I once got a 7 yr old german shepard bitch given that had been a gurad dog all her life and had never been on a lead, she was a total nightmre to lead train i ended up buying a halti it goes round the dogs head a bit like muzzle but the lead clips to the bottom of it and when they pull it pulls around there mouth it worked a treat within about 1 week i had her walking to heal without pulling then i just swapped the lead over to her collar but kept the halti on for a few weeks job sorted