Its the law here in Florida as well...they have to have the rabies shot by 4 mos...I have a 18 week old Harley, he is 3.5 lbs and he just got his rabies 1/22/11...He was a little sore in the injection area that day and slept most of the day but the next morning he was back to his playful self and getting into trouble again
I try not to worry to much I knew it was normal but I did take his temp every few hours just to be on the safe side and to help the soreness I massage it lightly every few hours as well.