Our 2 year old daughter was bitten by our dog - the wound is not bad but the skin is slightly broken. should we take her for a tetanus injection?

Depends: At least in the USA kids who follow the routine immunization schedule are well protected up to 4 years of age by that series. I would call her source of health care & see if she has received the shot ( part of the DTaP series). If so, nothing more is needed. Be sure to clean the wound well & watch for signs of infections. Regular germs can also be a problem.