Sunday, September 20, 2020

The Secret Life of the Sniffer Dog

 Zoë Sharp


It comes as no surprise that dogs have a really good sense of smell. What perhaps IS more surprising is just how much better it is than ours.


Back in 2002, scientists from the Sensory Research Institute at Florida State University designed and carried out a study to try to put a dog’s sense of smell into context. For this, they used a substance called n-amyl acetate—an organic compound with a scent similar to apples and bananas. It is commonly found in penicillin, as a paint solvent, or as a flavouring.

 

The study, documented by Dr James Walker, discovered that a dog can detect such tiny amounts of this substance they are hardly measurable—two parts per trillion, to be precise. That means a dog’s sense of smell can identify chemicals between ten-thousandth and one-hundred-thousandth more diluted than a human is capable of.

 

So, while a human might be able to tell from a sniff if a cup of coffee has a teaspoonful of sugar added to it, a dog would be able to tell if that teaspoonful of sugar had been added to a million gallons of water.

 

Or, if you relate this to vision, something a human could see clearly at a third of a mile, a dog would be able to see, just as clearly, at 3000 miles away.

 

Mind-boggling, isn’t it?

 

I recall reading, years ago, about cadaver dogs that would indicate for a corpse submerged in nearly a hundred feet of water. Since then, I have heard of drug-detection dogs who can find marijuana in sealed containers immersed in a vehicle fuel tank, or those who smell whale scat from a mile away across a sea inlet. Not to mention all those dogs who sniff out explosives.



More recently, I met two dogs working for my local authority. One of them had been trained to indicate hidden money. When he insisted that a fireplace in one property was a hotspot (pun intended) and it was knocked down, they found £20,000 in cash had been bricked in behind it. The occupants of the house claimed it must be a gift from Santa Claus…

 

The other dog was trained to help investigate arson by sniffing out when accelerants had been used. A study carried out in 2003 discovered that when tracker dogs meet a human trail at right-angles, they can distinguish the direction in which the person was travelling within five paces. And this is despite all the other scents and smells that have come along since the target passed that way.

 

All kinds of breeds are used as detection dogs. One of the reasons bloodhounds are favoured as trackers is apparently because those long floppy ears help to waft the odours into its nostrils as it moves, nose downward, along the ground. Dogs can also independently move each nostril, to further help divine the direction of the scent they’re following.



Not only do dogs have approximately 300 million olfactory receptors in their noses, compared to around six million for a human, but the area of their brains devoted to analysing those odours is forty times greater than ours, proportionally speaking.

 

And even the shape of a dog’s nostrils is designed to aid its sense of smell. The ‘comma’ shape allows a dog to exhale through the side slits, which creates a swirling air pattern that helps sweep more of the scent in via the front of the nose. A study carried out in Norway by the University of Oslo discovered that a hunting dog can sniff in a stream of air for up to forty seconds at the time, which covered about thirty actual breaths.



As if all this wasn’t enough, dogs have a secondary olfactory system that humans don’t possess. The vomeronasal or Jacobson’s organ, which is at the base of a dog’s nasal passage, picks up pheromones, related to sexual readiness. These signals are interpreted by a different area of the dog’s brain, quite separate from the rest of its scenting capabilities.

 

You may wonder what sparked this post today about the ability of dogs to detect chemicals by scent alone. The answer lies all around us at the moment—the Covid-19 pandemic. With testing apparently in disarray, the scares about asymptomatic carriers and threats of a second wave, could scent dogs provide part of the answer?

 

It was reported back in July 2020 that a charity in Milton Keynes, UK, called Medical Detection Dogs was training six canines to sniff out the virus. The charity’s co-founder, Dr Claire Guest, has previously trained dogs to detect various forms of cancer, as well as malaria, E.coli, and Parkinson’s disease. With the increasing scepticism towards vaccines, using the most sensitive biosensors known to man might just provide a worthwhile alternative.



MDD is continuing its trials, part-funded by the UK government and by public donations, in conjunction with the London School of Hygiene & Tropical Medicine and Durham University. It is hoped they might be able to screen up to 250 people an hour at points of entry into the UK and at testing centres.

 

Fingers crossed…

 

This week’s Word of the Week is nefelibata, meaning a cloud walker, one who lives in the clouds of their own imaginations or dreams, or one who does not obey the conventions of society, of Spanish and Portuguese origin.

 

Events:

 

I am delighted to announce that I’ve just signed with publisher Bookouture to write three books in a new crime series, featuring an ex-cop and a con artist. Read the full announcement here.

15 comments:

  1. Hi Zoë
    Thanks for the fascinating post...just this morning I read a local article where a woman was indicated by a drug dog at the airport - in spite of not taking any or having any... she is still mystified, though wondered whether it may have been from a train seat or casual contact.
    My hope is that sniffer dogs for Covid happen soon. Great to hear about your new series.

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    1. Thanks for your comment, K. I wonder what that dog recognised on the woman at the airport... Interesting to wonder, isn't it? While researching this post, I read about a cancer detection dog that 'insisted' on indicating for a particular patient, despite an initially negative result from conventional testing. A second test revealed minute cancerous cells. So, yes, let's hope for Covid-19 detection dogs soon.

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  2. Amazing post. Parts per trillion? Maybe all detective work should just be handed over to dogs. Surely they will be able to identify a murderer from the smell...
    Congrats on the new series!

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    1. Thanks, Michael. It is amazing just how sensitive a dog's nose really is, but perhaps what is even more amazing is how little use we put it to...

      Thank you -- to you and to K -- for the good wishes on the new series!

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  3. And I'm assuming dogs also have a memory bank for their smells. My brother's dog Kelsie, who passed some years ago, always knew who I was the moment I entered their home in MD, even if it had been more than 8 months since the last visit. Some of it could have been visual memory as well, but what was so funny was that she knew I was the guy who was willing to run around with her in the backyard with a play stick. As soon as I arrived at my brother's place, Kelsie would joyfully make a beeline for the backyard, looking behind her as if to say, "Come along! Let's continue our game from 8 months back." She was a sweetheart.

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    1. Thanks, Kwei. Love the story of your brother's dog. Weird, though, because I spent some time staying with friends who owned three spaniels, who used to sit and stare at you longingly at mealtimes. I got to know these dogs well, even looking after them while their owners were away, and they KNEW (the dogs, that is) that I never, ever, fed them from my plate while I was eating, but I was always the one they came and gathered around at mealtimes, as though they were determined to break me down, given time...

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  4. congrats Zoë on your fabulous new deal!

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  5. Congratulations on the new series, oh Grand Nefelibata you! I thinks the use of dogs' sense of smell is a vast untapped source of diagnostic support in so many ways. It's been talked about for decades, and perhaps now (in Covid times) it finally will be pursued with vigor!

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    1. Thank you, kind sir. Let's hope so. I'm voting for the dogs' noses, that's for sure.

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  6. Funny story: one day in class when I was a kid, the teacher caught me daydreaming. "Quartey!" he called out. "Stand up. Why are you not paying attention?"
    "Sorry, sir," I said. "I was just contemplating the fact that dogs have a sense of smell 10,000 times sharper than people."
    The rest of the class just didn't get it. I was a strange kid sometimes 😂

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    1. Strange? No. Sounds like exactly the kind of thing I would have been wondering about, too.

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  7. Congratulations on the new series deal, Zoe. I look forward to these new characters.

    Regarding sniffer dogs, I've wondered about that with Covid. Thanks to a post Michael put up years ago, I have for some time sent a small monthly donation to Apopo, a nonprofit that trains African pouched rats to find land mines and perform tuberculosis tests. This info about dogs is astonishing. I hope people who work with them can train them to detect covid and fast! We have too many members of our own species who are too dumb to properly deal with the virus. Reaching out to truly useful members of other species might be just the ticket.

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    1. Thank you, Annamaria. What a wonderful organisation Apopo sounds! Although now, of course, I have this image in my head of a little rat wearing a mask and gown and latex gloves, taking a swab from the inside of someone's cheek...

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  8. TEEHEE!! The thing is, that no matter how they are dressed, the little critters who work in medical labs can tell right away if the person who has walked four hours to get to the clinic has TB. With that old test, where they use that needle thing on one's arm, the docs used to have to say, come back in four days so we can look at your arm.

    And on the minefields the rats are light enough to find the explosives without setting them off. Saves a lot of limbs of people and bigger beasts.

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