The dog is sometimes called "man's best friend." A dog is also a creature of lower intelligence than man. Putting these things together, I believe that dreaming of your pet dog can symbolize issues with your physical body. Our bodies are our "best friends," in that they are our vehicles for going through life, but they are also part of our "lower nature," so to speak.
My hunch is that your dream is saying that you should start taking better care of your body-- eating right, getting enough sleep, exercising, yada yada yada...
I might be wrong, though. Does this seem to fit? If not, we'll try a different interpretation.
