My father had a Chesapeake Bay retriever when I was three years old. At the beach, Rusty would let me just get the bottomof my bathing trunks wet, and he would trot over to me, take a hold of the seat of the trunks, and drag me out of the water. He knew I couldn't swim, and he, on his own,
decided I needed protection, and gave it to me, no matter
how indignantly I protested, and tried to strike him.
His only reward was my Mother's grateful amusement, which I
doubt influenced his repeating the maneuver when needed.
I think his behaviour was altruistic, in that he gave up his chance to play in the water, with no expectation of
reward.