Pet Toothbrush

FIG. 1 is a front, left, top perspective view of a pet toothbrush, showing my new design; FIG. 2 is a rear, right, bottom perspective view thereof; FIG. 3 is a front elevational view thereof; FIG. 4 is a rear elevational view thereof; FIG. 5 is a left side view thereof; FIG. 6 is a right side view thereof; FIG. 7 is a top plan view of the enlarged scale thereof; FIG. 8 is a bottom plan view of the enlarged scale thereof; FIG. 9 is an enlarged view of detail 9 in FIG. 1 ; FIG. 10 is an enlarged view of detail 10 in FIG. 2 ; FIG. 11 is an enlarged view of detail 11 in FIG. 3 ; and, FIG. 12 is an enlarged view of detail 12 in FIG. 5 . The dashed broken lines in the figures are for the purposes of illustrating portions of the pet toothbrush and form no part of the claimed design. The dash-dot-dash broken lines are for notating enlarged views and form no part of the claimed design.