Overtoun Bridge

The Overtoun Bridge is an arch bridge located near Milton, Dumbarton, Scotland, over the Overtoun Burn. It has gained public attention because of the unusually large number of dogs that have allegedly leaped to their deaths over a number of decades. It is not known exactly when or why dogs began to leap from the bridge, but studies indicate that these deaths might have begun during the 1950s or 1960s, at the rate of about one dog a month.

The long leap from the bridge onto the waterfalls of the Overtoun Estate almost always results in immediate death. Inexplicably, some dogs have actually survived, recuperated, and then returned to the site to jump again. These dogs are known to the locals of Dumbarton as "second timers." The dogs have mostly jumped from one side of the bridge, during clear weather, and have mostly been breeds with long noses.

The phenomenon has received international attention, and the Scottish Society for the Prevention of Cruelty to Animals has sent representatives to investigate. No abnormality or explanation has yet been found.

From: http://en.wikipedia.org/wiki/Overtoun_Bridge#Overtoun_bridge_dog_deaths