Is it possible to de-condition a dog to specific scents?

[ferryman]

I've long tended to the view that it must be possible for a single and simple reason.

The US Forensic Canine Program broke with a hallowed tradition of (conventionally) both US and (specifically) English law enforcement (but not Scottish) in ruling as admissible (evidence in court) uncorroborated cadaver-dog alerts. 

Indeed, under the auspices of the FCP, an uncorroborated cadaver-dog alert was taken as proof in its own right of murder, and I long argued that that could only be because dogs working for that (US) program had been de-conditioned to the scent of blood.

But (argued those who objected to this view-point) how do you de-condition a dog to a specific scent?

Well, a paper found by Pathfinder (on another thread) suggests you can (de-condition a dog to specific scents).

Here is the relevant section from the paper Pathfinder found:

6) Dogs used to develop probable cause based upon residual scent must be negatively conditioned to human urine, feces, and semen[/u] in order to ensure that the animal will not alert when encountering these substances during a search. All dogs, no matter what level of training, used in the detection of decomposed human tissue should be negatively conditioned to the scent of decomposed non-human tissue. It must be kept in mind, however, that many dogs will react or show interest to any decomposed tissue at certain short times during the decomposition process.

http://www.csst.org/forensic_evidence_canines.html


So.

If you can de-condition a dog to those scents, why not blood?

[ferryman]

To add to my opening post, under the auspices of the (US) FCP, a cadaver dog would be teamed up with a second dog, specifically trained to react to the scent of just blood, so that the (potential) advantage to an investigation of finding blood would not be lost.

The weakness of the Eddie-and-Keela combination was always that both dogs would react to the scent of blood.

Of course, Keela was a late add-on long after Eddie had commenced operational service; distinct from dogs working for the FCP, where two dogs would be trained in tandem to operate as a team with distinct and unique (from each other) scent-detecting capabilities.

There was no overlap; rather, separate and discrete capabilities.

[Eleanor]

Eddie was already an old dog, already conditioned to scent blood when his training as a Cadaver Dog began.  This was a recipe for confusion.

[pathfinder73]

Eddie was already an old dog, already conditioned to scent blood when his training as a Cadaver Dog began.  This was a recipe for confusion.

"Training a cadaver dog requires regular contact with human blood, decaying flesh and bones. "

Meet Badger, Spud, Muzzy and Tito - highly trained specialists and crime fighters.

All four of the team went to Portugal in June last year, working with the Metropolitan Police.

But what is it that makes these springer spaniels so skilled? Partly, it’s because their olfactory glands - in their noses - are 400 times more powerful than a human’s.

Pc Newman said: “The dogs are tasked with looking for evidence which can be a minuscule piece of evidence like a blood drop which is pin-prick sized.”

[Eleanor]

"Training a cadaver dog requires regular contact with human blood, decaying flesh and bones. "

Meet Badger, Spud, Muzzy and Tito - highly trained specialists and crime fighters.

All four of the team went to Portugal in June last year, working with the Metropolitan Police.

But what is it that makes these springer spaniels so skilled? Partly, it’s because their olfactory glands - in their noses - are 400 times more powerful than a human’s.

Pc Newman said: “The dogs are tasked with looking for evidence which can be a minuscule piece of evidence like a blood drop which is pin-prick sized.”

But the dogs can't explain the difference.

However, this Thread is about desensitising dogs who have earlier been taught one thing and now need to forget that in favour of a new thing.
I don't know if this is possible, but Eddie was too old and seasoned by the time he was retrained to include Cadaver Odour.

[stephen25000]

But the dogs can't explain the difference.

However, this Thread is about desensitising dogs who have earlier been taught one thing and now need to forget that in favour of a new thing.
I don't know if this is possible, but Eddie was too old and seasoned by the time he was retrained to include Cadaver Odour.

Eleanor, how do you know what Eddie could or could not do ?

[Eleanor]

Eleanor, how do you know what Eddie could or could not do ?

We all know he alerted to Blood.  And presumably Cadaver Odour.  So he hadn't been desensitised.

[Carana]

I've long tended to the view that it must be possible for a single and simple reason.

The US Forensic Canine Program broke with a hallowed tradition of (conventionally) both US and (specifically) English law enforcement (but not Scottish) in ruling as admissible (evidence in court) uncorroborated cadaver-dog alerts. 

Indeed, under the auspices of the FCP, an uncorroborated cadaver-dog alert was taken as proof in its own right of murder, and I long argued that that could only be because dogs working for that (US) program had been de-conditioned to the scent of blood.

But (argued those who objected to this view-point) how do you de-condition a dog to a specific scent?

Well, a paper found by Pathfinder (on another thread) suggests you can (de-condition a dog to specific scents).

Here is the relevant section from the paper Pathfinder found:

http://www.csst.org/forensic_evidence_canines.html


So.

If you can de-condition a dog to those scents, why not blood?

It actually says "negatively conditioned", though. I understand that to mean "trained to ignore" - i.e., alerts to the unwanted substance don't get a treat.

My understanding is that if a dog is cross-trained, it will react to what it was originally trained for, plus whatever new substance is added to the training.

I don't see how you can successfully actively decondition a dog to something once it has already been trained to find it: if a dog has been rewarded for a correct alert to substance A for years, then all of a sudden no longer gets his treat for it, then you get one very confused dog.

I don't see how a dog could be trained not to react to blood when it's a core component of (or would be in close proximity to) the human remains it's meant to be searching for.

[slartibartfast]

We all know he alerted to Blood.  And presumably Cadaver Odour.  So he hadn't been desensitised.

Why would you desensitise to blood?

[Alice Purjorick]

Well it started off as a good idea.
It might pay to establish the principles actually do apply before making assumptions on the detail.

[Mr Gray]

"Training a cadaver dog requires regular contact with human blood, decaying flesh and bones. "

Meet Badger, Spud, Muzzy and Tito - highly trained specialists and crime fighters.

All four of the team went to Portugal in June last year, working with the Metropolitan Police.

But what is it that makes these springer spaniels so skilled? Partly, it’s because their olfactory glands - in their noses - are 400 times more powerful than a human’s.

Pc Newman said: “The dogs are tasked with looking for evidence which can be a minuscule piece of evidence like a blood drop which is pin-prick sized.”

so the task of the dogs is to look for evidence...something I have been saying for some time

[pathfinder73]

so the task of the dogs is to look for evidence...something I have been saying for some time

You said the dogs didn't find any in error. Samples were taken and stored. It's not up to the dogs to prove who they came from.

[ferryman]

Why would you desensitise to blood?

Simply this.

Uncorroborated cadaver dog alerts (traditionally) are not accepted as stand-alone evidence of murder because there is always the chance that the dog might have reacted to the scent of blood.

If you de-condition a (cadaver) dog (to the scent of blood) you can have greater certainty that if the dog reacts, the dog has, indeed, reacted to the scent of cadaver-odour.

At the same time, because you have a second dog, trained to react to nothing but blood, you don't lose the ability to find blood if blood-deposits are present at the crime-scene and you have a dog  to detect it.

[slartibartfast]

Simply this.

Uncorroborated cadaver dog alerts (traditionally) are not accepted as stand-alone evidence of murder because there is always the chance that the dog might have reacted to the scent of blood.

If you de-condition a (cadaver) dog (to the scent of blood) you can have greater certainty that if the dog reacts, the dog has, indeed, reacted to the scent of cadaver-odour.

At the same time, because you have a second dog, trained to react to nothing but blood, you don't lose the ability to find blood if blood-deposits are present at the crime-scene and you have a dog  to detect it.

It's why you have a blood dog as well. To discount cadaver dog alerts that are also alerted by blood dog. You need them to alert to blood as it is a major indicator off something serious. Blood usually remains inside bodies unlike other fluids frequently mentioned.

[ferryman]

It's why you have a blood dog as well. To discount cadaver dog alerts that are also alerted by blood dog. You need them to alert to blood as it is a major indicator off something serious. Blood usually remains inside bodies unlike other fluids frequently mentioned.

There is no advantage to two dogs trained to react to the same scent (the position with the Eddie-and-Keela combination).