Why does a doctor administer Tetanus antitexia & not Tetanus raceine to a child injured road side accident with a bleeding wound??

I think, you mean antitoxin by antitexia and vaccine by raceine, If so, here is the answer for your question:-

The bacterium, Clostridium tetani is responsible for causing tetanus and is found in soil. When a person falls down  & his wound comes in contact with the soil, there are high chances that the bacteria may enter the body. In such conditions the doctor administer an antitoxin. The antitoxin provides immediate relief to the person by killing the bacteria. A vaccine on the other hand is administered  as a preventory measure. An antitoxin also helps when the person has not been administered with a vaccine before.  Also, multiple doses of vaccination are necessary for effective prevention while a single dosage of antitoxin is usually administered.