# Search dogs smelling money?? **URL:** \ **Category:** Factual Questions\ **Created:** [October 10, 2015, 8:07pm UTC](https://boards.straightdope.com/t/search-dogs-smelling-money/734194 "2015-10-10T20:07:37Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![Canadjun](https://avatars.discourse-cdn.com/v4/letter/c/76d3ee/32.png) [@Canadjun](https://boards.straightdope.com/u/Canadjun)\ **Post date:** [October 10, 2015, 8:07pm UTC](https://boards.straightdope.com/t/search-dogs-smelling-money/734194/1 "2015-10-10T20:07:37Z")
I often watch Border Patrol and similar programs on TV. A couple of times I’ve seen mention of search dogs sniffing out undeclared currency. How?? What specifically are the dogs picking up on? Whether it is actual paper (like yours) or one of the newer plastic currencies (like ours) I am puzzled how the dogs distinguish it from non-monetary paper and plastic. ?? ---
**Author:** ![Sarabellum](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sarabellum/32/3492_2.png) [@Sarabellum](https://boards.straightdope.com/u/Sarabellum)\ **Post date:** [October 10, 2015, 8:15pm UTC](https://boards.straightdope.com/t/search-dogs-smelling-money/734194/2 "2015-10-10T20:15:26Z")
Hmm… American dollars have a unique smell to ME… I can only imagine that they do for dogs as well? ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [October 10, 2015, 8:16pm UTC](https://boards.straightdope.com/t/search-dogs-smelling-money/734194/3 "2015-10-10T20:16:04Z")
Money has its own particular scent, a combination of the paper & ink used, for those of us who still use such things to make our money. Or, they’re picking up on bills that have been used for snorting coke. ---
**Author:** ![jtur88](https://avatars.discourse-cdn.com/v4/letter/j/e9c0ed/32.png) [@jtur88](https://boards.straightdope.com/u/jtur88)\ **Post date:** [October 10, 2015, 8:20pm UTC](https://boards.straightdope.com/t/search-dogs-smelling-money/734194/4 "2015-10-10T20:20:37Z")
Maybe they can smell traces of controlled substances (cocaine, etc.) on paper money, which would be much less commonly encountered on other paper or plastic objects, which might have been handles by only one or two people in it’s lifetime… If a person has several $100 bills, there is a very high probability that there are detectable traces of drugs on at least one of them. Money is also printed with a unique ink, which would be absent on any other printed material . ---
**Author:** ![filmore](https://avatars.discourse-cdn.com/v4/letter/f/7993a0/32.png) [@filmore](https://boards.straightdope.com/u/filmore)\ **Post date:** [October 10, 2015, 8:38pm UTC](https://boards.straightdope.com/t/search-dogs-smelling-money/734194/5 "2015-10-10T20:38:24Z")
US currency is actually cotton rather than wood pulp. It’s treated in special ways and printed with special ink. No doubt the sensitive noses of dogs can be trained to pick up the unique scent of the chemicals in currency. ---
**Author:** ![Bones\_Daley](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@Bones\_Daley](https://boards.straightdope.com/u/Bones_Daley)\ **Post date:** [October 10, 2015, 8:54pm UTC](https://boards.straightdope.com/t/search-dogs-smelling-money/734194/6 "2015-10-10T20:54:47Z")
> [@jtur88](#): > > If a person has several $100 bills, there is a very high probability that there are detectable traces of drugs on at least one of them. I very much doubt that out of all the millions (?) of $100 bills in circulation, any more than a tiny fraction of them will have detectable traces of drugs. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [October 10, 2015, 9:56pm UTC](https://boards.straightdope.com/t/search-dogs-smelling-money/734194/7 "2015-10-10T21:56:02Z")
> [@Bones\_Daley](#): > > I very much doubt that out of all the millions (?) of $100 bills in circulation, any more than a tiny fraction of them will have detectable traces of drugs. You would be wrong > [@](#): > > four out of five dollar bills in Chicago suburbs contain traces of cocaine > > ```auto > around 80% of all British banknotes contain traces of drugs. > > Australia introduced plastic currency in 1988.These notes are less prone to contamination due to lack of the fabric that can hold crystalline structures that illicit drugs often take > > https://en.wikipedia.org/wiki/Contaminated_currency > > ``` ---
**Author:** ![Richox](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@Richox](https://boards.straightdope.com/u/Richox)\ **Post date:** [October 11, 2015, 2:50am UTC](https://boards.straightdope.com/t/search-dogs-smelling-money/734194/8 "2015-10-11T02:50:25Z")
A Dogs sense of smell is amazing. A few weeks ago I read some tidbit about it which sent me on one of those many hour long internet research marathons that you get caught up in randomly. I frequently see these currency and drug dogs in Australia - apparently one set of dogs does currency and drugs, and another set does explosives. Different native talent and training required for those fields. Anyway this article from the AFP (aust federal police) has some tidbits of information : > [@](#): > > The dogs are trained to sniff out amounts of $10,000 or more in new and used Australian and American currency and they can also detect other currencies, including > those from New Zealand, Thailand and Malaysia. The currencies that the dogs can detect > are all produced by standardised printing processes. [http://www.afp.gov.au/~/media/afp/pdf/8/8-july-09-canines.pdf](http://www.afp.gov.au/~/media/afp/pdf/8/8-july-09-canines.pdf) As well as having a much keener sense of smell than humans, dogs can apparently differentiate individual smells out of the medley, an ability which humans largely lack. So wrapping your drugs or money in coffee grounds or pepper might fool a human, but the dog can smell each of the individual scents. ---
**Author:** ![Flyer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/flyer/32/7298_2.png) [@Flyer](https://boards.straightdope.com/u/Flyer)\ **Post date:** [October 11, 2015, 5:40am UTC](https://boards.straightdope.com/t/search-dogs-smelling-money/734194/9 "2015-10-11T05:40:32Z")
> [@Bones\_Daley](#): > > I very much doubt that out of all the millions (?) of $100 bills in circulation, any more than a tiny fraction of them will have detectable traces of drugs. > [@bob\_2](#): > > You would be wrong Here’s the Snopes page on that. Summary–33% minimum, probably a lot higher. > **[FACT CHECK: Does Most U.S. Currency Bear Traces of Cocaine?](https://www.snopes.com/fact-check/cocaine-on-money/)** > > Does a large percentage of U.S. currency bear traces of cocaine? And I turned up an interesting legal case on the issue. > [@](#): > > The U.S. Court of Appeals for the Ninth Circuit ruled that the government did not have probable cause to seize $30,060 from a motorist based only on a drug-detection dog’s reaction. [http://www.ndsn.org/dec94/dog.html](http://www.ndsn.org/dec94/dog.html) ---
**Author:** ![Ignotus](https://avatars.discourse-cdn.com/v4/letter/i/ecc23a/32.png) [@Ignotus](https://boards.straightdope.com/u/Ignotus)\ **Post date:** [October 11, 2015, 6:01am UTC](https://boards.straightdope.com/t/search-dogs-smelling-money/734194/10 "2015-10-11T06:01:35Z")
Money will smell of _people_! (Underwear and socks will too, of course. But the dogs are probably used to it. And anyway, money will smell of _different_ people!) ---
**Author:** ![Siam\_Sam](https://avatars.discourse-cdn.com/v4/letter/s/d78d45/32.png) [@Siam\_Sam](https://boards.straightdope.com/u/Siam_Sam)\ **Post date:** [October 11, 2015, 6:18am UTC](https://boards.straightdope.com/t/search-dogs-smelling-money/734194/11 "2015-10-11T06:18:03Z")
Reminds me of [Lucky and Flo](https://en.wikipedia.org/wiki/Lucky_and_Flo), a pair of black Labs that were trained trained to detect optical discs by scent in a bid to combat piracy. They were sent to Malaysia and proved so good at their job that a bounty was supposedly put on their heads. ---
**Author:** ![Canadjun](https://avatars.discourse-cdn.com/v4/letter/c/76d3ee/32.png) [@Canadjun](https://boards.straightdope.com/u/Canadjun)\ **Post date:** [October 11, 2015, 1:41pm UTC](https://boards.straightdope.com/t/search-dogs-smelling-money/734194/12 "2015-10-11T13:41:10Z")
Thanks for the replies! I remain surprised, but since it’s obvious they are doing it I guess I’ll just have to accept the fact that they can do it. Weird. ---
**Author:** ![filmore](https://avatars.discourse-cdn.com/v4/letter/f/7993a0/32.png) [@filmore](https://boards.straightdope.com/u/filmore)\ **Post date:** [October 11, 2015, 3:04pm UTC](https://boards.straightdope.com/t/search-dogs-smelling-money/734194/13 "2015-10-11T15:04:38Z")
Dogs have about 50 times more scent receptors than we do and the part of their brain devoted to scent is about 40 times greater (proportionally) than it is in ours. So they are really, really, really good at smelling things. If you take a dog on a walk, you’ll often see them very interested in smelling things and searching out the source of the scent. I think dogs sense the world through scent the way we can with sight and sound. You can see a small object from far away or hear individual instruments in an orchestra. I think for dogs it’s the same way with scent. They are able to differentiate the air into discrete smells and recognize individual chemicals. A (sort of) example of this with humans is how we can recognize a familiar voice in a crowd. Any parent can tell you they can recognize their own kid’s voice in a crowded, noisy area. There can be hundreds of kids running around making lots of noise but somehow they can recognize one particular voice. So however we can do that to pick out once voice out of many, dogs are doing something similar to identify one scent out of many. ---
**Author:** ![Dallas\_Jones](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dallas_jones/32/3277_2.png) [@Dallas\_Jones](https://boards.straightdope.com/u/Dallas_Jones)\ **Post date:** [October 11, 2015, 4:31pm UTC](https://boards.straightdope.com/t/search-dogs-smelling-money/734194/14 "2015-10-11T16:31:02Z")
> [@filmore](#): > > US currency is actually cotton rather than wood pulp. It’s treated in special ways and printed with special ink. No doubt the sensitive noses of dogs can be trained to pick up the unique scent of the chemicals in currency. 75% cotton, 25% linen.