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

[Alice Purjorick]

"To successfully cross train a dog requires a few rules that cannot be broken. First, you must be able to clearly communicate to the dog, exactly what the task is and the circumstances.

Next, you must use a different command/word for each discipline so that the dog knows what you expect him to do. The dog must have a different signal for each discipline. For example, one signal for HRD, one for live finds, one for drowning, etc. Lastly, you must trust your dog and be able to "read” what the dog is communicating to you.

The only drawback to cross training a dog is that some authorities will not trust the dog’s findings if they are cross trained. They may feel that the dog could make a mistake and the evidence may not hold up in court".

http://cadaverdog.com/index.php

You could always have a five quid whip among 13 of you and buy Andy's book!

[pathfinder73]

[Mr Gray]

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.

so what evidence did they find

[pathfinder73]

so what evidence did they find

Keela alerted in a number of places for blood. Forensics found none.

'Keela' The Crime Scene Investigation (C.S.I.) dog will search for and locate human blood to such small proportions that it is unlikely to be recovered by the forensic science procedures in place at this time due to its size or placement.

Forensic testing may not produce evidence but any alert may provide intelligence to support other factors in the investigation of a crime.

http://www.mccannpjfiles.co.uk/PJ/MARTIN_GRIMES_PERSONAL.htm

[ferryman]

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.

Not quite!

This thread is about training two dogs (from scratch) distinct and different and different disciplines, one to react to cadaver scent (not blood); the other blood (not cadaver scent).

To do that, you need to desensitise  a dog to certain scents.

I agree it seems counter-intuitive to suppose that you can.

But the reference in the link Pathfinder found suggests it is, indeed, possible.

Just no clue how.

And the (potential) advantage (of a desensitising a dog to the scent of blood) is that you can have greater certainty that if your (cadaver) dog does react, it has detected cadaver-scent, you can have greater certainty that the dog has, indeed, reacted to a cadaver scent and can use that as stand-alone evidence of murder.

[ferryman]

Keela alerted in a number of places for blood. Forensics found none.

'Keela' The Crime Scene Investigation (C.S.I.) dog will search for and locate human blood to such small proportions that it is unlikely to be recovered by the forensic science procedures in place at this time due to its size or placement.

Forensic testing may not produce evidence but any alert may provide intelligence to support other factors in the investigation of a crime.

http://www.mccannpjfiles.co.uk/PJ/MARTIN_GRIMES_PERSONAL.htm

You don't think that might have been Grime, covering all bases for if a dog alerts and no (forensic) evidence is found?

[Carana]

Not quite!

This thread is about training two dogs (from scratch) distinct and different and different disciplines, one to react to cadaver scent (not blood); the other blood (not cadaver scent).

To do that, you need to desensitise  a dog to certain scents.

I agree it seems counter-intuitive to suppose that you can.

But the reference in the link Pathfinder found suggests it is, indeed, possible.

Just no clue how.

And the (potential) advantage (of a desensitising a dog to the scent of blood) is that you can have greater certainty that if your (cadaver) dog does react, it has detected cadaver-scent, you can have greater certainty that the dog has, indeed, reacted to a cadaver scent and can use that as stand-alone evidence of murder.

TBH... I don't quite follow, FM.

How on earth can you desensitise a dog to the scent of blood when it's part and parcel of what it's supposed to be searching for, which even then requires eliminating innocent explanations?

Which part of a decomposing human would you train it on that doesn't contain blood or hasn't been in close proximity to any?

It may be possible at some time in the future to physically isolate potentially suspicious VOCs not associated with human blood, nor in a combination of VOCs that can't be found in nature or in any naturally occuring situation and present them with advanced pseudo-scents... but that doesn't seem to be the state of affairs at the moment.

The bottom line - in this case - is that there was no forensic evidence of blood, nor of anything else aside from some incomplete DNA of no particular investigative value.

[ferryman]

TBH... I don't quite follow, FM.

How on earth can you desensitise a dog to the scent of blood when it's part and parcel of what it's supposed to be searching for, which even then requires eliminating innocent explanations?

Which part of a decomposing human would you train it on that doesn't contain blood or hasn't been in close proximity to any?

It may be possible at some time in the future to physically isolate potentially suspicious VOCs not associated with human blood, nor in a combination of VOCs that can't be found in nature or in any naturally occuring situation and present them with advanced pseudo-scents... but that doesn't seem to be the state of affairs at the moment.

The bottom line - in this case - is that there was no forensic evidence of blood, nor of anything else aside from some incomplete DNA of no particular investigative value.

Let's put it like this.

If you can train a dog to detect only blood (it seems you can, Keela was thus trained, and the whole point of the tandem-team is that one dog detects only blood; the other, only cadaver-scent) then how was the blood-dog desensitised to cadaver-scent?

It must have been, because otherwise, you can't call it a blood-dog.

And it seems you can train a dog to discriminate between scents, not that it detects (obviously all dogs will detect all scents, irrespective of training) but that it will react to

[Alice Purjorick]

Not quite!

This thread is about training two dogs (from scratch) distinct and different and different disciplines, one to react to cadaver scent (not blood); the other blood (not cadaver scent).

To do that, you need to desensitise  a dog to certain scents.

I agree it seems counter-intuitive to suppose that you can.

But the reference in the link Pathfinder found suggests it is, indeed, possible.

Just no clue how.

And the (potential) advantage (of a desensitising a dog to the scent of blood) is that you can have greater certainty that if your (cadaver) dog does react, it has detected cadaver-scent, you can have greater certainty that the dog has, indeed, reacted to a cadaver scent and can use that as stand-alone evidence of murder.

From the document linked by PF and me sometime ago the csst jobby.
"Unfortunately, in such a situation the trier of fact may easily be misled as to both the accuracy and precision of the dog's actions: Accuracy in the sense that the dog (depending upon its level of training) may be reacting to something other than residual scent from decomposed human tissue; precision in that the dog may be reacting correctly to the scent of decomposed human tissue, but imprecise in the sense that the dog is not differentiating between whose decomposed human tissue is giving the scent".

[ferryman]

From the document linked by PF and me sometime ago the csst jobby.
"Unfortunately, in such a situation the trier of fact may easily be misled as to both the accuracy and precision of the dog's actions: Accuracy in the sense that the dog (depending upon its level of training) may be reacting to something other than residual scent from decomposed human tissue; precision in that the dog may be reacting correctly to the scent of decomposed human tissue, but imprecise in the sense that the dog is not differentiating between whose decomposed human tissue is giving the scent".

So a dog can't differentiate between the decomposed human tissue of person A or the decomposed human tissue of person B.

Irrelevant to the point we are discussing.

Can you train a dog to differentiate between the specific material blood and non-blood-based remnants of a corpse?

[Carana]

Let's put it like this.

If you can train a dog to detect only blood (it seems you can, Keela was thus trained, and the whole point of the tandem-team is that one dog detects only blood; the other, only cadaver-scent) then how was the blood-dog desensitised to cadaver-scent?

It must have been, because otherwise, you can't call it a blood-dog.

And it seems you can train a dog to discriminate between scents, not that it detects (obviously all dogs will detect all scents, irrespective of training) but that it will react to

If a dog ONLY gets a reward in reaction to an isolated substance (in Keela's case dried human blood), isolated or mixed with other substances, then she only gets her treat when that is present.

Eddie was a wide-spectrum dog to narrow down the initial area of potential interest.

Let's try this a different way. Eddie smells anything with sugar. In theory, anything without sugar will be ignored. He reacts. A different dog, an expert in chocolate detection, is wheeled in to check if the sugar-marked areas show any sign of cocoa, a component of chocolate.

[Carana]

So a dog can't differentiate between the decomposed human tissue of person A or the decomposed human tissue of person B.

Irrelevant to the point we are discussing.

Can you train a dog to differentiate between the specific material blood and non-blood-based remnants of a corpse?

I think that you'd need to turn the question on its head: the first to be wheeled into a specific area for inspection is the GP. If the GP alerts, you call in a specialist to narrow the field for further examination and send off samples for lab analysis.

[Alice Purjorick]

So a dog can't differentiate between the decomposed human tissue of person A or the decomposed human tissue of person B.

Irrelevant to the point we are discussing.

Can you train a dog to differentiate between the specific material blood and non-blood-based remnants of a corpse?

It would be relevant in the case of murder.
You raised the issue of murder not me.  So you have made it relevant.

[ferryman]

It would be relevant in the case of murder.
You raised the issue of murder not me.  So you have made it relevant.

A dog's ability (or inability) to distinguish between (deceased) person A or (deceased) person B is not the subject of discussion (irrespective of the cause of death).

[Carana]

It would be relevant in the case of murder.
You raised the issue of murder not me.  So you have made it relevant.

I don't see where FM mentioned murder.

A problem seems to have been the assumption that "body fluids" should somehow be assumed to mean post-mortem ones.

That doesn't appear to be the case as Grime admitted (later, when asked) that the dogs would react to dried blood from LIVING people).

For some reason, some people in certain quarters appear to have steadfastly ignored that for reasons best known to themselves and continue to do so despite claiming to be experts on the files. At least one person set up some kind of 'study group' with only partial information (including long-debunked tabloid extracts) as material to, erm, study.

Why?