From our fishing rock on the edge of the lake, we could hear the whinny of the horses, hitched to fall-glorious trees on the ridge above. It was a wild sound, in a plaintive chord, and the woods seemed very quiet when it faded.

"I better go check those boys," said Dennis Diamond, who handed me his fishing rod, tugged his cowboy hat forward and began the steep climb. Diamond is very attentive to his horses, especially Trade Winds, the gray and white Arabian gelding that his wife, Cathy, rides.

"She does love that horse," Diamond once told me. "If that horse and I were in a burning building and she could only get one of us out, I think I'd start looking for the exit."

We were fishing at Rocky Gorge Reservoir, an 800-acre lake in eastern Montgomery County that would look at home in the Canadian wilderness. The lake, created by the Washington Suburban Sanitary Commission in 1953, is surrounded by woods thick enough to hide deer, pheasant and fox. Largemouth bass and northern pike live in the water. But it takes cunning, and luck, to catch them.

"There are some giant bass that usually sit right under this rock," said Diamond, looking into the water from a 40-foot cliff. "I don't see them today."

We didn't much care about the fish. Without a boat to carry us into the coves and shallows, there was not much expectation of catching more than a few sunfish and crappie. The fishing was a good excuse to ride horses along miles of serpentine trails and giddyap over rocks and mudholes.

The Diamonds pay a monthly fee to board their horses at a working farm, with cultivated fields and week-old piglets scampering under wagon wheels. Despite commercial development, new housing projects and restrictive zoning requirements, Montgomery County is still wild enough in places to provide trails for hundreds of private horse owners. They are a largely invisible subculture, middle class folks less likely to follow the horse show circuit than a path into the nearest wood.

It was late afternoon when we decided to ride back to the barn. Fred, a 12-year-old, brown quarter horse, was saddled and eager to run. But when Diamond began to tighten the cinch strap across Trade Winds' chest, the horse's legs buckled.

"Stay up, Trade Winds," said Diamond, pulling the horse's head up by the lead rope with his right hand while jerking the saddle off with his left. After a day of slow, deliberate movements, his reaction seemed electric.

"I don't know what it is, but something's wrong. A horse doesn't do that," said Diamond, who immediately began walking the horse up and down the trail. "It might be colic. God, I hope not."

Colic is one of the major horse killers. Blocked food and roughage can burst a horse's intestine. The pain can become so great a horse will run itself into walls trying to relieve it. Our main concern was to keep Trade Winds from going down here in the woods, a mile from the nearest road.

"I don't care if I have to put him on my shoulders and carry him out, this horse is not going to die," said Diamond, carrying the saddle on one shoulder and pulling the horse toward home. When Trade Winds stumbled twice within a few hundred yards, Diamond decided to find the closest phone and call a veterinarian.

There was no one home at the first house, just snarling dogs. We pulled Trade Winds another quarter-mile. Where the trail curved close to a suburban street, we found a man who interrupted his dinner to let us use the phone, then found a blanket to cover the horse.

"Don't thank me. I'm from the old school," said the samaritan, who joined our emergency team. "When people need help, you do what you can."

Cathy Diamond was the first to arrive. The 32-year-old mother of 3-year-old twins jumped out of her car with wet eyes. She had worked at an animal health lab in College Park, where she assisted at dozens of autopsies on horses who had died of colic.

"After all the good times we've had together, don't go this way, Trade Winds. Go of old age," said Diamond, who won her first horse in a name-the-pony contest at a Detroit Pistons basketball game when she was in first grade.

It was nearly dark and raining lightly when the veterinarian arrived. Dr. Ronald Buchanan had closed his office in Burtonsville to respond to the call. Now, after climbing through a barbed wire fence, he was sliding a rubber tube down one of Trade Winds' nostrils into the horse's stomach. That done, he pumped a quart of mineral oil and water into the horse and gave him a shot of muscle relaxer to relieve stomach cramps.

Diamond remained with her horse for the next 14 hours, walking him most of the night, then falling asleep beside him once the danger had passed. The next morning, she drove to a nearby McDonald's for coffee, smeared with dried blood from Trade Winds' nose bleed the night before.

"People were looking at me like I was an axe murderer," said Diamond. "I'm just glad nobody called the police."