Hero Dog Saves Another Dog in White Water Rapids
This video from Argentina shows a dog that slipped and fell into some river rapids while it was trying to get a stick. Then another dog grabs the other end of the stick as it's going by, and pulls the first dog up onto a rock.
The guy says they play there all the time though and the dog wasn't actually in any danger. It looks like the other dog was really just trying to get the stick, not save his friend.