A dream of a strong, powerful, but unknown, friend; to be bitten by one, injury from a friend (Gypsy). Jung and Freud classify all dreams of animals or of being bitten by animals as erotic, or sex dreams.
The mastiff is the modern symbol of loyalty, gentleness and fidelity.
Depth Psychology: Your principles are too rigid. You are also too formal in your dealings with other people. Stay cool and be tolerant. See Staring, Statue.