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It's a fairly common movie trope that when someone is being chased by dogs they will run through water to "lose their scent" and the dogs will no longer be able to follow the trail of the one pursued.

If this is true to a degree, a sub question would be if it's possible to "re-pickup the scent" by tracing the perimeter of the body of water. In other words, is it just the connectivity of the trail that's broken, or is the scent lost for good during this particular pursuit?

Jamiec
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Hendy
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    It was tested in at least one of Mythbusters episodes – vartec Dec 09 '11 at 11:55
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    How soon do you need to know? – John C Dec 09 '11 at 13:20
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    I have never heard the claim in the form of "lose a scent", only that it is difficult to find a track which is "broken" and cannot be followed continuously - that is why usually one does not leave the water at easily predictable spot. – Suma Dec 09 '11 at 15:59
  • @suma: I think the term might mean what you're saying. "Lose the scent," I think, means the dogs don't know where to go anymore. What I've never understood is when this happens with something like a stream, why not just cross it and search up and down with dogs... that is, if they can re-trace them once they're on land again? In movies, they just stop and give up. – Hendy Dec 09 '11 at 16:49
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    @Hendy - movies are not always exactly the truth... sorry to break it to ya this way :-) – Rory Alsop Dec 09 '11 at 22:56
  • @RoryAlsop: Don't be sorry, I've known this for some time. Even so, I'd love if the answer included how these kinds of things *did* work, then (if, indeed, not like in the movies)! – Hendy Dec 10 '11 at 01:57
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    @Hendy: Actually, they should search up-and-down on both sides of the stream in case their target decided to be sneaky and just run through the water only for a short distance without ever crossing to the other side. – Randolf Richardson Dec 10 '11 at 04:38
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    @John C: +1 for your comment-question -- that's just brilliant! – Randolf Richardson Dec 10 '11 at 04:39
  • Yes, you have to check in 4 directions, and will never know when it is time to search for the other directions - ok, at the waterfall obviously, and the ocean. – user unknown Dec 10 '11 at 06:32
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    @RandolfRichardson: Nice. Great point. I wonder if that's why they supposedly don't in movies. Say a murderer is fleeing. Is four directions a significant barrier (assuming they have some idea of how far behind they are)? Maybe an answer could be some police protocol for this stuff :) – Hendy Dec 10 '11 at 07:39
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    I would of course be greatly interested to see any observational data John C generates. – Monkey Tuesday Dec 10 '11 at 18:22
  • I once saw a TV program (documentary) where they trained two dogs (one a sheepdog and the other a bloodhound). One of the tests they gave the bloodhound: a man had been to a baseball game the day before, and the challenge was to find where he had sat. So the dog followed the day-old trail into the stadium, past the hot dog concession stands, where the man had been among a huge crowd the day before. The dog went to work for the police, after that. – ChrisW Apr 01 '12 at 16:19

1 Answers1

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No

This was actually tested in MythBusters (episode 74, which is in Season 8).

In fact, that personal perfume is strong enough that none of Jamie's bloodhound-busting tactics worked. He zigzagged and doubled back on his trail, ran through a river, washed and changed clothes, doused himself in coffee and cologne, and even covered his tracks in ground pepper — all to no avail. Each time, the bloodhound sniffed right through the ruse and found the hiding Hyneman.

They were only able to confuse the dog a little bit - when they changed out of their clothes, there was so much scent, that the dog wasn't sure where to go. But within a few minutes, the dog picked up the track again and found Jamie within minutes.

Ephraim
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  • Can you find something better than mythbusters? We do not consider it a reliable source. – Sklivvz Apr 01 '12 at 15:32
  • I will look for another source, however I must ask as to why mythbusters is not considered a reliable source? While it is on television, everything they test is done using the scientific method, and retested showing that it can be reproduced if tested again. I'm not sure what would disqualify them that wouldn't disqualify any other scientifically tested results by another source. – Ephraim Apr 01 '12 at 15:37
  • Well, because the experiment are usually very small, not peer reviewed, the methodology is not clear, etc. We have discussed it [here](http://meta.skeptics.stackexchange.com/questions/450/is-mythbusters-ancedotal-evidence) and [here](http://meta.skeptics.stackexchange.com/questions/132/list-of-useful-sources-for-skeptics-se) – Sklivvz Apr 01 '12 at 15:50