Headlong Pursuit on Horseback : Endurance riding: After plunging zestfully into the sport, Boyd Zontelli, 47, of Agoura has gone on to win the Tevis Cup three times.

Lost in the Sierra, ankle broken, no food or water for him and his horse, Boyd Zontelli had given up hope . . . of winning the 100-mile Tevis Cup endurance race. Now his only concern was finishing.

“I wanted to get my (finishing) buckle,” said Zontelli, a three-time winner of the Tevis Cup, endurance riding’s version of the Kentucky Derby.

Obviously, it takes a special person to excel in a tough, dangerous sport with little in the way of material rewards: “You have to be a fanatic like me,” said Zontelli, a 47-year-old real estate broker from Agoura.

A lifelong horseman, Zontelli didn’t discover endurance riding until the mid-’70s, “and it hooked me completely,” he said. “I love its simplicity--whoever gets there first is the winner--and I love going through beautiful, pristine areas you’d never see. In the Tevis, you have to plow through snowdrifts at the top of the mountains, then drop into canyons where the temperature is 120. It’s fascinating.”

Refocusing his life style, Zontelli plunged into the sport. In 1979, in his second Tevis Cup, he won in 11 hours 33 minutes, the second-fastest time ever and “the highlight of my life.” Two years later, he set the record of 10:46, “finishing with the sun still shining,” he said.

Zontelli was sitting in the living room of his house, which stands in a canyon nestled in the Santa Monica Mountains. The location of his seven-acre ranch--he boards 40 horses, 10 of them his--has been a major factor in his equestrian success.

“I have access to fabulous trails,” he said. “It’s actually better here than in Colorado or Montana, where there’s a lot of open space but where you can’t ride very far because ranchers put up fences. I can literally get on a horse here and go for 150 miles and never see a fence.”

Actually, Zontelli can ride only as far as his horse allows. Like Indy cars, endurance horses are delicate, precision machines likely to break down if conditions aren’t perfect. In races, veterinarian checkpoints are set up along the course to ensure that the animals aren’t being abused or overworked. Lame horses are disqualified.

Although riders need skill and fortitude, their most important ability may be their eye for horseflesh. Zontelli, who rode bareback as a youngster growing up in northern Minnesota, has a definite idea of what he requires in an endurance horse.

“I look for a bold attitude, an independence,” he said. “I prefer a horse that has been raised in open space and hasn’t been babied or coddled.”

When Zontelli got involved in endurance riding, he searched the country for the right horse. His travels brought him to the Rush Creek Land and Livestock Co., an old, 100,000-plus-acre ranch based in Lisco, Neb. Jokingly, the cowboys told him about a supposedly unridable horse, a big chestnut gelding running wild on the range--talk about independence.

Zontelli got in a pickup and found the horse. “The minute I saw him, he took my breath away,” Zontelli said. “I just had this feeling.”

Zontelli bought the horse, named Eaton, for $1,500. Like the other horses at Rush Creek, Eaton was an Arabian, bred not for beauty or style but for power and stamina.

Back in Agoura, Zontelli was faced with the task of riding an unridable horse. It wasn’t easy. “He fought for hours,” Zontelli said. But by using hobbles (leg restraints) and patience, Zontelli was able to get a saddle on Eaton at the end of the first day. Then they went riding into the mountains “and kept going. Once he learned to trust me, he became a fabulous, dependable horse.”

Two other horses, brothers of Eaton, also were purchased from Rush Creek. One of them, Hans, carried Zontelli to the Tevis Cup record in 1981.

Zontelli won his third Tevis Cup in 1985 but didn’t compete this year. His most eventful Tevis occurred in 1984. Early in the race--which goes from Squaw Valley, Calif., to Auburn, Calif.--Zontelli took a wrong trail and wound up lost in a deep canyon. He then broke his ankle in an accident on the way back up. Stopping at a veterinarian checkpoint, he expected to drop out of the race. Then his wife Karen and daughter Cheyenne rode in.

Karen, an experienced rider who puts on the annual Pacific Coast Ride--an endurance event--was sponsoring Cheyenne, who had turned 12 that year and became eligible to compete in the Tevis Cup with an adult riding along. But Karen’s horse came up lame at the vet check and she wasn’t allowed to continue. Despite the broken ankle, Zontelli decided not only to finish the race with his daughter but to try to ride the course as fast as possible. “I said to her, ‘Let’s see what we can do,’ ” Zontelli recalled. Hours behind, they still finished third.

On endurance rides, Zontelli travels light, wearing only jeans, T-shirt and running shoes and carrying neither water nor food. “You have to have the mind-set,” he said, “that you’re going to get hungry and thirsty but you can make it.” No matter what happens. “It’s good therapy,” Zontelli said.