The ornamental design for a dog harness, as shown and described.
FIG. 1 is a perspective view of a dog harness in use on a dog showing my new design;
FIG. 2 is a perspective view thereof;
FIG. 3 is another perspective view thereof;
FIG. 4 is a front elevational view thereof;
FIG. 5 is a rear elevational view thereof;
FIG. 6 is a left side elevational view thereof;
FIG. 7 is right side elevational view thereof;
FIG. 8 is a top plan view thereof; and,
FIG. 9 is a bottom plan view thereof.
The broken line showing of a dog and harness hardware (buckles and rings) depicts environmental subject matter only and forms no part of the claimed design. The broken line showing on the harness depicts stitching and forms no part of the claimed design.