The ornamental design for a horse tail protector, shown and described.
FIG. 1 is a perspective view of a horse tail protector, attached over the braided tail of a horse, showing my new design;
FIG. 2 is a right side perspective view thereof; and,
FIG. 3 is a left side perspective thereof.
The broken lines shown in FIG. 1 are for illustrative purposes only and form no part of the claimed design. It is understood that the two ribbon straps in FIG. 1 are shown in a tied position.