Bomb Sniffing Dogs – The Making of an Elite Bomb Dog

Bomb Sniffing Dog at Work“Dogs are still one of the best tools. We have yet to find an explosive odor that the dogs don’t hit on.”
-Robert Noll Explosives Enforcement Officer, ATF

The dog is Man’s best friend, and has been for thousands of years. Over the centuries people have used dogs for herding, tracking, hunting, and assisting the disabled. In the past 50 years, dogs have been introduced to the law enforcement arena. Their dedication, intelligence, and keen sense of smell make them ideally suited for the fight against terrorism.

Dogs are routinely used today by numerous federal agencies – US Customs Service, US Park Police, US Secret Service – for physical security and counter-bomb efforts. Additionally, many state and local law enforcement agencies, and all branches of the armed forces, use canine teams as well. This article takes a look at how several of these agencies use their bomb sniffing dogs to find explosives.

Bomb Sniffing Dogs – The Nose Knows

Among mammals, rats and dogs are credited with having the best sense of smell. In fact, most dogs are able to detect a vapor at concentrations up to 10,000 times lower than humans. (Pigs also have an excellent sense of smell, but their use by police has been ruled out for obvious reasons.) Due to the olfactory capabilities of dogs, they have found their way into the military, law enforcement and search and rescue arenas where they are used to detect and find humans and, more recently, bombs.

Bomb Sniffing Dogs – Best Breeds

Although many breeds of dog are suitable for explosives detection, most law enforcement agencies prefer German Shepherds since they can be cross-trained for patrol work, which requires aggressive behavior. The Secret Service uses German Shepherds and Belgian Malanois that come from a breeder in the Netherlands. The Malanois is a breed developed in Europe during the early 20th century by crossing Shepherds with hounds.

The Bureau of Alcohol, Tobacco and Firearms (ATF), however, swears by Labrador Retrievers, which are less expensive, more mild mannered and longer lived than a Shepherd. They also are said to have better noses.

Regardless of the breed eventually selected, the dog must be in excellent shape and be relatively young – ideally 12-18 months; no more than 24-36 months. In general, only males are used (especially if they are to be cross-trained for street patrol) because they are larger and more aggressive than bitches. Many agencies acquire their dogs through public donations.

Bomb Sniffing Dogs – Handler

Once a dog is selected, it is matched up with a handler, and both then go through several months of training. During this time, the dog is taught obedience work – both on and off the leash – how to respond to verbal commands, and how to cope with a variety of obstacles.

Bomb Sniffing Dogs – Training

As for explosives training, the dogs are typically taught a three-step sequence: smell the explosive compound, alert, receive a reward. Depending on the agency’s training philosophy, the reward can be food, praise or play. After doing this 70-150 times, the dog comes to realize what is expected of him. The process is repeated for each explosive that the dog is expected to detect. Most dogs are trained to find about 15 of the most common military and commercial explosives, such as TNT, C-4 and Semtex.

In some agencies, the dogs are taught how to follow a scent cone to the location of the strongest odor. Scent cones are the downwind waffings from a bomb. The dog learns to weave back and forth through this cone, upwind, toward its source. To assist with this process, the handler is trained to observe environmental conditions and interpret the dog’s behavior. He works the dog in a search pattern that takes advantage of air currents.

When a dog picks up on the scent of an explosive, he physically responds to it by salivating, bracketing or quickening his pace. The handler learns to recognize when the dog is exhibiting this behavior. The Secret Service teaches its canines to signal the presence of an explosive by alerting and then sitting down. The last thing they want the dog to do is bite and shake the hell out of a suspicious package.

Bomb Sniffing Dogs – In the Field

Once the dog and handler have completed the training, they are sent out into the field. But formal training does not end at this point. During work hours, the handlers challenge the dogs by hiding training aids scented with different explosive compounds. This is done at varying locations, at different times of the day. The concentration of the explosive is randomly altered.

The dog returns to its agency’s training facility on a regular basis for refresher courses and recertification. During this time, he is tested against several explosives that he has not recently encountered. This ensures that the dog is still properly responding to the whole range of explosive threats.

Bomb Sniffing Dogs – Pros and Cons

It should be noted before continuing that there are some disadvantages to using dogs as explosives detectors. Cost is one concern. It’s expensive to buy a dog, train it (and its handler), and provide on-going veterinary and kennel-associated services. Additionally, there are related expenses, such as the purchase and maintenance of a vehicle to transport the canine team around in. Because of this, agencies with tight budgets find it difficult to establish and justify an explosives canine team.

Second, explosives dogs do not operate by themselves. They always work in tandem with their handler, who is responsible for recognizing the subtle changes in the dog’s behavior that indicate the presence of an explosive. Reliance on this judgment introduces opportunities for mistakes. For instance, if the handler is bored and not alert, the team is likely to miss targets, even if the dog is performing well.

Bomb Sniffing Dogs – Weaknesses

When compared with electronic sensors, dogs have other weaknesses. Unlike machines, they are vulnerable to distraction by other animals, loud noises, novel scents, fatigue, illness, airborne pollutants, and new surroundings. Additionally, dogs cannot work for extended periods of time. Depending on the weather, a dog may only be able to work 20-30 minutes before needing a rest.

And last, dogs can respond to the wrong thing. For example, dogs have been known to respond to such things as shoe polish, VCR tapes, nitroglycerin pills, and electrical tape. These items contain elements that are typically found in explosives. Furthermore, since dogs rely on smelling airborne molecules, they are not able to detect an explosive if it is tightly wrapped or sealed.

So why use dogs at all if these drawbacks exist? Quite simply because they are effective. There is no mechanical sensor on the market today that is as fast, accurate, sensitive, mobile or durable as a well-trained explosives canine team. And since they operate in real-time, they can signal the presence of an explosive far quicker than a machine, pinpointing the explosive’s location.

Thus, while canine teams are expensive, they are cost-effective. Their appearance in public often hinders bombers from carrying out their deadly deed.

Bomb Sniffing Dogs – Searching for Bombs

The handler has the last word when it comes to determining the readiness of his dog for an assignment. This is because the handler and dog usually live together. Hence, the handler knows his animal inside and out. He can tell if the dog is being distracted or if it is ill or fatigued. If the handler doesn’t feel the dog is performing properly, he or she has the right to remove the animal from service without fear of being over-ruled by a supervisor.

The ability of a dog to detect an explosive depends on several things, including the terrain, the temperature, the humidity, and the amount of air movement. On hot, humid summer days, for example, a dog can detect an explosive much easier than on a cool, crisp day. That’s because in warm conditions, more explosive molecules are evaporated – saturating the air. The major drawback of hot days, obviously, is that the dog can only work 20-30 minutes before requiring a break. Also, if the dog is searching a paved area, the blacktop can become very hot, burning the dog’s feet and nose. Heat exhaustion is a concern, which is why handlers keep water on hand for the dogs to drink and cooling vests for them to wear.

A typical car search begins with the canine team approaching the vehicle downwind. This gives the dog the best chance of detecting odors. Some handlers – like those with the Secret Service – carry a small smoke generator to help them determine wind direction and its strength, thereby characterizing the size and shape of the scent cone.

The dog is then given the command to search the vehicle. Together, the dog and handler circle the car in a counter-clockwise fashion. The handler has the dog pay close attention to the locks and any ventilation outlets. This is because some cars are so tightly sealed when the doors and windows are shut that it can be difficult for odors to escape. The driver is often asked to open the trunk, for the same reason.

A vehicle search takes about 30 seconds to accomplish. If, during the search, the dog is interested in an area but does not alert, the handler notes the location, finishes the search and brings the dog back for a recheck. If the dog alerts at any time during the search, he is immediately rewarded and the bomb squad is called in to investigate. Handlers do not handle explosives or do render safe procedures. Their sole task is to detect the presence and location of a bomb.

As for room searches, the canine team is brought in after the room has been canvassed for boobytraps. The bomb techs’ search procedure entails dividing the room vertically by height: floor to waist, waist to chin, and chin to ceiling. The technicians overlap search areas for better coverage. Only when the room is deemed free of boobytraps is the canine team allowed in.

It should be noted that dogs are not 100% accurate in their detection efforts, and should not be expected to provide that level of accuracy. In fact, most law enforcement agencies consider a dog to be efficient if it is able to correctly detect an explosive 90-95% of the time while in training. This translates into a “street-wise” proficiency of about 75-80%. Dogs are never punished for giving a false alert. In the realm of explosive devices, false positives are tolerable, whereas false negatives are not.


As America’s lead agency when it comes to explosives and post-blast investigations, the ATF has been involved with explosives-detection techniques for decades. In 1984, in a pilot program, the ATF trained the first dog to detect accelerants, chemicals used by arsonists to make a fire burn faster and more furiously. The dog, a Labrador Retriever named “Nellie,” helped establish the feasibility of this new detection system. In May, 1986, the first operational dog, “Mattie,” began training in conjunction with the Connecticut State Police and hit the field later that year in September. Since then, the ATF has trained and certified 56 accelerant detection dogs, 47 of which are working at fire and police departments and fire marshals’ offices across the country. The ATF’s National Response Teams and field offices have access to these dogs when needed.

Based on the success of this program and the fact that the ATF investigates the majority of all bombings in America, the agency used the knowledge gained from the accelerant program to create the Explosives Detection Canine Program in 1992.

An ATF “bomb dog” sits next to a containment pot which is used to safely transport bombs from a scene to a location where they can be disarmed. Note the ATF badge/shield on the dog’s collar.
Photo courtesy – ATF
This program was implemented at the request of the State Department, which needed dogs to send to foreign governments in support of their anti-terrorism efforts, as well as to protect American travelers abroad. Since 1992, 160 dogs have been trained and certified for use by 10 different countries, including Italy, Israel and Australia. All of these dogs are able to detect minute quantities of explosives, and can find firearms and ammunition hidden in luggage, in vehicles and on people, as well as buried underground.

Much of the initial canine training was done at facilities owned by the Connecticut State Police. But this changed in 1995 when the ATF entered into an agreement to share the facilities at the US Customs Canine Enforcement Training Center, a 250-acre complex located in the Blue Ridge Mountains near Front Royal, VA. The ATF is now constructing its own administration building on site – 26,000 square feet – which will house classrooms and a training area large enough to accommodate three canine training classes simultaneously.

Although there are various breeds of canines used in law enforcement, the only breed used by the ATF for explosives detection is the Labrador Retriever. That’s because the Retriever is not only hearty, intelligent, adaptable and non-aggressive, but it tends to use and rely more on its nose than any other breed. (“They conduct their lives with their nose,” says Robert Noll, an ATF explosives enforcement officer.) Retrievers also get along with strangers, which is important since ATF dogs often interact with crowds, such as at the 1996 Olympics. The dogs are acquired from Guide Dog Foundations, which raise them in family environments until they are about 14-months-old.

Bomb Sniffing Dogs – Bomb School

The ATF’s explosives training program is unlike that observed by other agencies. After examining several training programs, the ATF realized that there was no consensus on what explosives are used to train the dogs. Most programs focused on a variety of commonly used explosives, like TNT and NG dynamite, but they overlooked improvised explosives. Recent bombing attacks have used improvised explosives, such as urea nitrate at the World Trade Center and ANFO at Oklahoma City.

Recognizing that it was impossible to train a dog to detect all 19,000 known explosive compounds, the ATF managed to classify the explosives into five distinct families. From this, they identified 20 explosive odors on which to train their dogs. By using pure samples of the major explosive compounds in each chemical family, the ATF is able to have their dogs recognize any one of the 19,000 explosive mixtures.

The training method itself is based on a food reward system. Every time the dog “alerts” correctly to the presence of an explosive, he is fed. This system allows the dogs to be subjected to many training repetitions in the course of a work day by measuring out small portions of food. This can’t be done with other reward systems, such as play or praise.

During a typical training day, a dog smells an explosive odor 125 times. The dog is never fed without exposure to an explosives odor. (Even during a routine work day, the handler tests the dog with numerous explosive odors to feed it until it eats its daily ration.) This conditioning stimulus means that the dog can train and work for longer periods, and can work with any handler who feeds him. The latter is a distinct advantage over the widely used “bonded team” – a concept used by other agencies – because a dog can still be used when his normal handler is ill or unavailable.

Dogs train with their handlers for 10 weeks. During this time, the dogs train with explosives varying from 1 gram to amounts exceeding 1,000 pounds. In one training scenario, 3 grams of an explosive is placed in sterile container, which is perforated with small holes. The container serves to focus the dog’s attention on an object and to prevent accidental ingestion. It also hides the color and shape that distinguishes some compounds, thereby preventing the dog from using visual cues. The dog is rewarded with food when he alerts properly.

Moving up the scale in difficulty is the “Training Wheel,” a device consisting of four containers on a rotating wheel. One can holds the explosive while the others contain either nothing or samples with distracting odors. The dog, searching on- and off-leash, has to discern which container has the explosive. By spinning the wheel, the dog can be repeatedly tested, without the trainer having to rearrange the containers himself to present a new challenge. Furthermore, the explosive compound can be changed at any time, and more than one container on the wheel can hold different explosives or distracting samples. A dog is considered trained when he ignores a food distracter in favor of the explosive odor.

Bomb Sniffing Dogs – Test Time

At the end of training, the ATF certifies its dogs on 20 different explosive compounds in quantities ranging from 1.7 grams to 15 grams. Two of the odors used are from samples of explosives that were never taught in training. This proves that if the dogs are trained using ATF’s five families of explosives, they will be able to detect any explosive mixture made from them. “We have yet to find an explosive that these dogs can’t find,” says Noll proudly.

To be certified, a dog must pass this test with 100% accuracy on all 20 compounds. If the dog misses an explosive or makes more than two false alerts, he fails. The ATF is the only program with proficiency standards this high. The dogs are recertified annually, with the same strict standards.

The ATF’s explosives-detection program has been very successful. Over the years, its dogs have been credited with finding a bomb, missed by humans, placed on a bus. They have also found munitions buried in the desert, guns hidden in sacks of flour, and a pistol stashed away in the glove box of a locked vehicle. The dogs also found an explosive device hidden in a purse during a sweep of a courtroom.

This partial list of accomplishments alone, justifies using trained dogs in America’s counter-bomb efforts.

K-9 team searches a vehicle parked near the Capitol for hidden explosives. As the ultimate symbol of democracy and freedom, the Capitol is on every terrorist’s target list.

Bomb Sniffing Dogs – US CAPITOL POLICE

With the number of government officials working on Capitol Hill and the frequency of visiting dignitaries, it is not surprising that the US Capitol is heavily guarded against terrorist attacks. It is, after all, the ultimate symbol of democracy. In 1971, the US Capitol Police established its first canine team in response to a bombing incident in a first-floor bathroom in the Senate wing of the Capitol. The canine unit consisted of 12 dog teams, all trained for street patrol. Six of these dogs were later trained in explosive detection.

Since then, the Canine Unit has expanded to a total of 30 dog teams, all of which are capable of detecting 14 different types of explosives. Each dog team has undergone 26 weeks of intensive training at the Unit’s headquarters, which is located at the former Metropolitan Police Department’s K-9 training facility in Blue Plains. The training includes on- and off-leash obedience commands, obstacle navigation, evidence searching, tracking, building searches, criminal apprehension, and handler protection.

Nearly half the course – 12 weeks – is dedicated to explosives detection. This training is done first, before the 14-week-long street patrol training section, because the department places a priority on a dog’s ability to detect explosive compounds. If the animal is unable to detect explosives, it is removed from the program. (Explosives work is so important that the department intends to expand the training from 12 weeks to 16 weeks.)

In order to pass, the dogs must attain 100% accuracy in identifying explosive odors and 80% overall proficiency. The dogs return every month for 16 hours of remedial training.

Additionally, every Canine Explosive Search Team is required to conduct a practice search every month, using explosives provided by the department.

The Canine Unit works exclusively with male German Shepherds. They once considered using Belgian Malanois, but found them to be too vicious. Considering that the US Capitol Police interact with nearly 18,000 visitors to the Capitol every day, the department opted for the better-natured Shepherds. However, this may change in the future: The department is looking at the possibility of bringing on Labrador Retrievers to do explosives work…on an exclusive basis. The dogs have a reputation for having a great nose for explosives.

Presently, the department’s German Shepherds are acquired from public donations, animal shelters and breeders. Most of the dogs range in age from 12 to 30 months old, with 24 months being the preferred age for training. They serve for five to seven years before being retired. All dogs live with their handlers at home.

To determine whether or not a dog is a good candidate for a Canine Explosive Search Team, the instructors test the dog using a black, conical-shaped toy called a “Kong.” Several trials are conducted. For example, an instructor may step on the Kong and see how the dog responds. If he tries to dig and dislodge it, it demonstrates that the dog is inquisitive and intelligent. That’s a good sign. In another test, an instructor suddenly opens an umbrella or clangs two trash can lids together while the dog is playing with the Kong. If the dog cocks its head out of curiosity and holds his ground – instead of startling and running away – it shows that he has courage. Again, another good sign.

All the training is done at the Canine Unit’s headquarters, which features five acres of classrooms, open fields for training, an obstacle course, indoor and outdoor kennels, and storage facilities.

The selection of dog handlers is based on their past police performance, experience, physical condition, attitude and basic knowledge of dogs. A review board evaluates a potential handler for training in dogmanship. This evaluation sometimes includes interviews with the applicant’s family and neighbors.

The Canine Unit teaches its handlers to use both play and food as the dog’s reward. Hence, you’ll find a Kong in every canine scout car.

The Canine Explosive Search Teams are used to search the grounds of the US Capitol every day, as well as to conduct advance counter-bomb work for dignitaries traveling in and out of the Washington, DC area.

The dogs are assigned to do searches at permanent posts – such as the delivery area for packages coming into the Capitol or on-going dignitary protection assignments – or to do searches from mobile units on the street. In the latter situation, a dog team may search vehicles parked along the streets adjacent to the Capitol or be sent out to support an arrest. The US Capitol Police canine vehicles are designed to transport two canine teams.

The dog teams conduct some 23,000 explosive searches each year. This includes building, vehicle and suspicious package searches. Whenever suspected explosives are found, the department’s Hazardous Device Section is immediately notified. The canine teams are not authorized to disarm bombs. That task is left for the bomb technicians.


For centuries now, trained dogs have been used by the US military forces for guard and patrol duties. The training of military dogs is conducted at Lackland AFB in San Antonio, TX. The majority of the dogs are purchased in Germany and northern Europe from selected breeders. German Shepherds are usually used, and are between 12 and 36 months old when they begin their training. Shepherds are at least 23-inches high at the shoulder, weigh 60 pounds or more, are in excellent shape, and have a mildly aggressive disposition.

The basic training course the dogs participate in is broken into nine distinct phases. Early on, the handler learns the principles and techniques of reward, and how to give verbal and manual obedience commands. As the training progresses, the dog learns how to work at greater physical distances from the handler, and how to respond to gunfire. The dog is also taught to master various obstacles that it will encounter during actual situations, such as tunnels, windows and elevated catwalks.

The later training phases address more advanced topics such as patrolling methods, building searches, intruder detection, vehicle patrolling, and tracking.

Upon completion of the course, the dog is certified and then either sent to a military installation or used at Lackland AFB for training other handlers. The dogs are generally not trained as explosives detectors until the need for such an animal arises. When it does, the dog/handler teams undergo additional training, with the dogs achieving a 95% accuracy rate in detecting explosive items. The dogs are trained to detect a variety of explosives, including ammonium nitrate dynamite, nitroglycerin dynamite, C-4, TNT, water gel, det cord and smokeless powder. Navy dogs are trained on black powder, in the form of time fuse. In addition, military dogs are trained to detect two types of pharmaceuticals – potassium chlorate and sodium chlorate – and firearms that have been previously fired.

Explosive detection dogs undergo recertification every three months. The validation test are made up of trials: at least five in every substance for which the dog is trained, and never less than 20 in total.

When it comes to searching for an explosive device, the team searches in a counter-clockwise fashion, keeping as low a presentation as possible. The search is ended before the suspect item is touched or picked up by the dog. This is because many explosives are poisonous, and the bombs in which they are used are sometimes equipped with anti-movement devices.

Unlike most law enforcement agencies, military explosives detection dog teams are accompanied by a spotter when responding to a bomb threat.

A spotter is a person who is trained with the team and, hence, is as familiar with the dog’s behavior as the handler. The spotter looks ahead of the team for boobytraps and other hazards. He also describes to EOD technicians the area in which the dog alerts to an explosive. And last, the spotter monitors the clock to ensure that the dog team is not on target too long and can be safely evacuated prior to a known detonation time.

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