Can Dogs Sense Illness | I Believe They Can

Our dogs are absolutely amazing creatures.  They can tell when we are having a tough day and they instantly react by giving us extra affection and cuddling up with us.   It is like they know exactly what we need from them. But it goes farther than them sensing just our emotional feelings.

We have all heard the stories from dog owners about their dogs ability to sense that something wasn’t quite right with them.

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Many times, it would start out by their dogs acting funny, or staying super close to them in an odd way.  This strange behavior from their dogs leads their owner to go to a doctor to get checked out.

For many years, doctors have seen dogs ability to sense when their owners or someone they love becomes sick.   Is this a real thing, and if so how do they do it?  Can dogs sense illness?

The nose knows

All of it starts with our dogs noses.  Dogs noses are 10,000 to 100,000 times better than our nose.

A dogs nose is shaped long and skinny.  This particular shape allows a dog to have an increased surface area that allows them to sniff out molecules in the air.   They can use their nostrils on the right or left side to sniff things in the air that we don’t smell.

Dogs have close to 300 million receptors in their nose, unlike us who have approximately 6 million.  Our dogs brain works in tandem with their nose receptors to sniff out different scents that they encounter along the way.  Compared to humans, dogs brains and smelling abilities are far greater than our own.

There are 2 chambers that dogs use when they breathe in a scent.  They are the lungs and the olfactory receptors.  The smaller portion of the air breathed in goes into the olfactory center that is filled with turbines that are small bony structures in our dogs nose.  These tiny bones act like a strainer for the turbines to connect with the brain to classify each separate scent.

They breathe in new scents and then exhale the old scents out the slit in the center of their nose.  This is why dogs are constantly sniffing and smelling all day long.

Dogs left and right nostril allow dogs to identify a particular scent depending on which side of the nose it comes from.   It then helps them determine the spot of the wonderful scent they smell.

History of dogs nose abilities

Going back in history to the 1800s and possibly even earlier than that.  Humans have capitalized on dogs noses and sniffing ability.  We started taking advantage of their abilities and started using dogs to first assist blind people.   By helping the blind get around it greatly improved their quality of life.

Around this same era, police began using dogs abilities to help them sniff out criminals.  When we look at a specific example from 1888 police used dogs to assist them in the Jack the Ripper case, to try to solve these horrific crimes.

In today’s world dogs are an important part of the police force, the military or as service dogs to aid people in distress from PTSD and even anxiety.

Dogs in the military are trained and used as bomb sniffing dogs.  They can alert the soldier that their is a danger ahead which allows the soldier to find and disarm the bomb before it goes off.

There are even dogs now that can be used to help diabetics that require insulin. They help identify when their blood sugar starts to dip to low.   They can sense when the diabetic starts to act funny, by giving them a nudge to let them know to check their blood sugar.


How do they sense when someone is sick

Over 30 years ago there was a case of a woman who reported that her dog kept sniffing a spot that she had on her skin.   Her dog was constantly sniffing that particular spot so the lady decided to go to the doctor to get it checked out.

Sure enough, the spot turned out to be the early stages of a malignant melanoma cancer that was caught so early that it was completely curable.  So thanks to her dog, she was able to be treated early and it saved her life.

The doctors started to try to figure out why and how a dog was capable of detecting her cancer so early.

When a human is sick either with cancer or a serious illness, our body omits changes in our VOC’s or Volatile Organic Compounds.  Basically a chemical change happens in our body.  It has been shown that these changes in our VOC or metabolic changes are what the dog is able to detect.

In an even more impressive test, dogs are able to sniff out prostate cancer by simply sniffing the urine of a sick patient.

How do they do it?  Doctors believe that dogs are detecting the VOC sarocosine which is just a by-product of amino acid synthesis.  This particular VOC is a bio marker for prostate cancer.  The dog can smell the change in the urine and detect that these men have prostate cancer.

These medical detection dogs are capable of assisting doctors and are highly trained dogs.  This training can cost upward of $25,000 per dog.

As much as we would love to see our dogs in white lab coats in hospitals and clinics, the cost makes them a high commodity in the health region.  Due to the cost to date this method of using dogs to assist doctors isn’t really being used that much.

The hope is that as we find out more about what a dog can do to help the medical community it will be more common than it currently is.


Scientists build an electronic dog nose

I know it seems far-fetched and years away, but scientists believed, that they could build an electronic version of a dogs nose.

An engineer named Otto Gregory from the University of Rhode Island and his students have already built a digital dog nose, that can detect explosive devices.  The best news is that it actually works.

So we may not be centuries away from building an electronic device that detects cancers and other serious illnesses.

The main issue is finding out the exact thing that dogs are able to do to sense serious illnesses and recreate that. Once we determine exactly how they can use their nose in every single case, we hope to be able to build a device that acts and operates the way a dogs nose does.

Recently there has been some research that has been done that shows 5 trained domestic dogs were able to accurately sniff out 99% of the people with lung cancer and 88% of people with breast cancer.  This was done simply by smelling the people’s breath.

Although we are not all the way to completely understanding every step and action of what a dogs nose can do. We are really making huge strides in that direction.

Our dogs nose

Your dogs nose is an important part of their overall health.  It is important that we allow our dogs to constantly encounter new smells.  Getting them out and about ensures that they constantly are using their noses to connect to the world around them.


Through all the scientists research and time spent on dogs and their noses, they have proven that yes dogs can sense illness in people.  It is a fascinating thing to think about.

Can your dog sense when you are unwell or not feeling well?

My dog Finn has a nickname we call him “Dr. Finnegan.”  Why do we call him that, well to be honest, he is that dog that can sniff out any cut, scrape, sickness or time when you are feeling unwell.

I believe that he is that dog that could sniff out if there was something seriously wrong with me or my partner.  He has already proven that with small illnesses and he has truly proven to me that dogs are capable of identifying things that we may not even know about our own health.

Listen to your dog and be aware that if they sense something is wrong, go get it checked out and make sure for yourself.

Dogs truly are amazing animals.  I believe that they have been put on this earth to provide companionship, love, to teach out about unconditional love and most importantly protect us from things we may not even see.

Dogs really do make you happier.

10 thoughts on “Can Dogs Sense Illness | I Believe They Can”

  1. I had life-saving brain surgery back in 2006 and when I was recovering although still very unwell, I bought a wee dog, Liberty and as a baby, she used to sleep really close to my left side of my head and she knew even as a small pup that I needed healing.

    Lib is coming up 13 now and still knows when I am not feeling ok and keeps very close to me. these days she sleeps next to me on her blanket but if she senses I’m not well, she will often try to get into my bed to get closer and give me her warmth

    Dogs are incredible creatures and they can also detect cancer in people 

    I absolutely love this post- thank you

    • Hi Vicki,

      Thank you so much for sharing your personal story about you and your dog Liberty.  I am so sorry that you had to go through that very serious surgery.  I am so glad that you had the comfort of Liberty with you through that difficult time. 

      Dogs give so much to us, it constantly amazes me.  They are absolutely amazing creatures.  Every time I hear a story of a dog doing something amazing it reiterates my sense that dogs really can help us through anything. 

      I am so happy you liked my post and it reasonated with you. 

      Best of luck Vicki… and Liberty!!!


  2. Well, Coralie, I can tell you that absolutely my dog knows when I am sick.  I didn’t actually attribute it to his nose but his overall sense of me, but you may be right.   Whatever it is, I can tell you that he will snuggle up to me, rub his face on me, and just be all over me when I’m not feeling well.  It’s crazy.  It’s comforting, but crazy.  I love it, and now I know the science behind it.  Pretty cool!

    • Hi Babsie,

      I love hearing that your dog has a good sense of you. Nice to have them close when you aren’t feeling good. It sure does make you feel better.

      Learning all the science was really a very interesting journey. 

      Thank you for sharing your personal story about you and your dog. I love hearing it.


  3. Good read. Dogs have been amazing companions and have helped their owners in so many ways. I also watched a video about the woman you were talking about. It is something unbelievable yet its true. 

    There are also some Asian beliefs that dogs can give up their life for you. We have numerous stories of dog owners that say their pets suddenly died to give their master an extra life to live. What I personally think about this is that dogs can stress out on biochemistry change of their owner. Might be the probable cause of them dying before their owner is the stress level that can lead them to have a sudden heart attack. Is it just coincidental that the owner lived but the dog died.

    Thanks for this highly informative article. I’ve learned so much about the reason behind dogs smelling capabilities. Good day!

    • Hello,

      I am so glad that you enjoyed my post and found the topic worth talking about.  I loved hearing about the history behind the Asian stories from their culture. I

      Have never heard that before. But I honestly believe that could be so true. Dogs in the military can and have done that exact thing. They sacrifice themselves from a bullet or a bomb to save their partner. 

      Dogs truly are fabulous creatures.

      Thank you for sharing your story with me. 


  4. Hello Coralie; Great article. Yes, I knew that there is remarkable sniffing power in the dog nose, I also knew that some dogs are trained to do various tasks. However, I never knew that a dog could sniff sickness. It is strange news to me.

     I had a blind neighbour who had a guard dog that takes her through the town in some of the busiest hours of the day and never misses one of the business places that she needs to go. 

    Do you think that dogs have that? Can dogs intelligence be trained to sniff sickness?


    • Hi Dorcas,

      I really appreciate your comments on my post.

      Yes I do believe dogs can sniff out sickness.  There is far to much evidence saying they can.  I am sure like everything it isn’t the same for all dogs.  Some dogs are just that intelligent and have amazing abilities.

      Dogs like your neighbors dog sounds like a very well trained extremely smart dog. Such a great story to hear. Dogs are amazing! 

      Thank you. 


  5. This is truly awesome!.  I hope they are able to further develop those electronic noses to detect cancers.  In the meantime, let’s set up doggie sniffing schools to train dogs in mass and keep the costs down.  I’ll volunteer to be sniffed by the dogs at the schools to further science.  Seriously, I wish them great success in developing the electronic noses and fully utilizing dogs.  I think everyone knows someone whose life has been negatively affected by cancer.  We have made great strides in the fight against cancer, but there is still a long way to go.  Are these electronic dog noses currently being funded, or is this just a great idea that has not gone very far?

    • Hi Karen,

      Thank your for your wonderful comments.  Since about 2016 these electronic noses are being used to sniff out bombs and drugs.  The fake noses are pretty good, but still not quite as good as the real thing yet. 

      I will stand right beside you in the doggie sniffing school. LOL! 

      Cancer is everywhere and we need to do everything we can to detect it as early as possible.

      I thank you. 



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