Mammals
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The text on this site is published with permission of RAND and taken from "Alternatives of Landmine Detection" Jacqueline MacDonald et.al, RAND report, ISBN 0-8330-3301-8, Document Number: MR-1608-OSTP, Year: 2003
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Dogs and Rats
Description:
Mine dog detection teams have long assisted in humanitarian demining efforts. For example, more than 200 mine detection dogs currently are at work in Afghanistan. These dogs can detect mines about 95 percent of the time under favourable weather and soil moisture conditions.
Dogs have a keen sense of smell, originating from their ancestral survival needs to find food, determine territorial boundaries, and sense the presence of enemies. By offering dogs a reward of food or play, they can be trained to signal when they smell mines. In the mine detection context, dogs walk ahead of their handlers, noses to the ground, and sit at the first scent of a mine. A manual deminer then follows and investigates the area with a probe.
In another application, known as Remote Explosive Scent Tracing mode, dogs sniff at filters that have collected vapors near suspected mine locations. If a dog identifies a filter as containing explosives, then a deminer returns to the location from which the vapor was sampled to look for a mine. Currently, dogs are capable of detecting explosive vapors at concentrations lower than those measurable by the best chemical sensors, so the lower limit at which they can detect explosives is uncertain.
One recent study recognized that available laboratory chemical analytical methods are far from the sensitivity limits of the dog. Nevertheless, it attempted to determine the detection threshold for dogs by diluting soil contaminated with explosives to varying levels, two of which were 10 and 100 times lower (based on extrapolation, not detection) than the current chemical detection limit. The researchers tested the ability of three different teams of trained dogs (one from the United States, one from Angola, and another from Norway) to identify explosives in samples from the various dilutions. They found that a few of the dogs could correctly identify samples containing an estimated 10–16 g per milliliter of TNT or DNT.
However, performance varied by many orders of magnitude depending on the individual dog, how it was trained, and the manner in which the training was reinforced. Further, detection performance of the dogs used in this study also appears to have been influenced by environmental conditions associated with the testing location and procedures followed, including the inadvertent use of TNT-contaminated soil samples as “clean” controls in testing at least one group of dogs.
As an alternative to using dogs or in conjunction with using dogs, researchers at the University of Antwerp have trained African giant pouch rats to detect mines. The rats are trained using food rewards to signal the presence of explosives by scratching the ground surface with their feet. Field tests of the use of rats in mine detection have begun.
Strengths:
Canines are proven to work exceptionally well in many scenarios and under many environmental conditions. The olfactory sensitivity of some, but not all, dogs is higher than the best currently available mechanical detection methods. Advantages of using rats include the possibility that they could be deployed in large numbers and that they do not weigh enough to trigger mines, which reduces the possibility of injury.
Limitations:
Dog performance varies widely depending on the individual dog, how it was trained, and the capabilities of the handler. Further, dogs may need to be retrained periodically because they can become confused if they discover behaviors other than explosives detection that lead to a reward. An additional limitation is that when trained to detect high levels of explosives, dogs may not automatically detect much lower levels and may need to be specially trained for this purpose.
Like other methods that rely on vapor detection, performance of mine detection dogs can be confounded by environmental or weather conditions that cause explosive vapors to migrate away from the mine or that result in concentrations of vapors that are too low even for dogs to detect. Rats likely would have similar limitations.
Summary and evaluation:
Canines are proven performers and a valuable asset in demining. However, continued investigation of the sensitivity of canine olfaction and how this varies with the dog and with training is necessary to understand the factors that affect reliability. Additionally, the vapor and particle signature of the mine in the field must continue to be investigated to better understand performance potential for canines. Additional research to explore the potential for deployment of African giant pouch rats in demining also is warranted.
