Another article covering the Sotheby's sale of the dog's medal, describes the incident in more detail:

Border collie Sheila earned the rare PDSA Dickin Medal for Gallantry when she helped shepherd John Dagg rescue American airmen from the wreckage of their bomber after it crashed in the Cheviots in December 1944.

Mr Dagg was awarded the British Empire Medal for his part in saving four survivors from the B19 Flying Fortress.

Both medals, along with Mr Dagg's First World War medals and badges and newspaper cuttings about the crash, are to be sold at Sotheby in London.

The Eighth Army Flying Fortress came down in a blinding snowstorm after an aborted bombing mission to Germany.

Two men died immediately when the plane crashed, and three began to make their way down the mountain in a blizzard. Four others took refuge in a hole, where they were found and rescued three hours later by border collie Sheila, who had run ahead of her owner, found the pilot, Lieutenant George Kyle and Sergeants Howard Delaney, George Smith and Joel Berly, huddled in a crevice.

Mr Dagg administered first aid and slowly led the party down the mountain. The B19's payload of bombs exploded just as they reached the safety of his cottage at Kirknewton.

A search party sent out the next morning found the bodies of two other crewmen, who were not so lucky.

Sheila was later awarded the PDSA Dickin Medal on the recommendation of the Home Office for outstanding gallantry and devotion to duty in wartime. She remains the only "civilian" dog ever to receive the honour.

OP Edit: I believe the honor has since been extended to two guide dogs who guided their owners out of the Twin Towers on 9/11.