Attach one end of a sturdy rope or strap to the trunk latch and the other end to a fixed point within the trunk, such as a cargo hook or handle. Then, loop a carabiner through the rope or strap ...

When your rope starts to fray ... you can simply tie a figure 8 knot into one end and attach a locking carabiner to the loop, where it will then clip onto your dogs harness or collar.