Can Dogs Sniff Cancer?

In an article by CNN, Lucy, a guide dog school dropout, found a new way to serve the community, becoming a cancer sniffing dog. You may think this is silly and impossible, but in fact many dogs can be trained to detect cancer in humans. Lucy, was trained to sniff out prostate, bladder, and kidney cancer. Lucy, along with many other cancer sniffing dogs, are saving lives detecting early stage cancer across the world.


Nose Goes

Dogs noses are unbelievably more powerful than human noses. A human nose has about 5 million sensors in it to control what we smell. A dog’s nose has roughly 300 million sensors. This allows dogs to break down smells into individual parts. Where we might smell a chocolate chip cookie in the oven, a dog smells flour, cocoa, sugar, and butter.

Something Stinks

When a dog sniffs you, it can tell a lot about you. Dogs can pick up on pheromones you release and by these pheromones a dog can tell your gender, mood, if you’re pregnant, and even what you ate for dinner the other night. Some of these pheromones released come from the cells inside your body. Cancerous cells release a different smell from healthy cells, and dogs can smell the difference. The difference between the two smells is very close, but most dogs can detect parts per trillion, the equivalent of two or three drops in an Olympic sized pool.

Saving Lives

The founder and CEO of Medical Detection Dogs, Claire Guest, had her life saved by her dog Daisy. Daisy repeatedly sniffed Claire and lunged at her chest. Claire later discovered a lump and was diagnosed with breast cancer. Because of Daisy’s early warning, Guest was able to avoid aggressive chemotherapy and the doctors were able to treat her and cure her cancer.


Testing the Dogs

A current British study tests if dogs are detecting cancer, or simply detecting other symptoms that cancer patients might also have such as old age. Dogs are sent to sniff eight urine samples, one of them belonging to a cancer patient, and others belonging to patients with similar symptoms to the cancer patient. The dogs accurately identified the cancerous sample 95% of the time.

Going Forward

Guest amongst other scientists believes these dogs can be used to detect many other diseases in the future. With an accuracy rating of 95%, the dogs are actually more accurate than some lab tests. These dogs think of the detection process as some kind of game, so they have no problem processing hundreds of these tests a day.




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6 thoughts on “Can Dogs Sniff Cancer?

  1. Gulianna E Garry

    This is a really interesting study. It really is amazing the things our dogs do that we don’t even realize.I read once that dogs can tell when something is wrong with someone. After I broke my hand and needed to get surgery, I had to stay home all of winter break sulking while all my friends went out and I was in pain. Sure enough, my dog was there by my side all of winter break. Here is an article discussing how dogs know when we are ill.

  2. Joe Garrett

    Dogs never fail to amaze me with what they can do. I knew dogs had an amazing sense of smell but I did not think that they would be able to smell the difference between a cancerous cell and a non-cancerous cell. Do you know if dogs can only detect certain types of cancer or is it all cancerous smells in general that the dogs can smell? I also found an article that discuses some studies that have looked into dogs smelling cancer –

    1. Chris North Post author

      Most dogs can detect all cancers but dogs are trained for specific cancers to make them more accurate. When dogs are used for testing, they sniff urine samples to determine whether or not the patient has cancer. From my understanding, cases like Daisy’s where she was able to alert her owner of her cancer are uncommon. Most dogs cannot run into a crowd and point out the people with cancer.

  3. Maria Jean Conti

    This is really interesting to me because one of my best friend’s mom has had lung cancer for a few years now, and she really believes her dog knew. Every time her mom would cough, the dog would go crazy barking. This happened for months, before she was diagnosed. When other people in her house would cough, the dog would completely ignore it. I didn’t know if I believed her or not, but this blog surprised me a lot and I’m glad I read it.

  4. Christina Rae Locurto

    This honestly astounds me. It’s so amazing what animals can do for us. I really hope we can further utilize this opportunity and make great strides in ending cancer. I found a particularly interesting National Geographic article that goes into detail about how dogs are not only able to sniff out cancer, but also other diseases like diabetes. The article also describes how dogs get trained to detect cancer and diabetes, and how it’s a very rigorous process. I really hope scientists and dog trainers alike can come together and realize that this is a very important step in detecting life-threatening diseases like cancer. Great blog post, thanks for sharing!

  5. Alexander Roker

    This is very interesting, I’ve never head of anything like it. I would be interested to know how the dog developed this talent; how did she know to detect cancer as a bad thing? Similarly, I wonder if Lucy can teach other dogs to catch the scent, or if she can detect cancer at its earliest stages.

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