From outside the fenced ring, the tiny girl looks motionless atop the broad, slightly curved back of the horse - a brown-and-white bay with dark, fluttering eyes. The child's body, soft and slumped forward, is supported by an adult who sits behind her, grasping her waist and encouraging her to straighten her back.
"Lift your head up," coos the instructor as they clop slowly around the ring. "Good girl."
From a distance, the toddler - who suffers from cerebral palsy - looks too small for the big, ambling horse. And she looks as if she's asleep. It's not until the horse comes to a stop that the reason for the ride becomes apparent.
"Did you have fun, Brianna?" asks her mother, Dana Costello, who first heard about therapeutic horseback riding in Anne Arundel County last year.
"More!" shouts the 3-year-old, laughing.
For Costello, the response is yet another sign that for her daughter, who has difficulty controlling the muscles in her upper body, horseback riding is a help.
"She's only been out here a few times, and I already notice a difference," says Costello, a Baltimore County resident. "Her abdominal muscles are getting stronger, and she's reaching for her toys - which she couldn't do a few weeks ago."
Founded by Annapolis resident Naomi Parry in 1996, Maryland Therapeutic Riding - located on Arden Farms, a sprawling, 10-acre property in Crownsville - is one of more than 700 equine programs across the country that help disabled people overcome challenges through riding and contact with horses.
There are more than a dozen such programs in Maryland, according to the North American Riding for the Handicapped Association.
At Maryland Therapeutic Riding, Parry and 20 NARA-certified instructors work with people who have a wide range of disabilities, including cerebral palsy, spina bifida, autism and attention-deficit disorder.
To those who fear horses and the injuries that can result from riding, healing through horses might sound suspect. But practitioners of therapeutic riding argue that there's nothing like the steady, rhythmic gait of a horse to stimulate human back, leg, hip and abdominal muscles.
Experts also say the connection between horse and human - a relationship that horse-lovers have long tried to articulate - is what makes therapeutic riding so effective for some people with disabilities.
"That bond is just amazing," said Parry. "It's like the horse provides some people with a safe relationship. They can relate to the horse better than [to] humans - they are such gentle animals."
Studies by the American Hippotherapy Association have shown that riding improves muscle tone, balance, posture and emotional well-being in people with disabilities -especially children with motor-control conditions such as cerebral palsy. Even the warmth of a horse's body is said to help riders with spastic muscles, relaxing their limbs and causing them to feel safe and comfortable.
"Equine therapy is a budding field," said Bethany Lee, an occupational therapist on the board of the American Hippotherapy Association. "As the research builds, more people will begin to take a better look at it as an option. From my own experience, I hardly ever see a patient for whom it's not effective."
Parry agreed: "Horses help ground people that are otherwise agitated, frustrated or can't communicate - people whose lives are difficult." "These people stand face to face with a horse and this serenity takes over."
Parry began riding at age 17, a year after a devastating car accident left her unable to participate in most sports. On a whim, she signed up for a cross-country horseback riding class while attending Westchester University in Pennsylvania. After a few classes, Parry said, she was hooked.
"I have not been away from horses since that day," she said.
Since Parry founded Maryland Therapeutic Riding, the nonprofit organization has attracted more than 90 riders a session, each of which ranges from five to eight weeks and costs about $360. (The classes are covered by some insurance companies.)
Parry said she and her instructors witness such significant improvements in their riders that they often are moved to tears.
There's the story of a 3-year-old who, after five weeks of riding, broke into her first, wobbly run at the sight of her horse. And a 5-year-old suffering from selective mutism spoke in public for the first time on the back of her horse, whispering "walk on" into his ear.
"It's the magic of a horse," said instructor Kerrie Mansfield. "Everything about them is healing. I've seen riders who won't even look people in the eye come in and look for their horse and their friends in the ring."
Randi Cowart of Baltimore County said her 6-year-old son, Tyler - who is autistic - talks often about Teddy, the snow-white horse he rides once a week at Maryland Therapeutic. Since her son began riding, Cowart said she has noticed marked progress in his physical strength.
"His balance and coordination have improved so much," she said. "He also just loves his horse."
Parry says the horses at Maryland Therapeutic are recruited for their unusually calm demeanor.
"They have to be absolutely bomb-proof," she said, adding that her horses remain unruffled when riders make loud noises or jerking motions.
On a recent afternoon, volunteers at Maryland Therapeutic pushed 13-year-old Jay Finnegan up a ramp in his wheelchair to greet his horse. After unbuckling the numerous straps on his chair, the volunteers picked him up and boosted him onto the horse.
Jay can't walk, and has difficulty communicating. He occasionally writhes with what looks like discomfort. But from the moment he was lifted onto his horse and the pair began to walk slowly into the muddy ring, a distinct smile broke across the boy's face.
"Good job, Jay," the instructors called out, walking by his side to secure his place on the horse's back. "Way to go."