I once sat a reactive dog, larger pittish mix. And I would have walked the dog and such but the HO was very controlling. Had a list of hand and arm commands she expected me to learn and use for a week long sit. I walked the dog once in the neighborhood but saw 2 other dogs, which I managed to stay away from and managed the dog but the owner freaked when she learned there were 2 other dogs on the street when I walked it. It was not big on fetch. Trying to get it to exercise was an issue. I tried, and I have sat a number of reactive dogs. I had an excellent sit in Atlanta with a large reactive dog, in an apartment so we had to get out. The HO was amazed that I took it to the park every day, which was a hike. And I had to manage the dog when sometimes a small dog, off leash would run up. But that is different than a dog that bites an owner in the face.