1 yr old daughter stepped on a thumb tact last dtap vaccine 7 months ago should we go to dr to get her tetanus shot?

No : Not necessary if up to date with tdap so far but wound itself should be looked at by dr.

6 month interval: You want and need a minimum 6 month interval for that 4th dtap. So if she was 7 months for the 3rd, if it is more than 6 months, she needs to get that 4th one now. If its not 6 months, she will be fine with what she has. Keep area clean and monitor for signs of infection.

Tetanus updates: Great question. Dtap shot schedule shows 4 vaccinations by 18 months. If she is 12 months old now and her last one was at age 5, she might have only had 2 instead of the usual 3 by 6 months of age. You can review your shot record and if she had her three shots already she should be fine before the 4th one given between 15-18 months. A visit to her doctor would not be wasted and is advised.