The mad dog represents the anger and frustration you are suffering from. You should also expect some hardships while dealing with your business, because there are people who wish to make damage to you or your family. If you are able to run away from this mad dog, no worries, because you will overcome all the obstacles. If someone else have killed the dog that was attacking you, you will receive some support.
Read more about dreaming of Mad dog in other dream meanings interpretations.