The ornamental design of a horse-boot upper, as shown and described.
FIG. 1 is a perspective view of a horse-boot upper showing my design, showing the retaining flap in closed position;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a left-side elevational view thereof;
FIG. 4 is a right-side elevational view thereof;
FIG. 5 is a rear elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is another rear elevational view thereof showing the retaining flap in open position.
The dash-dot broken line showing the sole of the horse-boot on the drawing disclosure is for illustrative purposes only and forms no part of the claimed design. The broken lines on the upper part of the horse-boot represent stiches.