There are many Boxers that are service dogs, police dogs, therapy dogs, I know some that work cattle, and a few (including one of my grand-pups) that herd sheep (for sport, though, not as an actual job). Most people don't have a need for a working dog these days, so the Boxer is not used as extensively for that purpose as they once were, but the ability is there and is used in many cases.
My Lilly is a Hearing Alert Dog. She has been training since she was 4 weeks old (first thing she started learning was recall). Lilly's breeder started her training and when I was blessed with her, I continued her training. She is a "golden child". She has saved my life several times.