Can Dogs Smell Cancer? The Science Behind Their Incredible Medical Detection Skills

Greta Wire

This episode explores the remarkable ability of dogs to detect diseases like cancer through their extraordinary sense of smell, sharing real

Key takeaways

Dogs can detect disease-related odors at parts-per-trillion levels due to up to 350 million olfactory receptors.
Claire Guest's Labrador Daisy detected her breast cancer beneath a benign lump, leading to early diagnosis and treatment.

Main topics

Medical detection dogs
Canine olfactory capabilities

Notable quotes

"If you detect cancer early, you're going to survive."

Conclusion

Dogs' ability to detect disease through scent offers promising non-inv

Transcript preview

Speaker 1 (0:00) The Greta Wire podcast is presented by Paramount+. On Speaker 2 (0:05) September 18th, prepare for uncivil war. Mobland, the hit crime series from the underworld of Guy Ritchie, returns to Paramount+. The Harrigans are back and their empire is spiraling into chaos from the inside out. As power plays, fractured loyalties, and reckless decisions collide, Fixer Harry is left to clean up the fallout. Don't miss Mobland starring Tom Hardy, Piers Brosnan, and Helen Mirren. Speaker 4 (0:31) Okay, this is absolutely incredible. You know that if you detect cancer early, you're going to survive. A lot of people can't afford it, and a lot of people don't take time to have all these tests. Well, what about dogs? Wait till you watch this Grout of Wire. This is an interview with Claire Guest, a doctor, and dogs can detect cancer. They can save lives. Watch this. Claire, nice to meet you. Speaker 3 (1:08) Nice to meet you too. Speaker 4 (1:10) Claire, I got to tell you, first of all, I love dogs. I got three giant ones myself. They are not gifted, but they are lovely and sweet. But anyway, I noticed that you train dogs who are quite gifted. So tell me about dogs that can smell diseases. Speaker 3 (1:27) Well, it sounds pretty incredible, doesn't it? But as we know, dogs have got this amazing sense of smell. So they have up to 350 million sensory receptors in their olfactory epithelium. They've also got a third of their brain dedicated to smells. And they have this incredible apparatus, actually, for drawing volatiles into their noses. they're incredibly good at using their nose and I genuinely believe that for many many centuries probably dogs have been detecting odours that are associated with disease but just we haven't in our relationship with them they haven't been able to communicate this to us so my sort of learning of this was from anecdotes you know I heard people anecdotally either talking about their dogs perhaps having a detected a cancer as a case of a friend, colleague who had a small mole on her calf and her pet dog kept licking and sniffing at this mole to the point where it was irritating. It wasn't just a sort of passing interest. And eventually she went to a GP, the mole was removed, but she was called back to be told she had malignant melanoma, so of course the most serious form of skin cancer in a very young lady. So from this story, I was then... wanted in my lifetime to prove that dogs could smell cancer and other diseases. So I kept hearing these anecdotes and a colleague of mine, Dr John Church, actually published the cancer anecdotes in the Lancet medical journal, just talking about the stories of dogs detecting disease. So it's been very much a journey now of discovering how well they can do it, what diseases they can detect. and what applications that might have to human health in the future. Speaker 4 (3:13) Well, you have dogs that are drug sniffers, you've got dogs that are explosives, but how do you train a dog to sniff a disease? I mean, how do you do this? Speaker 3 (3:26) So, medical detection dogs, we've got two different types, or two different categories of dogs, if you like. We have our assistance dogs that work alongside individuals. And then we have our sort of a biodelecting dogs that are more involved in research and supporting other diagnosis. So when you're talking about an assistance dog, you're very much using the odour of that individual and teaching the dog that when their odour changes to this odour, they're more than because it means there's an oncoming medical emergency. When you're talking about our biodelections, so finding out can dogs detect a particular disease and how can they do that best? So is it from a urine sample or sweat sample or breast sample. We train the dogs to find the disease by giving them the whole array of samples so we're basically asking the dog so these are healthy controls, these are control samples from people who may be unwell or have other diseases and these are Speaker 3 (4:25) target disease odours. What we do is we teach the dog a sort of almost like a, you know, a fine game. And we teach the dog that when you find this particular odour, you know, tell us about it and we'll reward you and ignore the rest of them, basically. It's a straightforward, the cleverness, I suppose, comes out of knowing what samples you need to train the dog with in the first place so the dog gets a real good understanding. It's a bit like... me teaching you to become a really good wine discriminator. So in order to teach you to discriminate I need to give you good wines, bad wines, wines from the same vineyard, I need to give you the whole so you can start to learn what it is in discrimination that's exactly the same with the dogs they learn that discrimination and we train them a way of communicating it to us when they find it. Speaker 4 (5:15) Well, they certainly can smell. I mean, I'm a vegan and sometimes we have vegan cheese wrapped in refrigerator, but doesn't have a label. And so I'm not sure if it's vegan or not. So I cut off a little piece and I'll give it to the dog and I had to roll right off his tongue if it's dogs because they won't eat that stuff. You know, they're telling me. But but if you have a dog who's acting in dog, you know very well, but also starts acting weird towards you. Would a dog do that who's not specifically trained, but who you made the example of the mole? I mean, will dogs just start acting odd or suspicious? Speaker 3 (5:52) They can. And I certainly wouldn't want everybody who sees a behavior change to worry that it's necessarily something about their health. But I think if you're looking at changes in behavior that seem quite targeted and quite specific, then I think it's always worth trying to understand what the dog might be trying to communicate. So my story, I was already training bladder cancer detection dogs and we published in the British Medical Journal in 2004 that dogs could detect the odour of human bladder cancer. And I was then continuing to work on a prostate cancer study with the same hospital. So we're looking