By Ceylan Yeginsu

New York Times News Service

DUMBARTON, Scotland — “I was sure she was dead,” Lottie Mackinnon said quietly.

Mackinnon was sitting huddled in the corner of a cafe with her two children, sipping hot chocolate as she described the day three years ago when she was walking with her border collie, Bonnie, over the Overtoun Bridge in Dumbarton, Scotland.

“Something overcame Bonnie as soon as we approached the bridge,” Mackinnon said. “At first, she froze, but then, she became possessed by a strange energy and ran and jumped right off the parapet.”

A bewitched dog lured to leap off a bridge by a malevolent force? It sounds like a preposterous scene from an old “Twilight Zone” episode.

But Mackinnon’s dog is one of hundreds that Scots insist have suddenly been compelled to throw themselves off the gothic stone structure since the 1950s. Many have ended up dead on the jagged rocks in the deep valley bed below.

Residents of Dumbarton, which is northwest of Glasgow, began calling Overtoun, a century-old bridge that stretches across a 50-foot gorge, the “dog suicide bridge.”

Mackinnon, who grew up in the neighboring village of Milton, winced at the memory of scurrying down the gorge through the trees and the bushes in a desperate hunt for Bonnie. But when she approached the dog’s body, Bonnie started to whimper and eventually tried to stand up.

“It was a miracle that she survived,” she said.

In a land rife with superstitions, myths and monsters — Scotland is the land of the Loch Ness legend, after all — the bridge has been at the center of an enduring mystery. Why do so many dogs jump?

Local researchers estimate more than 300 have sailed off the bridge; tabloid reports say it’s 600. At least 50 dogs are said to have died.

Some say there are rational explanations involving the terrain and the scents of mammals in the gorge.

Other explanations take on a more paranormal tone.

The bridge’s location, hushed, lush and still, fits the description of what the pagan Celts called a “thin place,” a mesmerizing spot where heaven and Earth overlap.

The leaps inspired an episode of the American TV series “The Unexplained Files.” A book is dedicated to exploring the phenomenon.

But despite all this attention, the mystery lives on, unsolved.

From a distance, it seems as if the Victorian bridge, built in 1895, is a mere extension of the driveway of an adjoining 19th-century manor built in Dumbarton by a wealthy industrialist, James White.

In the manor nearby, the current tenant, Bob Hill, said he and his wife had seen several dogs suddenly dive off the bridge since they moved into the property, now called Overtoun House, more than 17 years ago.

But Hill, a pastor from Texas who runs a center for women in crisis, had an earthbound explanation: The smell of animals scurrying around in the gorge below the bridge drives the dogs into a frenzy, then they break free of leashes and jump.

“The dogs catch the scent of mink, pine martens or some other mammal, and then they will jump up on the wall of the bridge,” Hill said.

Paul Owens, a teacher of philosophy in Glasgow, grew up in a town close to the bridge and published a book about the mystery.

“After 11 years of research, I’m convinced it’s a ghost that is behind all of this,” he declared, while sitting outside a pub in Glasgow.

Owens’ theory is popular among residents, who grew up hearing stories about the “White Lady of Overtoun,” known as the grieving widow of John White, James’ son.

“The lady lived alone in grief for more than 30 years after her husband died in 1908,” said Marion Murray, a Dumbarton resident. “Her ghost has been lurking around here since. She’s been sighted walking around the grounds.”