Adapted from War Dogs: Tales of Canine Heroism, History and Love, by Rebecca Frankel. Published by Palgrave Macmillan Trade © 2014. Excerpted with permission from the publisher. All Rights Reserved.

It’s not known, not really, when the first dog took the battlefield to wage war alongside his human companions. Historians believe that millennia ago, the ancient Egyptians used canines to carry messages. The Corinthians surrounded their seashore citadel with guard dogs in 400 BC, and the Romans employed them to raise alarms for their garrisons. The feared invasion forces of Attila the Hun brought ferocious hounds with them to protect their camps during battle.

The United States, historically, has been woefully behind in adopting dogs into its military ranks, not doing so officially until 1942 with the Army’s Dogs for Defense program. So crucial were these animals during World War II that the US canine ranks swelled to over 10,000 dogs strong. In Vietnam, scout dogs were so successful at thwarting the ambush tactics of the Vietcong that bounties exceeding $20,000 were placed on their heads while only half as much was promised for their human handlers. In recent years, working outside the wire in Iraq and Afghanistan, military dogs have become the single greatest advantage allied forces have against the signature weapon of the post-9/11 era—the improvised explosive device, or IED. Try though the military has to outdo them with technology and electronic machinery, nothing has been more effective at uncovering these unpredictably lethal roadside bombs than a handler and his detection dog.


If you know what to listen for, the sound is unmistakable. The attuned human ear can hear when a dog has found the sought-after odor usually long before he gives his final alert. And depending on the training and the kind of detection work, the dog will either sit at the source of odor or lie down to the ground. For obvious reasons, search-and-rescue dogs will bark. A practiced handler will recognize his dog’s personal tells—the dog may twitch his ears or his movements may slow down and become more deliberate, or he may even have an “I’m definitely on odor” expression—but it’s really the sound that is the big giveaway. It’s the deep, staccato inhale and then the rush of a perfunctory and heavy exhale. It is the sound of satisfaction. It is the sound of discovery.

The canine nose is a masterful creation; all earthly schnozes are not created equal, anatomically speaking. While the average dog has roughly 220 million scent receptors in his nasal cavity, the average human has around 5 million. The canine sense of smell is a thousand times more sensitive than a human’s. One of the best visual analogies of the dog’s acute sense of smell is given by author Mark Derr in Dog’s Best Friend: “Unfolded and flattened, the smell receptors from the average dog’s nose could cover it like a second coat with hair dragging on the ground.”

Even the way a canine nose functions is more developed than ours. A dog’s nose has four passages, two inner ones and two on the outside, almost like gills. The inner canals pull in the scent and then exhale to the outer, so that the exhaling air doesn’t disturb the ground or source of the next odor, allowing always for the intake of fresh scent. Humans, in contrast, have just the two nasal passages, and what goes up comes back out again the same way. (We can of course draw breath through our mouths when we ingest or exhale oxygen, but it is not the best way to smell, although it is one of the best ways to use our sense of taste for certain foods—by orthonasal, or mouth, breathing. On the other hand, while dogs are great perpetrators of mouth breathing, they’re not using it for scent. Though they have good reason to do so. Dogs actually pant through their mouths to cool off, whereas we humans sweat.) That always-damp and cool-to-the-touch quality of the canine nose also has its purpose; moisture that is “secreted by mucous glands in the nasal cavity captures and dissolves molecules in the air and brings them into contact with specialized olfactory epithelium inside the nose.”

It’s not that we humans don’t use our sense of smell, but as a sense it’s powerful for very different reasons. Scent recalls memories and awakens our emotional subconscious. We associate different odors, good and bad, with people and places—and there’s no accounting for taste in what we relish either. My father, for example, loves the smell of a good barn populated with fragrant livestock. As a family driving the New England interstates, we inevitably passed open pasture, and as we did, my father would lower his window to get his fill of the open air heavy with manure, while my sister and I groaned and pinched our noses. He was taking in the scent of his childhood on the farm and all the memories that came with it—we children of the suburbs were just smelling, well, shit.

Most people don’t make a conscious effort to imprint particular or special smells, to file them away for later use—they register more like background noise, though invariably certain things punch through the ether, people and places we are reminded of by the power of scent. But perhaps we should take our lead from dogs and program our brains to catalogue smells in more proactive and useful ways. In one of the great old Disney movies, The Parent Trap (with Hayley Mills and Maureen O’Hara), when one of the girls—Susan, pretending to be her twin sister, Sharon—meets her grandfather for the first time, she sniffs the lapel of his jacket with such earnest investigation that he pulls back. “My dear, what are you doing?” he asks. To which she replies, “Making a memory.” She puts her nose back to his tweedy chest, calling out the scents she identifies. “When I’m quite grown-up,” she tells him, “I will always remember my grandfather and how he smelled of tobacco and peppermint.”

Making a memory of a smell, or imprinting odor, is exactly how a dog learns to seek out bombs, weapons caches, narcotics, missing persons, and, sadly, human remains. The process involves training a dog to associate odors with a reward. Dogs become visibly excited when they’ve discovered an odor they have been trained to detect. The less disciplined ones will cast their heads back, looking, waiting, and watching for the Kong (or tennis ball, or treat) they know is coming, too eager to contain themselves.

In this age of modern warfare and police work, dogs are trained to detect homemade explosives. These bombs are potluck-style concoctions, and while the recipes vary greatly, the ingredients are basically the same.

So each dog is trained on—or should be trained on—a handful of key bomb-making ingredients. This catalog of explosive scents includes TNT, smokeless powder, potassium chlorate, C-4 plastic explosive, detonating cord, and ammonium nitrate. And in order for military trained detection dogs to become certified, military regulations require that they meet a very high accuracy rate—explosive-detection dogs must hit 95 percent accuracy, and drug dogs must meet 90 percent accuracy. The key to this kind of training is repetition and reinforcement. Maintaining proficiency at such a high rate requires a minimum of four hours of explosive-detection training a week.7 Whether or not this rate of accuracy also takes place in the arena of combat has not been proven and may be impossible to quantify.8 This is at least in part due to the fact that there really is no way to assess how many bombs or bomb materials go undetected—unless, of course, they go off after a dog team has cleared an area. Whereas in a controlled environment, when planted materials are used in training, their hiding spots marked and known, those finds can be quantified and qualified.

A dog hunting for scent is like a linguist who, even when standing before the Tower of Babel (or more practically speaking, an international airport), can hear not only a cacophony of many tongues clamoring at once, but who can pull apart the sounds to find and comprehend the individual voices.