11yr old son got bitten by a friends dog on his thumb last night. the wound is open, but not enough to warrant stitches. does he need a tetanus shot of the dog has had all its vaccinations?

Maybe: Any break in the skin can allow tetanus spores to enter & set up the process that triggers tetanus. If he had the primary series as a young kid & no booster it would be reasonable. Dog bites are more likely to introduce other bacteria for an infection & proper cleaning/local care may avoid any complication. The rest is your call. If you get a booster now you get 10 yrs from it also.