A black, fiery hound is read as guilt or dread that follows you closely. Dream tradition also sees it as a fierce guardian of a boundary, a sign that something is protected and not meant to be crossed lightly.
Has this come up in your dreams before? What was going on in your life then?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.