Throughout history, dogs have helped humans overcome physical handicaps. In the ancient city of Herculaneum, destroyed in the same volcanic blast that buried Pompeii in 79 AD, a fresco depicts a blind man being led by a dog. During World War I, a German doctor began training dogs to guide soldiers blinded by mustard gas. Decades later they're still helping, but their roles have expanded.

"Guide dogs led to hearing dogs, and we started to see the capacity of dogs to assist in different ways," says Darlene Sullivan, executive director of Canine Partners for Life in Cochranville, PA. Today's dogs can respond to seizures or pull wheelchairs. They can retrieve dropped or unreachable items for people who have balance problems because of Parkinson's disease or multiple sclerosis (MS). For people on the autism spectrum, dogs can be trained to stop destructive behavior such as head banging and prevent wandering.

Sarah Specht, a single parent in Lunenburg, MA, can attest to the therapeutic value of a working dog. Her son, Hunter, began having seizures after his third birthday, experiencing dozens each day and even more each night. Specht couldn't sleep for fear she'd miss a distress call. When her son was diagnosed with Doose syndrome, a rare form of epilepsy, Specht worried he'd never be able to go to school, never play outside with friends, never know independence. Then Angel arrived.

Peace of Mind

The aptly named golden retriever was bred and trained by 4 Paws for Ability, a nonprofit agency in Xenia, OH. When Hunter has a seizure, Specht says Angel barks to alert nearby adults before cuddling with "her boy" to comfort him. Because Hunter has trouble walking, Angel knows to walk slowly by his side so he can hold her vest for stability. Hunter, now 5, is in kindergarten, and Angel lies beside his desk each day. Specht can sleep at night, knowing Angel's on watch.

"Angel lets me know when Hunter needs help. I can't always see anything wrong, but Angel will wake me up when he needs oxygen," says Specht. "If it weren't for Angel, I don't know if Hunter would be here today."

There is no hard evidence that dogs can predict seizures, but they can be trained to alert others when a seizure happens or comfort someone having a seizure, says David C. Spencer, MD, FAAN, a professor of neurology with a focus in epilepsy at Oregon Health & Science University in Portland.

When Dr. Spencer's patients ask him about service dogs, he discusses the pros and cons. There is no guarantee that dogs can predict a seizure and warn people in advance, and owning a dog requires a substantial financial and emotional commitment. But animals can make a positive difference, he says. "The emotional benefits are unquestioned. We focus a lot of our discussions on whether patients need a trained service dog or if their needs would be met by a pet."

Emotional Rescue 

About six years ago, at age 62, Ron Casola got lost driving from his home to a local church. A choir singer at the church, he began forgetting lyrics. Eventually he couldn't explain what he did for a living, much less do his job—teaching people how to use highly technical equipment. He was diagnosed with early-onset Alzheimer's disease. "Losing my memory was like losing part of my identity," says Casola, now 68. "It's hard and embarrassing."

In 2011 he adopted Star, a miniature dachshund, from a breeder experienced with training dogs for emotional support. A trainer then helped Casola and Star learn to work together. Now, when Casola is in distress, Star will put his head on Casola's shoulder or chest to comfort him. "People can be really mean, not knowing I have Alzheimer's," says Casola, who lives in Universal City, TX. "Star helps me stay calm and not get upset."

The difference in Casola's demeanor when Star is nearby is noticeable. "Meg Barron, the executive director [of the San Antonio and South Texas Chapter of the Alzheimer's Association] says I'm a lot calmer and more at ease when I'm with Star," he says.

Some studies suggest Star's effect is actually physical. In a 2012 article published in Frontiers in Psychology, European researchers reviewed 69 studies on human-animal interactions. They concluded that contact with animals can trigger the release of oxytocin, the so-called "love hormone" that plays a role in intimacy and social bonding. That release can increase an individual's sense of well-being.

At the very least, dogs like Star can provide important tactile stimulation and affection, says Ruth Drew, director of Family and Information Services for the Alzheimer's Association. They can also help keep people engaged and connected. "One woman in the early stages of Alzheimer's told me her dog gave her a reason to get out of bed in the morning. She enjoyed being needed," says Drew.

Star also seems to help the people around Casola. "He takes attention away from my neurologic challenges," Casola explains. "If I walk into a crowd and get frazzled or lose my train of thought, people don't seem to be as bothered if I have Star with me. When they hear he's an emotional support dog because of Alzheimer's disease, they're much more understanding."

Using dogs to help people with Alzheimer's disease is a concept that's becoming more popular, says Barron. Tiffany Denyer, BSN, owner and founder of Wilderwood Service Dogs in Maryville, TN, who has been training dogs to assist people with Alzheimer's disease for about 10 years, agrees. The animals can alert a caregiver if a person with Alzheimer's is wandering or gently bump or block him or her from leaving. "Sometimes a little interruption of those obsessive thoughts—the urge to get out the door—is all they need to reorient themselves," she says.

Casola says he's aware that he may need Star to prevent him from wandering as his disease progresses. And if he forgets Star's name and their shared history, he knows Star will forgive him. Star's unconditional love is comforting, he says.

Research supports the emotional benefits of dogs, especially for people with Alzheimer's, says Sandra Barker, PhD, director of the Virginia Commonwealth University School of Medicine Center for Human-Animal Interaction, who has been publishing research on animal-assisted therapies since 1988.

For example, a study published in International Psycho-geriatrics in 2011 looked at whether interacting with therapy dogs in a variety of ways—talking to them, stroking, brushing, and playing with them, and taking them for short walks—would affect cognition and emotional status in people with Alzheimer's disease. The results suggested that people who interacted with dogs showed decreased anxiety and sadness and an increase in positive emotions and motor activities.

Safety Sentinels

Experts say therapeutic animals can serve as "social catalysts" for children and adults who have difficulties with social skills due to their neurologic conditions. That's something Mickey and Mark Stuart of Redmond, WA, experienced when Curly, a golden retriever/Labrador retriever mix, joined their family five years ago to help their son J.T., now 17, who has autism. Curly goes to school with J.T., where she serves as a social bridge and a conversation starter. Often a fellow student will come over at lunch and ask to pet the dog. "No one was coming up to J.T. to say hi before he had the dog," says Mark. That increased interaction has improved J.T.'s communication skills. "He's learning to pay attention when someone speaks and to answer questions when asked," says Mickey.

The Stuarts noticed other positive changes. For years, J.T. needed an adult to lie next to him in order to fall asleep. Now, with Curly beside him, he seems to fall asleep more quickly and to stay asleep longer, they say. A more worrisome habit has also been curtailed. J.T. used to run away several times a day, especially at school. "Since we got Curly, J.T.'s probably run off once a year," says Mickey. The dog even gets upset if J.T. runs during gym class.

Before Curly entered his life, J.T. required four people to hold him in place during a routine dental exam, says Mickey. Once, her son's attempts to escape knocked her into a wall. Curly's calming effect was obvious almost immediately. Less than a week after she joined their household, the Stuarts took the dog and their son to the hospital to have blood drawn. Curly sat at J.T.'s feet during the procedure. "I think we held his hand and that was it," says Mickey. "Things have only improved since then."

Research supports the Stuarts' experience. In a study published in Qualitative Health Research in December 2008, three Canadian researchers examined how service dogs affected the lives of 10 families with autistic children through observations, video recordings, and interviews. Many parents characterized the dogs as "sentinels of safety" for their child. They also said the dogs facilitated public outings and family activities, improved social skills for the children, and raised awareness of autism, according to the researchers.

Model Mutts

Rolanda Maxim Gott, MD, a specialist in developmental and behavioral disorders at Saint Louis University School of Medicine, often writes prescriptions for service animals for her patients. But with high demand and, in some cases, significant costs, not all families can get or afford one. That's why Dr. Gott has three dogs "on staff" at the Knights of Columbus Developmental and Autism Center, part of the SSM Health Cardinal Glennon Children's Hospital. One of them, a black goldendoodle named Dr. Higgins, has a resume, a business card, and his own appointment book.

When families are referred to the center, they talk to the staff about their children's behavioral problems. Typically, the children experience anxiety before a doctor visit. Some refuse to enter the office entirely; others reject physical contact, making exams and lab testing difficult. Dr. Higgins, or one of his canine colleagues, can then model the correct behavior. If, for example, the child has anxiety about a physical exam, a doctor may pretend to check the dog's vitals. If dental exams are nerve-wracking for a child, the dog sits next to the dentist's chair with a bib tied around her neck and allows staffers to brush her teeth. The child is then encouraged to mimic the observed actions.

It may require several sessions to help the child overcome the problem, says Dr. Gott. "We need to see the children frequently and have them practice at home, then come back so the dogs can facilitate the therapy."

After seeing how their children respond, many families are motivated to adopt a pet—and they soon reap other benefits, including getting exercise when the dog needs to be walked.

Pets for Parkinson's

Larry Schneider Jr., a musician in Gibbsboro, NJ, 45, was diagnosed with early-onset Parkinson's disease in 2003. After two deep brain stimulation surgeries, during which electrical leads were implanted in his brain to stimulate areas that control movement to reduce symptoms such as shaking, he is almost completely free of tremors. But he still has trouble controlling his legs, and walking, standing, and balance can be challenging.

Calamity Jane, a Great Dane who joined the family in November 2014, helps him with that. Adopted from Service Dog Project, Inc., a nonprofit organization in Ipswich, MA, that trains Great Danes to help people with mobility problems, Calamity Jane and Schneider had a shaky start.

The dog seemed uncomfortable and hesitant around Schneider initially. However, once Schneider slipped the service vest on Calamity Jane, her demeanor changed immediately. "It's as if she knew to set aside her fears and complete the tasks she was trained to do," he says. She walks on his left side when he uses his walker or scooter at whatever pace he's moving. If he freezes, a common symptom of Parkinson's disease, she gives him a nudge. She does that either by pulling on the leash or pawing at the stopped foot, explains Beth Vernaleo, PhD, associate director of research programs at the Parkinson's Disease Foundation. "People can get a bit stuck, and they need some cues to help get them moving again," she says.

Calamity Jane has helped in other ways, says Schneider's wife, Jennifer. "She gives him purpose to get up, dress, put braces on his legs, socks and shoes on his feet, and start the day," she says. Schneider agrees. "Calamity Jane is living, breathing medicine. She helps me in my daily struggle and its related complications, like depression."

Schneider's neurologist, Tsao-Wei Liang, MD, an associate professor at Sidney Kimmel Medical College at Thomas Jefferson University in Philadelphia, says Schneider is more confident and independent since Calamity Jane joined the family. Seeing his improvement has renewed Dr. Liang's interest in therapy dogs. "I recommend service animals to my patients with Parkinson's disease, but I need to do it more. There are so many patients who could benefit from this," he says, adding that he recently attended a seminar on service animals and left feeling energized.

"There's so much potential. We just have to tap it."

Heather Cianci, PT, a founding therapist at the Dan Aaron Parkinson's Rehabilitation Center at Pennsylvania Hospital in Philadelphia, who works with the Schneider family, often brings therapy animals into treatment sessions. Patients who are anxious about their tremors grow calmer if they pet an animal. In the later stages of Parkinson's disease, when people have difficulty grasping objects or are moving more slowly, she'll suggest they take a brush and groom a dog.

"For people who have had so much taken away from them by their disease, the dog provides undying love and companionship," she says. "Now they have someone to take care of. It provides them with another reason to be as safe and independent as possible."

Part of the Family

Jill Leverton, who has MS and uses a wheelchair, has had two different service dogs over the past 11 years. She had her first dog, Jewel, for nine years. Her current dog, Mina, has been with her since May 2014, and having her has required some adjustment, says the 68-year-old Napa, CA, resident. "I forgot how much you grow to know each other over a period of time," she says. "Mina is still young and gets distracted more easily than an older dog. Sometimes she sees something and it gets her attention. We have to run through her commands regularly."

Mina is trained to open and close doors and drawers, but Leverton mostly needs her to pick up dropped items. "Get" is the retrieve command, and it's the one Leverton most commonly uses. It's followed by "give" so Mina can pass over whatever Leverton needs.

"When you're always dropping things, you get tired of asking someone to pick them up," she says. "Mina does things so I don't have to ask someone else. It gives me some independence."

Another important command: "Go to Ian," Leverton's husband. "If I fall, she knows to go get him," Leverton says. "It's useful to have that one on the back burner."

Besides fetching items or opening doors, therapy and service dogs that work with people with MS can also be taught to turn on lights, pull wheelchairs, and provide support for people who feel unsteady on their feet, says Rosalind Kalb, PhD, vice president, Healthcare Information and Resources, for the National Multiple Sclerosis Society. "For people whose balance is poor, the biggest benefit is the comfort and reassurance about safety," she says. "And as with all pets, the dogs help people feel less isolated and alone."

Regina Berkovich, MD, PhD, an MS specialist and an assistant professor of clinical neurology at Keck School of Medicine of the University of Southern California, says her patients with MS who have service dogs have fewer emergency department visits, possibly because they have fewer panic attacks and fewer falls.

For Leverton, Mina has become more than a pet. "She certainly gives the comfort and support you get from a pet, and she's expected to act like a pet, but she's definitely not one," Leverton says. "She's my companion."

Canine Connections

For those interested in a service dog, experts recommend talking to your physician first. He or she may be required to write a letter in support of an application or simply confirm a diagnosis. Having family members on board is also crucial, as caring for any animal requires time and money. Once everyone is in agreement about getting a dog, it's time to look for a reputable service dog agency, says Toni Eames, president of the nonprofit International Association of Assistance Dogs Partners (IAADP), which represents people who have guide, hearing, and service dogs. Assistance Dogs International is another nonprofit advocacy group that provides accreditation to organizations that meet its standards.

It helps to do homework: Costs and wait times vary greatly between groups. Some organizations require those acquiring an animal to attend training classes in another city or state over multiple days.

These agencies are accredited by one or both organizations:

4 Paws for Ability 

• This Ohio-based nonprofit group provides service dogs for anyone with a disability, as defined by the 1990 American with Disabilities Act. There is no minimum age. The agency also provides dogs for select veterans with mobility problems or hearing loss caused by combat injuries in the most recent wars and conflicts. 4pawsforability.org ; 937-374-0385

Canine Companions for Independence 

• Founded in California in 1975, this organization has regional training centers throughout the country. It trains service dogs for adults with physical disabilities, including multiple sclerosis and cerebral palsy. cci.org; 800-572-BARK (2275)

Service Dog Project, Inc.

• This nonprofit agency in Massachusetts trains Great Danes to assist people, mainly veterans, with balance and mobility problems. servicedogproject.org; 978-356-0666

Canine Partners for Life

• In addition to companion animals and traditional service dog partners, this Pennsylvania organization also places seizure alert dogs, cardiac alert dogs, and diabetes alert dogs. k94life.org; 610-869-4902

Paws with a Cause

• This group, headquartered in Michigan, provides services to 30 states. It trains dogs to help people with physical disabilities and seizure disorders, as well as children with autism. pawswithacause.org; 800-253-7297

Kids and Canines

• This Florida organization teaches at-risk teenagers how to train service dogs, then places the animals with people with disabilities or children with autism. kidsandcanines.org; 813-558-5406

Support Dogs Inc.

• Based in St. Louis, MO, this nonprofit agency trains dogs to assist people with physical disabilities related to Parkinson's disease and multiple sclerosis. 314-997-2325

Laughing Eyes Kennels

• This New Mexico organization trains dogs to help those with psychiatric or mobility issues. It also helps individuals who want to train their personal dog as a service animal. lekennels.org; 575-354-4342

Wilderwood Service Dogs

• Based in Maryville, TN, this organization trains dogs of all breeds to help people with neurologic disorders. wilderwood.org; 865-660-0095

Going to the Dogs

Assistance animals follow rigorous training programs that prepare them for a life of service.

Training service dogs is time-consuming, but rewarding. Because there is such high demand and not all breeds are suited to this work, some organizations breed their own "family-friendly" dogs, either golden retrievers, Labradors, or those breeds mixed with standard poodles, says Kelly Camm, development director of 4 Paws for Ability, a nonprofit group in Xenia, OH. "With the great need, there's no way we could find that many qualified dogs in shelters or from rescue groups," she explains.

Training, which takes about two years, begins soon after the puppies are born, Camm says. "They're handled as soon as their eyes are open and taken out in public as soon as it's medically safe."

Training in Action

Once weaned, the puppies are farmed out to foster homes or one of five Ohio prisons where inmates are trained to teach them basic obedience. After the dogs are house-trained and learn simple commands, they are assigned to honor students at one of 12 colleges associated with the group.

"The students take dogs for a semester and work on socialization skills. They take them to class, restaurants, sporting events, shopping—any place to get them used to any kind of situation they may possibly encounter," says Camm.

After a semester at college, the dogs return to 4 Paws for advanced training, usually when they are about 9 months old. Every handler up to that point has kept track of the strengths of each dog so that 4 Paws trainers can build on those skills. "Dogs that love retrieving and picking up stuff might make good mobility dogs," for instance, Camm says.

Preparing Families to Adopt

Camm's organization, like many others, requires families that are adopting service animals to come to their facility for training. Matching dogs with families involves an intimate knowledge of the dogs' quirks and temperament, says Angie Escudero, a development associate and instructor for Canine Companions for Independence, a nonprofit organization in Medford, NY. "If, for example, a person has a neurologic disability or a slower processing speed, we might not put that person with a dog that's go-go-go all the time. We'll choose a dog that moves a little bit slower and has more patience," she says. "Other times dogs automatically gravitate toward certain people, and the matching process happens organically."

One of the challenges of a successful adoption is convincing people to believe in the dogs' abilities, says Darlene Sullivan, executive director of Canine Partners for Life in Cochranville, PA.

"In some cases, they're literally trusting their lives to the dogs," she says. "But when you take that fear out of someone's life, the world just opens up. [For people who have seizures, for example,]...if they know a seizure is coming, they can get to a safe place. A therapy dog allows for greater independence and physical security."