I looked up The Hound on the wiki. Though the reader never reads his death scene, the priest that found him tells Brienne that he is dead. He knows because he buried the hound himself and left his dog helm as a marker. Of course, the priest could be lying, trying to protect The Hound.
We are told by the priest that someone must have stolen the helm from his grave and continued on a rape/murder spree down the coast. I tend to believe he's lying because The Hound, like his brother, is a huge man. Not many other men in the seven kingdoms could be mistaken for The Hound simply because he's so tall. Of course, there's also the possibility that like Cat and potentially his brother, he's now the walking dead.
I'm kinda pissed the series departed so far from the book on this one. But I guess it doesn't matter. The outcome is the same. He's left for dead but we don't know if he actually died.
