Sardog

[Lablover]

Question please.

As a dog exhales, how impaired is their scenting ability?

Was reading a book, in bed today while suffering from the flu which indicated very little loss of function.

[Sardog]

LL: very little loss of function

You have answered your question.....

[Erny]

Good question LL.

Of the little that I know about the 'mechanics' of dogs in the action of scenting, I understand that air that is "sniffed" 'rests' in the nasal chambers and this allows smell molecules to remain there and to accumulate on a mucous layer containing millions of odour sensitive cilia.

There is also the "subethmoidal shelf" where scent is maintained and accumulated even after it has been passed on to the this nasal membrane lining.

I would expect this is why exhalation would have little impedance to the dog's ability to scent.

ETA: There is also a "vomeronasal organ" which is a pouch lined with receptor cells and which is located above the roof of the dog's mouth behind the incisors. (Can't say I've seen it but have read of it.) I've read different things about the function/purpose of this 'organ' and so it seems there is some uncertainty of it, but apparently it is more involved in the unconsious perception of sex hormones, rather than in the conscious appreciation of smells. Not sure in this, but if it does involve other scent as well, then I wonder if taste has a bearing/influence on scent as well, via this 'organ' and further enhancing dogs' extraordinary scenting talent.

ETA: Hope you are feeling better.

Edited August 15, 2007 by Erny

[NaturallyWild]

As well as all that, i read or heard somewhere that someone did some airflow (windtunnel like) tests on the dogs nose. Apparently the shape of the nose allows air to move in and out through different parts. They don't "breath" as such when they are scenting, the air moves in through the front main holes then out through the side slits.

[Erny]

That's interesting NW. Must admit I didn't really know what those side slits (there must be a name for them?) were for. Only thing I could think of at the time was for the dog to have greater capability of drawing in scent from greater angles and perhaps some relationship with brain computation as to sourcing the direction of the scent. Just my thoughts though - completely unfounded and nothing to do with anything previously written.

So, in what you've read, does it mean kind of like the way Aborigines (and others who sport the talent) use the digereedoo (sp?) IE breathing in and breathing out at the same time. Or like those who play the harmonica? Except we tend to use throat and nose, I think.

But in the dog's case air that is "sniffed" (as opposed to breathed, which would travel through to the lungs) comes in via the main of the nostril and escapes through the slit, leaving the scent molecules behind in the scent sensitive mucous membrane ????

Or have I completely misunderstood? :rolleyes:

If anyone has a book or books which dedicates a good amount to the mechanics of dog's sniffing and scenting, I'd appreciate knowing which they are. With what I've managed to learn of it has come from various snippets (some with bare reference to it, others only slightly more) from various books.

[Arya]

This is interesting stuff to me as I've just started to teach my girl to track. Heaps of fun! Can recommend it to anyone. Dog absolutely loves it :rolleyes:

[NaturallyWild]

But in the dog's case air that is "sniffed" (as opposed to breathed, which would travel through to the lungs) comes in via the main of the nostril and escapes through the slit, leaving the scent molecules behind in the scent sensitive mucous membrane ????

Yes thats what i remember it being like. I think someone did this research about 2 or so years ago. Will have to have a look if i have a spare minute.

I'm assuming that this would increase scenting ability because the air being expired would be directed away from the air being inspired directly in front of the nose.

Edited August 16, 2007 by NaturallyWild

[NaturallyWild]

Found an online paper in regards to this - can't remember if this was it or whether there was more recent research done.

http://www.mne.psu.edu/psgdl/cainebkchapter..pdf

[Erny]

Thanks for the link NW. Have printed it out to read through later.

And thanks for putting up the thread LL. I enjoy looking into stuff like this - but my googling never seems to lead me to very much. Must all be in the wrist action .

Of course - still interested to know if there are any books/more links on the subject, if anyone can point me in the right direction.

Cheers!

Erny

Edited August 17, 2007 by Erny

[Tangwyn]

Hmmm... I guess we're assuming that in tracking a human scent that the dog would have ongoing exposure to the same odour? In this case, of course a dog's scenting capability won't be reduced by exhaling as he is constantly re-exposed to the scent.

What about a detector dog that exhales just as it passes over the top of an odour in a single envelope packed tightly and vertically into a tray with 400 other letters? How will a dog detect an odour if it never inhales it and thus never exposes intranasal cilia to odour molecules?

In terms of tracking, how much do people believe panting affects odour detection? What about in a more refined detection environment?

[poodlesplus]

In terms of tracking, how much do people believe panting affects odour detection? What about in a more refined detection environment?

I am not a great one for the biology, but it was very interesting to see that the exhaled air caused an input air stream to develop. This is very good "design" From my field observations, a lot of dogs do a sort of shallow pant when they are attempting to find a lost scent. It could well be a way of increasing the number of processed scent particles.

In practical terms, my old Lab 13 1/2 years who does now pant a bit , is still capable of very easily detecting 3 odd hours old track scents. I don't let him do a lot, but it is still there.In his hey day he was a bit better and didn't pant anywhere as much.

I have also observed my mini poodle in "hard" corners just stand and process scent while her nostrils flex in a semi pant. She then makes very good tracking decisions based on this.

I have been mucking about with some CFD experiments on scent discrimination. All that I can say is that I would encourage dogs to scan, and i would expose them to different winds.. I would never correct for this excercise, the possibilites as to were the scent is congregated is so complex, so difficult. Modelling tracking is just way to difficult. I lack the light years neccessary to make it happen.

[Erny]

What about a detector dog that exhales just as it passes over the top of an odour in a single envelope packed tightly and vertically into a tray with 400 other letters? How will a dog detect an odour if it never inhales it and thus never exposes intranasal cilia to odour molecules?

In answer to the above, refer to the first para on page 5 of the link NW put up. It reads :-

"While sniffing a scent source on a gound plane, the orientation of the dog's nose is such that the expired air jets are directed to the rear and sides along the ground plane. The turbulent mixing of these jets entrains the surrounding air, drawing an air current toward the nostrils from perhaps several cm ahead along the ground plane. This extends the aerodynamic "reach" of the inspiratory olfaction phase and helps, in some scenarios, to draw scents forth from concealed locations. It is a form of aerodynamic ejector or inducer."

If you read further it goes on to talk about how the angle the dog puts its nose to the area being 'scented'. The dog might go beyond the direct source of the scent, but the jet of air caused by exhalation stirs the scent up so that it is 'caught' by the dog so the dog can re-direct to the source of the scent. Not forgetting that 'sniffing' is a very fast, repetative and ongoing conscious activity.

Well - that's my interpretation of it, anyway.

In terms of tracking, how much do people believe panting affects odour detection? What about in a more refined detection environment?

I certainly don't have any documented matter to refer to (at this moment) on this, so my own thoughts on this are that even when panting, the dog can still 'sniff'. Once a scent of particular interest is detected, I've found the dog will pause in its panting to better focus on locating the source of the scent. As I said, this is my own thoughts/guess.

Sardog is probably the best one to ask on this score. Or Lablover?

ETA: Sorry - there was a delay in me posting this already formatted post and I see Poodlesplus has already made reference to part of what I've said.

ETA: Thanks again NaturallyWild. Haven't fully read the paper you provided a link to, but what I have read has been quite informative.

Edited August 17, 2007 by Erny

[Arya]

This is great, thanks for the link NW. Just getting right into tracking and enjoy reading stuff like this.