Sowing grass seed on lawn used by dogs

Hi all,

Can anyone tell me what steps i need to take to get my lawn looking good again. We've got a Rottweiler who is 18 months old now but from a puppy she used a part of the garden as a toilet and the harsh nitrogen in her urine has killed my half of my lawn. Ive not sectioned off the grass so she cannot use it anymore and im wondering if anyone can help me get the grass growing again or whether its better to buy rolls or turf?