A detection dog or sniffer dog is a dog that is trained to and works at using its senses (almost always the sense of smell) to detect substances such as explosives, illegal drugs, or blood. Hunting dogs that search for game and search dogs that search for missing humans are generally not considered detection dogs. There is some overlap, as in the case of human remains detection dogs (sometimes called cadaver dogs), trained to detect human remains. They are also used for drug raids to find where the drugs are.
In the state of California, dogs are trained to detect the Quagga Mussel on boats at public boat ramps, as it is an invasive species. Sniffer dogs have also been enlisted to find bumblebee nests. The Bumblebee Conservation Trust has trained an English Springer Spaniel to detect the colonies, assisting them with the conservation of threatened species. Some prisons have dogs trained to detect illicit cell phones in prison cells.
Detection dogs have been trained to search for many substances, including:
- Animals in conservation settings (especially by Australian dog trainer, Steve Austin)
- Human remains
- Crime evidence
- Mobile phones (as contraband in prisons)
- Plants, animals, produce, and other agricultural items (used by customs services to detect possible invasive species such as Quagga mussel)
- Polycarbonate optical discs such as DVDs (used to search for bootleg recordings)
One notable quality of detection dogs is that they are able to discern individual scents even when the scents are combined or masked by other odors. In one case at an Australian prison, a detection dog foiled an attempt to smuggle drugs that had been hidden in a woman's bra and smeared with coffee, pepper and Vicks Vapo-rub. A sniffer dog can detect blood even if it has been scrubbed off surfaces. In one case, a sniffer dog sniffed a drop of blood on a wall although an attempt had been made to scrub it off. It was so small that it couldn't be seen without a microscope.
Their use has been criticized as allowing the police to conduct searches without cause, in a manner that is unregulated. They have been criticized as a form of show-policing, motivated more by the state's desire to be seen to be doing something than any serious attempt to respond to the dangers of drug use.
In 2001 the Australian state of New South Wales introduced legislation to provide police with powers to use drug detection dogs without a warrant in public places such as licensed venues, music festivals and public transport. The legislation was reviewed by the NSW Ombudsman who in 2006 handed down a report highly critical of the use of dogs for drug detection. The report stated that prohibited drugs were found in only 26% of searches following an indication by a drug sniffer dog. Of these, 84% were for small amounts of cannabis deemed for personal use. The report also found that the legislation was ineffective at detecting persons in supply of prohibited drugs, with only 0.19% of indications ultimately leading to a successful prosecution for supply.
During a 3-year period (from 2008) "probably more than 1000 pupils in about 90 classrooms" had been subjected to a drug dog coming into a classroom" where it was "voluntary for pupils to be present with the drug dog, but those who want to leave the classroom must answer some questions to police". An article in Tidsskrift for strafferett, Norway's journal of criminal law, claims that such searches breach Norwegian law.
United States of America 
In June 2012, three Nevada Highway Patrol officers filed suit against that state's Department of Public Safety Director, alleging that he destroyed the state's police dog program by training canines to be "trick ponies" and to falsely detect the presence of drugs on cues from handlers, thus allowing Highway Patrol troopers to conduct illegal searches of vehicles. The lawsuit also accuses the Director and other top Highway Patrol officers of violating the federal Racketeer Influenced and Corrupt Organizations Act.
Bed bug detection dogs 
Bed bug detection dogs are specially trained by handlers to identify the scent of bed bugs.
With the increased focus on green pest management and integrated pest management, bed bug detection dogs are gaining popularity in North America. Dogs are a safer alternative to pesticide use as a management strategy. If operators can find out exactly where bed bugs are located, they can minimize the area that needs to be sprayed. Dogs smell in parts per trillion, something a human cannot do, and detect bed bugs through all life cycle phases from eggs to nymphs to adults.
Bed bug detection dogs are quickly becoming mainstream. In 2011 The National Pest Management Association released their Bed Bug Best Management Practices  which outline the minimum recommendations regarding not only treatment, but the certification and use of bed bug detection canines. The NPMA Best Management Practices emphasize the importance of having a bed bug detection dog team certified by a third party organization with no affiliation to the trainer or company that sold the canine.
Bed bug detection dogs are a viable and scientifically-proven alternative to traditional methods of pest detection. A 2008 report by the University of Kentucky Department of Entomology endorsed bed bug detection dogs by stating that the “reliability of the dogs has been impressive provided they are properly trained.” Scientists at the university reviewed studies on the dogs and concluded that although expensive for operators, canine detection dogs were promising.
Bed bug detection is complicated by the fact that the insects can hide almost anywhere. Bed bug detection dogs solve this problem because they are small and agile, finding bugs in places humans cannot such as wall voids, crevices and furniture gaps.
With the increase in global travel and shared living accommodations, bed bugs have become more prevalent. The U.S. Environmental Protection Agency held a bed bug summit in April 2009 to address the ongoing problem of bed bugs and how to eradicate them. The certification of bed bug detection dogs was discussed.
- NPR's All Things Considered Using Dogs to Sniff Out Bed Bugs
- Fox Philadelphia Bed Bug Dog and Bed Bug Control Experts discussing use of Bed Bug Dogs
See also 
- Austin Jenkins (22 July 2009). "KPLU: Dogs Used to Sniff Out Cell Phones in NW Prisons (2009-07-22)". Publicbroadcasting.net. Retrieved 11 November 2010.
- Anderson, Jessica. "Prisons enlist dogs to keep out phones: Canines part of effort to keep contraband out of state facilities." Baltimore Sun 10 July 2008.
- Dogs in the News. Dog Sniffs Drugs in Woman's Bra and the Top 8 Things People Hide in Their Underwear. Canine Nation 2002.
- Saville, Sebastian (9 July 2008). "Sniffer dog checks bite into our civil liberties". The Guardian (London). Retrieved 1 May 2010.
- Marks, Amber (31 March 2008). "Smells suspicious". The Guardian (London). Retrieved 1 May 2010.
- Race K (2009): Pleasure Consuming Medicine: The queer politics of drugs Durham: Duke University Press.
- Police Powers (Drug Detection Dogs) Act 2001
- Review of the Police Powers (Drug Detection Dogs) Act 2001. 14 September 2006. ISBN 1-921131-36-5.
- Dunn M, Degenhardt L (November 2009). "The use of drug detection dogs in Sydney, Australia". Drug Alcohol Rev 28 (6): 658–62. doi:10.1111/j.1465-3362.2009.00065.x. PMID 19930020.
- Svarstad, Jørgen (19 November 2011). "Over 1000 osloelever narkosjekket (Over 1000 Oslo students drug checked)". Aftenposten (Oslo, Norway). Retrieved 11 September 2012.
- Hinkel, Dan; Mahr, Joe (6 January 2011). "Tribune analysis: Drug-sniffing dogs in traffic stops often wrong". Chicago Tribune.
- Vogel, Ed (26 June 2012). "Officers file suit alleging wrongdoing in police dog training program". Las Vegas Review Journal. Retrieved 11 September 2012.
- NPMA Bed Bugs Best Management Practices
- "EPA's National Bed Bug Summit – April 14–15, 2009" (PDF). Retrieved 11 November 2010.
Media related to Detection dogs at Wikimedia Commons