Westown Block Watch

there is a mean dog that lives on the s/w corner of 31 av & surrey. the gate is open most of the time and the dog is allowed to get out. it is a brown pit bull mix with no tags. i have talked to the owner and called animal control 5 times but still the dog blocks the sidewalk and growls at people. Im hoping someone has an idea on what to do about this before the dog bites someone.