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The use of scent-detection dogs

Authors:

Abstract

Domestic dogs (Canis familiaris) can detect substances at much lower concentrations than humans (Thorne, 1995) and their area of olfactory epithelium (18 to 150 cm2 ; Dodd and Squirrel, 1980, cited in Thorne, 1995) is much greater than that of humans (3 cm2; Albone, 1984). Dogs are used by humans to locate a range of substances because of their superior olfactory acuity. This paper reviews the use of scent-detection dogs to detect non-biological scents (explosives, chemical contaminants, illegal drugs) and biological scents (human odours, animal scents) and their role in conservation.
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Focus Volume 58 (4) : April, 2005
Irish Veterinary Journal
CONTINUING EDUCATION Volume 59 (2) : February, 2006
Irish Veterinary Journal
Detection dogs for non-biological scents
Dogs trained to detect explosives and land mines are now the largest
group of working scent-detection dogs in the world (Gazit and Terkel,
2003). They are considered to be the most reliable, versatile and cost
efficient explosives-detectors (Furton and Myers, 2001; Lorenzo et al.,
2003). The ability of dogs to locate their target scents while ignoring
the many non-target scents encountered in their search environments
(e.g., airports) is claimed to be better than that of instruments (Furton
and Myers, 2001). There are over 100 million laid land mines around
the world. They block access to productive land, curb economic
growth, and kill and maim people (McLean, 2001). Mine-detection
dogs search for buried land mines and are used to confirm that areas
are free from mines (Phelan and Webb, 2003). They are trained to
detect the explosive chemicals in land mines but also to recognise the
scent of tripwires (Fjellanger, 2003; Hayter, 2003). Experts believe that
the detection abilities of land mine-detection dogs are superior to all
comparable methods (Bach and McLean, 2003).
Accelerant-detection dogs are trained to locate the residual scent of
flammable products used as accelerants by arsonists and to ignore
the smell of pyrolysis products such as burned carpet or wood (Katz
and Midkiff, 1998). Dogs find vestiges of accelerants at fire scenes
more quickly and precisely than humans (Kurz et al., 1994). When
dogs are used to locate accelerants, fewer samples from a scene
need to be submitted for analysis, and this improves the efficiency
of investigations and saves time and money (Tindall and Lothridge,
1995; Katz and Midkiff, 1998). Dogs can detect extremely low volumes
(5.0 to 0.005μL) of accelerants, levels which are at or beyond the
sensitivity of laboratory techniques and equipment (Kurz et al., 1994;
Tindall and Lothridge, 1995; Kurz et al., 1996).
Dogs can be trained to identify areas contaminated with hazardous
chemicals, such as toluene (Arner et al., 1986). They are capable
of locating very small (0.1g) quantities of these chemicals over
large distances where instruments have failed to detect them. This
improves human safety by identifying the outer limits of a polluted
area before dangerously high levels of toxins are encountered and
can determine point sources for more efficient sampling (Arner et al.,
1986). Organochlorine residues have been found in beef exports from
Australia and dogs are now used routinely to detect aldrin, dieldrin,
and DDT contamination on farmland. The level of contamination in
the soil can be very low (1 part per million and less) (Crook, 2000)
and trained dogs can identify point sources of organochlorines with
sensitivity levels of up to 99%. Using dogs saves time and reduces
the number of soil samples required to identify contaminated sites
(Crook, 2000).
Dogs are used by customs services to find illegal drugs including
cocaine, heroin, methamphetamine and marijuana (Lorenzo et al.,
2003) and are used routinely to screen the millions of people and
items crossing international borders through airports, seaports and
by post (Adams and Johnson, 1994; Rouhi, 1997). Drug-detection dogs
are also used by police and in schools and workplaces to detect and
deter the use and trading of illicit substances (Ritz, 1994).
Detection dogs for biological scents
Human scents
Dogs are able to identify an individual’s scent even when it is mixed
with the scent of another person or with other strong smelling
substances (Kalmus, 1955). Police in some countries use dogs to
identify criminals by matching the scent of a perpetrator at a crime
scene to the scent of a suspect. To some police forces this is the
The use of scent-detection dogs
Clare Browne1, Kevin Stafford2 and Robin Fordham1
1 Ecology Group, Institute of Natural Resources, Massey University, Palmerston North, New Zealand
2 Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
Domestic dogs (Canis familiaris) can detect substances at much lower concentrations than humans (Thorne, 1995) and their area of
olfactory epithelium (18 to 150 cm2 ; Dodd and Squirrel, 1980, cited in Thorne, 1995) is much greater than that of humans (3 cm2;
Albone, 1984). Dogs are used by humans to locate a range of substances because of their superior olfactory acuity. This paper reviews
the use of scent-detection dogs to detect non-biological scents (explosives, chemical contaminants, illegal drugs) and biological scents
(human odours, animal scents) and their role in conservation.
Dogs have
amazing
capacities to
detect
scents.
Author for Correspondence:
Clare Browne
Ecology Group
Institute of Natural Resources
Massey University
Palmerston North
New Zealand
Tel: +64 6 355 9235
Email: clare_browne@yahoo.co.nz
most valuable task a police dog can perform but it is controversial
(Schoon, 1997). Because the information provided by dogs in ‘scent
identification line-ups’ is used as evidence in court (Schoon, 1996),
its reliability has been investigated in several studies. Results indicate
that, with sufficient training, dogs are capable of matching scents from
different parts of the same human body (Schoon and De Bruin, 1994;
Settle et al., 1994). In addition, dogs can follow trails of human scent
through busy urban centres 48 hours after they were laid with 77.5%
average success (Harvey and Harvey, 2003).
Dogs trained for search and rescue are used to search for missing
people, avalanche victims, survivors at disaster sites (such as
earthquakes, floods and plane crashes) and drowned persons (Fenton,
1992; Hebard, 1993). Cadaver-detection dogs are trained to find
decomposing human bodies (Lasseter et al., 2003) and are used to
locate the victims of misadventure. Cadaver dogs are trained to find
traces of human corpses, such as skeletal remains or fluid and tissue
remnants, on the surface, buried underground, or in water (Fenton,
1992; Lasseter et al., 2003). Cadaver dogs can rapidly search large
areas for human remains, saving a considerable amount of human time
and effort (Komar, 1999). Detection rates of cadaver dogs range from
30% to 81% in field trials (Komar, 1999; Lasseter et al., 2003).
Scent detection dogs can aid in the diagnosis of some types of
cancer. They can detect the odour of melanoma cells and that of
urine from people with bladder cancer, with accuracy levels of 100%
and 41%, respectively (Pickel et al., 2001; Pickel et al., 2004; Willis et
al., 2004). Cancerous cells may produce volatile chemicals, enabling
their detection by dogs (Pickel et al., 2004). Edney (1993) described
the behaviour of 37 dogs that responded to their owners’ epileptic
events. Of these dogs, 57% displayed characteristic behaviours prior
to a seizure and 68% performed similar behaviours during a seizure.
Activities of the dogs prior to the onset of a human seizure were
predominantly attention-seeking such as barking, jumping up and
becoming overly attentive; while the behaviour of the dogs reacting
during their owners’ seizures were mainly described as protective,
including sitting and staying beside their owners. Dogs trained to alert
their owners to impending epileptic attacks were able to consistently
indicate to their owners that a seizure was imminent, with warning
times ranging from 10 to 45 minutes (Strong et al., 1999; Brown and
Strong, 2001). It has been suggested that dogs are able to detect
scents exuded by their owners before the epileptic fit and sense
behavioural changes in their owners at this time (Edney, 1993).
More than a third of people with diabetes reported that their
dogs react to their hypoglycaemic attacks (Lim et al., 1992; cited in
Chen et al., 2000). Three case studies described dogs detecting a
hypoglycaemic attack before their owners had noticed any symptoms
(Chen et al., 2000). The dogs displayed a range of abnormal behaviours
prior to and during their owners’ hypoglycaemia, including running
and hiding, barking and preventing the owner from leaving the house.
None of the dogs described resumed normal behaviours until their
owners had eaten food to correct blood glucose concentrations. The
mechanisms by which dogs detect changes in human blood glucose
levels are unknown, but it is suspected that the dogs recognise
olfactory changes attributed to increased sweating, possibly combined
with muscle tremors and behavioural changes (Chen et al., 2000).
Clare Browne’s
dog Apple sniffs
a dead tuatara,
a reptile used in
training.
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Animal scents
Dogs are used for biosecurity purposes in a variety of circumstances,
including containment and border control. Dogs are used in Guam, for
example, to search outward-bound cargo for brown tree snakes (Boiga
irregularis) and prevent accidental introduction of this pest elsewhere
(Engeman et al., 1998a; Engeman et al., 1998b). These snake-detection
dogs have an average location rate of 62% (Engeman et al., 2002).
Dogs can locate insects that damage plants. The red palm weevil
(Rhynchophorus ferrugineus) can inflict severe damage on date palms
(Phoenix dactylifera L.), the most important fruit crop in the Middle
East (Nakash et al., 2000). Affected trees are extremely difficult to
find, but can be saved if identified in the early stages of infestation
(Nakash et al., 2000). Nakash et al. (2000) reported that two dogs
were trained to respond to the secretions of infested trees and
produced very high success rates in initial tests. Dogs can also be
trained to detect the egg masses of gypsy moths (Porthetria dispar
L.) which are laid close to the ground in leaf litter or debris and are
particularly hard to find (Wallner and Ellis, 1976). Two dogs evaluated
at searching for egg masses had a combined average detection rate of
73%, with the results showing a strong correlation between one dog’s
number of indications and egg mass density (Wallner and Ellis, 1976).
There is potential for calibrating and using a dog to estimate egg mass
density by the number located within a specific time period.
In the USA subterranean termite damage and control are estimated
to cost up to US$2 billion per annum (Culliney and Grace, 2000).
Early infestations are often impossible to detect visually and can cause
significant damage before they are discovered (Brooks et al., 2003).
Trained termite-detection dogs can locate eastern subterranean
termites (Reticulitermes flavipes Kollar) with average success rates of
over 95%, and can discriminate between termites, other insects (ants
and cockroaches) and termite-damaged wood (Brooks et al., 2003).
When the ability of dogs to detect western subterranean termites
(Reticulitermes hesperus Banks) was compared with electronic odour
detection devices, the dogs correctly identified 98% of artificially
set-up infestations while the electronic device had a low detection
rate (Lewis et al., 1997). However, the dogs also produced 28%
false positives, where there was no infestation, although this may be
attributable to training techniques (Brooks et al., 2003).
Screwworms (Cochliomyia hominivorax) are obligate parasites that
can kill warm-blooded animals and cause significant economic losses
(Welch, 1990). A dog trained to detect both screwworm pupae
and screwworm-infested wounds on animals had an extremely high
success rate (99.7%) at finding them (Welch, 1990).
Dogs may even be used to detect microorganisms. Some
cyanobacteria species in commercial catfish ponds produce odorous
compounds which accumulate in the flesh of the fish, causing an
unpleasant flavour (Shelby et al., 2004). The cost of rejecting affected
fish ranges from $15 to 23 million annually for catfish producers in
the United States (Hanson, 2003; cited in Shelby et al., 2004). Shelby
et al. (2004) showed that dogs could identify the two most common
‘off-flavours’, 2-methylisoborneol and geosmin, in pond water samples
with high levels of accuracy. Three dogs detected the off-flavours at
levels of 1μg/L with 79% to 93% accuracy and 10ng/L with 37% to 49%
success. Trained dogs are a practical method of detecting off-flavours
and are a reliable alternative to chemical analysis or human taste-
testers (Shelby et al., 2004). Microbial growth in buildings can have
detrimental effects on human health and cause costly deterioration
of construction materials. The initial detection of microbial growth
is extremely difficult and Kauhanen et al. (2002) tested the efficacy
of dogs trained to find rot fungi, typical building moulds and bacteria.
They found that their two study dogs were able to locate 75% of
hidden microbial growth samples.
Dogs can identify dairy cows that are in oestrus from the scent of
vaginal fluid, urine, milk and blood plasma, with accuracies ranging
from 78% to 99% (Kiddy et al., 1978; Kiddy et al., 1984). Dogs can also
discriminate between the milk of cows in pre-oestrus, oestrus and
dioestrus (Hawk et al., 1984).
Detection dogs used for conservation
Dogs are used to locate and monitor a number of endangered
mammals and birds and are a comparatively unobtrusive method for
researchers and conservationists to use when studying rare species.
Dogs can offer safer methods of studying potentially dangerous
animals, reduce some sample collection biases and decrease the
time spent searching for animals. It is often difficult to collect
information on endangered species due to their low densities and
the large, remote areas they commonly inhabit. The use of scat
(animal droppings)-detection dogs is becoming increasingly popular in
many countries due to the problems inherent in traditional methods
of researching threatened species. Mark-recapture techniques
and attaching radio-tracking devices, for example, are invasive and
potentially harmful to the animals (Long et al., 2002). Using dogs to
find scats is a non-invasive method of studying rare animal populations,
and it can increase sample numbers while reducing collection bias
(Wasser et al., 2004). The information that can be extracted from
scats is comparable to data provided by traditional methods.
Applying molecular techniques to scats provides information on the
species, sex, individual identity, diet and parasitology of animals (Kohn
and Wayne, 1997; Mills et al., 2000). Reproductive and stress hormones
from scats can indicate reproductive productivity and impacts of
disturbance on physiological condition (Wasser et al., 2000; Wasser
et al., 2004). By systematically sampling scats over a large geographic
area, population characteristics such as sex ratio, relatedness, habitat
and home ranges may be estimated (Kohn and Wayne, 1997; Kohn
et al., 1999; Wasser et al., 2004). Scats may provide more information
and be a more accessible source of DNA than materials such as hair,
skin, feathers, nails, bones, or saliva (Kohn and Wayne, 1997). The
distribution of animals determined by dog-assisted scat sampling has
been found to correspond well with methods such as hair sampling
and GPS radio-tracking (Wasser et al., 2004).
Apple at work in
the New Zealand
countryside.
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Dogs are used to locate bears in North America for management of
game populations and conservation purposes. A study by Wasser et al.
(2004) described the use of scat-detection dogs to assess the impacts
of human disturbances on black bear (Ursus americanus) and grizzly
bear (Ursus arctos horribilis) populations in Canada. The dogs were
trained to locate bear scats along transects within a 5,200km2 area
and DNA was extracted from the scats to determine species and
individual identities. By using scat-detection dogs, Wasser et al. (2004)
were able to effectively and non-invasively identify land use patterns
for both black and grizzly bears. Mark-recapture methods, using dogs
trained to locate bear scent along transect routes, are also used to
estimate bear population in North America (Akenson et al., 2001); and
dogs can be trained to discriminate between black and grizzly bear
scats, reducing the need for laboratory tests (Hurt et al., 2000).
Dogs trained to find the scats of endangered San Joaquin kit foxes
(Vulpes macrotis mutica) in the US are more efficient than humans at
finding scats for demographic and population studies (Smith et al.,
2003). Trained dogs are able to find up to four times more kit fox
scats along transects than an experienced person, and even the dogs’
worst detection rate in difficult scenting conditions was as good
as that of humans (Smith and Ralls, 2001; Smith et al., 2003). Dogs
searching for kit fox scats must distinguish them from coyote (Canis
latrans), skunk (Mephitis mephitis) and badger (Taxidea taxus) scats, and
have been found to be 100% correct in their species identification
(Smith and Ralls, 2001; Smith et al., 2003). Kit fox latrines (areas where
one or more individuals repeatedly defaecate) can also be found by
dogs (Ralls and Smith, 2004). As the cost of extracting DNA from
faecal samples and using laboratory methods to determine species is
expensive, this extremely accurate species identification ability of scat-
detection dogs saves thousands of dollars.
Biologists studying the endangered amur tiger (Panther tigris altaica)
in Russia use dogs to identify individual tigers. The dogs identify the
tigers by smelling the collected urine and scat samples and matching
them to a reference collection of known tigers (L. Kerley, personal
communication, 2004). The movements of individual tigers are
monitored using a combination of observation, conventional tracking
and the dog-identified scats (Kerley, 2003). However, information
on the population dynamics of the tigers can be obtained by using
the dogs alone. Tigers new to the area can also be identified by this
method (L. Kerley, personal communication, 2004) and two dogs used
in this project have proved to have accuracy rates of 89% and 96%
(Kerley, 2003).
Trained dogs assist researchers studying ringed seals (Phoca hispida) in
the North American Arctic. Dogs have been relied on to locate these
seals in a number of studies, which assessed the impacts of human
activity and industry on the seals, examined possible links between
lair characteristics and predation success, and obtained measures of
territory size (Lydersen and Gjertz, 1986; Smith, 1987; Furgal et al.,
1996). Specially trained dogs can locate, by scent, subnivean (beneath
the snow) lairs and breathing holes on the ice shelf at distances over
1.5km, through drifted snow up to 2m deep, and in winds of up to 46
km/hour (Smith, 1987).
Dogs traditionally used for hunting game birds are now frequently
employed to locate birds and help carry out studies on threatened
species. Yellow rails (Coturnicops noveboracensis), for example, are
classified as a vulnerable species in Quebec (Robert and Laporte,
1997). Because their patchy, localised distribution makes them
extremely difficult to locate, study, or catch, dogs have been used to
find their nests during research projects (Robert and Laporte, 1997).
Management programs of rare avian species have also benefited
from dogs’ innate behaviour. Border collies, for example, were used
to help capture endangered aleutian canada geese (Branta canadensis
leucopareia) in Alaska for relocation to predator-free islands (Shute,
1990). The terrain of the island inhabited by the geese made catching
them extremely dangerous for humans, and many researchers and
geese sustained injuries. The use of dogs not only made the exercise
much safer, but also much more efficient. Scientists took three weeks
to catch 120 geese; two dogs were able to round up 143 in four days
(Shute, 1990).
Dogs have been used in New Zealand for more than a 100 years
to locate a number of endangered species, such as blue duck
(Hymenolaimus malacorhynchos), kiwi (Apteryx spp.) and kakapo
(Strigops habroptilus) (Browne, 2005). Reliable kiwi-detection dogs are
considered essential to kiwi field research because the birds are so
difficult to locate (Colbourne, 1992).
Surveys of bird carcasses can be used to estimate mortality caused by
disease, poisoning or pollution (Homan et al., 2001). Quick recovery
of carcasses before decomposition or scavenging takes place is
important to obtain accurate population estimates. Homan et al.
(2001) compared the searching efficiency of humans and dogs looking
for house sparrow (Passer domesticus) carcasses amongst vegetation.
They found that dogs were significantly more efficient at detecting
avian carcasses than humans, finding twice as many, even at very low
carcass densities.
Summary
Dogs are reliable and efficient scent-detectors. Numerous studies
have established dogs’ proficiency at locating an extremely wide range
of scents. Trained dogs can significantly reduce the amount of time
spent searching for a target object, chemical or species. Often more
sensitive, reliable and practical than electronic scent-detection devices,
dogs are also easy and cheap to train and put into action. Scent-
detection dogs make a significant contribution to the conservation
programmes of many endangered species. In the future we can
expect to see dogs involved more widely in chemical detection,
conservation and disease diagnosis, both human and veterinary. The
major restriction to the use of trained scent-detection dogs appears
to be human imagination.
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Volume 59 (2) : February, 2006 CONTINUING EDUCATION
Irish Veterinary Journal
... Domestic dogs (Canis lupus familiaris) are commonly trained to detect targets of interest in workplaces, airports, and other settings (Browne et al., 2006;Furton and Myers, 2001;Helton, 2009;Lorenzo et al., 2003). They have been trained to locate missing people and human remains (Hepper and Wells, 2005;Killam, 2004;Lorenzo et al.;Oesterhelweg et al., 2008), explosives (Furton & Myers;Gazit et al., 2005;Lazarowski and Dorman, 2014), narcotics Lorenzo et al.;Nash, 2005), native and threatened animals (Browne et al., 2015;Cablk and Heaton, 2006), and pest species (Cooper et al., 2014;Gsell et al., 2009), for example. ...
... Scent-detection dogs frequently make crucial contributions to socially significant projects (Browne et al., 2006), but working with these dogs involves substantial time and financial commitments (Orkin et al., 2016). For these reasons, it is crucial to maximize detection dogs' effectiveness. ...
Article
Scent-detection dogs assist humans with many socially significant tasks and hold promise for assisting with many others. However, the methods used to train scent-detection dogs and the conditions under which they work are highly variable, and the influences of many relevant factors on scent-detection performance are poorly understood. Using an automated scent-detection apparatus that allowed the dogs to work independently from a handler, we evaluated the influence of two factors on scent-detection performance with amyl acetate as the target. In the first experiment in this study, we examined the influence of the indication response requirement on the performance of five dogs trained to perform a scent-detection task. The indication response consisted of the dogs breaking an infrared beam in a port through which they accessed samples. The response requirement was manipulated by adjusting the duration of the beam break that was required to activate food reinforcement if the target was present. As the indication response requirement increased, dogs’ ability to detect the target remained unchanged, as indicated by stable log d measures across durations (p =.09), but their response bias, represented by log B, shifted from a tendency to indicate that targets were present to a tendency to indicate that targets were absent (p <.001). In the second experiment, we examined the influence of target prevalence, or the proportion of samples that are target samples, on four dogs’ scent-detection performance. As target prevalence decreased, the dogs’ ability to detect the target remained unchanged (p =.13), but their response bias shifted from a tendency to indicate that the targets were present to a tendency to indicate that targets were absent (p <.001). This finding aligns with the “low-prevalence effect,” which is commonly observed in human signal detection research. The findings from both experiments have important theoretical and practical implications. For example, by adjusting response effort, we can alter dogs’ response bias toward or away from indicating the presence of targets and, by having a clear understanding of the influence of target prevalence on bias, we can make informed decisions about the need to artificially increase target prevalence when dogs are searching for rare targets.
... Due to their extraordinary olfaction capabilities and trainability dogs can be deployed not only for the detection of explosives, drugs, or missing persons but also for the identification of medical conditions including viral infections (1,2). Since April 2020, we have been training and deploying dogs to detect samples from individuals with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, using different human body fluids, such as sweat, saliva and urine of infected patients (3,4). ...
Article
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There is a growing number of COVID-19 patients experiencing long-term symptoms months after their acute SARS-CoV-2 infection. Previous research proved dogs' ability to detect acute SARS-CoV-2 infections, but has not yet shown if dogs also indicate samples of patients with post-COVID-19 condition (Long COVID). Nine dogs, previously trained to detect samples of acute COVID-19 patients, were confronted with samples of Long COVID patients in two testing scenarios. In test scenario I (samples of acute COVID-19 vs. Long COVID) dogs achieved a mean sensitivity (for acute COVID-19) of 86.7% (95%CI: 75.4–98.0%) and a specificity of 95.8% (95%CI: 92.5–99.0%). When dogs were confronted with Long COVID and negative control samples in scenario IIa, dogs achieved a mean sensitivity (for Long COVID) of 94.4 (95%CI: 70.5–100.0%) and a specificity of 96.1% (95%CI: 87.6–100.0%). In comparison, when acute SARS-CoV-2 positive samples and negative control samples were comparatively presented (scenario IIb), a mean sensitivity of 86.9 (95%CI: 55.7–100.0%) and a specificity of 88.1% (95%CI: 82.7–93.6%) was attained. This pilot study supports the hypothesis of volatile organic compounds (VOCs) being long-term present after the initial infection in post-COVID-19 patients. Detection dogs, trained with samples of acute COVID-19 patients, also identified samples of Long COVID patients with a high sensitivity when presented next to samples of healthy individuals. This data may be used for further studies evaluating the pathophysiology underlying Long COVID and the composition of specific VOC-patterns released by SARS-CoV-2 infected patients throughout the course of this complex disease.
... Because of their extremely sensitive olfactory sense, dogs are often used for professional or non-professional work involving the detection of human remains (e.g. Browne et al., 2006;Baker et al., 2020), drugs and explosives (e.g. Lit et al., 2011;Troisi et al., 2019, Goss, 2019, or as conservation detection dogs (e.g. ...
Article
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Ground SAR work is a demanding activity that requires trained dogs to work reliably for hours in various terrain and environmental conditions. Factors that would affect a dog’s physical performance in conditions imitating a real SAR mission remain poorly studied. We tested a total of 50 shepherd dogs between 2 and 10 years of age. The group comprised dogs that were both certified and uncertified in SAR work. Testing took place during 5 simulated all-day search sessions. We wanted to know how terrain slope, vegetation cover, ambient temperature, and the number of search rounds would affect locomotor activity of both certified and uncertified dogs. The locomotor activity of dogs was described by vertical and horizontal speed, duration of the search as well as the ratio of time spent in vertical (i.e. uphill) locomotion to total time of locomotion (this ratio is herein referred to as “effectiveness”), and duration of the search. We found out that SAR certification was associated with an increased effectiveness; certified dogs spent more time in energy-conserving horizontal locomotion along contour lines. Terrain and environmental factors influenced both certified and uncertified dogs; a slope of 11° or greater increased vertical speed and duration of searching but decreased effectiveness. Thick vegetation slowed horizontal and vertical locomotion, impaired effectiveness and prolonged search times. Relatively high temperatures (>20 °C) also contributed to longer search times. In order to make quick decisions and attain success during SAR operations, authorities responsible for SAR missions must have a sound knowledge of the locomotor characteristics and skill level (certification level) of SAR dogs in relation to terrain and environmental conditions.
... Despite the vast number of publications demonstrating dogs detection for a variety of different targets such as explosives devices [89][90][91][92][93], narcotics [94,95], conservation [96][97][98][99], reproductive health of North Atlantic Right Whales [100], cancer [3][4][5]101] , search and rescue [102,103,[103][104][105], semen stains for crime scenes [106], and bed bugs [107,108], almost no publications measure dogs' detection limits for those targets, and remain unknown. ...
... Canines are representative species that use their olfactory sense for diverse tasks. They have been used to sniff out explosives, landmines, illegal substances, stashed currency, missing humans, contraband, cancers, and so on (Browne et al., 2006;Edwards et al., 2017;Williams and Johnston, 2002). They possess a well-developed olfactory sense, but there are some crucial weaknesses in using them for odor detection: 1) they are easily distracted by loud noise, bright lights, new environmental conditions, and other factors, 2) their olfactory ability is reduced by increased panting under severe physical conditions, and 3) they have a high cost for acquisition, training, and maintenance (Gazit and Terkel, 2003;United States. ...
Article
Rodents have a well-developed sense of smell and are used to detect explosives, mines, illegal substances, hidden currency, and contraband, but it is impossible to keep their concentration constantly. Therefore, there is an ongoing effort to infer odors detected by animals without behavioral readings with brain-computer interface (BCI) technology. However, the invasive BCI technique has the disadvantage that long-term studies are limited by the immune response and electrode movement. On the other hand, near-infrared spectroscopy (NIRS)-based BCI technology is a non-invasive method that can measure neuronal activity without worrying about the immune response or electrode movement. This study confirmed that the NIRS-based BCI technology can be used as an odor detection and identification from the rat olfactory system. In addition, we tried to present features optimized for machine learning models by extracting six features, such as slopes, peak, variance, mean, kurtosis, and skewness, from the hemodynamic response, and analyzing the importance of individuals or combinations. As a result, the feature with the highest F1-Score was indicated as slopes, and it was investigated that the combination of the features including slopes and mean was the most important for odor inference. On the other hand, the inclusion of other features with a low correlation with slopes had a positive effect on the odor inference, but most of them resulted in insignificant or rather poor performance. The results presented in this paper are expected to serve as a basis for suggesting the development direction of the hemodynamic response-based bionic nose in the future.
... Above all remains the logistics of reopening and returning from quarantines that will resume physical contact, and the invasiveness of current tests that depend on tracheal or blood collections. Using canine smell to locate buried people, drugs, and ammunition in different environments is a well-known, recognized, and applied activity (7,8). The reason for this is confidence in the canine response to the most diverse volatile compounds emitted. ...
Article
Full-text available
The aim of the present study is to apply the canine olfactory sensitivity to detect COVID-19-positive axillary sweat samples as a One Health approach in Latin America. One hundred volunteers with COVID-like symptoms were invited to participate, and both axillary sweat samples for dog detection and nasopharynx/oropharynx swabs for qPCR were collected. Two dogs, previously trained, detected 97.4% of the samples positive for COVID-19, including a false-negative qPCR-test, and the positive predictive value was 100% and the negative predictive value was 98.2%. Therefore, we can conclude that canine olfactory sensitivity can detect a person infected with COVID-19 through axillary sweat successfully and could be used as an alternative to screen them without invasive testing.
... Working dogs are prevalent around the world and fulfill many roles, adding social, cultural, and economic value to human lifestyles. They are valuable co-workers, providing labor that would be more costly for humans to do (3,4), or performing specialized tasks that people are unable to accomplish, such as scent detection or as the focus of animal-assisted therapy (5,6). Despite their value, many working dog providers only graduate around half of the dogs bred or recruited to their programs to operational working service, indicating inherent wastage (7). ...
Article
Full-text available
Working dogs are prevalent throughout our societies, assisting people in diverse contexts, from explosives detection and livestock herding, to therapy partners. Our scientific exploration and understanding of animal welfare have grown dramatically over the last decade. As community attitudes toward the use of animals continue to change, applying this new knowledge of welfare to improve the everyday lives of working dogs will underpin the sustainability of working with dogs in these roles. The aim of this report was to consider the scientific studies of working dogs from the last decade (2011–2021) in relation to modern ethics, human interaction, and the five domains of animal welfare: nutrition, environment, behavioral interaction, physical health, and mental state. Using this framework, we were able to analyze the concept and contribution of working dog welfare science. Noting some key advances across the full working dog life cycle, we identify future directions and opportunities for interdisciplinary research to optimize dog welfare. Prioritizing animal welfare in research and practice will be critical to assure the ongoing relationship between dogs and people as co-workers.
Preprint
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We used a detection dog and camera trapping (CT) to compare wolf scat detectability during winter and the reproductive season.
Book
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During two retreats in 2017 and 2020, a group of international scientists convened to explore the Human-Animal Bond. The meetings, hosted by the Wallis Annenberg PetSpace Leadership Institute, took a broad view of the human-dog relationship and how interactions between the two may benefit us medically, psychologically or through their service as working dogs (e.g. guide dogs, explosive detection, search and rescue, cancer detection). This Frontiers’ Special Topic has collated the presentations into a broad collection of 14 theoretical and review papers summarizing the latest research and practice in the historical development of our deepening bond with dogs, the physiological and psychological changes that occur during human-dog interactions (to both humans and dogs) as well as the selection, training and welfare of companion animals and working dogs. The overarching goals of this collection are to contribute to the current standard of understanding of human-animal interaction, suggest future directions in applied research, and to consider the interdisciplinary societal implications of the findings.
Article
Prostate cancer (PCa) is one of the most prevalent cancers of men worldwide. Currently, evaluating serum prostate-specific antigen, combined with digital rectal examination, is used as the diagnostic approach for early detection of PCa, but it has low sensitivity and difficulty in discriminating from non-malignant conditions such as prostatitis and benign prostate hyperplasia. As an alternative, a number of previous studies have reported detection of volatile organic compounds (VOCs) from biofluids of patients with PCa. However, as biofluids have several drawbacks including limited availability and lack of standardization,. Therefore, as a proof-of-concept study, VOCs from extracellular medium of PCa cell line were used in this present study. The detection of the VOCs was performed by canine olfaction as dogs have a superior olfactory system. and the purpose of this study was to evaluate whether canine olfaction can be used to detect VOCs of cancer cell line. Two dogs were trained to discriminate VOCs of the PCa cell line (PC3) from those of control groups. Tests were performed by evaluating the ability to detect VOCs of PC3 and those of PCa cell line (DU145) and bladder cancer cell line (EJ cell) for which the dogs were not trained. Sensitivity, specificity, and area under the curve (AUC) by receiver operating characteristic curve analysis were evaluated. In detecting VOCs of PC3, the AUC values of the two dogs were 0.956 and 0.976, which represented excellent detection capability. The AUC values of the DU145 were 0.892 and 0.840 and the AUC values of the EJ cell were 0.921 and 0.965. The dogs not only showed good detection ability against DU145 which originated from the same organ as PC3, but also exhibited excellent detection ability against EJ cell which originated from a different organ. In conclusion, VOCs of PCa cell line can be used to train scent-detection dogs. Further study is needed to define specific factors among VOCs that create differences between cells and to identify whether VOCs of PCa cell line can replace that of real PCa. Although further studiesareneeded to define specific factors among VOCs that create differences between cells, canine olfaction can betrained to discriminate VOCs of cancer cell from unwanted VOCs.
Article
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Laboratory blind trials were conducted to evaluate the ability of beagles and an electronic odor device to detect termites in wood. In the first test, pine blocks artificially infested with either 0, 5, 50, or 200 workers of the western subterranean termite, Reticulitermes hesperus Banks, were randomly presented to five beagles and one electronic odor device. Blocks were presented one at a time to beagles and the electronic odor device. The beagles correctly identified 81 percent of the blocks while the electronic odor device correctly identified 48 percent. A second laboratory test comparing five additional electronic odor devices from the same manufacturer resulted in a slightly higher correctly identified value, 62 percent. Beagles performed best for blocks containing 50 or more termites. However, the percentage of misidentified controls (false positives) for beagles was high, 28 percent. The electronic odor device did not demonstrate statistically significant detection ability. Although beagles were almost perfect (49 of 50 blocks) in detecting termites in blocks with 50 or more individuals, neither detection method was reliable with control samples or with samples with a low number of termites. The implications of these findings to the use of either of these termite detection methods are discussed.
Article
Full-text available
The accidental introduction of the Brown Tree Snake Boiga irregularis to Guam has resulted in the extirpation of most of the island's native terrestrial vertebrates, has created a health hazard to infants and children, and has resulted in economic losses. Cargo inspections using teams of handlers and their detector dogs form a last line of defense for preventing Brown Tree Snake dispersal from Guam. To assess the efficacy of the teams of handlers and their dogs for locating stowed Brown Tree Snakes, we planted Brown Tree Snakes (in escape-proof containers) in cargo without the knowledge of the handlers inspecting the cargo. We found that when an observer attended the inspection to monitor procedures, 80% of the planted snakes were located. Without an attending observer present, 70% of the planted snakes were discovered, but only after such plantings had become a routine procedure. Prior to the routine planting of snakes, efficacy was nearly 50% less (38%). The reasons some planted snakes were missed by the dog teams were split between: an insufficient search pattern by the handler, or the dog giving no discernable indication that a snake was present.
Article
From 1993-1995, we captured Yellow Rails (Coturnicops noveboracensis) and searched for their nests in southern Quebec. All rails were caught at night, when males call constantly, by attracting birds with imitated calls (waiting) or by approaching birds and immobilizing them with a powerful beam of light (approaching). We were successful 183 times, capturing and recapturing 111 individuals. Most captures (66.6%) were made by waiting, 9.3% by approaching, and 24.0% by approaching after an unsuccessful attempt by waiting. Capture success was higher when we combined waiting and approaching than when we used either waiting or approaching alone. In 1994 - 1995, capture success was 24% higher when we used the combination technique, compared to attempts made with the waiting technique alone. We captured 81.6% of rails in those years and up to seven in a single night. The combination of waiting and approaching was more effective in 1994 - 1995 than in 1993 (X2 = 7.20; P < 0.01), possibly owing to experience acquired in 1993 and to a larger net being used the last two years. In 1994-1995, waiting was more effective on rails captured for the first time than on rails previously captured (X2 = 7.66; P < 0.01), probably because birds previously caught are warier. We searched for nests with the help of a German short-haired pointer and a French pointer. In 1994, they searched for 18.5 and 7.8 h, respectively, and in 1995 the German short-haired searched for 8.8 h. Only the German short-haired pointer found nests, three in 3 h in 1994 and two in 2.5 h in 1995. We believe the effectiveness of this type of search depends on the dog's abilities and training, the dog's handler, and probably weather conditions.
Article
We estimated black bear (Ursus americanus) population density in the Blue Mountains of northeastern Oregon based on summer mark-recapture surveys in 1996 and 1997. We developed a mark-recapture technique to estimate black bear density using houndsmen with dogs to detect bear scent on driving transects. We conducted 53 surveys and recorded 72 instances where dogs detected bear scent (a strike). We used strike frequency as a bear density index. Strike frequency did not differ between years; dogs detected bear scent at a rate of 1.47 strikes/20 km in 1996 and 1.18 strikes/20 km in 1997. We recorded each scent detection and pursued every bear to determine if the bear was marked or unmarked. On 55 occasions bears were treed after being pursued by dogs from transect routes; 33 of these were marked and 22 were unmarked. Applying the NOREMARK software, we estimated 59 bears in 1996 and 48 bears in 1997 in the 234-km2 survey area. We calculated a density of 25.2 bears/100 km2 in 1996 and 20.5 bears/100 km2 in 1997 in the survey area. This compares with a minimum known population density based on 3 years of marking bears prior to this study of 10.8 bears/100 km2 in the 485 km2 capture area that encompassed the survey area. We believe this technique holds promise as a practical tool for wildlife managers. Potential applications of this technique are to produce an index of black bear population trends or, in combination with other techniques, to more accurately assess density of a black bear population. The advantages, considerations, costs, concerns, and limitations of this technique are discussed.
Article
Canines trained to alert to traces of flammable liquids at a fire scene are useful to identify locations to collect samples for laboratory analysis. In some instances, no samples are collected or laboratory testing of samples collected following a canine scent alert fails to identify a residual flammable liquid and potential accelerant. In these, an attempt may be made, through testimony of the dog's handler, to introduce at trial, information regarding the canine alert to indicate the presence of an ignitable liquid at the scene. Canine handlers contend that the dog has greater sensitivity to typical accelerants than laboratory techniques but scientists counter that, while sensitive, the specificity of canine detection is unknown. Unverified canine indications have been used in a number of cases and challenges to several of these have reached the appellate level. Examination of court decisions on admissibility of canine alerts shows that they have been as varied as the arguments pro and con.
Article
It is estimated that over 200 accelerant detection canines (ADCs) are currently assisting in fire investigations throughout the United States. On many occasions, their ability and reliability have been called into question. The Pinellas County Forensic Laboratory evaluated 42 accelerant detection canine teams in their ability to discriminate between common accelerants and pyrolysis products, to detect common accelerants at low concentrations, to precisely locate accelerants and, to detect different classes of accelerants. Ultimately, the accuracy, dependability and overall effectiveness varied from canine to canine and handler to handler and appeared to be somewhat limited by the canine's training, handling and maintenance. While most of the canine teams performed extremely well and could be an asset to fire investigation, some proved to be unreliable. A universal endorsement or condemnation of all accelerant detection canines could not be made; however, endorsements of specific canine teams and trainers were possible. Every working canine team should be evaluated independently. Routine testing is imperative to establish the canine abilities and limitations.
Article
Unlocking The Secrets Of Supersniffing Dogs In Sydney, Australia, Jamie begins a busy day with grooming, exercise, and a health check. He then travels to the airport for the day's first task, inspecting cargo from a number of jumbo jets parked on the tarmac. From the airport, he moves to the location where mail is imported to check half a million or so articles. Next, he goes to the waterfront to search a ship—and the day isn't over yet. Jamie, an athletic, black Labrador retriever trained by the Australian Customs Service to search for narcotics, epitomizes the unrivaled ability of dogs to locate objects through their sense of smell. Yet, it is not fully understood how dogs do what they do and why they are so good at it. Basic studies of canine olfaction and breeding are helping researchers figure out the secrets of the dog's exquisite detection capabilities. They are also generating knowledge ...