Perhaps it’s because our furry friends have long provided us with comfort, camaraderie, and unconditional love. Cats and dogs are our unending source of kisses, cuddles, slobber, claws, and laughs. Watch as NATURE shares the stories of pet owners and their beloved animals. From a very special dog named Jerry, to a cat that saved a man’s life, Why We Love Cats and Dogs presents a portrait of some of the most powerful and remarkable connections we experience as humans—the unbreakable bonds with our pets.

Four-time Emmy Award winner, filmmaker and director Ellen Goosenberg Kent kept the 10-month production of NATURE’s Why We Love Cats and Dogs on the right track. Ellen brings a strong visual sense to the art of storytelling and was able to illuminate the dynamic human-pet relationship, revealing how dogs and cats share our emotions in many significant ways.

Update February 19, 2009: Professional dog trainer and behaviorist Sarah Wilson answers Five Good Questions on PBS Engage.

Online content for Why We Love Cats and Dogs was originally posted February 2009.

Photo by Joe Sinnot © EBC

NATURE’s two-part special Dogs That Changed the World tells the epic story of the wolf’s evolution, how “man’s best friend” changed human society and how we in turn have radically transformed dogs.

From the tiniest Chihuahua to the powerful and massive English Mastiff, modern domesticated dogs come in a bewildering array of shapes and sizes, with an equally diverse range of temperaments and behaviors. And yet, according to genetics, all dogs evolved from the savage and wild wolf — in a transformation that occurred just 15,000 years ago.

In Part One, “The Rise of the Dog,” you’ll learn about how the domestication of dogs might have taken place, including the theory of biologist Raymond Coppinger that it was the animals themselves — and human trash — that inspired the transformation. The genetic analysis of Peter Savolainen of the Royal Institute of Technology in Sweden has placed the origins of domesticated dogs — and those of the first dog — in East Asia. You’ll also discover 14 dog breeds that controversial genetic studies show are the most ancient — and the best living representatives of the ancestors to all living dogs.

Preview Part Two: Dogs by Design

Over 400 breeds of dog are recognized around the world, each unique for its personality, habits, and form. Most of these breeds exploded onto the scene over the past 150 years, spurred by the Victorian-era passion for the “dog fancy” — the selective breeding of dogs to enhance particular characteristics. By tinkering with its genetics, humans made the dog the most varied animal species on the planet — and also created a host of hereditary health problems.

Despite the plethora of new shapes and sizes, dogs have retained the instincts bred into their ancestors by thousands of years of work: the urge to herd or hunt, to dig and to guard. In Part Two, “Dogs by Design,” you’ll discover how these hard-wired behaviors help different types of dogs, from hounds to herders, excel at different tasks (and why it can sometimes be so difficult to train them to do otherwise). You’ll also learn how dogs’ finely tuned senses are serving humans and saving lives. Buy the DVD. This film premiered April 2007.

Holly and Herbie were renegade youths. Troubled and defiant, they were shuttled from home to home throughout their young lives; no family could manage their unruly conduct. But finally, each found someone who saw that beneath their mischievous veneers were two highly intelligent and gifted animals.

Holly, an 85-pound bloodhound, chewed everything in sight and by the time she was 10 months old, had been removed from six different homes. She was languishing in a shelter, with her days numbered, until professional dog trainer Larry Allen intervened. Having trained countless bloodhounds for law enforcement agencies across the United States, Allen sets out to help Holly harness her natural abilities as a tracker in the hope that one day she would become a competent police dog.

Herbie, a two-year-old bearded collie, couldn’t rein in his impish personality or his penchant for attacking livestock. His errant ways had put him at risk of being shot by a local farmer. Fortunately, sheepdog trainer Barbara Sykes sensed Herbie was more than just a marauder. In her gentle yet firm manner, she coaches him hoping to hone his skills to herd rather than bite sheep on her working farm in England.

Beginning with the initial meeting between dog and trainer, viewers follow Sykes and Allen as they apply their professional skills to transform these misfit mutts into the noble working dogs they were bred to be. As their stories unfold, we witness the powerful bond that develops between trainer and pupil.

Celebrate the beauty of a second chance with these remarkable and resilient Underdogs.

To order a copy of Underdogs, visit the NATURE Shop.

Online content for Underdogs was originally posted January 2006.

Dogs That Changed the World introduced Daisy and Tangle, dogs able to sniff out cancer cells, and Delta, a German Shepherd who can sense changes in the blood sugar levels of her young master. The talents of these special animals are matched by those of tens of thousands of remarkable canines — dogs trained to sense disease and seizures, to assist the physically and emotionally disabled, and to provide comfort, affection, and therapy to their human companions.

Medical Research

Daisy and Tangle were trained to detect the unique odor of bladder cancer cells in urine samples, but researchers have found that dogs can also nose out other forms of cancer. At the Sensory Research Institute at Florida State University in Tallahassee, scientists have trained dogs to detect the odor of skin melanomas and prostate cancer. In 2006, researchers at the Pine Street Foundation in Northern California reported that they had taught dogs to pinpoint patients with lung cancer (with 97 percent accuracy) and breast cancer (with 88 percent accuracy)-simply by sniffing their breath. The researchers are now training dogs to detect ovarian cancer.

Service Dogs

Dogs like Delta are trained to detect subtle changes in a diabetic patient’s body chemistry that occur when the levels of glucose in the blood drop too low or rise too high. Either can lead to seizures, convulsions, diabetic coma, and death. Other dogs have been trained to respond to heart attacks, and to recognize changes in the blood pressure of their owners.

Delta, a German Shepherd, can sense changes in the blood sugar levels of her young diabetic master.

Dogs known as seizure dogs (or seizure response dogs) have been trained or have learned to react when a person with epilepsy is having a seizure. These dogs might bark to notify others of the seizure, lie down next to the person to prevent them from harm, remove dangerous objects from the vicinity so the person is not harmed, or attempt to revive the person after the seizure ends if they lose consciousness. More remarkably, the companion dogs of epileptics may learn to sense an impending seizure in their owner before it happens. In a 1998 survey by researchers at the University of Florida, 10 percent of epileptic patients with companion dogs reported that their dogs seemed to know when they were going to have a seizure. Although experts aren’t sure exactly how dogs do this, it may be that they are detecting subtle changes in body chemistry or in the behavior of their owner. In some cases, these dogs have been trained to perform a particular activity — running in circles, for example-to notify their owner of what they have sensed.

The most widely used and well-known service dogs are those trained to provide assistance to blind or visually impaired people, acting as the eyes of their owner. There are also hearing dogs, trained to assist deaf people and to alert them to sounds such as smoke alarms, doorbells, and crying babies; mobility assist dogs, which pull wheelchairs and provide help to the physically impaired; and walker dogs, which help provide balance when walking to individuals suffering from movement disorders such as Parkinson’s disease and spasms. In addition, dogs have been trained to assist persons with psychiatric conditions such as bipolar disorder, post-traumatic stress disorder, autism, schizophrenia, and anxiety disorder. These dogs learn to recognize changes in their owner’s behavior or environment that indicate paranoia, panic attacks, hallucinations, or potentially harmful repetitive actions, for example, and may remind them to take medication.

Therapy Dogs

Therapy dogs provide comfort and affection and improve the general well-being of people in hospitals, nursing homes, mental institutions, retirement homes, schools, and even prisons. In addition to providing companionship, researchers are now finding that the dogs are legitimately therapeutic. For example, in a 2005 study by the American Heart Association of hospitalized heart failure patients, researchers found that a 12-minute visit with a therapy dog reduced blood pressure and levels of stress hormones, and eased anxiety. Therapy dogs have been shown to improve the focus and memory of patients with Alzheimer’s, encourage speech and simple physical activities among stroke victims and individuals with impaired mobility.

Many organizations now test and provide accreditation to therapy dogs. The dogs must meet rigorous standards of temperament and obedience; they have to be accepting toward friendly strangers, sit and stay on command, be able to walk through a crowd with wheelchairs, and not startle easily.