Dog meant he had sharper senses, he could hear and smell better, was the first to detect military presence. He knew they were coming and still he did not run.
Dog made him fast, he cut others down, eager to defend his home, yet inside he knew he was on the losing side.
Dog, that meant he was loyal by nature. When given the chance to run, he stayed, unable to abandon the creature that had rescued them. He knew it was for naught, how was he to know that Greed would not run? Loyalty drove the dog to Death.