The ornamental design for a horse-boot upper, as shown and described.
FIG. 1 is a perspective view of a horse-boot upper showing my design with 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 blank portion contained within the dash-dot lines in the center area of FIGS. 1 and 6 forms no part of the claimed design. 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 stitches.