I've only had a dream about this like twice. But I remember when I had a dream with a black dog with red eyes, which was in a far corner just staring at me while I was hanging out with a couple of friends. No one noticed the dog except for me. It just sat there. ahh this probably doesn't mean anything, but could it?
i don't think it really means anything. usually a black dog with red eyes is known as a "hell hound". you are just probably having nightmares.
Until I was nine, I would see three black dogs with red eyes in nearly every nightmare I had. (Nearly every night) After every nightmare when I woke up, every single bad dream, I could hear them laughing. They eventually went away, and I stopped having nightmares altogether. Recently I looked into the whole black dog thing, and the results that were most accurate to what I saw involved demons. I'm not really the sort to believe in that kind of thing, and if it was only one dream, I wouldn't think much of it.