At least you kept it to get it tested. We didn't and then decided later to have the whole family get the shots as a precaution...not fun.
My Wife had to go through that--a Dog bit her in Mexico and then disappeared. She was not allowed out of the Country until she had 2 of the shots and then signed a contract to get the last to in the US.
They were not as bad as the 20 in the stomach but bad enough!