it a second and then a third time. After the third time, Sierra went and hid. I mean hid!”
The Baltimore Sun noted that Heidi “began burying her snout into her owner’s chest and pawing at her anxiously” when she detected cancerous cells in her lungs.
These stories show that there isn’t one single way dogs will react to the smell of cancer, as much of their reaction will be based on their individual temperaments and training. But the one thing dogs in all stories had in common was a distinct change in their normal behavior that indicated to their pet parents that something was off. If you notice a change in your dog’s behavior, that doesn’t necessarily mean there is anything to be concerned about; however, consistent patterns could be worth exploring. If a visit to the veterinarian shows that your pooch is healthy but their behavior continues, it may be worth scheduling a visit to your doctor as well.
Dogs have long been celebrated for their extraordinary sensory abilities. Their keen sense of smell, in particular, is known to surpass that of humans by several orders of magnitude. While we often associate this superpower with tracking and detecting hidden objects, dogs have also demonstrated an astonishing talent: the ability to detect certain diseases, including cancer, through their sense of smell. In this article, we will explore the fascinating world of canine cancer detection and how these loyal companions are contributing to early diagnosis and improved outcomes for patients.
The Power of Canine Olfaction
A dog’s sense of smell is truly remarkable. They possess over 220 million scent receptors in their noses, compared to our meager 5 to 6 million. This incredible olfactory prowess enables them to detect even the faintest of scents, making them exceptional at identifying unique odors associated with various medical conditions.
Cancer Detection: The Canine Connection
The notion that dogs can detect cancer may sound like science fiction, but it’s firmly rooted in scientific research. Several studies have shown that dogs can indeed sniff out cancer with remarkable accuracy. In fact, they can identify the scent of certain cancer-related molecules in a person’s breath, urine, or sweat.
How Do They Do It?
The precise mechanism by which dogs detect cancer remains an area of ongoing research, but there are some leading theories. One theory suggests that cancer cells release specific volatile organic compounds (VOCs) or metabolic byproducts that dogs can detect in a person’s bodily fluids or exhalations. These compounds create a unique odor that differs from the scent of healthy cells.
Training the Canine Detectives
The key to harnessing dogs’ cancer-detection abilities lies in their training. Highly trained dogs, often referred to as “cancer-sniffing dogs,” are exposed to the scent of cancer samples during their training. These samples could include breath, urine, or tissue specimens from cancer patients. The dogs learn to associate the distinct cancer scent with a reward, typically a treat or praise. Through repetition and reinforcement, they become proficient at recognizing the scent of cancer.
Real-Life Success Stories
Numerous anecdotes and studies illustrate the incredible potential of dogs in cancer detection. For instance, a study published in the journal “Gut” in 2011 reported that trained dogs were able to detect colorectal cancer by sniffing patients’ breath samples with 95% accuracy. Other studies have shown similar success rates in detecting various types of cancer, including lung, breast, and ovarian cancer.
Potential Applications
The ability of dogs to detect cancer has far-reaching implications for early diagnosis and improved treatment outcomes. Here are some potential applications:
Early Detection: Canine cancer detection can help identify cancer at its earliest stages, often before symptoms become apparent. This early detection can lead to more successful treatment and improved survival rates.
Non-Invasive Screening: Unlike many current diagnostic methods, canine detection is non-invasive and requires only a breath or urine sample, making it more comfortable for patients.
Complementary Tool: Canine cancer detection can be used alongside traditional diagnostic methods to enhance accuracy, particularly in cases where conventional tests may yield inconclusive results.
Cost-Effective Screening: Training and maintaining cancer-sniffing dogs may prove to be a cost-effective and efficient way to screen large populations for cancer.
Dogs have long been cherished for their loyalty and companionship, but their remarkable sense of smell is now shining a new light on their potential to save lives. The ability of dogs to detect cancer is a testament to the power of nature’s design and human ingenuity. As research in this field continues to evolve, we can look forward to a future where our canine companions play an even more significant role in the fight against cancer, offering hope, comfort, and a unique form of early detection that may one day change the way we approach this devastating disease.
A Strong Sense of Smell
A dog’s sense of smell is on average 10,000 to 100,000 times superior to that of humans.
While it remains unclear what exactly makes dogs such good smellers, it is indisputable that much more of a dog’s brain is devoted to smell than it is in humans.
It is the cancer researchers’ hope that in the future dogs can help detect cancer from the comfort of a doctor’s office. Since the Pine Street Foundation study, dogs have also been tested to detect breast , prostate and bowel cancers.
The 9 Signs to Look for When a Dog Smells Cancer
1.Persistent Sniffing in One Area of Your Body
One of the reasons humans discovered that dogs could smell cancer was that, when they do, they hone in on the affected area of your body and sniff like crazy. In many cases, when a dog smells cancer, you won’t be able to keep them from sniffing, even by pushing them away, saying “no,” or telling them to stop.
If your dog suddenly starts to sniff you in a specific area of your body and won’t stop no matter how hard you try, it might be time to visit your physician for a checkup.
2.Persistent Licking on One Part of your Body
When dogs are sick, hurt themselves, or have an open wound, one of the first things they do is lick that area to help it heal. Researchers have seen the same behavior when dogs smell cancer in their owners’ bodies. They lick on the specific site constantly, trying to “heal” it the only way they know how.
3.Biting or Nipping on a Certain Part of Your Body
Like licking, a dog will often bite a part of your body where they’ve smelled cancer. By biting the cancerous area, your dog is trying to get rid of the cancer and make you well. It won’t, of course, but dogs will do anything to help their parent.
4.Staring at You Intently, Sometimes for Hours
Dogs sometimes like to stare off into space, especially if they’re bored. Typically, however, they won’t stare at you for long unless you have something they want, like a bone or a treat. If they smell cancer in your body, your dog might stare at you constantly, day in and day out.
They suspect something is wrong and, researchers believe, stare at you because they’re concerned and don’t know what else to do. Lauren Gauthier, the founder of Magic Mission hound rescue organization, had this very thing happen to her when her dog Victoria couldn’t stop staring at her.
5.Tapping on You With Their Paws
We’ve all had our dogs tap on us when they want something, including when they’re hungry, thirsty, or need to go outside for a potty break. If a dog smells cancer, it will often tap on you incessantly, possibly in a specific area of your body where they smell cancer. This tapping is their way of telling you that something might be wrong, which is a not-so-subtle hint that you should get examined by your doctor.
6.Snuggling With You Much More Than Usual
Many dogs are snugglers who love to curl up on your lap or lay at your feet. That’s a dog’s way of showing how much they care for their pet parent. If a dog smells cancer, while it might not know what’s wrong, they detect that something is amiss and, in many cases, will snuggle with you far more than usual.
It can be challenging to push your dog away because they’re so concerned. They might also snuggle up to you much closer than they usually do, a possible sign you should get a cancer screening.
7.Whining and Tilting their Head When They Look at You
Many dog owners have wondered what it would be like if their dogs could talk. In a way, they do, usually with whines, growls, and other doggy noises. If a dog smells cancer, it might whine more than usual when it’s around you or stare at you with its head tilted to the side.
It’s your dog’s way of saying, “Hey, I don’t know what’s going on, but something doesn’t seem right.” They might also be upset about something else, but if your dog is whining around you and doing it much more than usual, don’t ignore it.
8.Hiding From Their Pet Parent
While this reaction to smelling cancer might sound odd, researchers believe it’s because your dog fears the problem they’ve detected. Just ask Stephanie Herfel. In 2014 Stephanie’s Siberian Husky, Sierra, was acting very strangely, including hiding in a closet in their home. To make a long story short, Stephanie found out she had cancer, and Sierra was so upset that she hid in fear.
Amazingly, Sierra detected Stephanie’s cancer two more times and noticed it in two other people! Every time, this fantastic dog went and hid in the closet.
9.Hyper-focusing on a Body Area or Part
We’ve seen that dogs will stare, sniff, lick and even nip on a body part where they have smelled cancer. In some cases, they may do all of these things, becoming hyper-focused on a specific area or part of your body in a way they’ve never done before.
They do this because they know something is amiss, and they’re trying to do something about it by alerting you to the problem. At least, that’s what researchers surmise. If you have breast cancer, for example, they may focus on your chest. The same can be said for bladder, prostate, and many other cancers that affect a specific part of your body.
How Do Dogs Smell Cancer?
It’s well known that dogs have an incredible sense of smell. To give you a better idea, consider that humans have about 6 million olfactory receptors (smell receptors) in our noses, while dogs have approximately 300 million, about 50 times more than we do. Dogs also have a tendency known as neophilia, which means they’re attracted to new and different smells and will investigate them to see what they are. This incredible sense of smell and neophilia help dogs detect cancer. Below are a few other factors that enable dogs to smell cancer.
Cancer Has a Specific Smell
When a disease state is affecting your body, the disease has a specific odor or trace signature. Cancer is the same, and when a person has cancer, the odor trace will be detectable to a dog as it’s different from the “normal” smell your body emits.
Several Body Parts and Excretions Can Smell
When a person has cancer, the odor of their disease can be detectable by a dog’s amazing nose. Excretions like sweat, urine, and feces can also have a cancer odor, and dogs can smell it on your breath.
Dogs Can Smell Minuscule Smell Concentrations
Humans have a smelling power ranging from .04 ppm (parts per million) to about 57 ppm. Dogs, however, can smell things in the parts per trillion, which means they can smell a single odor-causing cell in over a trillion non-odorous cells. This incredible sensitivity to smells and odors is why dogs can smell cancer when no human can.
Dogs are Better Than Most Medical Instruments at Detecting Cancer
This fact doesn’t pertain to how dogs smell cancer, per se, but it does prove how well they can do it. Dr. George Pretti, a chemist at the Monell Chemical Senses Center in Philadelphia, PA, has spent almost his entire career isolating the chemicals in cancer that cause it to have a distinct odor. He said this when talking about the canine sense of smell; “I’m not embarrassed to say that a dog is better than my instruments.”
Which Dog Breeds Smell Cancer the Best?
All dogs have the same powerful smelling ability, but some are better at sniffing out cancer than others, just like some dogs are better at sniffing out drugs and explosives. Today, several breeds are being trained specifically to detect cancer by smell. They include German Shepherds, Beagles, Australian Shepherds, and Belgian Malinois.
That’s not to say that these are the only four dog breeds that can smell cancer, only that they seem to be the best-suited to train for cancer detection. Many of the anecdotal stories we read during the research for this article revolved around other dog breeds that smelled their owner’s cancer, including Siberian Huskies, Treeing Walker Hounds, Labrador Retrievers, and several others.
Are Cancer Sniffing Dogs Considered Medically Valuable?
Determining if a person has cancer can involve an invasive and often traumatic array of tests that, in some cases, can cause even more health problems, especially for seniors. That makes a cancer sniffing dog, and the growing advancement of canine cancer detection, invaluable. With a cancer-sniffing dog, detecting cancer is simple, safe, and, most importantly, non-invasive.
Cancer-sniffing dogs can also detect cancer in its early stages, giving the patient time to treat their cancer before it spreads. Moreover, cancer sniffing dogs cause no side effects (aside from a possible allergic reaction), and the tests can be easily performed anywhere, including in a patient’s home.
In short, canine cancer detection and training dogs to detect cancer are incredibly valuable. Because scientists now know that dogs can detect cancer due to smell, they’re developing machines that detect the odor signature of various types of cancer.
Which Cancers Can a Dog Smell?
There seems to be no limit to the types of cancers that dogs can smell, as all cancers have an odor signature they can detect. That being said, there do seem to be some cancers that are easier for dogs to detect than others, including:
- Colorectal cancer (from feces)
- Ovarian cancer (from blood samples)
- Prostate cancer (from urine)
- Lung cancer (from breath)
- Breast cancer (from the skin)
How Are Dogs Trained to Detect Cancer?
Although a dog’s powerful sense of smell is something they’re born with, cancer-sniffing dogs are highly trained to detect and respond to cancer. To do this, trainers start training puppies at a young age, around 8 weeks. The training is similar to dogs trained to sniff out bomb-making materials and illegal drugs. Puppies are exposed to the smell repeatedly and then tested to see if they can detect it.
A trainer holds two vials: one with cancer cells and one that’s benign. The puppy sniffs both so that they can get the scent of each. After that, they are exposed to other smells and items with the cancer smell on them and without it. When the puppy detects and reacts to the cancer smell, they’re rewarded with a treat.
From what researchers and trainers have found, the best dogs to detect cancer are those dogs that are very precise in their movements and manners when searching for the smell of cancer. They’re also methodical in searching and are more introverted and aloof than most dogs.
How Can Dogs Smell Cancer?
The dog’s sense of smell is up to 10,000 times more acute than that of humans 1. This means they can detect odors that we cannot, including certain disease related chemicals that are released by tumors.
What Are the Dogs Sniffing?
Cancer emits unique chemicals. It’s possible that there are several compounds that dogs can smell. One type that has been studied is called volatile organic compounds (VOCs). These VOCs are expelled in very small amounts through a person’s breath, skin, and urine. Studies have shown that certain dogs can be trained to detect VOCs associated with cancer. In one study, Labrador retrievers were trained to discriminate between the breath samples of people with lung cancer and those without the disease. The dogs were able to do this with 97% accuracy 2. In another study, a dog was able to correctly identify skin cancer lesions 100% of the time.
While there is still much research to be done in this area, these findings suggest that dogs may one day be used as inspiration for “cancer-sniffing” machines in hospitals and clinics. They could be especially helpful in detecting hard-to-spot cancers, such as ovarian cancer, at an early stage when treatment is most successful.
Compiled & Shared by- Team, LITD (Livestock Institute of Training & Development)
Image-Courtesy-Google
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APPLICATION OF SNIFFING DOGS AS A DIAGNOSTIC TOOL IN INFECTITOUS DISEASES
