Jen there are mixed studies on that. Some will say that its best to let them sort it out themselves, but others who think that dogs are too modernised now and it may not work. Like Kat said sometimes, rarely they keep going.

Personally when we had issues with our dogs, I noticed who was boss and encouraged that. Then we didn't have as many fights. Also I kept them apart for a week when we weren't at home and did it very slowly letting them back together.