Our fights were always in the house and sometimes we never did know what started it as you cannot watch them every second. They also got on fine for a few months at a time, then boom, it would start all over again.
One of the worst fights (and last I might add) happened in one of their crates! The AB was in hers and for some reason our Grey went in there with her. My husband was by himself (I was at home in the UK at the time) and he had a hell of a time trying to break it up. He had a couple of bites but nothing serious thank goodness. After another trip to the vet and us talking it over, he called the Greyhound rescue where we got her and she was rehomed immediately. I did get to see her a couple of times after and we kept in touch with her new owners and still are actually. Dog fights are horrible things, really distressing for all concerned.