When the man in "To Build a Fire" fails to save himself with a fire, he lunges for the dog. What are his intentions?

His intent is to kill the dog and bury hmself within the dogs body for warmth.

The sight of the dog put a wild idea into his head. He remembered the tale of the man, caught in a blizzard, who killed a steer and crawled inside the carcass, and so was saved. He would kill the dog and bury his hands in the warm body until the numbness went out of them.