They should have brought the dog to the grave + problem solved!
That way he would have smelled what was up. What I found stupid in this story is they show us the dog warning the master not to go to work. I was sure the train was going to crash. Dogs can smell cancer in fact they use them in hospitals to detect both cancers and death. So then the dog knows his master died. He knew before it happened. They should have brought him to the grave and just let him smell and figure it out for himself.
Anything less is dog cruelty. Joan Allen's evil face and her character's demeanor towards the dog kinda killed the movie for me. Couldn't they find someone less despicable? And no, not Marcia Cross, her evil twin, someone who can actually convey "caring". Allen's frozen face at the end got a lot of help, not from botox this time but from the cello, violin and piano.