How good are sniffer dogs?

Sniffer dogs are used to detect drugs but how good are they? Can they sniff out all drugs? Or just a select few? And how are they trained?
30 October 2014

Interview with 

Sergeant Owen Rogers, Cambridgeshire Police Dog Unit


Do the cutting edge technologies used at airport to detect drugs and other dangers, Sniffer dogsmean that more traditional practices, like the use of sniffer dogs for example, have had their day? Sergeant Owen Rogers, from the Cambridgeshire Police Dog Unit, told Ginny Smith how our furry, four-legged friends continue to help us out...

Owen -  Well, they'll be looking for a number of different substances.  We have dogs that detect explosives and we have other dogs that will be looking for drugs or cash or weapons.

Ginny -  Why do you use dogs?  Is it because of their particularly good sense of smell?

Owen -  Dogs have massively enhanced sense of smell over humans.  Also, they can detect such small traces of any substance that might be being imported into the country.  

Ginny -  Just how good is their sense of smell compared to ours?

Owen -  It's not exactly known.  However, estimates vary between a hundred and one million times better sense of smell than humans.  It all depends on two things within the dog in comparison to the human.  The first being, the size of the olfactory membrane.  Estimates reckon that a German shepherd dog would have 100 million olfactory cells in comparison to a human's 5 million olfactory cells.  But it's not just that.  It's the area within the brain that is set aside for the detection of smells.  Once again, it's massively enhanced in a dog than a human.  Again, estimates are about 10% of the brain in a dog and about 0.25% in a human.

Ginny -  As well as being able to smell all these different smells, they'll actually be able to tell them apart as well.

Owen -  Scent discrimination is what we call it.  So for instance, a dog will be able to tell constituent ingredients of any substance whereas a human could just smell the entire substance.  For instance, tomato ketchup, we would just smell tomato and ketchup, but a dog would smell all the e-numbers, the sugar, the tomatoes themselves, and the salt.

Ginny -  Are there certain dogs that are better at this than other, certain breeds?

Owen -  We tend to use gundog breeds because of their level of drive, so we use spaniels or Labradors.  Sheep dogs are used, but generally, gundog breeds even up to the continental point of breeds.

Ginny -  I guess the Chihuahua wouldn't be quite as intimidating either.

Owen -  Intimidation isn't particularly high on the list, but a Chihuahua I think would - due to its size - find it difficult to cover the area.

Ginny -  How do you go about training a dog to become a sniffer dog?

Owen -  It's not just the breed that counts.  It's the actual dog and once you've identified a dog that has sufficient drive to take on the job, you then introduce the substances and you make the dog interested in the substance by rewarding it, for sniffing the substance in question.

Ginny -  So, lots of dog biscuits.

Owen -  Personally, I'm not in favour of biscuits.  But a tennis ball goes down very, very well indeed and you will condition the dog, essentially ,to stare at the source of the scent until the delivery of a ball.  So, dogs are not that intelligent and they will actually think that the ball will appear from the source.

Ginny -  How do you stop them getting distracted if someone had some tasty dog treats in their pocket or something?

Owen -  Well, that is very important.  However, for some reason, dogs just take to it and they are so driven by the delivery of their toy or the praise, or whichever other method of reward we give them, that they will avoid those distractions.

Ginny -  Can you give me an example of something that dogs have found?

Owen -  We've recently had a very, very large find of heroine.  The street value of which would've funded the existence of the dog section for many, many years.  Another excellent job was an armed robbery where one of my handlers arrived, tracked the robber from the scene to his home address then found him and then he got his other dog out and found the weapon that had been used in the robbery.  So, it's the whole thing that was all down to that one handler.

Ginny -  Do you think there's any way, if you wrapped it in sort of lots and lots of layers that you could ever hide the scent or something?

Owen -  Well, you have to be so forensically aware in order to ensure that there are no leakages of anything.  There is no scent without moisture and as a result over time, substances will dry out or the residual substance will dry out.  So yes, there are ways of doing it, but you've got to be very, very good.

Ginny -  How long does it take to train the dog and is it a case of, once it's trained then it's good to go for years and years, and years or do you have to keep refreshing them?

Owen -  It depends on what you're trying to achieve.  But for the scents to become imprinted within the dog, it can take just a matter of a few weeks.  But yes, you have to refresh the dogs very, very regularly, just to reinforce the reward for the find that they have.

Chris -  Owen, have you got tons of these stuff at home for personal consumption?

Owen -  I've got loads of them.

Chris -  Really, and you must presumably have this material in the workplace and in the car for dog retraining?

Owen -  Yes.  We do hold substances and they are used regularly for training, yes.


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