Do I need to take anti rabies injection?

My pet dog regularly takes injection so that if he bites the victim wont have to take any vaccine against rabies. He takes his injections regularly! But unfortunately, the expiry of injection was on February, 2011. In this state he bit me on June 2011. Though I must say..there is no scar, or tear on my skin(I tried to find then very minutely but failed)...and blood didn't even come out! So do I have to take anti-rabies injection? Some Doctors said that the effect of the injection stays 3years from the date of inoculation...please let me know!