welcome to health care magic
In your query you have said that your son was scratched by a pet dog,cleaned the wound and applied antiseptic good..
i will ask you one thing that your pet dog was vaccinated for rabies
or not..if your pet dog is vaccinated no problem..
If not observe the dog for 11 days..if it is healthy then no problem..If your dog becomes crazy,,mad enough biting every one,,then you need to vaccinate your child with a full course on days 0 3 7 14 28 .
Instead of waiting and observing your pet dog,you may give vaccine
for your child according to the schedule...
Mean while vaccinate your dog at veterinary hospital for anti rabies..
Regarding the triple antigen given to your baby,,it is irrespective or rabies status..you should vaccinate for anti rabies..
no food restrictions..you can feed him what ever he usually eat..
Hope you understand my suggestion..