The rule: Some Draw It Out® horse-care products can be used on open skin or open wounds when their current directions support that use. That does not make every product appropriate for every wound. Check the exact label, wound type, location, contamination, and veterinary plan first.
A superficial rub and a deep puncture are not the same problem. Seek veterinary guidance for deep, gaping, heavily contaminated, actively bleeding, infected-looking, or rapidly swelling wounds, and for wounds near an eye, joint, tendon sheath, hoof, or other high-risk structure. Tetanus status and appropriate cleaning may also matter.
If the label supports application to the area, use the directed method and keep the process clean. Do not pack product into a puncture, seal drainage, or cover a wound simply because the surrounding tissue is swollen.