The ornamental design for a therapeutic horsescrim, as shown and described.
FIG. 1 is a perspective view of the therapeutic horse scrim showing my new design;
FIG. 2 is a rear elevation view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a right elevation thereof;
FIG. 5 is a left elevation thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
Broken lines are included for depicting environmental subject matter and form no part of the claimed design. The crisscross pattern of lines in the drawings represent mesh material that is understood to be distributed uniformly over the surface of the therapeutic horse scrim.