Introduction to Dogs at Work
Throughout a chilly night in April 1996, more than 50 search-and-rescue team members and 6 specially trained dogs combed the New Mexico foothills of the Sangre de Cristo Mountains and the banks of the Rio Grande searching for a missing 3-year-old girl. The child, accompanied by three neighborhood dogs, had wandered away that evening from her home in Pilar, a community 17 miles south of Taos. The next morning, a search-and-rescue dog named Samson spotted the child under a tree surrounded by the three dogs, who had kept her warm all night. Samson raced back to his handler, alerted him to the find, and led him to the child.
Dogs have been helping people for thousands of years. They were first used to guard property, help people hunt, and pull sleds or carts. In more recent times, dogs have been trained to sniff out drugs, explosives, illegal food substances, and even termites; to help people who are blind, deaf, or disabled, or who have epileptic seizures; and to enrich the lives of people living in institutions or troubled by emotional or psychological problems.
What qualities make dogs work so well, and so willingly, with people at such a wide variety of tasks? And how do certain kinds of dogs pass on to their offspring specific traits—such as Newfoundlands with their love of water or border collies with their instinct to herd anything in sight? Scientists have been working to find the answers to these questions for many years. They have learned much about the ancestors of dogs and how to choose and train the best dogs for specific tasks. Then, in the 1990's, researchers began trying to determine how dogs' behavior may be coded in their genes.
How Dogs Joined Human Society
Dogs belong to the family (group of related animals) called the Canidae. The domestic dog, Canis familiaris, was the first member of the Canidae to become fully tamed from its wild state. This family also includes foxes, wolves, jackals, and coyotes. Researchers believe that dogs descended from wolves, Canis lupus, because the two species are similar in many ways. Some dogs, such as huskies and German shepherds, resemble wolves in appearance. But regardless of physical appearance, these two species have many genes in common. Moreover, dogs and wolves show similar behaviors, and both species are more social animals than the other members of the Canidae.
Paleontologists have traced the relationship between canines and people back at least 400,000 years, when the bones of wolves first began to be mingled with human bones at habitation sites. Scientists theorize that individual wolves who were the least afraid of people had begun to scavenge for food at the sites and were gradually accepted into human communities. By 11,000 to 14,000 years ago, the descendants of those wolves had begun to evolve into domestic dogs. By 3,000 to 4,000 years ago, distinct breeds began to appear. But scientists are not sure how this process occurred. They do know that a modern wolf cannot simply be taken from the wild and tamed to become as docile as a dog.
The friendliness of dogs toward human beings has always made them natural companions for people. But dogs also have other qualities that people have found extremely useful. One of those traits is an exceptional sense of smell. Lawrence J. Myers, founder of the Institute for Biological Detection Systems at Auburn University's School of Veterinary Medicine in Auburn, Alabama, investigated why dogs have a sense of smell that is so superior to that of humans. Based on research estimates that the average dog has 200 million scent receptors in its nose and the average person has 5 million, it would be logical to expect that dogs could detect smells about 40 times better than people. However, experiments Myers conducted with odors from various substances revealed that dogs can detect a scent at only one one-hundred-thousandth of the concentration required for human detection. Myers speculated that dogs may be up to 1 million times more sensitive to some odors than humans.
Besides having more scent receptors than people, dogs may also have a better sense of smell because their air-sampling processes—the mechanisms by which chemicals are moved from the air into a dog's nasal cavity and then to the scent receptors—are more efficient than people's. Furthermore, researchers speculate, the way that scent receptors relay nerve impulses to the brain may be superior in dogs.
Dogs have a sense of hearing that is also much more acute than that of humans. Scientists estimate that dogs can hear certain sounds four times farther away than a person. Moreover, a dog can turn its ears to locate the source of a sound in about six hundredths of a second.
In some ways, dogs see better than people do, too. Dogs with widely spaced eyes have more acute peripheral (side) vision than people. Dogs also have better night vision, in part because their eyes have more rods (cells that are sensitive to dim light) in their retina than people do.
Traits That Set Dogs Apart
But superior senses of smell, sight, and hearing are not exclusive to dogs. Pigs and other mammals are just as sensitive as dogs to scents, for example. In Europe, pigs have long been used to sniff out truffles—an edible fungus favored by gourmets—under several inches of soil. Yet, people do not use pigs to sniff out drugs, explosives, or forbidden foodstuffs in airports. What makes dogs more valuable in such tasks than other animals? One factor is their convenient body size. Most working dogs are medium sized, weighing about 30 to 35 kilograms (70 to 80 pounds). In comparison, the average weight of a full-grown pig is between 135 and 230 kilograms (300 and 500 pounds).
Another reason that dogs are preferred in working with people is their human-oriented behavior. Unlike most other domestic animals, dogs are very cooperative, and they allow people to take the authoritative role. Behaviorists believe dogs inherited these traits from wolves. Wolves acknowledge one pack member as dominant, and they share food, hunt together, and guard the pack's terrritory. Dogs acknowledge people as dominant, guard people's “territory”—home and property—and work willingly with them. Even in our highly industrialized society, people have found that dogs, because of their physical characteristics and eagerness to please, are valuable helpers in many tasks.
The use of dogs is growing in a number of areas. One in particular is in fields that require “sniffers.” A leading center for the training of sniffing dogs to be used by the armed forces, the Bureau of Alcohol, Tobacco and Firearms, and the Federal Aviation Administration is at Lackland Air Force Base in San Antonio. Trainers at Lackland conduct 12-week programs for bomb-sniffing and drug-sniffing dogs and their handlers. According to Walt Burghardt, a veterinary behaviorist who serves as a consultant to the program, a dog can learn to pick out a particular scent from a multitude of odors. Certified bomb-detecting dogs, for instance, can distinguish the scent of nine basic explosives even when the explosives are mixed with any of tens of thousands of other compounds.
During the training course the dogs are exposed to various substances such as cocaine (for dogs who will be used in drug-detecting) or nitroglycerine (for explosive-detecting dogs). The dogs are taught to detect the odor of the substance from up to 2 meters (6 feet) away and are rewarded with praise and a food treat for finding it. Many of the dogs chosen for the program are Labrador or Chesapeake Bay retrievers, German shepherds, and Belgian Malinois. These breeds tend to be quick learners, persistent searchers, and hardy enough to work in rugged terrain. Trainers note, however, that the qualities of an individual dog, such as its drive and eagerness to work, are usually more important than its breed. A mixed-breed dog can perform as well as—and sometimes better than—a purebred dog.
Putting Those Sensitive Noses to Good Use
One of the places where sniffer dogs were being increasingly used in the 1990's was at airports, to screen luggage for smuggled drugs and terrorist bombs. Dogs can sniff an entire baggage area or waiting room, making them much more flexible in their ability to uncover drugs or explosives than a stationary scanning machine. The importance of dogs to national security has not gone unnoticed by the federal government. In October 1996, President Bill Clinton signed the Federal Aviation Reauthorization Act, which requires the operators of the 50 largest airports in the United States to supplement existing bomb and weapons-detection facilities with dogs. Congress set aside $8.9 million for the training of more than 100 explosive-detection dog teams.
Dogs are also used at airports to find agricultural products that some travelers might bring into a country illegally. In the United States, for example, a number of such items, including many fruits, vegetables, plants, and seeds, have been banned because they often harbor diseases or insects that can infect plants and animals on American farms. Beagles are the dogs most often used for this task, carried out by the U.S. Animal and Plant Inspection Service, because of their excellent sniffing ability. And most passengers view beagles as less threatening than some other breeds of dogs.
The low-tech, but highly effective, canine nose was also being used more frequently in the 1990's by termite inspectors. Dogs, especially beagles, can be trained to detect the odor of termites and carpenter ants, among other insects. The dogs can alert human inspectors to the presence of termites and other damaging insects living in the soil around building foundations and other hard-to-inspect places.
Their keen sense of smell has long made dogs valuable for search-and-rescue work. Federal agencies and city police departments, as well as private organizations, train dogs to do such work. When the federal building in Oklahoma City was bombed in 1995, German shepherds from the Rocky Mountain Rescue Dogs helped search for victims in the rubble. Iin the search for the Pilar, New Mexico, child, it was a dog from the Los Alamos Mountain Canine Corps that found her.
What Makes A Good Search-and-rescue Dog
Just as with sniffing dogs, a dog's breed is not considered as important for search-and-rescue work as its individual temperament. Nevertheless, German shepherds, Labrador and golden retrievers—and Newfoundlands for water search-and-rescue—are among the most popular breeds. In addition to being intelligent and having a good nose, a search-and-rescue dog must be willing to master many training exercises; it must be agile and hardy, because it may need to search in wilderness areas or through rubble or snow; and it must be able to stay calm and focused in frightening or distracting situations. Perhaps most important, the dog should be eager to please its handler, so that it will persevere in searches that yield no rewards for hours or days at a time.
Some search-and-rescue dogs begin training as puppies; others are older when they enter a training program. All dogs must first pass a basic obedience course. Then they learn to find people and objects and develop agility. They climb ladders, jump hurdles, crawl through pipes, and perform other maneuvers that may be needed in an actual search.
One of the most important skills of search-and-rescue dogs is tracking or scenting. Dogs track (follow a scent on the ground) when the trail of a fugitive or lost person is visible or when clothing worn by the person being sought can be used. Many times, however, a person's tracks have already been obscured by the tracks of others, or the starting point and path the person took are unknown. Then, dogs must scent (follow a smell through the air) in order to find the individual.
Search-and-rescue dog trainers have learned that people shed about 40,000 dead skin cells, called rafts, per minute. The rafts contain bacteria and vapors unique to each individual. Wind currents carry the rafts away from people and spread them in a roughly cone-shaped volume of air. Dogs learn to detect this cone of scent and follow it. That is why dogs on a scent typically move back and forth across an area—they are staying within the boundaries of the cone as they follow it to its source.
Some police dogs are trained in search-and-rescue work, but they must master many other tasks as well. In addition to following the scent of fugitives, police dogs must protect officers from hidden threats—a task for which dogs' excellent peripheral and night vision are of great help. Often dogs can see the slight movement of a suspect in dark shadows and alert the officer in time to prevent an ambush. Police dogs can also be trained to find hidden caches of drugs.
German shepherds are one of the most popular breeds for police work because of their intelligence, strength, persistence, and eagerness to work. A police dog stays with the officer it has been paired with almost around the clock and lives with the officer's family. German shepherds, like wolves, seem to need the close social contact that living with their “pack” provides. This social bonding also benefits the officers, according to a 1997 study of California police officers conducted by one of the authors, animal behaviorist Lynette Hart of the University of California's School of Veterinary Medicine at Davis, and police officer and dog trainer Sandy Bryson of the Alpine and El Dorado County, California, Sheriff's Department. They found that officers who let their dogs sleep indoors liked their jobs and trusted their dogs more than officers who kept their dogs outside. A close relationship at home with a dog seemed to improve the working partnership.
Helping Disabled People
Very different skills are needed by dogs who work with people with disabilities. These dogs help people who are blind, deaf, or physically disabled to lead more independent lives.
The first dogs to guide blind people were trained in Germany in 1916 to help soldiers injured in World War I (1914–1918). The first guide-dog school in the United States, The Seeing Eye in Morristown, New Jersey, began training dogs in 1929. At first, German shepherds were the only dogs used for such work, but trainers later found that such dogs as golden and Labrador retrievers, and sometimes mixed breeds, make excellent guide dogs as well. It is not any particular sensory skill that makes a good guide dog, but rather the guarding behavior acquired through training and the bond the dog forms with its caretaker. The training includes teaching the dog to ignore an owner's command when it sees a danger that the blind person is unaware of.
The use of dogs to help physically disabled people dates to 1975, when Canine Companions for Independence (CCI), the first center for training these dogs, was founded in Santa Rosa, California. Service dogs for the disabled are taught to perform practical tasks, helping people with serious medical conditions such as muscular dystrophy, cerebral palsy, and spinal cord or head injuries to lead more independent lives. For this kind of work, German shepherds and Labrador and golden retrievers once again became the dog of choice.
The first dogs for people with hearing disabilities, called hearing-ear or signal dogs, were trained in 1976 by the American Humane Association in Denver, Colorado. Hearing-ear dogs learn to respond to such sounds as doorbells, telephones, or a baby's cries, and then to alert their owner. Hearing-dog programs often train adult dogs that are already in homes or dogs found in animal shelters. Dogs of many breeds, and often mixed breeds as well, make effective hearing dogs, though CCI, which began training hearing dogs in 1986, favors Welsh corgis and border collies. Signal dogs need not be large or strong, but they must be alert and quick to respond when they hear certain sounds.
Training Dogs to Help People With Disabilities
By the late 1990's, dozens of organizations had been formed to train seeing-eye dogs, signal dogs, and dogs to assist people with physical disabilities. Each group differed somewhat in its methods and standards. However, the programs generally followed the same basic sequence.
Most of the dogs in these programs begin their training as puppies, living with a volunteer “foster family.” The puppies learn basic commands, such as “sit,” “lie down,” and “stay.” And they go everywhere the family members go, to become accustomed to a variety of places and activities. When they are about 13 or 14 months old, the puppies are moved to a training school, where they learn their service skills.
Guide dogs learn to wear a harness and practice such skills as stopping at curbs and leading a blind person around obstacles. Hearing-ear dogs learn such tasks as waking their owner when the alarm clock goes off and running to the door when the doorbell rings. A signal dog must not only master tasks, as seeing-eye dogs do, but must also learn to perform the tasks without a command from its human partner. Dogs that assist the physically disabled learn about 60 to 80 specific commands, including picking things up carefully, opening and shutting doors and drawers, turning lights on and off, and pulling wheelchairs. Training programs for guide and hearing dogs take about five or six months. The training of disabled-assistance dogs takes about eight months, because these dogs need to master a greater number of tasks.
Once the guide, hearing, or disabled-assistance dog has been trained, the dog is placed with an owner based on the person's needs and on the compatability of the temperament of the dog and the new owner. Owners review and reinforce commands with their dogs regularly, so that the dogs will continue to perform specific tasks.
One intriguing trait of some dogs that help people is the dogs' ability to detect and warn their owners of an epileptic seizure before it occurs. Usually, the dog uses some uncharacteristic behavior—such as whining for a dog that never whines—to alert the person of an impending seizure. The warning gives the person with epilepsy time to sit or lie down in a safe place. No one is sure how the dogs sense that a seizure is about to occur. However, studies published by British veterinarian Andrew Edney in 1993 suggest that a dog may detect an odor that a person produces at the time that a seizure is beginning. Or, the dog may note some slight changes in the owner's behavior that neither the person nor other people present are aware of. Collies, retrievers, terriers, and mixed-breed dogs are among those that have this ability.
Researchers have found that guide, hearing, and disabled-assistance dogs benefit their owners in ways that go far beyond helping with everyday tasks. In a 1996 study by Lynette Hart and her colleagues, deaf individuals with assistance dogs reported feeling less stress and loneliness than they did before they had dogs. The owners of hearing dogs said the animals made it easier for them to meet new people. They explained that because a hearing dog makes the disability of the owner more evident to other people, social situations became less stressful for them. In other studies, psychiatrists James Lynch and Aaron Katcher at the University of Pennsylvania in Philadelphia and psychologist Erika Friedmann at the City University of New York's Brooklyn College found that interacting with a dog can actually slow people's heart rate, lessen their muscle tension, and make their breathing more regular.
Dogs themselves have been the subject of much research. In the 1980's, for example, Lynette Hart and her husband, Benjamin Hart, also an animal behaviorist at the University of California at Davis, conducted a study of canine behavior. They sought to learn how specific traits, such as aggressiveness, excitability, and sociability, may have changed in various breeds when dogs were bred for certain physical attributes or specific tasks. The Harts interviewed nearly 100 authorities—mainly dog show judges and veterinarians—and documented what dog fanciers had always claimed: dogs display an incredibly varied range of behavior.
Studying Canine Genes
Scientists now want to learn whether dogs' behavior is transmitted in their genes, and if so, how. To find out, geneticist Jasper Rine at the University of California at Berkeley and biologist Elaine Ostrander at the Fred Hutchinson Cancer Research Center in Seattle, Washington, launched the Canine Genome Initiative in 1992. The project seeks to decipher the dog genome—the sum of canine genetic material—and to relate that information to the behavior of various breeds.
Rine began by breeding dogs from two species known for several very obvious traits. He and his colleagues then began to explore which gene or genes might be responsible for the traits. Rine chose his own male border collie, Gregor, and his wife's female Newfoundland, Pepper, for the experiment. Border collies weigh about 18 kilograms (40 pounds), are work-oriented, and are passionate about herding sheep. Their behavior includes crouching, staring, and driving the sheep—or any other creatures that they may encounter. “Newfies,” on the other hand, can reach 65 to 70 kilograms (140 to 150 pounds), love water, are people-oriented, and are known for their water-rescue abilities.
Rine and his collaborators mated Gregor and Pepper, and then the seven dogs that were born to them. By early 1997, the matings had produced 23 grandpuppies of the original dogs. Each of the young dogs exhibited a different combination of identifiable traits. One dog, for example, had the intent stare of the border collie but, like a Newfoundland, also loved people. Two grandpuppies that differed in almost all behavioral and physical traits shared Pepper's love of water. Rine and his colleagues then began correlating these various characteristics with the dogs' genetic makeup to identify the gene that determines each trait. But the process is complex and time consuming, and it was expected to occupy the scientists for many years to come.
Someday, people may know enough about dogs and their genes to breed animals with the exact physical and behavioral traits they desire. However, regardless of how future dogs may look or act, it is virtually certain that they will continue to be the helpers, companions, and “best friends” to people that they have been throughout the ages.