Treating a Dog's Cut from a Harness?

I have a female chocolate Lab that had a harness on. Because we live in the city and she liked to escape out the gate with her brother. My family and I thought that maybe if we put the harness on her she would be easier to catch. About a week ago I noticed she had a deep cut under her front leg from the harness. My parents said that the other 2 dogs that live with us would help keep the wound clean and help it heal and that the vet can't really do anything due to the location of the wound. Is this true?

By HAB