# The Effects of Metronidazole and Doxycyline on the scenting ability of detector dogs



## EdA (May 13, 2003)

*Effects of oral administration of metronidazole and doxycycline on olfactory capabilities of explosives detection dogs
*

Eileen K. Jenkins DVM, MS; Tekla M. Lee-Fowler DVM, MS; T. Craig Angle PhD; Ellen N. Behrend VMD, PhD; George E. Moore DVM, PhD 
Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL 36489. (Jenkins, Lee-Fowler, Behrend); Department of Canine Performance Sciences Program, College of Veterinary Medicine, Auburn University, Auburn, AL 36489. (Angle); Department of Comparative Pathobiology, College of Veterinary Medicine, Purdue University, West Lafayette, IN 47907. (Moore)
Dr. Jenkins' present address is 248th Medical Detachment (Veterinary Service Support), Fort Bragg, NC 28310.
Address correspondence to Dr. Lee-Fowler ([email protected]).

*OBJECTIVE* To determine effects of oral administration of metronidazole or doxycycline on olfactory function in explosives detection (ED) dogs.
*ANIMALS* 18 ED dogs.
*PROCEDURES* Metronidazole was administered (25 mg/kg, PO, q 12 h for 10 days); the day prior to drug administration was designated day 0. Odor detection threshold was measured with a standard scent wheel and 3 explosives (ammonium nitrate, trinitrotoluene, and smokeless powder; weight, 1 to 500 mg) on days 0, 5, and 10. Lowest repeatable weight detected was recorded as the detection threshold. There was a 10-day washout period, and doxycycline was administered (5 mg/kg, PO, q 12 h for 10 days) and the testing protocol repeated. Degradation changes in the detection threshold for dogs were assessed.
*RESULTS* Metronidazole administration resulted in degradation of the detection threshold for 2 of 3 explosives (ammonium nitrate and trinitrotoluene). Nine of 18 dogs had a degradation of performance in response to 1 or more explosives (5 dogs had degradation on day 5 or 10 and 4 dogs had degradation on both days 5 and 10). There was no significant degradation during doxycycline administration.
*CONCLUSIONS AND CLINICAL RELEVANCE* Degradation in the ability to detect odors of explosives during metronidazole administration at 25 mg/kg, PO, every 12 hours, indicated a potential risk for use of this drug in ED dogs. Additional studies will be needed to determine whether lower doses would have the same effect. Doxycycline administered at the tested dose appeared to be safe for use in ED dogs.

Could a similar effect occur in the scenting ability of hunting dogs?


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## Peter Balzer (Mar 15, 2014)

That's pretty interesting. Do you have a link to the full study?


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## EdA (May 13, 2003)

You will need to register to have access to the full study

American Journal of Veterinary Research

http://avmajournals.avma.org/doi/pdfplus/10.2460/ajvr.77.8.906


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## Brad B (Apr 29, 2004)

Isn't that a pretty high dosage though?


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## EdA (May 13, 2003)

Brad B said:


> Isn't that a pretty high dosage though?


Standard dose for giardia and certain types of inflammatory bowel disease


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## ehf (May 13, 2010)

EdA said:


> Standard dose for giardia and certain types of inflammatory bowel disease


I have a Malinois that had Lymes and was treated with standard dose of Doxycycline with no results. So on the next try the dose was doubled. It cured the Lymes just fine with no organ damage and all the blood and urine test are all in normal range. I use him for tracking and I believe the meds affected his nose as He is nowhere near as accurate as before the meds. Dr. EDA could this be possible?


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## Gerry Clinchy (Aug 7, 2007)

Interesting ... what would be the "normal" course (in days) of metronidazole? Did they also study how long it would take for the olfactory accuracy to return to normal?

ehf, what was the dosage level of doxy that caused your dog to lose its olfactory accuracy?


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## Brad B (Apr 29, 2004)

EdA said:


> Standard dose for giardia and certain types of inflammatory bowel disease


Thanks, for some reason I had it in my head that it was 2 mg/lb.


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## ehf (May 13, 2010)

Gerry Clinchy said:


> Interesting ... what would be the "normal" course (in days) of metronidazole? Did they also study how long it would take for the olfactory accuracy to return to normal?
> 
> ehf, what was the dosage level of doxy that caused your dog to lose its olfactory accuracy?


The dosage He took was 200mg twice a day. Also was give 10mg enalapril once daily for one month.


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## EdA (May 13, 2003)

ehf said:


> I have a Malinois that had Lymes and was treated with standard dose of Doxycycline with no results. So on the next try the dose was doubled. It cured the Lymes just fine with no organ damage and all the blood and urine test are all in normal range. I use him for tracking and I believe the meds affected his nose as He is nowhere near as accurate as before the meds. Dr. EDA could this be possible?


It is known that the lyme borrelia has affects on both the central and peripheral nervous systems therefore I suspect your dog's poor performance was a result of the disase not the cure.


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## mjh345 (Jun 17, 2006)

EdA said:


> *Effects of oral administration of metronidazole and doxycycline on olfactory capabilities of explosives detection dogs
> *
> 
> Eileen K. Jenkins DVM, MS; Tekla M. Lee-Fowler DVM, MS; T. Craig Angle PhD; Ellen N. Behrend VMD, PhD; George E. Moore DVM, PhD
> ...


I'd bet good money on it


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## Gerry Clinchy (Aug 7, 2007)

ehf said:


> The dosage He took was 200mg twice a day. Also was give 10mg enalapril once daily for one month.


Don't know the weight of your dog ... but when I treated my 52# Golden for Lyme, I used 500 mg/day ... split into two doses off 300 & 200, AM and PM. So, your 400 mg sounds like a "standard" dose to me.


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## DarrinGreene (Feb 8, 2007)

I'm sure it would however - scenting a bird is relatively easy relative to scenting most explosives. A human can smell a bird, even previously frozen and thawed. Not so with explosives. Also - successful trial and hunting test dogs do little with their nose (supposedly).


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## EdA (May 13, 2003)

Gerry Clinchy said:


> Don't know the weight of your dog ... but when I treated my 52# Golden for Lyme, I used 500 mg/day ... split into two doses off 300 & 200, AM and PM. So, your 400 mg sounds like a "standard" dose to me.


The dose is 5-10 mg/lb/day, with TBD most are using the high end of the dose range which is what your dog got.


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## EdA (May 13, 2003)

DarrinGreene said:


> I'm sure it would however - scenting a bird is relatively easy relative to scenting most explosives. A human can smell a bird, even previously frozen and thawed. Not so with explosives. Also - successful trial and hunting test dogs do little with their nose (supposedly).


I know and understand far less about scenting my 47 years as a veterinarian and retriever owner notwithstanding but I can say without reservation that a keen sense of smell is paramount to success in retriever field trials. If you can smell a duck I will give you that one, if you can smell a pheasant, chukar, or quail you have a championship nose.


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## ehf (May 13, 2010)

EdA said:


> It is known that the lyme borrelia has affects on both the central and peripheral nervous systems therefore I suspect your dog's poor performance was a result of the disase not the cure.


Thank You Dr. EDA for the reply this explains a lot about his performance.


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## AAA Gundogs (Mar 17, 2016)

EdA said:


> *Effects of oral administration of metronidazole and doxycycline on olfactory capabilities of explosives detection dogs
> *
> 
> Eileen K. Jenkins DVM, MS; Tekla M. Lee-Fowler DVM, MS; T. Craig Angle PhD; Ellen N. Behrend VMD, PhD; George E. Moore DVM, PhD
> ...


I don't know the effects of these medicines on canines but I remember reading another study that scenting ability is improved by a reduction in core temp while an increase in core temp hinders scenting.

Is this along those lines?


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## Gerry Clinchy (Aug 7, 2007)

EdA said:


> The dose is 5-10 mg/lb/day, with TBD most are using the high end of the dose range which is what your dog got.


Yes ... one vet recommended low dose; another the higher dose. The one who recommended the higher dose had had more experience with treating dogs with TBD.


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## J. Walker (Feb 21, 2009)

On a related note, one of my dogs was on Cipro a couple of times. The first time, his markng fell off significantly. I wrote it off to just not feeling himself. The second time, he was breaking down half-way to 80 yard marks so I knew it wasn't my imagination. I asked my vet who I had a really good relationship with about any side effects. He said Cipro has been known to affect vision in cats but said if I noticed it in my dog, he believed it. My dog was taken off of Cipro and within a few days, his marking was back to normal.


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## ehf (May 13, 2010)

Gerry Clinchy said:


> Don't know the weight of your dog ... but when I treated my 52# Golden for Lyme, I used 500 mg/day ... split into two doses off 300 & 200, AM and PM. So, your 400 mg sounds like a "standard" dose to me.


Gerry My dog weight was seventy pounds. The dosage was determined by two vets. one being a liver and kidney specialist the other being the head vet at a very respected vet college in the US. I can not give out names. They was trying not to damage any organs with that dosage and it worked.


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## mjh345 (Jun 17, 2006)

DarrinGreene said:


> I'm sure it would however - scenting a bird is relatively easy relative to scenting most explosives. A human can smell a bird, even previously frozen and thawed. Not so with explosives. Also - successful trial and hunting test dogs do little with their nose (supposedly).


You would be hard pressed to post something more wrong!!!

Crazy nutso post of the month nominee!!!!


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## wheelhorse (Nov 13, 2005)

mjh345 said:


> Quote Originally Posted by DarrinGreene View Post
> I'm sure it would however - scenting a bird is relatively easy relative to scenting most explosives. A human can smell a bird, even previously frozen and thawed. Not so with explosives. Also - successful trial and hunting test dogs do little with their nose (supposedly).
> 
> You would be hard pressed to post something more wrong!!!


there is quite a difference between scenting a 3-5 lb dead bird and trace amounts of explosives, cadaver or drugs. The key phrase is "relatively easy" 

Also, an explosive dog can not set up a "big hunt", because that would mean a dead dog. A cadaver/drug dog can not set up big hunt either, because they would then be contaminating a crime scene.


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## DarrinGreene (Feb 8, 2007)

EdA said:


> I know and understand far less about scenting my 47 years as a veterinarian and retriever owner notwithstanding but I can say without reservation that a keen sense of smell is paramount to success in retriever field trials. If you can smell a duck I will give you that one, if you can smell a pheasant, chukar, or quail you have a championship nose.


The winning dog will (appear to) not use his nose at all in a trial, front footing his marks and ignoring it on blinds. He may get away with honoring his nose on a blind but I've never heard anyone say give extra points for doing so. We all know they smell foot scent, bird scent and many other things that help them succeed (and fail) but the exercises we test them on actually do nothing to test/reward a dog for having a good nose.

As for the study, 18 is an infinitesimally small sample size. 

I find it hard to argue with the idea that scenting a gram of cocaine or a trace of explosive is many times more difficult than finding a freshly killed or semi decomposed game bird.


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## ErinsEdge (Feb 14, 2003)

> Also - successful trial and hunting test dogs do little with their nose (supposedly).


I agree you probably can't compare explosive scenting to bird scenting, but if you think dogs running AA stakes or even qualifying stakes don't use their noses, you are really showing your lack of experience and success at those levels. I agree with Marc, only maybe the dumbest post in a *year*, for someone that constantly professes to know dogs better than the rest of us. Good bird placement makes it crucial for dogs to have a good nose if they aren't able to front foot those upper level marks.
Stick to your naughty pets.


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## steve schreiner (Jun 15, 2009)

DarrinGreene said:


> The winning dog will (appear to) not use his nose at all in a trial, front footing his marks and ignoring it on blinds. He may get away with honoring his nose on a blind but I've never heard anyone say give extra points for doing so. We all know they smell foot scent, bird scent and many other things that help them succeed (and fail) but the exercises we test them on actually do nothing to test/reward a dog for having a good nose.
> I find it hard to argue with the idea that scenting a gram of cocaine or a trace of explosive is many times more difficult than finding a freshly killed or semi decomposed game bird.



When I was training bird dogs the subject always came up about what was the dog actually scenting when it went on point..Some said it was body scent others believed it was the birds breath.. big difference..The reason they gave was because some dogs would run in a grab a dead bird on a retrieve and that same dog would point a wounded bird..some also tossed out the idea the dog was pointing the wounded bird because of blood scent...The dog could tell the difference from a live bird and a dead one though..Some dogs would grab a wounded bird but would point if unharmed..scent discrimination for sure though..Steve S


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## DarrinGreene (Feb 8, 2007)

ErinsEdge said:


> I agree you probably can't compare explosive scenting to bird scenting, but if you think dogs running AA stakes or even qualifying stakes don't use their noses, you are really showing your lack of experience and success at those levels.


You could win the lottery using a strategy I gave you and still say I was wrong. 

I said trials don't reward dogs for using their nose. Quite the opposite, in fact. 

Front foot the marks. Ignore scent as a factor on blinds. 

For Christ's sake they run em down wind of the flier crates and old falls to see if they CAN ignore their nose. 

The fact that the dog is smarter than the human and uses it's nose anyway isn't exactly a surprise to me.


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## DarrinGreene (Feb 8, 2007)

steve schreiner said:


> [/COLOR]
> 
> 
> When I was training bird dogs the subject always came up about what was the dog actually scenting when it went on point..Some said it was body scent others believed it was the birds breath.. big difference..The reason they gave was because some dogs would run in a grab a dead bird on a retrieve and that same dog would point a wounded bird..some also tossed out the idea the dog was pointing the wounded bird because of blood scent...The dog could tell the difference from a live bird and a dead one though..Some dogs would grab a wounded bird but would point if unharmed..scent discrimination for sure though..Steve S


That wouldn't surprise me a bit Steve. The study was about a general reduction in the dog's ability to "smell" though. 

I would argue that finding a bird from what we would call a reasonable distance takes only a percentage of the dog's nose capabilities though. Taking a few percentage points off the top wouldn't effect it enough to be noticeable, I don't believe. 

I've seen a lab turn on a dime at 120 feet to find an item that when you put it to your nose you couldn't smell yourself. Put a bird directly to your nose and smell it - it has a discernable odor even to a human. 

I'll admit never having snorted explosives but I have handled them enough to know they don't smell at all like a game bird. 

I may or may not have any experience with recreational drugs


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## DarrinGreene (Feb 8, 2007)

ErinsEdge said:


> I agree you probably can't compare explosive scenting to bird scenting


Oh and I've seen more dogs personally working explosives while on metro that the sample size of this study. I've worked hundred upon hundreds of finds with trainers who had literally thousands of detection dogs under their belts and not once, not a single time, did anyone ever use a dog being on metro as a justification for a failure. 

I guess in two years of teaching dogs to hunt while running blinds and imprinting dogs for explosive detection 50 hours a week, under the best trainers in the country, I didn't learn a single thing. 

Metro may have been a factor that we never noticed but we had dogs that were chronically on the stuff and did their jobs just fine.


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## ErinsEdge (Feb 14, 2003)

DarrinGreene said:


> You could win the lottery using a strategy I gave you and still say I was wrong.


I would follow Dr Ed's strategy in the field because he has made numerous field champions, he has respect for the dogs' innate intelligence, discrimination of smells, and what makes a great dog great. You are just spinning the facts as you understand them.


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## jrrichar (Dec 17, 2013)

Darrin:

1. FT dogs are not rewarded for their nose but they do use them and some of the best likely have a good one. Birds do have a smell that we may detect if we are right in front of it on a table but dealing with the "field" element adds a huge level of difficulty that separates good noses and great noses. If I had to guess, I would say your FC/AFC dogs have phenomenal eyes, intelligence, and noses. The last two would likely be the reason that bomb and narcotics dogs come from these FT lines. It would be impossible in a trial to know that the dog that front footed a bird did it solely by sight/memory. It is likely a combination of all its senses and intelligence. A dog doesn't need to have his nose to the ground to be using it. 

2. To my knowledge many forms of drugs have no odor but for obvious reasons none of us would care to get close enough to them. I have handled a number of the drugs that dogs are trained against- hard task indeed. 

3. An n value of 18 is more then adequate for the RESEARCH. Since I have sat on committees (IACUC) that have determined approval for such studies n value is determined by multiple things. Unless you have unlimited funds and resources, large sample studies are typically reserved for clinical trials- supported by big money. In the world of research you use the n value that is required for the hypothesis, no less and no more. It's not based on what the public sees as an adequate sample size-thankfully.


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## steve schreiner (Jun 15, 2009)

jrrichar said:


> Darrin:
> 
> 1. FT dogs are not rewarded for their nose but they do use them and some of the best likely have a good one. Birds do have a smell that we may detect if we are right in front of it on a table but dealing with the "field" element adds a huge level of difficulty that separates good noses and great noses. If I had to guess, I would say your FC/AFC dogs have phenomenal eyes, intelligence, and noses. The last two would likely be the reason that bomb and narcotics dogs come from these FT lines. It would be impossible in a trial to know that the dog that front footed a bird did it solely by sight/memory. It is likely a combination of all its senses and intelligence. A dog doesn't need to have his nose to the ground to be using it.
> 
> ...


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## mjh345 (Jun 17, 2006)

DarrinGreene said:


> The winning dog will (appear to) not use his nose at all in a trial, front footing his marks and ignoring it on blinds. He may get away with honoring his nose on a blind but I've never heard anyone say give extra points for doing so. We all know they smell foot scent, bird scent and many other things that help them succeed (and fail) but the exercises we test them on actually do nothing to test/reward a dog for having a good nose.
> 
> As for the study, 18 is an infinitesimally small sample size.
> 
> I find it hard to argue with the idea that scenting a gram of cocaine or a trace of explosive is many times more difficult than finding a freshly killed or semi decomposed game bird.


Darren the more you try to convince us of your "Expertise and experience" with FT dogs the more I need to ask: 

Have you ever actually run in or even seen a Field Trial?


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## EdA (May 13, 2003)

The reason for posting this study was threefold, first I thought retriever people would find it interesting, second to inform everyone that some drugs can impair scenting ability, and third to alert someone who might be running an important event that their dog should probably not be on long term metronidazole therapy. As to Darrin's complaint that "18 is an infinitesimally sample" it is, as Janell pointed out, a fairly normal sampling size for most clinical studies. 

As as with many things posted here it turned into a debate about scenting ability in detector dogs and how much easier it was to scent a bird than a minute amount of a chemical. These two different uses of the dog's exceptional olfactory apparatus which allows them to identify a single distinctive odor to the exclusion of hundreds of background odors is proof of what remarkable creatures they are. Wouldn't you love to smell what a dog smells even if for only one day, I would.


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## Vicky Trainor (May 19, 2003)

Dr. Ed, your post has also shown up in my Search and Rescue group forum on Facebook. SAR dogs and horses use their noses and many of the K9 handlers found the information you shared very interesting.

Thanks for posting!!


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## kjrice (May 19, 2003)

Is it permanent or improves with time? Interesting....


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## EdA (May 13, 2003)

kjrice said:


> Is it permanent or improves with time? Interesting....



"Degradation in the ability to detect odors of explosives ​during metronidazole administration at 25 mg/kg........." suggests that the effect is temporary and reversible.


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## kjrice (May 19, 2003)

EdA said:


> "Degradation in the ability to detect odors of explosives ​during metronidazole administration at 25 mg/kg........." suggests that the effect is temporary and reversible.


I wish I had degraded odor detection during periods of administering metronidazole.


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## DarrinGreene (Feb 8, 2007)

ErinsEdge said:


> I would follow Dr Ed's strategy in the field because he has made numerous field champions, he has respect for the dogs' innate intelligence, discrimination of smells, and what makes a great dog great. You are just spinning the facts as you understand them.


None of this has anything to do with Dr. Ed's experience. It's a discussion of an 18 dog study revolving around the effect of a common drug on scenting ability. I guess Ed posting it is an endorsement of the results? I didn't see it that way. 

If I as trying to train a field champion and could get Dr. Ed's coaching - I'd take it, without question.


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## ErinsEdge (Feb 14, 2003)

Darrin you are the one that brought the winning at trials "The winning dog will (appear to) not use his nose at all in a trial, front footing his marks and ignoring it on blinds"and "Also - successful trial and hunting test dogs do little with their nose (supposedly)"after Dr Ed said "but I can say without reservation that a keen sense of smell is paramount to success in retriever field trials." You are the one that derailed the thread with your on going spin along with chest thumping that doesn't enhance your credibility. Dr Ed posted an interesting study and I appreciate it.


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## DarrinGreene (Feb 8, 2007)

and I agreed with Ed in a follow up


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## steveMO (Nov 26, 2011)

Interesting thread. ..mostly. Thanks for the initial post.


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## DarrinGreene (Feb 8, 2007)

mjh345 said:


> Darren the more you try to convince us of your "Expertise and experience" with FT dogs the more I need to ask:
> 
> Have you ever actually run in or even seen a Field Trial?


This is where you're wrong Marc. I'm not trying to convince anyone I have any expertise in anything. I really don't care what most of you think. If you want to throw out the observations of someone whose seen as many dogs do scent detection/discrimination exercises as I've seen, you go ahead and do that. I'd say I'm thousands of observations ahead of most people who want to argue with me. Dr. Ed isn't part of that list BTW.

I didn't say my experience made me an expert in any way shape or form, not for scent detection dogs or field trial dogs. Not once, not ever. I've never said that about anything related to dogs actually. You all just don't like the fact that anyone without a dozen field champions under their belt has anything to say at all and hell, those don't even have to be dogs that person trained. You'd rather accept the viewpoint of someone who uses a pro for all their training than someone who has their hands on dogs day in day out 300 days a year. 

I simply said I've seen a lot of finds and worked with a lot of great trainers who had seen many thousands themselves. That is only to give context to my remarks for those interested. 

As for the rest of you who are so set in your ways not to see that for simply what it is, sharing information that's available on the topic at hand in a take it or leave it way.

If you all want to leave your dog with the ****s for weeks because you're concerned it might not to be able to find a freshly killed game bird in an area of disturbed vegetation covered in dog and human scent, have at it. 

I say they can smell it a mile away without even trying, metro or no metro. That's my experience, worth what you paid for it.

Now get off my ass already.


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## ErinsEdge (Feb 14, 2003)

> Now get off my ass already.


Sure, when you quit posting your spin, just so you can have the last word.


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## EdA (May 13, 2003)

DarrinGreene said:


> This is where you're wrong Marc. I'm not trying to convince anyone I have any expertise in anything. I really don't care what most of you think. If you want to throw out the observations of someone whose seen as many dogs do scent detection/discrimination exercises as I've seen, you go ahead and do that. I'd say I'm thousands of observations ahead of most people who want to argue with me. Dr. Ed isn't part of that list BTW.
> 
> I didn't say my experience made me an expert in any way shape or form, not for scent detection dogs or field trial dogs. Not once, not ever. I've never said that about anything related to dogs actually. You all just don't like the fact that anyone without a dozen field champions under their belt has anything to say at all and hell, those don't even have to be dogs that person trained. You'd rather accept the viewpoint of someone who uses a pro for all their training than someone who has their hands on dogs day in day out 300 days a year.
> 
> ...


This was purely an informational post, do what you will with it, no reason for it to get personal. This study comes from well respected scientists, we don't know the source of the funding but I suspect a Federal Government grant form the DOD. No one ever brought up to make a choice between your dog having diarrhea and finding a bird. Metronidazole is probably the first or second most widely used drug in veterinary medicine and is given by many indiscriminately. And just for your information I have known more than one very talented FC who had a poor nose and were mostly successful in all duck field trials.


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