Is it normal to have violent dreams?

Now, this isn't all that frequent, perhaps it only occurs once every couple of weeks, but when it does, I am very disturbed. I occasionally have very graphic dreams that normally involve a lot of blood and gore. As far as I can remember, I am never creating the violence, I am only an observer. What bothers me is that sometimes my emotions during the dreams are apathetic. I will be witnessing a person covered in lacerations whose leg snaps off while they are walking (for no apparent reason), and I will be completely indifferent. Once I walked into a darkly lit, random kitchen where a young, dark-skinned man had just cut up an old, fat, white man. The old man was in at least 20 pieces on the kitchen table, with blood everywhere. His heart was out, still beating. His face was cut off clean, and laid out flat on the table. It was so vivid...it freaks me out to recall it. The most emotion I felt during the dream was discomfort. Only after I woke up did I feel fear. I didn't recognize either man. I can't figure out what the symbolism is.
There are exceptions where I do feel fear. I once had a dream where I was in a strange house and there was a man in there with a knife. He killed a white rabbit. I can vividly remember the vibrant, red blood stains on the white fur. I knew the man would soon come after me, so I hid in a bed under a blanket, holding my breath, trying not to make noise. It seemed like a lot of time passed in my dream while I hid and waited. The man eventually found me, however, and I remember him pressing the knife to my skin, on my side. It seemed he wanted to elicit my fear first, to make me scream and squirm under the knife. I can't remember what happened after that.
Another dream I've had with emotion was when I witnessed my dog die by getting crushed under a tree. Again, there was a lot of blood, and I saw her mangled body in vivid detail. Obviously, I was very upset to see this.
When I'm not having violent dreams, my dreams are normally very detailed, yet they consist of mundane, everyday events, like a conversation. What puzzles me the most is normally these boring dreams involve very deep emotions, especially sadness. Something small and seemingly insignificant will happen, but to me it will be the worst thing in the world. I cry very, very often in these dreams. It just bothers me that I can have these dreams and be so upset, but when I have a dream that normally would be very disturbing I can feel nothing. Maybe in the violent dreams without emotion I am normally detached from the characters.