308 Pounds

As I recall, that's the equivalent of 22 stone as mentioned in this article (via Megan McArdle) about an English family, their dog, and an unlucky would-be thief.

.....the dog's owner heard a 'scream, a roar and a commotion' from the back garden.

George Watson, 43, had been having a bath and ran outside in his towel, to see the thief zooming off down the driveway in his van.

Apart from a very agitated dog, the only evidence the man left behind was the torn Tshirt.

We had a St. Bernard-Black lab mix when I was in high school. He weighed about 180 pounds or so, and stayed in shape by dragging around 20 feet of 1/4-inch-link tow chain, eventually wearing a nice 8-inch-deep arc in the yard. We had to use that when he was outside because he snapped standard dog chain whenever he felt like it. For the first few years I was the only one of the kids big enough to even hang onto him when he got loose, and that only happened after he'd gone on a merry jog around town and decided to let me catch him.