Brian Lewis/The Gazette Rider Elizabeth Shaffer, 15, of Potomac, rides her mother's horse, Fritz, through a series of obstacles intended to desensitize horses to distractions common during trail rides while Anne Boccia (right) assists at a horse training clinic Sunday.

Manders said she remembers when a ride through her community meant traveling down Darnestown Road past open fields toward the horizon. Now, she must detour around housing developments and dodge obstacles as basic as a trash bag blowing across a path, both of which can startle her horse. A leisurely ride can sometimes turn dangerous when her horse is overwhelmed by unfamiliar elements, she said.

"If a horse doesn't recognize something, it can really hit the panic button," said Manders, who grew up in Potomac.

So Manders joined about 20 equestrians at a Sunday clinic sponsored by Potomac Bridle and Hiking Trails Association on desensitizing horses to distractions commonly encountered on suburban and urban trails.

Held at Potomac Horse Center on Quince Orchard Road, the clinic encouraged riders and their horses to participate in drills led by Frederick-based Pelicano Equine Training. Instructor Rick Pelicano used a variety of techniques to ease horses into unfamiliar situations and teach riders how to control their horses.

A spooked horse can be a danger. Horses have tunnel vision, and do not think of their surroundings when a threat is in front of them, so a startled horse in an urban area could leap into traffic or trample people nearby, Pelicano said.

Sunday's training session started with exercises to train horses to walk in a straight path while ignoring unrecognizable objects. In one exercise, horses walked past a bicycle covered by a blue tarp, an object commonly found propped against backyard fences. An inquisitive or fearful horse might turn its body to face the foreign object, a hazard in narrow areas where horses could fall off elevated ground.

Some horses had more difficulty as the obstacle course expanded. To accustom horses to unsure footing, large mats were laid on the ground. Some horses perceived the differences in color between the mats and ground as a whole, prompting them to jump over the mats or avoid them altogether. Jumps in inappropriate places can be hazardous, so riders instead attempted to guide their horses over the mats.

Other objects, such as rubber balls and inner tubes, placed in the horses' paths made some horses hesitant to walk through the horse center's cluttered aisles.

Foreign sounds, an obstacle commonly encountered on trails that pass through neighborhoods, can also strike fear in a horse. Pelicano fired blanks from a 38-caliber handgun four times and turned on a motorized grass trimmer, sounds intended to mimic backfiring cars and other loud automobile noises, to see how the horses reacted.

The horses jumped in response, while the most aggravated grunted and skittered around the riding ring.

While a horse cannot be trained to understand every environment or be desensitized to every possible distraction, Pelicano said a well-trained horse could be taught generally how to react to new elements.

"Once you acclimate [your] horse to ride through a city environment, it's not a big deal when they see something new," Pelicano said.

The temperaments of horses also depend on their breeds. Fore example, thoroughbreds and Arabian horses are often more highly strung than draft horses or typical working horses, Pelicano said.

Bobbi Frost, a association member and equestrian for more than 30 years, said she has learned to be cautious when riding her horse on trails past homes and along streets. Children's play sets with swaying swings or balloons tied to mail boxes often startle her horse. Cyclists and hikers sometimes cause alarm also, she said.

"There is a lot more of everything around the area now," Frost said.

Congestion prompted Nancy Shaffer of Potomac to move her horses from Potomac Horse Center to a farm in Boyds a few years ago.

"There is more open space there," Shaffer said. "[Here] you have to contend with [all-terrain vehicles], cars and motorbikes."

But other Potomac equestrians, such as Manders, said they plan to continue working to acclimate themselves and their horses to the changing community. Manders, who watched the class while another association member rode her horse, Tucker, said she would tailor her riding schedule to avoid rush-hour traffic and travel less-frequented areas.

Change may be inevitable, but she said she believes Potomac will find a way to preserve its equestrian culture.