In 1986, the Bureau of Alcohol, Tobacco and Firearms (BATF) conducted a feasibility study into using canines to detect accelerants used in arson fires. This study identified the unique training methodologies and protocols necessary to traine canines in accelerant detection. The first accelerant-detecting canine was trained by the Emergency Services Unit (Canine Section) of the Connecticut State Police and the BATF.

In May of 1986, after a 38-day training program, a black female Labrador Retriever named Mattie was placed in service and is considered to be the world's first certified Accelerant Detection Canine. During subsequent training, Mattie learned to detect flammable liquids in very small quantities and could detect 17 different odors. Connecticut State Police Trooper Douglas Lancelot, Mattie's handler, was continually amazed by her abilities throughout her career. On several occasions, Mattie alerted Lancelot to an onlooker, as they waited for a fire to be extinguished, who was later convicted of arson for setting the fire. Mattie was retired from active duty in 1997 after 11 years of service.

The BATF began a training program for accelerant-detecting canines for use by state and local police and fire departments in 1989. Each dog is certified by BATF through its national laboratory and requires that the canine and its handler be recertified yearly. Over 50 canines have been trained and certified by the BATF since the program began. In 1995, the BATF and U.S. Customs Service entered into an agreement where the BATF initiated and staffed a full-time training facility for both the Canine Accelerant Detection Program and Canine Explosives Detection Program at the U.S. Customs Canine Enforcement Training Center in Fort Royal, Virginia.

Various breeds can be trained in accelerant detection, but the Labrador breed appears to be the breed of choice, mostly due to their calm disposition and excellent noses. The breed is not as important as evaluating the dog's nature, ability to learn and willingness to work a fire scene. The characteristics of the dog are carefully evaluated before the dog is accepted for training.

Accelerant detecting canines are trained to give a "passive alert" when they encounter any trace of a flammable liquid. This alert consists of the dog sitting and pointing their nose at the point of strongest concentration of the accelerant detected, then looking to the handler for reward. The area is marked for evidence gathering and the dog is then rewarded with food. The dog's unique ability is reinforced daily by having to hunt for a sample placed by the handler before feeding.

Canines are able to perfrom this valuable service because their olfactory systems differ from that of a human's in three ways:

1. Odor Lock - In humans the brain decreases or eliminates the stimulus of an odor after approximately 10-15 minutes. This is true whether the odor is present for five minutes or five years. The canine olfactory system and brain "lock" onto the odor and the stimulus remains as long as the canine searches.
2. Olfactory Direction Location - The human sense of smell is conveyed to the brain by the olfactory nerve and generally is capable of only detecting whether or not an odor is present. The canine brain is able to detect which nostril has the greatest concentration of a scent. If the stronger concentration is in the left nostril, the dog knows to move to the left, and vice versa. when the concentration of the scent is equal in both nostrils, the dog knows that whatever they were searching for is right in front of them.
3. Odor Layering - When humans enter a fast food restaurant, they are usually able to smell hamburgers and fries. The canine is able to smell the meat, the pickles, the onions, the mustard and even the vinegar used to make the ketchup and the oil used in frying th French fries. This is the reason drug smugglers are unable to mask the scent of drugs with coffee grounds or other distracting scents

This tremendous sense of smell, which humans cannot duplicate or even fully comprehend, has afforded law enforcement and fire officials a valuable tool in the fight against arson fires nationwide. Arsonists using accelerants will quickly discover that these "canine detectives" are their worst enemy. Many have been arrested and convicted with evidence discovered by accelerant-detecting canines and many more will be in the future, thanks to this program pioneered by the Connecticut State Police and the Bureau of Alcohol, Tobacco and Firearms.